阅读说明：本技术 磨粒 (Abrasive grain ) 是由 劳拉·M·拉拉·罗德里格斯 德怀特·D·埃里克森 查尼卡·江古 阿梅莉亚·W·柯尼希 于 2018-06-12 设计创作，主要内容包括：本发明提供了成形陶瓷磨粒,其包含多种陶瓷氧化物。所述颗粒还包含多种第一氧化物、多种第二氧化物或它们的混合物。所述多种第一氧化物包括钇、镨、钐、镱、钕、镧、钆、镝、铒的氧化物、或它们的组合。所述多种第二氧化物包括铁、镁、锌、硅、钴、镍、锆、铪、铬、铈、钛的氧化物、或它们的组合。所述成形陶瓷磨粒还包括多个边,每个边具有独立地在约0.1μm至约5000μm范围内的长度。所述成形陶瓷磨粒还包括由至少两个所述边的交叉点限定的顶端,所述顶端可具有约0.5μm至约80μm范围内的曲率半径。(The present invention provides shaped ceramic abrasive particles comprising a plurality of ceramic oxides. The particles further comprise a plurality of first oxides, a plurality of second oxides, or mixtures thereof. The plurality of first oxides include oxides of yttrium, praseodymium, samarium, ytterbium, neodymium, lanthanum, gadolinium, dysprosium, erbium, or combinations thereof. The plurality of second oxides include oxides of iron, magnesium, zinc, silicon, cobalt, nickel, zirconium, hafnium, chromium, cerium, titanium, or combinations thereof. The shaped ceramic abrasive particles further comprise a plurality of edges, each edge independently having a length in a range from about 0.1 μm to about 5000 μm. The shaped ceramic abrasive particles further comprise an apex defined by an intersection of at least two of the sides, the apex can have a radius of curvature in a range from about 0.5 μm to about 80 μm.)

1. A shaped ceramic abrasive particle comprising:

a plurality of ceramic oxides;

a plurality of first oxides, a plurality of second oxides, or mixtures thereof, wherein

The plurality of first oxides include oxides of yttrium, praseodymium, samarium, ytterbium, neodymium, lanthanum, gadolinium, dysprosium, erbium, or combinations thereof, and

the plurality of second oxides comprise oxides of iron, magnesium, zinc, silicon, cobalt, nickel, zirconium, hafnium, chromium, cerium, titanium, or combinations thereof;

a plurality of sides, each side having a length independently in a range of about 0.1 μm to about 5000 μm; and

an apex defined by an intersection of at least two of the sides, the apex having a radius of curvature in a range from about 0.5 μm to about 80 μm.

2. The shaped ceramic abrasive particles of claim 1, wherein the ceramic oxide independently comprises a fused alumina material, a heat treated alumina material, a sintered alumina material, a silicon carbide material, titanium diboride, boron carbide, tungsten carbide, titanium carbide, cubic boron nitride, garnet, fused alumina-zirconia, ceria, zirconia, titania, or mixtures thereof.

3. The shaped ceramic abrasive particles of any one of claims 1 or 2, wherein the plurality of first oxides ranges from about 0.01 wt% to about 70 wt% of the abrasive particle.

4. The shaped ceramic abrasive particles of any one of claims 1-3, wherein the plurality of second oxides ranges from about 0.01 wt% to about 15 wt% of the abrasive particles.

5. The shaped ceramic abrasive particles of any one of claims 1-4, wherein the plurality of second oxides comprises magnesium oxide.

6. The shaped ceramic abrasive particles of claim 5, wherein the magnesium oxide ranges from about 0.1 wt% to about 10 wt% of the abrasive particles.

7. The shaped ceramic abrasive particles of any one of claims 1-6, wherein the plurality of second oxides comprises iron oxide.

8. The shaped ceramic abrasive particles of any one of claims 1-7, wherein the plurality of second oxides comprises MgO and Fe₂O₃。

9. The shaped ceramic abrasive particles of any one of claims 1-8, wherein the individual ceramic oxides independently range from about 0.05 μ ι η to about 1 μ ι η in length.

10. The shaped ceramic abrasive particles of any one of claims 1-9, wherein the body of the shaped ceramic abrasive particles is tetrahedral and comprises four faces joined by six sides terminating in four vertices, each of the four faces contacting the other three of the four faces.

11. A method of making shaped ceramic abrasive particles, the method comprising:

molding a dispersion comprising ceramic particles or precursors thereof, a plurality of first oxides, a plurality of second oxides, or mixtures thereof, wherein

The plurality of first oxides include oxides of yttrium, praseodymium, samarium, ytterbium, neodymium, lanthanum, gadolinium, dysprosium, erbium, or combinations thereof, and

the plurality of second oxides comprise oxides of iron, magnesium, zinc, silicon, cobalt, nickel, zirconium, hafnium, chromium, cerium, titanium, or combinations thereof;

drying the molded dispersion to form a solid; and

the solid is calcined to form particles.

12. The method of claim 11, further comprising introducing a seed iron oxide to the dispersion.

13. The method of any one of claims 11 or 12, further comprising adding an oxide of magnesium to the solid.

14. The method of claim 13, wherein the oxide of magnesium is added to the solid after calcining the particles.

15. The method of any one of claims 11-14, further comprising sintering the particles.

16. An abrasive article comprising a plurality of ceramic oxides, the ceramic oxides independently comprising:

a plurality of first oxides, a plurality of second oxides, or mixtures thereof, wherein

The plurality of first oxides include oxides of yttrium, praseodymium, samarium, ytterbium, neodymium, lanthanum, gadolinium, dysprosium, erbium, or combinations thereof, and

the plurality of second oxides comprise oxides of iron, magnesium, zinc, silicon, cobalt, nickel, zirconium, hafnium, chromium, cerium, titanium, or combinations thereof;

a plurality of sides, each side having a length independently in a range of about 0.1 μm to about 5000 μm, an

An apex defined by an intersection of at least two of the sides, the apex having a radius of curvature in a range from about 0.5 μm to about 80 μm.

17. The abrasive article of claim 16 wherein the abrasive particles are selected from the group consisting of nonwoven abrasive articles, structured abrasive articles, coated abrasive articles, and bonded abrasive articles.

18. A method of using the abrasive article of any one of claims 16 or 17, the method comprising:

contacting the abrasive article with a substrate; and

moving at least one of the abrasive articles relative to the substrate, and moving the substrate relative to the abrasive article.

19. The method of claim 18, wherein the movement of the abrasive article and the substrate is lateral or rotational.

20. The method of any one of claims 18 or 19, wherein the substrate is selected from the group consisting of a lacquer, a primer, a plastic, and combinations thereof.

Background

Abrasive particles and abrasive articles made from abrasive particles are useful for abrading, finishing or grinding a variety of materials and surfaces during the manufacture of products. Accordingly, there is a continuing need for improved cost, performance, or life of abrasive particles or articles.

Disclosure of Invention

The present disclosure provides a shaped ceramic abrasive particle.

The shaped ceramic abrasive particles comprise a plurality of ceramic oxides. The particles further comprise a plurality of first oxides, a plurality of second oxides, or mixtures thereof. The plurality of first oxides include oxides of yttrium, praseodymium, samarium, ytterbium, neodymium, lanthanum, gadolinium, dysprosium, erbium, or combinations thereof. The plurality of second oxides include oxides of iron, magnesium, zinc, silicon, cobalt, nickel, zirconium, hafnium, chromium, cerium, titanium, or combinations thereof. The shaped ceramic abrasive particles further comprise a plurality of edges, each edge having a length independently ranging from about 0.1 μm to about 5000 μm. The shaped ceramic abrasive particles further comprise a tip defined by an intersection of at least two sides, the tip may have a radius of curvature in a range from about 0.5 μm to about 80 μm.

The present disclosure also provides a method of making shaped ceramic abrasive particles. The shaped ceramic abrasive particles comprise a plurality of ceramic oxides. The particles further comprise a plurality of first oxides, a plurality of second oxides, or mixtures thereof. The plurality of first oxides include oxides of yttrium, praseodymium, samarium, ytterbium, neodymium, lanthanum, gadolinium, dysprosium, erbium, or combinations thereof. The plurality of second oxides include oxides of iron, magnesium, zinc, silicon, cobalt, nickel, zirconium, hafnium, chromium, cerium, titanium, or combinations thereof. The shaped ceramic abrasive particles further comprise a plurality of edges, each edge having a length independently ranging from about 0.1 μm to about 5000 μm. The shaped ceramic abrasive particles further comprise a tip defined by an intersection of at least two sides, the tip may have a radius of curvature in a range from about 0.5 μm to about 80 μm. The method includes molding a dispersion including ceramic particles or precursors thereof, a plurality of first oxides, and at least one of a plurality of second oxides. The molded dispersion can be dried to form a solid and calcined to form particles.

