阅读说明：本技术 一种中空结构的超硬材料聚晶多层复合片及其制备方法 (Superhard material polycrystalline multilayer composite sheet with hollow structure and preparation method thereof ) 是由 陈家荣 陈超 莫培程 贾光 林峰 于 2019-11-28 设计创作，主要内容包括：本发明公开了一种中空结构的超硬材料聚晶多层复合片及其制备方法。所述的制备方法包括：1)根据聚晶层配方称取超硬磨料和粘结剂,混匀后作还原、高温净化,得到聚晶层混合粉料；2)将高度相同、口径不同的大、小两个金属杯同心放置并将其底部焊接,得到焊接后的金属杯；3)获得与前述聚晶层混合粉料相匹配且形状与焊接后的金属杯相匹配的硬质合金基体；4)向内层结构中填充氯化钠,装满后盖紧盖子；在外层结构中交替填充聚晶层混合粉料和硬质合金基体直至外层结构填满；5)将装满物料的金属杯进行还原、高温净化,在外层结构上加盖盖紧；6)将加盖后的金属杯置于介质中进行压制,取出后去除外层结构、内层结构及其中的氯化钠,即得。(The invention discloses a superhard material polycrystalline multilayer composite sheet with a hollow structure and a preparation method thereof. The preparation method comprises the following steps: 1) weighing the superhard abrasive and the binder according to the formula of the polycrystalline layer, uniformly mixing, and then carrying out reduction and high-temperature purification to obtain polycrystalline layer mixed powder; 2) placing two large and small metal cups with the same height and different calibers concentrically and welding the bottoms of the two metal cups to obtain welded metal cups; 3) obtaining a hard alloy matrix which is matched with the mixed powder of the polycrystalline layer and the shape of which is matched with the welded metal cup; 4) filling sodium chloride into the inner layer structure, and tightly covering the cover after the inner layer structure is filled with the sodium chloride; alternately filling the polycrystalline layer mixed powder and the hard alloy matrix in the outer layer structure until the outer layer structure is filled; 5) reducing and purifying the metal cup filled with the materials at high temperature, and covering and tightly covering the outer layer structure; 6) and (3) placing the metal cup covered with the cover into a medium for pressing, taking out the metal cup, and removing the outer layer structure, the inner layer structure and sodium chloride in the outer layer structure, thus obtaining the metal cup.)

1. A preparation method of a superhard material polycrystalline multilayer composite sheet with a hollow structure comprises the following steps:

1) weighing a superhard abrasive and a binder according to a formula of a polycrystalline layer of the superhard material polycrystalline composite sheet to be prepared, uniformly mixing, then placing in a hydrogen atmosphere for reduction, then placing in a vacuum condition for high-temperature purification, and cooling to obtain polycrystalline layer mixed powder for later use;

2) selecting a large metal cup and a small metal cup which are the same in height and different in caliber, placing the small metal cup in the large metal cup and placing the small metal cup and the large metal cup concentrically, and then welding and fixing the bottoms of the two metal cups to obtain a welded metal cup; the welded metal cup is provided with an inner layer structure and an outer layer structure, wherein the inner layer structure corresponds to the small metal cup, the outer layer structure corresponds to the large metal cup, the axes of the inner layer structure and the outer layer structure are coincident, and the inner layer structure and the outer layer structure form a ring shape;

3) obtaining a hard alloy matrix which is matched with the mixed powder of the polycrystalline layer and has a shape matched with the ring shape of the welded metal cup;

4) filling sodium chloride into the inner layer structure of the welded metal cup, and tightly covering the cover after the inner layer structure is filled with the sodium chloride; then placing the mixed powder of the polycrystalline layer in an outer layer structure of a welded metal cup, paving and compacting, and then placing a hard alloy matrix into the outer layer structure and compacting; repeatedly putting mixed powder of polycrystalline layers, paving and compacting, and then putting a hard alloy matrix and compacting until the outer layer structure is filled;

5) reducing the metal cup filled with the materials in a hydrogen atmosphere, then purifying at high temperature under a vacuum condition, cooling, taking out, and covering tightly on an outer layer structure;

6) and (2) placing the metal cup with the cover in a heat-preservation pressure-transmitting medium, performing high-temperature high-pressure synthesis, taking the metal cup out of the heat-preservation pressure-transmitting medium after the high-temperature high-pressure synthesis is completed, grinding an outer layer structure of the metal cup to expose alternate polycrystalline layers and hard alloy matrix layers, then punching a hole on a cup cover of an inner layer structure, washing with water to remove sodium chloride in the inner layer structure, and removing the inner layer structure to obtain the superhard material polycrystalline multilayer composite sheet with the hollow structure.

