阅读说明：本技术 用于制作耐火陶瓷零件的方法 (Method for making refractory ceramic parts ) 是由 奥利维尔·博里 于 2019-07-26 设计创作，主要内容包括：本发明涉及一种用于标记耐火陶瓷零件的表面的方法,所述表面称为“待标记表面”,所述零件具有：-由晶粒组成的微观结构,晶粒由硅酸盐粘结相连接并分别包含按质量计大于50％的ZrO_2,以及-按体积计小于5％的总孔隙率,所述方法包括用激光束辐射所述表面,所述激光束由设置成符合以下关系式(1)的激光装置发射：a.V~2+b.F~2+c.VF+d.V+e.F+f<0,其中：a＝10~4.D+2×10~6,b＝0.5×10~6.D-150×10~6,c＝0.5×10~6.D-300×10~6,d＝5×10~3.D-2.5×10~6,e＝-5×10~3.D+2.0×10~6,f＝-5×10~9.D+1.8×10~(12),V以mm/秒表示,D以mm表示,F以kHz表示。(The invention relates to a method for marking the surface of a refractory ceramic part, called "surface to be marked", said part having: -a microstructure consisting of grains which are adhesively bonded by silicates and which each contain more than 50% by mass of ZrO 2 And-a total porosity of less than 5% by volume, the method comprising irradiating the surface with a laser beam emitted by a laser device arranged in accordance with the following relation (1): a.V 2 +b.F 2 +c.VF+d.V+e.F+f<0, wherein: a 10 4 .D+2×10 6 ，b＝0.5×10 6 .D‑150×10 6 ，c＝0.5×10 6 .D‑300×10 6 ，d＝5×10 3 .D‑2.5×10 6 ，e＝‑5×10 3 .D+2.0×10 6 ，f＝‑5×10 9 .D+1.8×10 12 V is expressed in mm/sec, D is expressed in mm, and F is expressed in kHz.)

1. Method for marking a surface of a refractory ceramic part, said surface being called "surface to be marked", said part having

-a microstructure comprising grains connected by silicate bonds, said grains respectively containing more than 50% by mass of ZrO₂，

-a total porosity of less than 5% by volume,

the method comprises irradiating the surface with a laser beam emitted by a laser device arranged to comply with relation (1) below:

a.V²+b.F²+c.VF+d.V+e.F+f<0, wherein:

a＝10⁴.D+2×10⁶

b＝0.5×10⁶.D-150×10⁶

c＝0.5×10⁶.D-300×10⁶

d＝5×10³.D-2.5×10⁶

e＝-5×10³.D+2.0×10⁶

f＝-5×10⁹.D+1.8×10¹²

v is expressed in mm/sec, D is expressed in mm, and F is expressed in kHz.

2. Method according to the preceding claim, wherein the frequency F is less than 300kHz and/or the speed V is less than 5000 mm/sec.

3. The method of the immediately preceding claim, wherein the frequency F is less than 100kHz and/or the velocity V is less than 3000 mm/sec.

4. A method according to any preceding claim, wherein, to make the mark erasable, F/V < D/800.

5. The method according to any one of the preceding claims, wherein the exposure energy is adapted to remove the binder phase over a depth of between 5 μm and 100 μm and/or to remove the binder phase over a depth of more than 10% and less than 50% of the average size of the grains of the surface to be marked.

6. The method according to any one of the preceding claims, wherein, prior to irradiation, the surface to be marked has a roughness Ra of less than 20 μ ι η measured according to standard ISO4287/1997, and/or the moisture percentage of the refractory ceramic part is less than or equal to 1%.

7. The method according to any of the preceding claims, wherein the grains comprise more than 95% ZrO based on mass percentage of oxides₂。

8. The method of any one of the preceding claims, wherein the refractory ceramic part is made of a molten material.

9. As claimed in any one of the preceding claimsThe method of item (1), wherein the refractory ceramic part is made of more than 90% by mass of a material selected from the group consisting of ZrO₂、Al₂O₃、SiO₂、Cr₂O₃、Y₂O₃And CeO₂One or more oxides of the group.