The present disclosure also provides a coated abrasive article. The coated abrasive article includes a backing defining a surface in the x-y direction. The coated abrasive article includes an abrasive layer comprising shaped ceramic abrasive particles attached to a backing via a make coat. The shaped ceramic abrasive particles comprise a plurality of ceramic oxides. The particles further comprise a plurality of first oxides, a plurality of second oxides, or mixtures thereof. The plurality of first oxides include oxides of yttrium, praseodymium, samarium, ytterbium, neodymium, lanthanum, gadolinium, dysprosium, erbium, or combinations thereof. The plurality of second oxides include oxides of iron, magnesium, zinc, silicon, cobalt, nickel, zirconium, hafnium, chromium, cerium, titanium, or combinations thereof. The shaped ceramic abrasive particles further comprise a plurality of edges, each edge having a length independently ranging from about 0.1 μm to about 5000 μm. The shaped ceramic abrasive particles further comprise a tip defined by an intersection of at least two sides, the tip may have a radius of curvature in a range from about 0.5 μm to about 80 μm.

The present disclosure also provides a bonded abrasive article. The bonded abrasive article includes a first major surface and an opposing second major surface, each of the major surfaces contacting a circumferential side. A central axis extends through the first and second major surfaces. The bonded abrasive article includes a layer comprising shaped ceramic abrasive particles. The shaped ceramic abrasive particles are dispersed within a binder material. The shaped ceramic abrasive particles comprise a plurality of ceramic oxides. The particles further comprise a plurality of first oxides, a plurality of second oxides, or mixtures thereof. The plurality of first oxides include oxides of yttrium, praseodymium, samarium, ytterbium, neodymium, lanthanum, gadolinium, dysprosium, erbium, or combinations thereof. The plurality of second oxides include oxides of iron, magnesium, zinc, silicon, cobalt, nickel, zirconium, hafnium, chromium, cerium, titanium, or combinations thereof. The shaped ceramic abrasive particles further comprise a plurality of edges, each edge having a length independently ranging from about 0.1 μm to about 5000 μm. The shaped ceramic abrasive particles further comprise a tip defined by an intersection of at least two sides, the tip may have a radius of curvature in a range from about 0.5 μm to about 80 μm.

The present disclosure also provides a method of using a coated abrasive article or a bonded abrasive article each comprising shaped ceramic abrasive particles comprising a plurality of ceramic oxides. The shaped ceramic abrasive particles comprise a plurality of ceramic oxides. The particles further comprise a plurality of first oxides, a plurality of second oxides, or mixtures thereof. The plurality of first oxides include oxides of yttrium, praseodymium, samarium, ytterbium, neodymium, lanthanum, gadolinium, dysprosium, erbium, or combinations thereof. The plurality of second oxides include oxides of iron, magnesium, zinc, silicon, cobalt, nickel, zirconium, hafnium, chromium, cerium, titanium, or combinations thereof. The shaped ceramic abrasive particles further comprise a plurality of edges, each edge having a length independently ranging from about 0.1 μm to about 5000 μm. The shaped ceramic abrasive particles further comprise a tip defined by an intersection of at least two sides, the tip may have a radius of curvature in a range from about 0.5 μm to about 80 μm.

The method includes contacting the coated abrasive article or the bonded abrasive article with a substrate. Moving at least one of the coated abrasive article or the bonded abrasive article relative to the substrate, or moving the substrate relative to the coated abrasive article or the bonded abrasive article.

The shaped ceramic abrasive particles and abrasive articles of the present disclosure provide several benefits, at least some of which are unexpected. For example, according to some embodiments, the radius of curvature of the tips of the particles is maintained for a greater number of cycles during abrasion of the workpiece than a corresponding shaped abrasive particle that does not contain at least one of the first plurality of oxides and the second plurality of oxides. According to some embodiments, the abrasive particles have a porosity that is less than a corresponding shaped abrasive particle that does not contain at least one of the first plurality of oxides and the second plurality of oxides. According to some embodiments, lower porosity may result in tougher shaped ceramic abrasive particles. In some embodiments, the length of the ceramic oxide is less than the length of a ceramic oxide of a corresponding shaped abrasive particle that does not contain at least one of the first plurality of oxides and the second plurality of oxides.

In some embodiments, shaped ceramic abrasive particles having a particle size along the major dimension of about 0.01 μm to about 200 μm or less exhibit less cracking than corresponding shaped abrasive particles that are free of at least one of the plurality of first oxides and the plurality of second oxides.

Drawings

In the drawings, which are not necessarily drawn to scale, like reference numerals describe substantially similar components throughout the several views. Like reference numerals with different letter suffixes represent different examples of substantially similar components. The drawings illustrate generally, by way of example, but not by way of limitation, various embodiments discussed in this document.

Fig. 1A-1D are schematic illustrations of shaped ceramic abrasive particles having a planar triangular shape according to various embodiments.

Fig. 2A-2E are schematic illustrations of shaped ceramic abrasive particles having a tetrahedral shape according to various embodiments.

Fig. 3 is a cross-sectional view of a coated abrasive article according to various embodiments.

Fig. 4 is a cross-sectional view of a bonded abrasive article according to various embodiments.

Fig. 5 is a photograph of abrasive particles SAP1 according to various embodiments.

Fig. 6 is a photograph of abrasive particles SAP8 according to various embodiments.

Fig. 7 is a photograph of abrasive particles SAP9 according to various embodiments.

Detailed Description

Reference will now be made in detail to specific embodiments of the presently disclosed subject matter, examples of which are illustrated in the accompanying drawings. While the presently disclosed subject matter will be described in conjunction with the recited claims, it will be understood that the exemplary subject matter is not intended to limit the claims to the disclosed subject matter.

Throughout this document, values expressed in a range format should be interpreted in a flexible manner to include not only the numerical values explicitly recited as the limits of the range, but also to include all the individual numerical values or sub-ranges encompassed within that range as if each numerical value and sub-range is explicitly recited. For example, a range of "about 0.1% to about 5%" or "about 0.1% to 5%" should be interpreted to include not only about 0.1% to about 5%, but also include individual values (e.g., 1%, 2%, 3%, and 4%) and sub-ranges (e.g., 0.1% to 0.5%, 1.1% to 2.2%, 3.3% to 4.4%) within the indicated range. Unless otherwise indicated, the expression "about X to Y" has the same meaning as "about X to about Y". Likewise, unless otherwise indicated, the expression "about X, Y or about Z" has the same meaning as "about X, about Y, or about Z".

In this document, the terms "a", "an" or "the" are used to include one or more than one unless the context clearly indicates otherwise. The term "or" is used to refer to a non-exclusive "or" unless otherwise indicated. The expression "at least one of a and B" has the same meaning as "A, B or a and B". Also, it is to be understood that the phraseology or terminology employed herein, and not otherwise defined, is for the purpose of description only and not of limitation. Any use of section headings is intended to aid in the reading of the document and should not be construed as limiting; information related to a section header may appear within or outside of that particular section.

In the methods described herein, various actions may be performed in any order, except when a time or sequence of operations is explicitly recited, without departing from the principles of the invention. Further, the acts specified may occur concurrently unless the express claim language implies that they occur separately. For example, the claimed act of performing X and the claimed act of performing Y may be performed simultaneously in a single operation, and the resulting process would fall within the literal scope of the claimed process.

As used herein, the term "about" can allow for a degree of variability in a value or range, e.g., within 10%, within 5%, or within 1% of the stated value or limit of the range, and includes the exact stated value or range.

The term "substantially" as used herein refers to a majority or majority, such as at least about 50%, 60%, 70%, 80%, 90%, 95%, 96%, 97%, 98%, 99%, 99.5%, 99.9%, 99.99%, or at least about 99.999% or more, or 100%.

As used herein, the term "shaped ceramic abrasive particles" refers to abrasive particles having at least a portion of the abrasive particle with a predetermined shape that is replicated from a mold cavity. Except in the case of abrasive shards, the shaped ceramic abrasive particles will typically have a predetermined geometry that substantially replicates the mold cavity used to form the shaped ceramic abrasive particles. As used herein, "shaped ceramic abrasive particles" does not include abrasive particles obtained by a mechanical crushing operation.

With respect to the three-dimensional shape of the shaped ceramic abrasive particles according to the present disclosure, the term "length" shall mean the largest particle dimension. The longest dimension may refer to, for example, a side length or a body length. Width shall mean the largest particle dimension perpendicular to the length. The thickness referred to herein is also generally perpendicular to the length and width. The particle size may be a weight average particle size or a number average particle size.