2. The method of claim 1, wherein: the superhard abrasive is one or the combination of more than two of cubic boron nitride, diamond and titanium diboride.

3. The method of claim 1, wherein: the binder is one or the combination of more than two of iron, cobalt and nickel.

4. The method of claim 1, wherein: the reduction is carried out at the temperature of 450-900 ℃, and the reduction time is 1-3 h.

5. The method of claim 1, wherein: the high-temperature purification is carried out under the vacuum degree of 10^-2-10^{- 4}Pa, the temperature of 600-1200 ℃, and the dehydrogenation time of 1-3 h.

6. The method of claim 1, wherein: the process conditions of the high-temperature high-pressure synthesis are as follows: the pressure is 4.5-5.5GPa, the temperature is 1400-1750 ℃ and the time is 150-800 s.

7. A polycrystalline multilayer compact of superhard material of hollow structure produced by the method of any one of claims 1 to 6.

Technical Field

The invention relates to a preparation method of a superhard composite material, in particular to a preparation method of a superhard material polycrystalline multilayer composite sheet with a hollow structure.

Background

The polycrystalline composite material of the superhard material with the multilayer structure has the advantages of both the ultrahigh hardness of the superhard material and the toughness of hard alloy, is a hard and tough composite material suitable for manufacturing tools for processing other materials, has incomparable superiority particularly in the aspect of processing and cutting hard materials, and occupies irreplaceable importance. As such, superhard materials have found wide industrial application. Besides being used for manufacturing cutters, the wear-resistant material can also be applied to the field of wear resistance and can resist long-term friction of fluid or solid. For parts such as bearings which need to be impact resistant and wear resistant, polycrystalline compacts of superhard materials with high wear resistance and high compressive strength are required. At present, no report related to a method for preparing the superhard material polycrystalline multilayer compact with a hollow structure exists.

Disclosure of Invention

The invention aims to provide a novel superhard material polycrystalline multilayer composite sheet with a hollow structure and a preparation method thereof.

The preparation method of the superhard material polycrystalline multilayer composite sheet with the hollow structure comprises the following steps:

1) weighing a superhard abrasive and a binder according to a formula of a polycrystalline layer of the superhard material polycrystalline composite sheet to be prepared, uniformly mixing, then placing in a hydrogen atmosphere for reduction, then placing in a vacuum condition for high-temperature purification, and cooling to obtain polycrystalline layer mixed powder for later use;

2) selecting a large metal cup and a small metal cup which are the same in height and different in caliber, placing the small metal cup in the large metal cup and placing the small metal cup and the large metal cup concentrically, and then welding and fixing the bottoms of the two metal cups to obtain a welded metal cup; the welded metal cup is provided with an inner layer structure and an outer layer structure, wherein the inner layer structure corresponds to the small metal cup, the outer layer structure corresponds to the large metal cup, the axes of the inner layer structure and the outer layer structure are coincident, and the inner layer structure and the outer layer structure form a ring shape;

3) obtaining a hard alloy matrix which is matched with the mixed powder of the polycrystalline layer and has a shape matched with the ring shape of the welded metal cup;

4) filling sodium chloride into the inner layer structure of the welded metal cup, and tightly covering the cover after the inner layer structure is filled with the sodium chloride; then placing the mixed powder of the polycrystalline layer in an outer layer structure of a welded metal cup, paving and compacting, and then placing a hard alloy matrix into the outer layer structure and compacting; repeatedly putting mixed powder of polycrystalline layers, paving and compacting, and then putting a hard alloy matrix and compacting until the outer layer structure is filled;

5) reducing the metal cup filled with the materials in a hydrogen atmosphere, then purifying at high temperature under a vacuum condition, cooling, taking out, and covering tightly on an outer layer structure;

6) and (2) placing the metal cup with the cover in a heat-preservation pressure-transmitting medium, performing high-temperature high-pressure synthesis, taking the metal cup out of the heat-preservation pressure-transmitting medium after the high-temperature high-pressure synthesis is completed, grinding an outer layer structure of the metal cup to expose alternate polycrystalline layers and hard alloy matrix layers, then punching a hole on a cup cover of an inner layer structure, washing with water to remove sodium chloride in the inner layer structure, and removing the inner layer structure to obtain the superhard material polycrystalline multilayer composite sheet with the hollow structure.