10. The method according to any of the preceding claims, wherein the equivalent diameter of the cross section of the laser beam is larger than 30 μ ι η and smaller than 100 μ ι η when the laser beam encounters the surface to be marked.

11. A refractory ceramic part has

-a microstructure consisting of grains bonded by silicates and containing more than 50% by mass of ZrO₂，

-a total porosity of less than 5% by volume,

the refractory ceramic part comprises a marking, preferably imprinted by the marking method according to the invention, which defines such a cavity:

-a depth of between 5 μm and 100 μm, and/or

-the grains protrude from the bottom of the cavity by more than 5% and less than 50% of the average size of the grains on average.

12. The refractory ceramic part of the immediately preceding claim, wherein the marking comprises a plurality of dots, the dot density being 100 to 1000 dots per square millimeter.

13. The refractory ceramic part of any one of the two immediately preceding claims, wherein the marking is an alphanumeric character, a line or dot matrix or a graphical representation.

14. A method for manufacturing a furnace, in particular a glass furnace or a metallurgical furnace, comprising the steps of:

1) producing a plurality of refractory ceramic parts and imprinting indicia on each part according to the marking method of any one of claims 1 to 9, the indicia imprinted on the parts depending on the intended location of the part in the furnace;

2) assembling the refractory ceramic parts such that each part is in a position corresponding to the marking imprinted thereon.

Technical Field

The invention relates to a method for marking refractory ceramic parts, in particular intended for glass or metallurgical melting furnaces.

Background

Generally larger dense refractory ceramic parts can be used at high temperatures, particularly in glass or metal smelting furnaces.

The dense refractory ceramic parts may in particular be made by electrofusion. The method includes melting raw materials in an electric arc furnace, and then casting the molten materials in a mold and cooling to solidify. The resulting "fused" brick may then be machined to a size suitable for the application.

The composition of the refractory ceramic part and the method for manufacturing the part are adapted to the furnace area in which it is intended to be used.

In order to ensure traceability of the parts and to be able to identify them during assembly of the furnace, in particular so that they can be placed in predetermined positions, the parts must be marked at the production site.

The mark must be

-a control is formed by the reaction of,

wear resistance during its handling, in particular during assembly operations,

resistance to temperatures higher than 600 ℃, in particular allowing the marking of the joining or cold faces of the parts.

Depending on the application, the mark will or will not need to be erasable.

On the cold side, the indelible mark enables the part to be verified and tracked after assembly, even after use of the furnace.

On the other side, the erasable marking enables the marking to be modified during assembly and avoids too rapid deterioration, in particular with regard to blistering in glass furnace applications.

The marking process must be fast and efficient, with a marking speed of a few centimeters per second. Preferably, within one minute shouldThe mark can be 400cm²Surface area of (a).

In addition to simple wiping, drying with ambient air after underwater machining, or sandblasting (to reduce burrs or burrs observed on the original manufactured or machined part), preferably, the marking process does not require preparation of the surface.

Finally, the marking should not cause any change in the formulation of the material, which would always reduce the performance properties.

For marking parts, it is known practice to deposit ink on their surface. However, the ink is not resistant to the operating temperature of the furnace and is harmful to the environment.

Laser marking methods are also known. When applied to ceramic parts comprising grains comprising zirconia, this method often results in a color gradient and/or a black mark, which impairs the readability of the mark.

For example, US 5272120 discloses a method of using YAG or CO₂A marking method by laser irradiation, which has a typical power of about 7 to 10W, a frequency of 8kHz, and a traveling speed of 22 mm/sec in an oxygen-depleted atmosphere.

US 5543269 proposes a marking method using multimode Nd: YAG laser radiation. The mark is erasable.

JP 2005-4175624 suggests the use of oscillating laser radiation (unlike YAG lasers) in a simple mode, in particular YVO with a power of 6.5W and a wavelength of 1064nm₄A marking method of a laser.

US 4769310 suggests changing the composition of the ceramic parts to be marked by incorporating therein inorganic pigments sensitive to laser radiation. However, these additives can significantly reduce the performance of the ceramic parts in use and contaminate the molten glass bath in the case of glass furnace applications.