The term "thickness" when applied to a shaped ceramic abrasive particle having a thickness that varies with its planar configuration shall mean the maximum thickness. If the particles have a substantially uniform thickness, the minimum, maximum, average, and median values of the thickness should be substantially equal. For example, in the case of a triangle, if the thickness is equal to "a", the length of the shortest side of the triangle may be at least "1.5 a" or "2 a". The above relationship is maintained for particles in which two or more of the shortest face dimensions are of equal length. In most cases, the shaped ceramic abrasive particles are polygonal having at least three sides, each side having a length greater than the thickness of the particle. In the particular case of a circle, an ellipse, or a polygon with very short sides, the diameter of the circle, the smallest diameter of the ellipse, or the diameter of a circle that can circumscribe around the polygon with very short sides is considered the shortest face dimension of the particle.

Abrasive grain

To further illustrate, in the case of tetrahedrally shaped ceramic abrasive particles, the length will correspond to the side length of one triangular edge, the width will be the dimension between the apex of one triangular edge and a perpendicular to the opposing side edge, and the thickness will correspond to the so-called "height of the tetrahedron", i.e., the dimension between the apex and a perpendicular to the base (or first side).

The shaped ceramic abrasive particles of the present disclosure each have a substantially precisely shaped three-dimensional shape. The shape of the shaped ceramic abrasive particles, for example, substantially replicates the shape of the mold cavity used to form the shaped ceramic abrasive particles.

In some examples, the shaped ceramic abrasive particles can be characterized as thin bodies. The term "thin body" is used herein to distinguish from elongated or filamentous particles (e.g., a grinding rod) in which one particle dimension (length, longest particle dimension) is substantially larger than each of the other two particle dimensions (width and thickness), as opposed to the particles disclosed herein, in which three particle dimensions (length, width and thickness as defined herein) are of the same order of magnitude, or two particle dimensions (length and width) are substantially larger than the remaining particle dimensions (thickness). Conventional filamentary abrasive particles can be characterized by an aspect ratio, i.e., a ratio of length (longest particle dimension) to largest cross-sectional dimension (largest cross-sectional dimension perpendicular to length) of about 1:1 to about 50:1, about 2:1 to about 50:1, or about 5:1 to about 25: 1. Further, such conventional filamentous abrasive particles are characterized by a cross-sectional shape that does not vary along the length (the shape of a cross-section taken perpendicular to the length or longest dimension of the particle). In contrast, shaped ceramic abrasive particles according to the present disclosure can be characterized by a cross-sectional shape that varies along the length of the particle. The variation may be based on the size of the cross-sectional shape or the form of the cross-sectional shape.

The shaped abrasive particles typically each include at least a first side and a second side separated by a thickness t. The first side generally includes a first face (which may be planar or non-planar) having a perimeter of a first geometry. In some examples, the thickness t is equal to or less than the length of the shortest side-related dimension of the particle (shortest dimensions of the first and second sides of the particle; the length of the shortest side-related dimension of the particle may also be referred to herein as the length of the shortest face dimension of the particle).

In some examples, the second side includes a top end at a thickness t from the first side, or the second side includes a ridge at a thickness t from the first side, or the second side includes a second face at a thickness t from the first side. For example, the second side can include an apex and at least one sidewall connecting the apex to the perimeter of the first face (illustrative examples include pyramidal particles, such as tetrahedral particles). Alternatively, the second side may include a ridge line and at least one sidewall connecting the ridge line to the perimeter of the first face (illustrative examples include roof-shaped particles). Alternatively, the second side surface may include a second face and at least one sidewall (which may be an inclined sidewall) connecting the second face with the first face (illustrative examples include triangular prisms or truncated pyramids).

The thickness t may be the same (e.g., in embodiments where the first and second sides comprise parallel planes) or vary with the planar configuration of the particle (e.g., in embodiments where one or both of the first and second sides comprise a non-planar surface, or in embodiments where the second side comprises an apex or ridgeline, as discussed in more detail later herein). The size of the thickness of the particles is not particularly limited. For example, the thickness can be about 5 μm to about 4mm, 10 μm to about 3mm, about 25 μm to about 1600 μm, about 30 μm to about 1200 μm, or about 200 μm to about 500 μm.

In some examples, the ratio of the length of the shortest side-related dimension of the shaped ceramic abrasive particles to the thickness of the shaped ceramic abrasive particles can be in a range of about 1:1 to about 10:1, about 2:1 to about 8:1, about 3:1 to about 6:1, or less than, equal to, or greater than about 1:1, 2:1, 3:1, 4:1, 5:1, 6:1, 7:1, 8:1, 9:1, or 10: 1. This ratio may also be referred to as the principal aspect ratio.

The shaped ceramic abrasive particles can be selected to have a length (e.g., side length) in a range from 0.1 μm to 5000 μm, from about 1 μm to about 200 μm, or from about 150 μm to about 180 μm, or can be less than, equal to, or greater than about 0.1 μm, 0.5 μm, 1 μm, 5 μm, 10 μm, 15 μm, 20 μm, 25 μm, 30 μm, 35 μm, 40 μm, 45 μm, 50 μm, 100 μm, 150 μm, 200 μm, 250 μm, 300 μm, 350 μm, 400 μm, 450 μm, 500 μm, 550 μm, 600 μm, 650 μm, 700 μm, 750 μm, 800 μm, 850 μm, 900 μm, 950 μm, 1000 μm, 1100 μm, 1150 μm, 1200 μm, 1250 μm, 1300 μm, 1600 μm, 1450 μm, 1700 μm, 1550 μm, 1850 μm, 1900 μm, 1950 μm, 20002050 μm, 2100 μm, 2150 μm, 2200 μm, 2250 μm, 2300 μm, 2350 μm, 2400 μm, 2450 μm, 2500 μm, 2550 μm, 2600 μm, 2650 μm, 2700 μm, 2750 μm, 2800 μm, 2850 μm, 2900 μm, 2950 μm, 3000 μm, 3050 μm, 3100 μm, 3150 μm, 3200 μm, 3250 μm, 3300 μm, 3350 μm, 3400 μm, 3450 μm, 3500 μm, 3550 μm, 3600 μm, 3650 μm, 3700 μm, 3750 μm, 3800 μm, 3850 μm, 3900 μm, 3950 μm, 4000 μm, 4050 μm, 4100 μm, 43050 μm, 4200 μm, 42050 μm, 4950 μm, 4750 μm, 45050 μm, 4750 μm, or 45050 μm. In some embodiments, the length may be expressed as a portion of the thickness of the bonded abrasive article comprising the abrasive particles. For example, the shaped ceramic abrasive particles can have a length greater than half the thickness of the bonded abrasive wheel. In some embodiments, the length may be greater than the thickness of the bonded abrasive wheel. The shaped ceramic abrasive particles are selected to have a width in the range of 0.001mm to 26mm, 0.1mm to 10mm, or 0.5mm to 5mm, although other sizes may also be used.

The shaped ceramic abrasive particles can have various volumetric aspect ratios. The volumetric aspect ratio is defined as the ratio of the largest cross-sectional area through the centroid of the volume divided by the smallest cross-sectional area through the centroid. In various examples of the present disclosure, the volumetric aspect ratio of the shaped ceramic abrasive particles may range from about 1.15 to about 10.0, from about 1.20 to about 5.0, from about 1.30 to about 3.0, or less than, equal to, or greater than about 1.15, 1.20, 1.30, 2, 2.5, 3, 3.5, 4, 4.5, 5, 5.5, 6, 6.5, 7, 7.5, 8, 8.5, 9, 9.5, or 10.

For some shapes, the maximum or minimum cross-section may be a plane that is tilted, angled, or skewed relative to the outer geometry of the shape. For example, the volumetric aspect ratio of a sphere would be 1.000 and the volumetric aspect ratio of a cube would be 1.414. The volumetric aspect ratio of a shaped ceramic abrasive particle in the form of an equilateral triangle with each side equal to length a and uniform thickness equal to a would be 1.54, while if the uniform thickness is reduced to 0.25A, the volumetric aspect ratio is increased to 2.64.

The abrasive particles can be in the shape of thin three-dimensional bodies having various three-dimensional shapes. Suitable examples include particles (e.g. thin bodies) in the form of: flat triangles and flat rectangles having at least one or both faces that are inwardly shaped (e.g., concave or concave).

The first side generally includes a first face having a perimeter of a first geometry. For example, the first geometry may be selected from geometries having at least one apex, two or more, or three or more, at most, or three or four apices. Suitable examples of geometries having at least one apex include polygons (including equilateral, equiangular, star-shaped, regular, and irregular polygons), lens shapes, half-moon shapes, circular shapes, semi-circular shapes, elliptical shapes, circular sectors, circular segments, drop shapes, and hypocycloids (e.g., superellipses). Specific examples of suitable polygonal geometries include triangular shapes and quadrilateral shapes (e.g., square, rectangular, diamond, rhomboid, trapezoidal, kite, or super-elliptical).