In the step 1) of the preparation method, the formula of the diamond polycrystalline layer is the same as that of the prior art, and the preferable formula comprises the following components in percentage by mass: 0.1-15% of adhesive and the balance of super-hard abrasive. The selection of the adhesive and the super-hard abrasive is the same as that of the prior art, and specifically, the adhesive can be one or the combination of more than two of iron, cobalt and nickel; the superhard abrasive material can be one or a combination of more than two of cubic boron nitride, diamond and titanium diboride, and therefore, the superhard material polycrystalline multilayer compact with the hollow structure in the invention refers to a polycrystalline diamond multilayer compact with the hollow structure or a polycrystalline cubic boron nitride multilayer compact with the hollow structure. The binder and the superabrasive material are both present in powder form and their particle size is selected as in the prior art, wherein the binder preferably has a particle size of 0.1-5 μm and the superabrasive material preferably has a particle size of 0.5-30 μm.

In steps 1) and 5) of the preparation method, the reduction and dehydrogenation treatment is the same as the prior art, preferably, the reduction is carried out at the temperature of 450-900 ℃, and the reduction time is 1-3 h; high temperature purification is carried out under the vacuum degree of 10^-2-10^-4Pa, temperature of 600-1200 ℃, and the purification time is usually 1-3 h.

In step 2) of the above preparation method, the metal cup of the present invention is a cup conventionally used for containing powder in the prior art, such as a cup made of a ductile material, such as a molybdenum cup, a niobium cup or a zirconium cup with a lid, and the corresponding cup lid may be a molybdenum lid or a zirconium lid, which is similar to the conventional lid.

In step 3) of the above preparation method, the hard alloy matrix and the polycrystalline layer mixed powder in step 1) are matched according to materials known by those skilled in the art. Specifically, the hard alloy matrix is the conventional alloy of tungsten carbide and cobalt, the alloy of tungsten carbide and titanium or the alloy formula of tungsten carbide and nickel. In this step, the cemented carbide substrate is obtained by a conventional method, such as preparing according to a conventional method (weighing the components according to the formula, mixing the components, forming according to a ring shape formed by welded metal cups, and sintering), or directly purchasing a conventional cemented carbide substrate such as YG16, YG16C, YG12, YG12C, YG10, YG10C, YG13H, YG8, etc. on the market. The thickness of the hard alloy matrix is the conventional thickness of the matrix in the existing composite sheet, and the shape of the hard alloy matrix is matched with the ring shape presented by the welded metal cup.

In the step 4) of the preparation method, the filling thickness of the mixed powder of the polycrystalline layer is the conventional thickness of the polycrystalline layer in the prior art. After all operations of filling and compacting the polycrystalline layer mixed powder and the hard alloy matrix are completed, the metal cup is preferably placed in a cold-pressing die for compaction and then subjected to subsequent reduction operation.

In step 6) of the above preparation method, the heat-insulating pressure-transmitting medium and the subsequent high-temperature high-pressure synthesis are the same as those in the prior art, specifically, the heat-insulating pressure-transmitting medium is usually pyrophyllite, and the process conditions of the high-temperature high-pressure synthesis are preferably as follows: the pressure is 4.5-5.5GPa, the temperature is 1400-1750 ℃ and the time is 150-800 s. Usually, a metal cup taken out of a heat-preservation pressure-transmission medium is put into a centerless grinder to grind an outer layer structure of the metal cup to expose alternate polycrystalline layers and hard alloy matrix layers, then a drill bit is used for punching a cup cover of an inner layer structure, water is used for washing to remove sodium chloride in the inner layer structure, and finally a spray-exchange machine is used for removing the inner layer structure.

The invention also discloses the superhard material polycrystalline multilayer composite sheet with the hollow structure prepared by the method.

Compared with the prior art, the invention adopts two metal cups with different sizes to be concentrically arranged and welded together, the small metal cup is filled with sodium chloride which is easy to remove to form a hollow structure, the large metal cup is alternately filled with polycrystalline layer mixed powder and a hard alloy matrix, and the sodium chloride and the large and small metal cups are removed after high-temperature and high-pressure synthesis to obtain the superhard material polycrystalline composite sheet with the hollow structure. The method has simple process and easy operation, and the obtained superhard material polycrystalline compact with the hollow structure can be used for parts needing impact resistance and abrasion resistance due to the hardness and the abrasion resistance of the superhard abrasive material.

Drawings

Fig. 1 is a schematic structural view of a polycrystalline diamond multilayer compact having a hollow structure according to example 1 of the present invention.

The reference numbers in the figures are:

1 polycrystalline diamond multilayer composite sheet with a hollow structure, 1-1 polycrystalline layer and 1-2 hard alloy matrix layer.

Detailed Description

The present invention will be better understood from the following detailed description of specific examples, which should not be construed as limiting the scope of the present invention.

Diamond powder and cubic boron nitride powder described in the following examples were subjected to conventional chemical acid-base purification treatment.