US 5030551 or US 6238847 propose depositing a layer sensitive to laser radiation onto the surface to be marked. However, the layer has poor adhesion and poor abrasion resistance.

Therefore, there is a need for a method for marking dense refractory ceramic parts that meets the limitations listed above and does not have the drawbacks of the known methods.

It is an object of the present invention to at least partially address this need.

Disclosure of Invention

The invention relates to a method for marking the surface of a refractory ceramic part, called the "surface to be marked", said part being called a "dense refractory ceramic part", having

-a microstructure comprising grains, preferably ZrO, bonded by silicate bonds₂Crystal grains containing more than 50% by mass of ZrO₂Or even grains of the microstructure connected by silicate bonds, preferably ZrO₂A crystal grain composition containing more than 50% by mass of ZrO₂And are and

-a total porosity of less than 5% by volume,

the method comprises irradiating the surface with a laser beam emitted by a laser device arranged to comply with relation (1) below:

a.V²+b.F²+c.VF+d.V+e.F+f<0, wherein:

a＝10⁴.D+2×10⁶

b＝0.5×10⁶.D-150×10⁶

c＝0.5×10⁶.D-300×10⁶

d＝5×10³.D-2.5×10⁶

e＝-5×10³.D+2.0×10⁶

f＝-5×10⁹.D+1.8×10¹²

v is expressed in mm/sec, D is expressed in mm, and F is expressed in kHz.

The inventors have found that such a method enables advantageous labelling meeting the previously expressed needs.

In particular, the inventors have found that the marking has very good contrast and uniform color, even around the edges of the marked character or area, the gradation or black mark is not visible to the naked eye.

Without being bound by theory, the inventors explain this result by the specificity of the laser beam, which removes some of the binder phase and a portion of the grains, but does not expose the grains.

Preferably, the exposure energy is adapted to remove the binding phase over a depth of more than 10% and/or less than 50%, preferably less than 30%, or even less than 20% of the average size of the grains of the surface to be marked.

Preferably, the method according to the invention also has one or more of the following optional features:

-frequency F less than 300kHz and/or speed V less than 5000 mm/sec;

-frequency F less than 100kHz and/or speed V less than 3000 mm/sec;

to make an erasable marking, the laser device is set to 800.F/(V.D) < 1;

-to improve the legibility, the laser device is set to 800.F/(V.D) >0.1, preferably 800.F/(V.D) > 0.15;

the exposure energy is suitable for removing the binder phase over a depth of 5 μm to 100 μm, preferably less than 75 μm, preferably less than 50 μm;

-before irradiation, the surface to be marked has a roughness Ra of less than 20 μm measured according to standard ISO4287/1997 and/or the refractory ceramic part has a moisture percentage of less than or equal to 1%;

-a content of ZrO in the grains of more than 95% by mass₂；

-the refractory ceramic part is made of a molten material;

the refractory ceramic part is made of a material consisting of more than 90% by mass of a material selected from the group consisting of ZrO₂、Al₂O₃、SiO₂、Cr₂O₃、Y₂O₃And CeO₂One or more oxides of group (b);

-the laser beam has an equivalent diameter of 30 μm to 100 μm on the surface to be marked;

exposure energy at 5J/mm³To 3000J/mm³In the meantime.

The invention also relates to a dense refractory ceramic part comprising a marking, preferably imprinted by means of the marking method according to the invention, the marking defining a cavity, the cavity:

-has a depth of between 5 μm and 100 μm, preferably less than 75 μm, preferably less than 50 μm, and/or

From the bottom of the cavity, the grains protrude by more than 5% of the average size of the grains on average, preferably more than 10% of the average size of the grains, and/or less than 50% of the average size of the grains, preferably less than 30% of the average size of the grains, or even less than 20% of the average size of the grains.

The indicia may be, inter alia, alphanumeric characters, a line or a matrix of dots, or a graphical representation.

Preferably, the indicia comprises a plurality of dots, the dot density being 100 to 1000 dots per square millimeter.

The invention also relates to a method for manufacturing a furnace, in particular a glass furnace or a metallurgical furnace, comprising the following steps:

1) producing a plurality of refractory ceramic parts and marking each part with a mark according to the marking method of the present invention, the mark marked on the part depending on the intended position of the part in the furnace;

2) the refractory ceramic parts are assembled such that each part is in a position corresponding to the marking imprinted thereon.