Suitable quadrilateral shaped apices may be further divided into a pair of opposing primary apices intersecting the longitudinal axis and a pair of opposing secondary apices located on opposite sides of the longitudinal axis. Shaped ceramic abrasive particles including a first side having a quadrilateral shape of this type can be characterized by an aspect ratio of the maximum length along the longitudinal axis divided by the maximum width transverse to the longitudinal axis of about 1.3 to about 5, about 2 to about 4, or less than, equal to, or greater than about 1.3, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, or 5. This aspect ratio is also referred to herein as the minor aspect ratio.

In some examples, the first geometric shape is selected from a triangular shape, such as an isosceles triangle shape (such as an equilateral triangle shape), a right triangle shape, a scalene triangle shape, an acute triangle shape, or an obtuse triangle shape. In other examples, the first geometric shape is selected from a quadrilateral shape, such as a square, rectangle, rhombus, rhomboid, trapezoid, kite, or super-ellipse, or from a rectangle, rhombus, rhomboid, kite, or super-ellipse.

For purposes of this disclosure, geometric shapes are also intended to include regular or irregular polygons or stars, where one or more sides (perimeter portions of faces) may be arcuate (inward or outward).

Thus, for the purposes of this disclosure, triangular shapes also include three-sided polygons in which one or more sides (perimeter portions of the face) may be arcuate, e.g., the definition of a triangle expands to a spherical triangle and the definition of a quadrilateral expands to a hyperelliptical shape.

The second side may comprise a second face. The second face may have a perimeter of a second geometric shape. The second geometry may be the same or different from the first geometry. In some examples, the second geometry is selected to have substantially the same shape as the first geometry and is arranged in a manner that is fully equivalent to the first geometry (although the geometries may differ in size or area, e.g., one face may be larger than the other).

As used herein, the term "arranged in a manner that is congruent to the first geometry" is intended to include instances where the first and second geometries are slightly rotated relative to each other, for instances where the first and second geometries are substantially identical. The degree (or angle of rotation) depends on the particular geometry of the first and second faces and the thickness of the particles. Acceptable rotation angles may range from 0 degrees to +/-30 degrees, 0 degrees to +/-15 degrees, 0 degrees to +/-10 degrees, or about 0 degrees (e.g., 0 degrees to +/-5 degrees).

Examples of suitable geometries for the perimeter of the second face include those described herein for the first geometry.

In some examples, the first geometry and also the second geometry are selected from triangular shapes, such as isosceles triangular shapes or equilateral triangular shapes.

The first face may be substantially planar or the second face (if present) may be substantially planar. Additionally, both faces may be substantially planar. In some cases, the first face is planar (and the same as the first side face). Alternatively, at least one of the first and second faces (if present) may be non-planar. Additionally, both faces may be non-planar. For example, one or both of the first and second faces (if present) may be inwardly shaped (e.g., concave or concave) or may be outwardly shaped (e.g., convex).

For example, the first face (or second face, if present) may be inwardly shaped (e.g., concave or concave), and the second face (or first face, if present) may be substantially planar. Alternatively, the first face (or second face, if present) may be outwardly shaped (e.g., convex) and the second face (or first face, if present) may be inwardly shaped (e.g., concave or concave), or the first face may be inwardly shaped (e.g., concave or concave) and the second face (if present) may also be inwardly shaped (e.g., concave or concave).

The first and second faces (if present) may be substantially parallel to each other. Alternatively, the first and second faces (if present) may not be parallel, e.g., such that an imaginary line tangent to each face intersects a point (as is the exemplary case where one face is tilted relative to the other face).

The second face may be connected to the perimeter of the first face by at least one sidewall, which may be a sloped sidewall. The side wall may comprise one or more facets, which may be selected from quadrilateral facets. Specific examples of shaped particles having a second face include prisms (e.g., triangular prisms) and truncated pyramids.

In some examples, the second side includes a second face and four facets forming a sidewall (draft angle α between the sidewall and the second face equals 90 degrees) or a sloping sidewall (draft angle α between the sidewall and the second face is greater than 90 degrees.) when the draft angle α is greater than 90 degrees, the shaped ceramic abrasive particles resemble truncated pyramids as the thickness t of the shaped ceramic abrasive particles with the sloping sidewall becomes greater.

The shaped ceramic abrasive particles can include at least one sidewall, which can be a sloping sidewall. The first and second faces may be connected to each other by at least one sidewall. In other examples, the spine and the first face are connected to each other by at least one sidewall. In other examples, the top end and the first face are connected to each other by at least one sidewall.

In some examples, there may be more than one (e.g., two or three) sloped sidewalls, and the slope or angle of each sloped sidewall may be the same or different. In some embodiments, the first and second faces are connected to each other by a sidewall. In other embodiments, the sidewalls may be minimized for particles where the faces taper to thin edges or points where they meet, rather than having sidewalls.

The sidewall can vary and it generally forms the perimeter of the first and second faces (if present). In the case of the sloped sidewall, it forms the perimeter of the first face and the perimeter of the second face (if present). In one example, the perimeters of the first and second faces are selected to have a geometric shape, and the first and second faces are selected to have the same geometric shape, but they may be different sizes, i.e., one face is larger than the other.

The draft angle α between the second face and the sloping sidewall of the shaped ceramic abrasive particles can be varied to vary the relative size of each face in various embodiments of the present disclosure, the area or size of the first face is substantially equal to the area or size of the second face.

In one example of the present disclosure, draft angle α may be about 90 degrees such that the area of two faces is substantially equal, in another embodiment of the present disclosure, draft angle α may be greater than 90 degrees such that the area of a first face is greater than the area of a second face, in another embodiment of the present disclosure, draft angle α may be less than 90 degrees such that the area of a first face is less than the area of a second face, in various examples of the present disclosure, draft angle α may be about 95 to about 130 degrees, about 95 to about 125 degrees, about 95 to about 120 degrees, about 95 to about 115 degrees, about 95 to about 110 degrees, about 95 to about 105 degrees, or about 95 to about 100 degrees.

The first and second faces may also be connected to each other by at least a first sloping sidewall having a first draft angle and by a second sloping sidewall having a second draft angle (selected to be a different value than the first draft angle). Furthermore, the first face and the second face may also be connected by a third sloped sidewall having a third draft angle (which is a different value than either of the other two draft angles). In one embodiment, the values of the first draft angle, the second draft angle, and the third draft angle are all different from each other. For example, the first draft angle may be 120 degrees, the second draft angle may be 110 degrees, and the third draft angle may be 100 degrees.

Similar to the case of abrasive particles having one sloping sidewall, the first, second, and third sloping sidewalls of the shaped ceramic abrasive particles having a sloping sidewall can vary and can generally come from the perimeter of the first and second faces.

In general, the first, second, and third draft angles between the second face of the shaped ceramic abrasive particles and the respective sloping sidewall can vary, with at least two of the draft angles differing in value, and advantageously all three differing in value. In various embodiments of the present disclosure, the first, second, and third draft angles may be between about 95 degrees to about 130 degrees, or between about 95 degrees to about 125 degrees, or between about 95 degrees to about 120 degrees, or between about 95 degrees to about 115 degrees, or between about 95 degrees to about 110 degrees, or between about 95 degrees to about 105 degrees, or between about 95 degrees to about 100 degrees.

In addition, the various sloping sidewalls of the shaped ceramic abrasive particles can have the same draft angle or different draft angles. Further, a draft angle of 90 degrees may be used on one or more sidewalls. However, if shaped ceramic abrasive particles having sloping sidewalls are desired, at least one of the sidewalls is a sloping sidewall having a draft angle greater than about 90 degrees, or 95 degrees or greater.

The sidewall may be precisely shaped, and may be, for example, concave or convex, alternatively, the sidewall (top surface) may be a uniform plane, so-called "uniform plane" refers to a sidewall that does not have an area that protrudes from one face to another, or an area that is concave from one face to another, for example, at least 50%, or at least 75%, or at least 85% or more of the sidewall surface may be planar.

The second side may include a ridge. The ridge line may be connected to the perimeter of the first face by at least one sidewall, which may be a sloped sidewall, as discussed herein. The side wall may include one or more facets, which may be selected from triangular facets and quadrilateral facets, or a combination of triangular facets and quadrilateral facets.

The ridge line may be substantially parallel to the first side face. Alternatively, the ridge line may not be parallel to the first side face, for example, such that an imaginary line tangent to the ridge line intersects the first side face at a point (as in the exemplary case where the ridge line is inclined with respect to the first face). The ridge may be straight or may be non-straight, as is the case where the ridge comprises an arcuate structure.

The facets may be planar or non-planar. For example, at least one of the facets may be non-planar, such as concave or convex. In some embodiments, all facets can be non-planar facets, such as concave facets.

In some embodiments, the first geometry is selected from a quadrilateral having four sides and four vertices (e.g., selected from the group consisting of a rhombus, a rhomboid, a kite, or a superellipse), and the second side may include a ridge line and four facets forming a structure similar to a four-pitched roof. Thus, two opposing facets will have a triangular shape and two opposing facets will have a trapezoidal shape.

The second side can include a top end and at least one sidewall connecting the top end to a perimeter of the first face. The at least one sidewall may be a sloped sidewall, as discussed above. The side wall may include one or more facets, which may be selected from triangular facets. The facets may be planar or non-planar. For example, at least one of the facets may be non-planar, such as concave or convex. In some embodiments, all facets can be non-planar facets, such as concave facets.

In some examples, the second side includes a tip and a sidewall and may include triangular facets, forming a pyramid. The number of facets formed by the side wall will depend on the number of sides (defining the perimeter of the first face) present in the first geometry. For example, a pyramid-shaped ceramic abrasive particle having a first side characterized by a trilateral first geometry will typically have three triangular facets that meet at an apex, thereby forming a pyramid, and a pyramid-shaped ceramic abrasive particle having a first side characterized by a quadrilateral first geometry will typically have four triangular facets that meet at an apex, thereby forming a pyramid, and so on.

In some examples, the second side includes an apex and four facets, forming a pyramid. In some examples, the first side of the shaped ceramic abrasive particles comprises a quadrilateral first face having four sides and four vertices, which have a quadrilateral shape or are selected from the group consisting of a rhomboid, a kite, or a super-ellipse. The shape (e.g., first geometry) of the perimeter of the first face may be selected from the above-described group as these shapes will produce shaped ceramic abrasive particles having opposing major tips along the longitudinal axis and produce shapes that taper from the transverse axis toward each of the opposing major tips.

The taper can be controlled by selecting a particular aspect ratio of the particles, defined by the maximum length L along the longitudinal axis divided by the maximum width W along a transverse axis perpendicular to the longitudinal axis. For tapered shaped ceramic abrasive particles, the aspect ratio (also referred to herein as a "minor aspect ratio") should be greater than 1.0, which may be desirable in some applications. In various embodiments of the present disclosure, the minor aspect ratio is between about 1.3 to about 10, or between about 1.5 to about 8, or between about 1.7 to about 5. When the secondary aspect ratio becomes too large, the shaped ceramic abrasive particles may become too brittle.

The shaped ceramic abrasive particles can have a perimeter of the first face and optionally the second face that includes one or more corner points with sharp tips. In some examples, all corner points made up of the perimeter have sharp tips. The shaped ceramic abrasive particles can also have a sharp tip along any edge that may be present in the sidewall (e.g., between two converging facets formed by the sidewall).

The sharpness of a corner point may be characterized by a radius of curvature along the corner point, wherein the radius extends to the inside of the periphery. In various embodiments of the present disclosure, the radius of curvature (also referred to herein as the mean apical radius) can range from about 0.5 μm to about 80 μm, from about 0.5 μm to about 60 μm, from about 0.5 μm to about 20 μm, or from about 1 μm to about 10 μm, or can be less than, equal to, or greater than about 0.5 μm, 1 μm, 5 μm, 10 μm, 15 μm, 20 μm, 25 μm, 30 μm, 35 μm, 40 μm, 45 μm, 50 μm, 55 μm, 60 μm, 65 μm, 70 μm, 75 μm, or 80 μm. Without intending to be bound by any theory, it is believed that the sharper edges may promote more aggressive cutting and improved fracture of the shaped ceramic abrasive particles during use.

A smaller radius of curvature means that the particle more completely replicates the edge or corner features of the mold used to make the particle (e.g., the desired shape of the particle), and thus the shaped ceramic abrasive particle is more accurately made. In some examples, shaped abrasive articles (particularly, shaped ceramic abrasive particles) can be made by using a mold of a desired shape that provides particles that are more precisely made than methods based on other methods for making shaped ceramic abrasive particles, such as methods based on stamping, perforating, or extrusion.

As one example of a shaped ceramic abrasive particle having a planar triangular shape, fig. 1A-1B show a triangular shaped ceramic abrasive particle 10 bounded by a triangular base 11, a triangular top 12, and a plurality of sidewalls 13A, 13B, 13C connecting the base 11 and the top 12. The base 11 has tips 14A, 14B, 14C having an average radius of curvature of less than 50 microns. Fig. 1C-1D illustrate one face of the shaped ceramic abrasive particle 10 to better illustrate the radius of curvature of the apex 14A. Generally, the smaller the radius of curvature, the sharper the sidewall edge will be. In some cases, the base and top of the shaped ceramic abrasive particles are substantially parallel, resulting in a prismatic or truncated pyramidal (as shown in fig. 1A-1B) shape, although this is not required. As shown, the sidewalls 13A, 13B, 13C are of equal size and form dihedral angles with the base 11 of about 82 degrees. However, it should be understood that other dihedral angles (including 90 degrees) may be used. For example, the dihedral angle between the base and each sidewall may independently range from 45 degrees to 90 degrees, 70 degrees to 90 degrees, or 75 degrees to 85 degrees.

Fig. 2A-2E illustrate examples of shaped ceramic abrasive particles 16 having a tetrahedral shape. As shown in FIGS. 2A-2E, the tetrahedral abrasive particles 16 are shaped as regular tetrahedrons. As shown in fig. 2A, tetrahedral abrasive particle 16A has four faces (20A, 22A, 24A, and 26A) joined by six sides (30A, 32A, 34A, 36A, 38A, and 39A) terminating in four peaks (40A, 42A, 44A, and 46A). Each face contacts the other three faces at the edges. Although a regular tetrahedron (e.g., having six equal sides and four faces) is depicted in fig. 2A, it will be appreciated that other shapes are also permissible. For example, the tetrahedral abrasive particles 16A may be shaped as irregular (e.g., edges having different lengths) tetrahedra.

Referring now to fig. 2B, tetrahedral abrasive particle 16B has four faces (20B, 22B, 24B, and 26B) joined by six edges (30B, 32B, 34B, 36B, 38B, and 39B) terminating in four tips (40B, 42B, 44B, and 46B). Each face is concave and contacts the other three faces at respective common edges. Although particles having tetrahedral symmetry (e.g., four axes of cubic symmetry and six planes of symmetry) are depicted in fig. 2B, it will be appreciated that other shapes are also permissible. For example, the tetrahedral abrasive particle 16B may have one, two, or three concave surfaces, with the remaining surfaces being planar.

Referring now to fig. 2C, tetrahedral abrasive particle 16C has four faces (20C, 22C, 24C, and 26C) joined by six sides (30C, 32C, 34C, 36C, 38C, and 39C) terminating in four tips (40C, 42C, 44C, and 46C). Each face is convex and contacts the other three faces at respective common edges. Although particles having tetrahedral symmetry are depicted in fig. 2C, it will be appreciated that other shapes are also permissible. For example, the tetrahedral abrasive particle 16C may have one, two, or three convex surfaces, with the remaining surfaces being planar or concave.

Referring now to fig. 2D, tetrahedral abrasive particle 16D has four faces (20D, 22D, 24D, and 26D) joined by six edges (30D, 32D, 34D, 36D, 38D, and 39D) terminating in four tips (40D, 42D, 44D, and 46D). Although particles having tetrahedral symmetry are depicted in fig. 2D, it will be appreciated that other shapes are also permissible. For example, the tetrahedral abrasive particle 16D may have one, two, or three convex surfaces, with the remaining surfaces being planar.

There may be deviations from those depicted in fig. 2A-2D. One example of such tetrahedral abrasive particle 16E is depicted in fig. 2E, which shows tetrahedral abrasive particle 10E having four faces (20E, 22E, 24E, and 26E) joined by six edges (30E, 32E, 34E, 36E, 38E, and 39E) terminating in four vertices (40E, 42E, 44E, and 46E). Each face contacts the other three faces at respective common edges. Each face, edge and apex has an irregular shape.

The shaped ceramic abrasive particles (e.g., 10 or 16A-16E) can comprise any suitable component or components. Examples of suitable components include ceramic oxides and optionally a plurality of first and second oxides. The ceramic oxides may include those comprising alumina materials, such as fused alumina materials, heat treated alumina materials, sintered alumina materials, silicon carbide materials, titanium diboride, boron carbide, tungsten carbide, titanium carbide, cubic boron nitride, garnet, fused alumina-zirconia, ceria, zirconia, titania, or mixtures thereof. The plurality of first oxides may include oxides of rare earth metals. Examples include oxides selected from the group consisting of yttrium, praseodymium, samarium, ytterbium, neodymium, lanthanum, gadolinium, dysprosium, erbium, and mixtures thereof. The plurality of second oxides may include oxides of metals, such as alkaline earth metals or other suitable metals. For example, the plurality of second oxides can include oxides selected from the group consisting of iron, magnesium, zinc, silicon, cobalt, nickel, zirconium, hafnium, chromium, cerium, titanium, and mixtures thereof. In the shaped ceramic abrasive particles, at least one of the ceramic oxide, the first plurality of oxides, and the second plurality of oxides can be uniformly distributed throughout the abrasive particles.