The invention also relates to a method for controlling the assembly of refractory parts of a furnace lining, in particular of a glass or metallurgical furnace lining, in which method, after the assembly of the refractory parts, the markings imprinted on the refractory parts are read and the real position of the parts is then compared with a predetermined position identified by means of the markings.

Definition of

The term "refractory ceramic part" refers to a part made of non-metallic inorganic material.

"hot-face" is the face exposed to the interior of the furnace, i.e. the face in contact with the molten material (e.g. glass or metal) and/or with the gaseous environment of the material. The cold side is generally the side opposite the hot side. The cold and hot surfaces of the brick are connected together in the following way:

-by a side or "faying surface" facing the side of an adjacent brick in the same row of bricks, and

-by an upper face facing the lower face of at least one upper side brick resting on said brick and a lower face facing the upper face of at least one lower side brick resting on said brick.

The thickness of the brick is usually its smallest dimension. Typically, the thickness measures the distance between a hot side in contact with the atmosphere of the furnace and an opposite cold side.

The equivalent diameter of the cross section of the beam is the diameter of a disc having the same area as the cross section.

The term "grains" refers to crystalline elements having a homogeneous or eutectic composition and a size greater than 10 μm.

The term "crystallites" means a surface area of more than 0.1 μm²And less than 10 μm²The surface area is measured on an image taken on a section of the product by an optical microscope.

The term "grain size" refers to the sum of the total length and half the total width of the grains, measured on an image taken by an optical microscope on a section of the product, the width being measured in a direction perpendicular to said length.

The term "average" means the arithmetic mean.

The term "ZrO₂The term "grains" is intended to include more than 80%, preferably more than 90%, preferably more than 95%, preferably more than 98% ZrO in mass percent on the basis of the oxides₂The crystal grains of (1).

All composition-related percentages are mass percentages based on oxides, unless otherwise indicated.

The total porosity is generally given by the following relation:

total porosity is 100 × (absolute density-apparent density)/absolute density.

The apparent density is measured in the healthy area according to standard ISO 5017 from test bars taken from the core of the part. Absolute density was measured on the ground powder using a helium pycnometer.

The terms "comprising", "having" and "including" should be interpreted in a broad, non-limiting sense.

Drawings

Other features and advantages of the present invention will become more apparent upon reading the following detailed description and upon reference to the accompanying drawings in which:

fig. 1 shows a cross-sectional view on a cutting plane perpendicular to a marking surface of a part according to the invention marked by laser radiation;

fig. 2 shows the transition between the marked and unmarked surfaces of a refractory ceramic part obtained according to the method of the invention, the marked area of the left half of the photograph having a glassy appearance, the area on the right half of the photograph not irradiated by the laser exhibiting the texture of the base product;

FIG. 3 shows an example of a data matrix imprinted on a refractory part according to the method of the invention, the approximately 30mm by 30mm square mark consisting of a set of squares with a side length of approximately 1 mm.

Detailed Description

The refractory ceramic part to be marked comprises or consists of a sintered material or preferably a molten material. The total porosity of the refractory ceramic part is preferably less than 5%, preferably less than 3% or preferably less than 1%.

Preferably, the refractory ceramic part to be marked is obtained by: a raw material consisting of refractory particles is melted, the liquid bath thus obtained is cast in a mould and then cooled to solidify the liquid mass in the mould. Preferably, the refractory ceramic parts to be marked are obtained by electric melting, preferably using an electric arc furnace.

Preferably, the maximum thickness of the refractory ceramic part is greater than 50mm or 75mm, and/or preferably less than 300mm, less than 200mm or even less than 100 mm.

In particular, the refractory ceramic parts to be marked may be selected from the group consisting of channel bricks, plate bricks, burner arches or other parts of the superstructure of a glass melting furnace, preferably from channel bricks.

The surface to be marked may be on any surface of the refractory ceramic part. Preferably, the surface is on a hot side or a cold side.