The ceramic oxide can range from about 5 wt% to about 99 wt%, 20 wt% to about 80 wt%, about 95 wt% to about 99 wt%, or less than, equal to, or greater than 5 wt%, 10 wt%, 15 wt%, 20 wt%, 25 wt%, 30 wt%, 35 wt%, 40 wt%, 45 wt%, 50 wt%, 55 wt%, 60 wt%, 65 wt%, 70 wt%, 75 wt%, 80 wt%, 85 wt%, 90 wt%, 95 wt%, or 99 wt% of the shaped ceramic abrasive particles. The plurality of first metal oxides can range from about 0.01 wt% to about 70 wt%, about 2 wt% to about 20 wt%, or less than, equal to, or greater than about 0.1 wt%, 0.5 wt%, 1 wt%, 5 wt%, 10 wt%, 15 wt%, 20 wt%, 25 wt%, 30 wt%, 35 wt%, 40 wt%, 45 wt%, 50 wt%, 55 wt%, 60 wt%, 65 wt%, 70 wt%, 75 wt%, 80 wt%, 85 wt%, 90 wt%, 95 wt%, or 99 wt% of the abrasive particles. The plurality of second metal oxides similarly can range from about 0.01 wt% to about 70 wt%, about 2 wt% to about 20 wt%, about 7 wt% to about 15 wt%, or less than, equal to, or greater than about 0.1 wt%, 0.5 wt%, 1 wt%, 5 wt%, 10 wt%, 15 wt%, 20 wt%, 25 wt%, 30 wt%, 35 wt%, 40 wt%, 45 wt%, 50 wt%, 55 wt%, 60 wt%, 65 wt%, 70 wt%, 75 wt%, 80 wt%, 85 wt%, 90 wt%, 95 wt%, or 99 wt% of the abrasive particles.

In some examples of shaped ceramic abrasive particles, the particles may comprise a mixture of ceramic oxides, iron oxides, and magnesium oxides. In other examples of shaped ceramic abrasive particles, the particles can comprise a mixture of ceramic oxides, rare earth metal oxides, and magnesium oxides. In other examples of shaped ceramic abrasive particles, the particles may comprise a mixture of ceramic oxides, rare earth metal oxides, and iron oxides.

In an example of a shaped ceramic abrasive particle comprising magnesium oxide, the oxide can be MgO. The MgO may range from about 0.1 wt% to about 10 wt%, about 0.7 wt% to about 2 wt%, or less than, equal to, or greater than about 0.1 wt%, 0.5 wt%, 0.7 wt%, 1 wt%, 1.5 wt%, 1.7 wt%, 2 wt%, 2.5 wt%, 2.7 wt%, 3 wt%, 3.5 wt%, 3.7 wt%, 4 wt%, 4.5 wt%, 4.7 wt%, 5 wt%, 5.5 wt%, 5.7 wt%, 6 wt%, 6.5 wt%, 6.7 wt%, 7 wt%, 7.5 wt%, 7.7 wt%, 8 wt%, 8.5 wt%, 8.7 wt%, 9 wt%, 9.5 wt%, 9.7 wt%, or 10 wt% of the abrasive particles.

The plurality of second metal oxides may include iron oxide. As a non-limiting example, the iron oxide may be selected from FeO, Fe₂O₃、Fe₃O₄Or mixtures thereof. In some examples, the iron oxide is exclusively Fe₂O₃. When present, the iron oxide can range from about 0.1 wt% to about 10 wt%, about 0.5 wt% to about 8 wt%, about 1 wt% to about 2 wt%, or less than, equal to, or greater than 0.1 wt%, 0.5 wt%, 1 wt%, 1.5 wt%, 2 wt%, 2.5 wt%, 3 wt%, 3.5 wt%, 4 wt%, 4.5 wt%, 5 wt%, 5.5 wt%, 6 wt%, 6.5 wt%, 7 wt%, 7.5 wt%, 8 wt%, 8.5 wt%, 9 wt% of the abrasive particles%, 9.5 wt%, or 10 wt%.

In some examples of the shaped ceramic abrasive particles, the plurality of second metal oxides includes MgO and Fe₂O₃A mixture of (a). MgO and Fe₂O₃May be varied relative to each other. In some examples, the shaped ceramic abrasive particles can include Fe relative to Fe₂O₃And more MgO. In other examples, the shaped ceramic abrasive particles may include more Fe relative to MgO₂O₃。

In some examples of shaped ceramic abrasive particles comprising alumina particles and MgO, the magnesium and aluminum may be present as elongated objects comprising aluminum and magnesium. The porosity of the shaped ceramic abrasive particles can range from about 0.01% to about 5%, from about 0.5% to about 2%, or less than, equal to, or greater than about 0.01%, 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, or 5%. In some examples, the number average size (largest dimension of the particles, e.g., length) of the individual ceramic oxides can independently be in a range of about 0.05 μm to about 1 μm, about 0.5 μm to about 0.8 μm, or less than, equal to, or greater than about 0.05 μm, 0.1 μm, 0.15 μm, 0.2 μm, 0.25 μm, 0.3 μm, 0.35 μm, 0.4 μm, 0.45 μm, 0.5 μm, 0.55 μm, 0.6 μm, 0.65 μm, 0.7 μm, 0.75 μm, 0.8 μm, 0.85 μm, 0.9 μm, 0.95 μm, or 1 μm.

Abrasive article

The shaped ceramic abrasive particles can be included in a variety of different types of abrasive articles, such as coated abrasive articles or bonded abrasive articles. Fig. 3 is a cross-sectional view of a coated abrasive article 50. Coated abrasive article 50 includes backing 52 defining a surface along the x-y direction. The backing 52 has a first adhesive layer (hereinafter primer layer 54) applied to a first surface of the backing 52. The plurality of shaped ceramic abrasive particles 16 are attached to or partially embedded in the make coat 54. In other examples, the shaped ceramic abrasive particles 10 may be included. A second binder layer (hereinafter size layer 56) is dispersed over the ceramic abrasive particles 16.

The backing 52 may be flexible or rigid. Examples of suitable materials for forming the flexible backing include polymeric films, metal foils, woven fabrics, knitted fabrics, paper, vulcanized fiber, staple fiber, continuous fiber, nonwoven, foams, screens, laminates, and combinations thereof. Backing 52 may be shaped to allow coated abrasive article 50 to be in the form of a sheet, disc, tape, pad, or roll. In some embodiments, backing 52 may be sufficiently flexible to allow coated abrasive article 50 to be shaped into a ring to produce an abrasive belt that can be run on suitable grinding equipment.

Make coat 54 secures abrasive particle 16 to backing 52 and size coat 56 may help to consolidate tetrahedral abrasive particle 10. Primer layer 54 and/or size layer 56 may comprise a resin binder. The resin binder may comprise one or more resins selected from the group consisting of: phenolic resins, epoxy resins, urea-formaldehyde resins, acrylate resins, aminoplast resins, melamine formaldehyde resins, acrylic modified epoxy resins, urethane resins, and mixtures thereof.

Fig. 4 is a perspective view of a bonded abrasive article 60 comprising shaped ceramic abrasive particles 10. In other examples, the bonded abrasive article 60 may include the shaped ceramic abrasive particles 16A-16E. As shown in fig. 4, the bonded abrasive article 60 includes a first major surface 62 and an opposing second major surface 64, each of which contacts a circumferential side 66. A central axis extends through the first and second major surfaces 62, 64.

The bonded abrasive article 60 includes an abrasive layer 68 comprising shaped ceramic abrasive particles 10. The shaped ceramic abrasive particles 16 remain in the binder 70. The shaped ceramic abrasive particles 16 may be fully or partially retained in the binder and may be arranged in a specified pattern as shown or randomly distributed. The binder can be any suitable binder material. Suitable examples of binder materials include organic binder materials, ceramic binder materials, metallic binder materials, or mixtures thereof.

The coated abrasive article 50 or the bonded abrasive article 60 may be formed into any suitable tool. Examples of suitable tools include cutoff wheels, cutting grinding wheels, depressed center cutoff wheels, reel grinding wheels, grinding heads, tool grinding wheels, roller grinding wheels, hot press grinding wheels, face grinding wheels, double disc grinding wheels, belts, or portions thereof.