Ceramic parts typically include an intercrystalline bonding phase connecting the grains.

The grains comprise preferably more than 80%, more than 90%, more than 95%, or even essentially 100% by volume of ZrO₂Grains, and optionally a corundum-zirconia eutectic mixture.

Preferably, more than 80%, more than 90%, more than 95%, or even substantially 100% of the grains, in mass percent, are ZrO₂And (4) crystal grains.

The zirconia in the refractory ceramic part is present in the form of grains. These single-crystal or polycrystalline grains contain the element Zr and are preferably composed of ZrO₂Composition of, ZrO₂Is greater than 95%, greater than 98%, greater than 99% or essentially 100% of its mass.

The average grain size, in particular on the surface to be marked, is preferably greater than 10 μm, preferably greater than 20 μm, preferably greater than or equal to 30 μm and/or less than 200 μm, preferably less than 100 μm.

More than 90% by mass of the refractory ceramic parts are preferably made of a material selected from ZrO₂、Al₂O₃、SiO₂、Cr₂O₃、Y₂O₃And CeO₂One or more oxides of the group. Preferably, ZrO₂、Al₂O₃And SiO₂Together account for more than 90% of the mass of the refractory ceramic part.

Preferably, the refractory ceramic part comprises more than 15% ZrO₂And more preferably contains 26 to 95% of ZrO₂。

In various preferred embodiments, the composition of the base product is such that, for a total of up to more than 90%, up to more than 95% or even up to more than 98%:

-ZrO₂: 26% to 45%;

-Al₂O₃: 40% to 60%;

-SiO₂: 5% to 35%;

or such that:

-ZrO₂: 50% to less than 80%;

-Al₂O₃: 15% to 30%;

-SiO₂: 5% to 15%;

or such that:

-ZrO₂: 80% to 98%;

-Al₂O₃: 5% to 20%;

-SiO₂: 1% to 12%;

or such that:

-10％<ZrO₂≤25％；

-50％<Al₂O₃<75％；

-5％<SiO₂<35％。

preferably, in particular for all these embodiments, Na is based on the mass percentage of the oxide of the base product₂O and B₂O₃Is less than 2 percent.

The binder phase comprises and preferably consists of one or more glass or glass-ceramic phases. Preferably, the binder phase constitutes from 5% to 50%, preferably from 10% to 40%, by mass of the refractory ceramic part.

Preferably, the binder phase is a silicate phase, Na thereof₂The proportion by mass of O is preferably less than 20%, preferably less than 10% and/or Al₂O₃Is less than 30 percent.

To mark the surface of a refractory ceramic part, a predetermined amount of energy is concentrated on a small surface area at a predetermined time.

Preparation of

Before the laser beam is projected, a refractory ceramic part to be marked is prepared.

Preferably, the refractory ceramic part to be marked is ground so that the surface to be marked is flat. Preferably, the flatness or "radian" of the surface, measured using a micrometer feeler gauge over a representative length of at least 10cm, is less than 100 μm, preferably less than 50 μm.

Preferably, the roughness of the surface to be marked is such that the roughness Ra, measured according to standard ISO4287/1997, is less than 20 μm, preferably less than 15 μm, more preferably less than 10 μm, over a reference length of 100 microns. Thus, for example, in AZS type materials, the variation in z (valleys and peaks) measured with a feeler gauge over a 150 micron profile is +30/-30 microns, preferably +20/-20 microns.

Preferably, the part to be marked is dried so that its moisture percentage is less than or equal to 1%, preferably less than 0.5%.

Radiation of radiation

The means for emitting the laser beam may be a conventional laser device, preferably CO₂Type, preferably with a wavelength of 1065 ± 5nm, preferably with an average laser beam power (or "average output power") of 10W to 100W, preferably 20W to 60W.

The device may comprise aiming means which help to position the laser beam and/or the graphical interface for introducing an image representing the symbol or trademark or two-dimensional code to be reproduced on the refractory ceramic part, for example in JPEG format.