The shaped ceramic abrasive particles 10 can range from about 1 wt% to about 70 wt%, about 8 wt% to about 30 wt%, or less than, equal to, or greater than about 1 wt%, 2 wt%, 4 wt%, 6 wt%, 8 wt%, 10 wt%, 12 wt%, 14 wt%, 16 wt%, 18 wt%, 20 wt%, 22 wt%, 24 wt%, 26 wt%, 28 wt%, 30 wt%, 32 wt%, 34 wt%, 36 wt%, 38 wt%, 40 wt%, 42 wt%, 44 wt%, 46 wt%, 48 wt%, 50 wt%, 52 wt%, 54 wt%, 56 wt%, 58 wt%, 60 wt%, 62 wt%, 64 wt%, 66 wt%, 68 wt%, or 70 wt% of the coated abrasive article or the bonded abrasive article.

Either the coated abrasive article or the bonded abrasive article can comprise additional abrasive particles in addition to the shaped ceramic abrasive particles described herein. Examples of additional abrasive particles include crushed abrasive particles. When present, the crushed abrasive particles can range from about 5 wt% to about 96 wt%, or about 15 wt% to about 50 wt%, or can be less than, equal to, or greater than about 5 wt%, 10 wt%, 15 wt%, 20 wt%, 25 wt%, 30 wt%, 35 wt%, 40 wt%, 45 wt%, 50 wt%, 55 wt%, 60 wt%, 65 wt%, 70 wt%, 75 wt%, 80 wt%, 85 wt%, 90 wt%, or 96 wt% of the abrasive layer. Examples of suitable crushed abrasive particles include, for example, the following crushed particles: fused aluminum oxide, heat treated aluminum oxide, white fused aluminum oxide, CERAMIC aluminum oxide materials such as those commercially available under the trade designation 3M CERAMIC ABRASIVE GRAIN from 3M Company, st. paul, Minn., of saint paul, Minn., mn), black silicon carbide, green silicon carbide, titanium diboride, boron carbide, tungsten carbide, titanium carbide, diamond, cubic boron nitride, garnet, fused alumina zirconia, sol-gel process-made abrasive particles, iron oxide, chromium oxide (chromia), ceria, zirconia, titania, silicates, tin oxide, silica (such as quartz, glass beads, glass bubbles, and glass fibers), silicates (such as talc, clay (e.g., montmorillonite), feldspar, mica, calcium silicate, calcium metasilicate, sodium aluminosilicate, and sodium silicate), flint, and emery.

The abrasive layer may also contain, for example, additives such as fillers, grinding aids, wetting agents, surfactants, dyes, pigments, coupling agents, adhesion promoters, and combinations thereof. Examples of fillers include calcium carbonate, silica, talc, clay, calcium metasilicate, dolomite, aluminum sulfate, and combinations thereof. Suitable examples of grinding aids include particulate matter that affects the chemical and physical processes of grinding, thereby resulting in improved performance. Grinding aids encompass a wide variety of different materials and can be inorganic or organic. Examples of chemical groups of grinding aids include waxes, organic halides, halide salts, metals, and alloys thereof. The organic halide may decompose during milling and release a halogen acid or a gaseous halide. Examples of such materials include chlorinated waxes, such as tetrachloronaphthalene and pentachloronaphthalene; and polyvinyl chloride. Examples of halide salts include sodium chloride, potassium cryolite, sodium cryolite, ammonium cryolite, potassium tetrafluoroborate, sodium tetrafluoroborate, silicon fluorides, potassium chloride, and magnesium chloride. Examples of metals include tin, lead, bismuth, cobalt, antimony, cadmium, iron, and titanium. Other grinding aids include sulfur, organic sulfur compounds, graphite, and metal sulfides. It is also within the scope of the present disclosure to use a combination of different grinding aids; in some cases, this may produce a synergistic effect. In one embodiment, the grinding aid is cryolite or potassium tetrafluoroborate. The amount of such additives can be adjusted to impart desired properties. When present, the additive may range from about 5 wt% to about 95 wt% of the abrasive layer, or from about 20 wt% to about 70 wt% of the abrasive layer, or may be less than, equal to, or greater than 5 wt%, 10 wt%, 15 wt%, 20 wt%, 25 wt%, 30 wt%, 35 wt%, 40 wt%, 45 wt%, 50 wt%, 55 wt%, 60 wt%, 65 wt%, 70 wt%, 75 wt%, 80 wt%, 85 wt%, 90 wt%, or 95 wt%.

Method of using an abrasive article

Methods of using the coated abrasive article 50 or the bonded abrasive article 60 can include contacting the coated abrasive article 50 or the bonded abrasive article 60 with a substrate. The method may further include moving at least one of the coated abrasive article 50 or the bonded abrasive article 60 laterally or rotationally relative to the substrate, and moving the substrate relative to the coated abrasive article 50 or the bonded abrasive article 60. The substrate can be a variety of different types of substrates. Non-limiting examples of suitable substrates include paint, primers, stone, plastic, or combinations thereof.

Method of forming abrasive particles

Briefly, the method may comprise the operations of preparing a seeded or unseeded ceramic precursor dispersion that is capable of being converted to a corresponding ceramic (e.g., a boehmite sol-gel capable of being converted to α alumina), which may also be a non-colloidal slurry dispersion of ceramic particles, filling one or more mold cavities having a desired exterior shape of the shaped ceramic abrasive particles with the ceramic precursor dispersion, drying the ceramic precursor dispersion to form shaped ceramic abrasive precursors, removing the shaped ceramic abrasive precursors from the mold cavities, calcining the shaped ceramic abrasive precursors to form calcined shaped ceramic abrasive precursors, and subsequently sintering the calcined shaped ceramic abrasive precursors to form shaped ceramic abrasive particles.

The method can include an operation of providing a seeded or unseeded ceramic precursor dispersion that can be converted to a ceramic. In the example of seeding a ceramic precursor, the precursor may be seeded with iron oxide (e.g., Fe)₂O₃). The ceramic precursor dispersion may comprise a liquid as the volatile component. In one example, the volatile component is water. The dispersion may contain a sufficient amount of liquid to make the viscosity of the dispersion low enough to fill the mold cavity and replicate the mold surface, but not so much liquid as to cause subsequent removal of the liquid from the mold cavityThe cost of (2) is too high. In one example, the ceramic precursor dispersion comprises 2 to 90 wt% of particles capable of being converted to ceramic, such as alumina monohydrate (boehmite) particles, and at least 10 wt%, or 50 to 70 wt%, or 50 to 60 wt% of a volatile component, such as water. Conversely, in some embodiments, the ceramic precursor dispersion comprises from 30 wt% to 50 wt%, or from 40 wt% to 50 wt% solids.

Examples of suitable ceramic precursor dispersions include zirconia sol, vanadia sol, ceria sol, alumina sol, and combinations thereof suitable alumina dispersions include, for example, boehmite dispersions and other alumina hydrate dispersions boehmite can be prepared by known techniques or is commercially available examples of commercially available boehmites include products under the trade designations "DISPERAL" and "DISPAL" both available from Sasol North America, Inc.

The physical properties of the resulting shaped ceramic abrasive particles may generally depend on the type of material used in the ceramic precursor dispersion. As used herein, a "gel" is a three-dimensional network of solids dispersed in a liquid.

The ceramic precursor dispersion may comprise a modifying additive or a precursor of a modifying additive. Modifying additives may be used to enhance certain desired characteristics of the abrasive particles or to increase the efficiency of subsequent sintering steps. The modifying additive or precursor of the modifying additive may be in the form of a soluble salt, such as a water soluble salt. They may include metal-containing compounds and may be precursors of oxides of magnesium, zinc, iron, silicon, cobalt, nickel, zirconium, hafnium, chromium, yttrium, praseodymium, samarium, ytterbium, neodymium, lanthanum, gadolinium, cerium, dysprosium, erbium, titanium, and mixtures thereof. The specific concentrations of these additives that may be present in the ceramic precursor dispersion may vary.

Nucleating agents suitable for use in the present disclosure may include α aluminum oxide, α iron oxide or precursors thereof, titanium dioxide and titanates, fine particles of chromium oxide, or any other substance that nucleates the transformation.

A peptizing agent can be added to the ceramic precursor dispersion to produce a more stable hydrosol or colloidal ceramic precursor dispersion. Suitable peptizing agents are monoprotic acids or acidic compounds, such as acetic acid, hydrochloric acid, formic acid and nitric acid. Polyprotic acids may also be used, but they may rapidly gel the ceramic precursor dispersion, making it difficult to handle or introduce additional components. Some commercial sources of boehmite contain acid titers (e.g., absorbed formic or nitric acid) that aid in the formation of stable ceramic precursor dispersions.

The ceramic precursor dispersion may be formed by any suitable process; for example, in the case of a sol-gel alumina precursor, it can be formed by simply mixing alumina monohydrate with water containing a peptizing agent, or by forming an alumina monohydrate slurry with added peptizing agent.

An anti-foaming agent or other suitable chemical may be added to reduce the tendency of air bubbles or entrained air to form during mixing. Other chemicals such as wetting agents, alcohols, or coupling agents may be added if desired.