The device is arranged to irradiate the surface to be marked with an incident beam of laser light, so as to be preferably greater than 5J/mm³Preferably greater than 7J/mm³Preferably more than 10J/mm³Preferably more than 20J/mm³Or even greater than 30J/mm³And/or less than 2000J/mm³Preferably less than 1500J/mm³Preferably less than 1000J/mm³Preferably less than 500J/mm³Is transmitted to the surface.

The exposure energy is the ratio of the power per unit area of the beam to the speed at which the incident beam travels over the surface to be marked.

The power per unit area is incidentThe power of the light beam (watts) divided by the surface area (mm) of the cross-section of the incident light beam when it meets the surface to be marked²) The ratio of.

The cross-section of the incident light beam may have various shapes, such as a circular cross-section.

The equivalent diameter or "radiation width" of the cross-section of the incident light beam is preferably larger than 10 μm, preferably larger than 30 μm, preferably larger than 35 μm, and/or smaller than 100 μm, preferably smaller than 55 μm, when the incident light beam encounters the surface to be marked. Such equivalent diameters are particularly suitable for marking refractory ceramic parts having ceramic grains connected by a glass phase or glass-ceramic.

Preferably, the beam width is dependent on the ZrO present at the surface of the substrate product₂The average size of the grains varies. Preferably, the larger the average grain size, the larger the beam width. Preferably, the beam width is ZrO₂Between 0.5 and 2 times the average size of the grains.

The power per unit area of the incident beam is greater than 1000W/mm²Preferably greater than 5000W/mm²Preferably more than 7000W/mm²Preferably greater than 10000W/mm²And/or preferably less than 100000W/mm²Preferably less than 50000W/mm²Preferably less than 30000W/mm²。

Energy must be supplied to the surface to be marked to limit the depth of removal of the binder phase.

The device used is a pulsed laser, the pulse frequency "F" preferably being greater than 10kHz, preferably greater than 20kHz, and/or less than 300kHz, preferably less than 200kHz, preferably less than 100 kHz.

Advantageously, the combination of the pulsation and the travel of the light beam makes it possible to create a mark consisting of a plurality of points, each point resulting from the action of a pulse on the surface to be marked.

Preferably, the dot density is at 100 dots/mm²To 1000 dots/mm²In the meantime.

A marking is a visual indication that has meaning for a person or machine, such as an alphanumeric character or a two-dimensional code, such as a dot matrix (e.g. a data matrix or QR code) or a graphical representation, such as a symbol or a drawing. Preferably, the indicia is a Datalogic matrix 210 Datamatrix reader sold by Trumpf corporation or In-sight 7210 camera readable code sold by 7tech corporation equipped with a sensor of 600 x 800 pixel resolution.

Preferably, the marker consists of one or more sets of said points. Preferably, the indicia, especially when it represents an alphanumeric character or code, has a maximum dimension of between 1cm and 5 cm.

The surface area or "marking area" (e.g., the surface area over which a plurality of alphanumeric characters extend) of all markings on the refractory ceramic part is preferably greater than 100cm²And/or less than 1000cm²Preferably less than or equal to 200cm². The marking area may be, for example, a square with a side of 30 cm.

The marking zone may comprise a set of alphanumeric characters, for example a sequence of 5 to 15 digits, each digit preferably having a height of 1cm to 5 cm. These characters preferably pass through a density of 100 to 1000 dots/mm²Is obtained.

The linear travel speed "V" (in mm/s) of the incident light beam on the surface of the refractory ceramic part is preferably greater than 30mm/s, greater than 40mm/s, preferably greater than 50mm/s, and/or less than 3000mm/s, preferably less than 2000mm/s, preferably less than 1500mm/s, preferably less than 1000 mm/s.

Typically, the incident beam is obtained by focusing a primary beam.

The shorter the focal length "D", the higher the power per unit area.

The focal length D is preferably between 50mm and 500mm, preferably between 100mm and 450mm, preferably between 150mm and 400 mm. Advantageously, such a focal length is compatible with the equivalent diameters described above, in particular between 10 μm and 100 μm.