After the ceramic precursor is gelled or after the ceramic precursor is calcined, an oxide of magnesium (e.g., MgO) may be impregnated into the ceramic precursor. Impregnation of the ceramic precursor with magnesium oxide can help limit ceramic oxide growth and help reduce porosity of the shaped abrasive particles.

Further operations may include providing a mold having at least one mold cavity, or a plurality of cavities formed in at least one major surface of the mold. In some examples, the mold is formed as a production tool, which may be an applicator roll such as a belt, sheet, continuous web, rotary gravure roll, sleeve mounted on an applicator roll, or die. In one example, the production tool may comprise a polymeric material. Examples of suitable polymeric materials include thermoplastics such as polyesters, polycarbonates, poly (ether sulfone), poly (methyl methacrylate), polyurethanes, polyvinyl chloride, polyolefins, polystyrene, polypropylene, polyethylene, or combinations thereof, or thermosets. In one example, the entire mold is made of a polymeric or thermoplastic material. In another example, the surface of the mold (such as the surface of the plurality of cavities) that is in contact with the ceramic precursor dispersion when the ceramic precursor dispersion is dried comprises a polymeric or thermoplastic material, and other portions of the mold may be made of other materials. By way of example, a suitable polymer coating may be applied to the metal mold to alter its surface tension characteristics.

Polymeric or thermoplastic production tools can be replicated from a metal master tool. The master tool can have the inverse pattern desired for the production tool. The master tool can be made in the same manner as the production tool. In one example, the master tool is made of metal (e.g., nickel) and diamond turned. In one example, the master tool is formed at least in part using stereolithography techniques. The polymeric sheet material can be heated along with the master tool such that the master tool pattern is imprinted on the polymeric material by pressing the two together. A polymer or thermoplastic material can also be extruded or cast onto the master tool and then pressed. The thermoplastic material is cooled to harden it, thereby producing the production tool. If a thermoplastic production tool is utilized, care should be taken not to generate excessive heat, which can deform the thermoplastic production tool, thereby limiting its life.

The cavity is accessible from an opening in either the top or bottom surface of the mold. In some examples, the cavity may extend through the entire thickness of the mold. Alternatively, the cavity may extend only a portion of the thickness of the mold. In one example, the top surface is substantially parallel to the bottom surface of the mold, wherein the cavities have a substantially uniform depth. At least one side of the mold, i.e., the side in which the cavity is formed, may remain exposed to the ambient atmosphere during the step of removing the volatile component.

The cavities have a particular three-dimensional shape to produce the shaped ceramic abrasive particles. The depth dimension is equal to the vertical distance from the top surface to the lowest point on the bottom surface. The depth of a given cavity may be uniform or may vary along its length and/or width. The cavities of a given mold may have the same shape or different shapes.

Further operations involve filling the cavities in the mold with the ceramic precursor dispersion (e.g., by conventional techniques). In some examples, a knife roll coater or a vacuum slot die coater may be used. If desired, a release agent may be used to aid in the removal of the particles from the mold. Examples of release agents include oils (such as peanut oil or mineral oil, fish oil), silicones, polytetrafluoroethylene, zinc stearate, and graphite. Generally, a release agent such as peanut oil in a liquid such as water or alcohol is applied to the surface of the production mold in contact with the ceramic precursor dispersion such that when release is desired, between about 0.1mg/in is present per unit area of mold²(0.6mg/cm²) To about 3.0mg/in²(20mg/cm²) Or between about 0.1mg/in²(0.6mg/cm²) To about 5.0mg/in²(30mg/cm²) A release agent therebetween. In some embodiments, the top surface of the mold is coated with the ceramic precursor dispersion. A ceramic precursor dispersion can be pumped onto the top surface.

In a further operation, a doctor blade or smoothing bar may be used to fully press the ceramic precursor dispersion into the cavity of the mold. The remainder of the ceramic precursor dispersion that does not enter the cavity can be removed from the top surface of the mold and recycled. In some examples, a small portion of the ceramic precursor dispersion may remain on the top surface, and in other examples, the top surface is substantially free of dispersion. The pressure applied by the doctor blade or smoothing bar may be less than 100psi (0.6MPa), or less than 50psi (0.3MPa), or even less than 10psi (60 kPa). In some examples, the exposed surface of the ceramic precursor dispersion does not substantially extend beyond the top surface.

In those instances where it is desirable to form a plane of shaped ceramic abrasive particles using exposed surfaces of the cavities, it may be desirable to overfill the cavities (e.g., using a micro-nozzle array) and slowly dry the ceramic precursor dispersion.

Further operations involve removing volatile components to dry the dispersion. Volatile components can be removed by a rapid evaporation rate. In some examples, the removal of the volatile component by evaporation is performed at a temperature above the boiling point of the volatile component. The upper limit of the drying temperature generally depends on the material from which the mold is made. For polypropylene molds, the temperature should be below the melting point of the plastic. In one example, for an aqueous dispersion containing about 40% to 50% solids and a polypropylene mold, the drying temperature may be between about 90 ℃ to about 165 ℃, or between about 105 ℃ to about 150 ℃, or between about 105 ℃ to about 120 ℃. Higher temperatures can lead to improved production speeds, but can also lead to degradation of the polypropylene mold, thereby limiting its useful life as a mold.

During drying, the ceramic precursor dispersion shrinks, typically causing retraction from the cavity walls. For example, if the cavity has flat walls, the resulting shaped ceramic abrasive particles can tend to have at least three concave major sides. It has now been found that by recessing the cavity walls (and thus increasing the cavity volume), it is possible to obtain shaped ceramic abrasive particles having at least three substantially flat major sides. The extent of dishing generally depends on the solids content of the ceramic precursor dispersion.

Further operations involve removing the resulting precursor shaped ceramic abrasive particles from the mold cavity. The precursor shaped ceramic abrasive particles can be removed from the cavity by using the following method: the particles are removed from the mold cavity using gravity, vibration, ultrasonic vibration, vacuum or pressurized air methods on the mold alone or in combination.

The precursor shaped ceramic abrasive particles can be further dried outside the mold. This additional drying step is not required if the ceramic precursor dispersion is dried to the desired extent in the mold. However, in some cases, it may be economical to employ this additional drying step to minimize the time that the ceramic precursor dispersion stays in the mold. The precursor shaped ceramic abrasive particles will be dried at a temperature of 50 ℃ to 160 ℃, or 120 ℃ to 150 ℃, for 10 minutes to 480 minutes, or 120 minutes to 400 minutes.

Further operations involve calcining the precursor shaped ceramic abrasive particles. During calcination, substantially all of the volatile materials are removed and the various components present in the ceramic precursor dispersion are converted to metal oxides. Typically, the precursor shaped ceramic abrasive particles are heated to a temperature of 400 ℃ to 800 ℃ and maintained within this temperature range until free water and 90 wt.% or more of any bound volatile materials are removed. In an optional step, it may be desirable to introduce the modifying additive by an impregnation process. The water soluble salt can be introduced into the pores of the calcined precursor shaped ceramic abrasive particles by impregnation. The precursor shaped ceramic abrasive particles are then pre-fired again.

Further operations may involve sintering the calcined precursor shaped ceramic abrasive particles to form ceramic particles. However, in some examples where the ceramic precursor includes a rare earth metal, sintering may not be necessary. Prior to sintering, the calcined precursor shaped ceramic abrasive particles are not fully densified and therefore lack the hardness needed to function as shaped ceramic abrasive particles. Sintering is performed by heating the calcined precursor shaped ceramic abrasive particles to a temperature of 1000 ℃ to 1650 ℃. The length of time that the calcined, precursor shaped ceramic abrasive particles can be exposed to the sintering temperature to achieve this degree of conversion depends on a variety of factors, but five seconds to 48 hours are possible.

The precursor shaped ceramic abrasive particles (or calcined precursor shaped ceramic abrasive particles), whether calcined or not, can be sintered. Prior to sintering, the (optionally calcined) precursor shaped ceramic abrasive particles are not fully densified and, therefore, lack the hardness needed to be useful as shaped ceramic abrasive particles. Sintering can be performed by heating the (optionally calcined) precursor shaped ceramic abrasive particles to a temperature of 1000 ℃ to 1650 ℃. The heating time required to achieve densification depends on various factors, but a time of five seconds to 48 hours is acceptable. Additional details regarding this process can be found in U.S. published patent application 2015/0267097 (Rosenflanz).

In another embodiment, the duration of the sintering step is in the range of one minute to 90 minutes. After sintering, the shaped ceramic abrasive particles can have a Vickers hardness of 10GPa (gigapascal), 16GPa, 18GPa, 20GPa, or greater.

The process can be modified using additional operations such as rapid heating of the material from the calcination temperature to the sintering temperature and centrifuging the ceramic precursor dispersion to remove sludge and/or waste. Furthermore, the method can be modified, if desired, by combining two or more of the method steps.