The inventors have found that it is particularly advantageous to have the laser device arranged in accordance with the following relation (1): a.V²+b.F²+c.VF+d.V+e.F+f<0, wherein:

a＝10⁴.D+2×10⁶

b＝0.5×10⁶.D-150×10⁶

c＝0.5×10⁶.D-300×10⁶

d＝5×10³.D-2.5×10⁶

e＝-5×10³.D+2.0×10⁶

f＝-5×10⁹.D+1.8×10¹²

v is expressed in mm/sec, D is expressed in mm, and F is expressed in kHz.

In one embodiment, F/V is greater than D/800. The marking is then very heat resistant and still recognizable, in particular after a heat treatment of the refractory ceramic parts in air at 800 ℃ for 24 hours.

In one embodiment, F/V is less than D/800. The glassy phase is then removed by a laser beam at a depth typically less than 20% of the average size of the grains of the refractory ceramic part. The marking remains identifiable and contrasts, but does not affect the wear resistance of the refractory ceramic part. However, it was erased after heat treatment at 800 ℃ for 24 hours in air.

Preferably, the tightness of the radiation is generally ensured by the dome, in which the positive pressure of air is maintained, isolating the surface to be marked.

Marking method is carried out on ZrO₂Cavities are formed among the crystal grains, and the roughness of the surface of the refractory ceramic part is increased. However, the depth of the cavities is less than the average size of the grains. For example, in the case of AZS-type materials, the roughness of the marking surface is such that Ra, measured according to the standard, is typically between 5 μm and 50 μm. The z variation measured with a feeler on a profile with a length of 800 microns is on average about +5/-20 microns, forming a groove of 10 to 100 microns over a length of about one hundred microns. Such a surface profile seems to constitute a feature of the method according to the invention.

Examples of the invention

The following embodiments are provided for illustrative purposes only and do not limit the present invention.

Dry product sold by the company Zefpro, made of the molten product ER1681, having dimensions 500mm x 600mm x 75mmDry block (32% ZrO)₂，51％Al₂O₃，15％SiO₂) The IV-level laser solution F-30 fiber laser using an ytterbium-doped YAG source was marked in air with a wavelength of 1064nm, an average output power of 30W, and a beam with a circular cross-sectional diameter of about 50 microns. Two focal lengths of 160mm and 330mm are used. The function of the laser is managed by a control unit directly connected to the fiber laser.

The total porosity of the molten product ER1681 was 2.5%.

The molten product ER1681 has the conventional microstructure of AZS molten products, i.e. ZrO bonded by silicate bonds₂And (4) crystal grains.

For marking, each brick is placed on a face of dimensions 500mm x 600mm and the laser beam is then moved along the other face. The block was then observed.

In order to observe whether or not the mark was erased, the marked portion was fired in air at 800 ℃ for 24 hours, and whether or not the mark was erased was observed.

Table 1 shows these observations.

The molten product ER1681 has the conventional microstructure of AZS molten products, i.e. ZrO bonded by silicate bonds₂And (4) crystal grains.

The examples according to the invention show that if the variables F and V are chosen so as to comply with relation (1), the marking has a uniform color, no fading, and a contrast which ensures very good recognizability.

Comparative example 1a, performed at a lower pulse frequency, had a non-erasable but difficult to identify contrast mark than example 1a according to the present invention. The average roughness of the marked surface is high.

The travel speeds of comparative examples 2a and 2b were significantly changed with respect to examples 2a and 2b according to the present invention, respectively. Therefore, the identifiability of the label is significantly reduced.

A comparison of examples 1c and 1b shows that lowering the pulse frequency F makes it possible to erase the mark after a heat treatment at 800 c for 24 hours.

Examples 3 and 4 according to the invention show that at a constant frequency, the marking can become erasable (for a product according to the invention) by varying the speed of travel of the laser beam along the surface of the refractory brick to be marked.

A satisfactory reaction with respect to blistering of parts marked according to the invention was observed in a conventional blistering test with soda-lime glass at 1100 c for 30 hours. Thus, the parts marked according to the marking method of the present invention are suitable for lining glass melting furnaces.

It is evident that the present invention provides an easy-to-implement marking method which does not alter the properties of the refractory ceramic parts and which enables to obtain a marking of refractory ceramic parts suitable for metallurgical or glass melting furnaces.

It goes without saying that the invention is not limited to the described embodiments, which are provided as non-limiting examples.