Corrosion-resistant diamond compact and method of making
By adding tantalum powder to the matrix of diamond composite sheets, Co-Ni-Ta and Co-Ni-Cr-Ta composite systems are formed, which solves the problem of insufficient corrosion resistance of diamond composite sheets under high temperature environment and achieves better corrosion resistance and strength.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- CHONGQING BEISIKA NEW MATERIALS CO LTD
- Filing Date
- 2026-03-31
- Publication Date
- 2026-05-29
AI Technical Summary
Existing diamond composite sheets lack sufficient corrosion resistance and wear resistance under high-temperature environments, making it difficult to meet the needs of modern applications.
A corrosion-resistant matrix and a polycrystalline diamond layer are used. Tantalum powder is added to the matrix to form Co-Ni-Ta and Co-Ni-Cr-Ta composite systems through in-situ diffusion, which enhances the connection strength. TaC is formed under high temperature and high pressure to improve the chemical inertness and oxidation resistance of the matrix.
It significantly improves the corrosion resistance of diamond composite sheets, especially reducing corrosion weight loss by more than 30% in acidic drilling fluids, while maintaining good strength and toughness.
Smart Images
Figure CN122099341A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of superhard materials, specifically to a corrosion-resistant diamond composite sheet preparation technology. Background Technology
[0002] Diamond composite sheets are a type of composite material made by sintering diamond micropowder and cemented carbide matrix under ultra-high pressure and high temperature conditions. They possess both the high hardness, high wear resistance and thermal conductivity of diamond and the strength and impact toughness of cemented carbide. They are currently widely used in fields such as oil drilling and machining.
[0003] Diamond composite sheets mainly consist of an alloy matrix and a diamond layer. During preparation, diamond micropowder and the matrix are sintered under high temperature and high pressure. In order to connect the diamond micropowder and the matrix, the commonly used method is as shown in the polycrystalline diamond layer composite sheet and its preparation method disclosed in patent number CN120249769A, where cobalt and nickel are used as binders to connect the diamond layer formed by diamond micropowder to the matrix.
[0004] However, in the aforementioned binder phase, the cobalt content is 8.5%-10% of the mass of the cemented carbide matrix layer, and the nickel content is 1.5%-3% of the mass of the cemented carbide matrix layer. Although the tungsten carbide cemented carbide matrix layer improves the wear resistance and chemical corrosion resistance of diamond composite sheets compared with diamond composite sheets with ordinary matrix, it is still difficult to meet the current requirements for wear resistance and corrosion resistance in high-temperature environments. Summary of the Invention
[0005] The present invention aims to provide a corrosion-resistant diamond composite sheet and a preparation method thereof, so as to further improve the corrosion resistance of the diamond composite sheet.
[0006] To achieve the above objectives, the present invention adopts the following technical solution: a corrosion-resistant diamond composite sheet, comprising a corrosion-resistant matrix and a polycrystalline diamond layer, wherein the polycrystalline diamond layer comprises cobalt, and 0.8-1.5 parts by weight of nickel, 0.1-1.0 parts by weight of chromium, and 0.05-0.5 parts by weight of tantalum, wherein the weight of cobalt is greater than zero and less than or equal to 6.0 parts. The corrosion-resistant matrix comprises, by weight, 86.4-91.8 parts of tungsten carbide, 4.0-8.0 parts of cobalt, 2.0-4.0 parts of nickel, 0.1-0.8 parts of chromium, and 0.1-0.8 parts of tantalum.
[0007] Furthermore, the bonding phase of the polycrystalline diamond layer includes Co-Ni-Cr, Co-Ni-Ta, and Co-Ni-Cr-Ta.
[0008] Furthermore, the cobalt content in the polycrystalline diamond layer is 3-5.5 parts by weight.
[0009] Furthermore, the chromium content in the corrosion-resistant matrix is 0.1-0.8 parts by weight.
[0010] Furthermore, the tantalum content in the polycrystalline diamond layer is 0.1-0.3 parts by weight.
[0011] A method for preparing a corrosion-resistant diamond composite sheet, used to prepare any of the above-mentioned corrosion-resistant diamond composite sheets, includes the following steps: Step 1: Preparation of corrosion-resistant matrix. Tungsten carbide powder is mixed with metal powder, including cobalt powder, nickel powder and tantalum powder. After pressing and molding, vacuum sintering is performed. The sintering time is 40-120 min, the sintering temperature is 1400-1450℃ and the sintering pressure is 10-20 MPa to obtain the corrosion-resistant matrix. Step 2: Encapsulation. After the diamond micro powder and catalyst are mixed evenly, they are placed into a high-temperature resistant metal cup, then the above-mentioned corrosion-resistant matrix is placed in and encapsulated. Finally, it is placed into a high-temperature and high-pressure container. Step 3: High temperature and high pressure synthesis and sintering. The high temperature and high pressure container is placed in a six-sided top press and pressurized and heated until the pressure reaches 5.5-9.0 GPa and the temperature is 1350-1550℃. The temperature is held for 30s-8min to obtain diamond composite sheets.
[0012] Furthermore, the average particle size of the diamond powder is 5-50 μm.
[0013] Furthermore, in step 2, the weight ratio of the catalyst to the diamond micron powder is (0-3.0):(97-100).
[0014] The beneficial effects of this plan are: The corrosion-resistant matrix in this scheme includes tantalum powder. During the preparation of the corrosion-resistant matrix, tantalum is dispersed throughout the matrix. Therefore, in the assembly and sintering step 3, the corrosion-resistant matrix acts as an element diffusion source. Through in-situ diffusion, tantalum in the corrosion-resistant matrix diffuses into the polycrystalline diamond layer and combines with tantalum, cobalt, and chromium in the polycrystalline diamond layer. When chromium is present in the corrosion-resistant matrix, it also enters the polycrystalline diamond layer through in-situ diffusion. Therefore, the corrosion-resistant matrix in this scheme is not only connected to the polycrystalline diamond layer under the catalysis of cobalt and nickel, but also the tantalum in the matrix combines with cobalt, nickel, and chromium, thereby increasing the bonding strength between the polycrystalline diamond layer and the corrosion-resistant matrix.
[0015] Furthermore, the tantalum in this solution exists within the corrosion-resistant matrix in the form of Co-Ni-Ta and Co-Ni-Cr-Ta composite systems. Compared to adding TaC powder to diamond micron powder, the addition of tantalum powder to the corrosion-resistant matrix in this solution improves the corrosion resistance of the matrix. Moreover, compared to a tantalum metal coating only on the surface of the corrosion-resistant matrix, the tantalum in this solution is also distributed within the interior of the corrosion-resistant matrix, inhibiting the growth of WC grains at high temperatures and maintaining the excellent strength and toughness of the alloy. During the use of the diamond composite sheet, even if the corrosion-resistant matrix is worn, the exposed parts inside the corrosion-resistant matrix still have good corrosion resistance.
[0016] Secondly, some existing patented technologies typically involve directly adding TaC powder to diamond micron powder, which may be beneficial for diamond particle bonding under high temperature and pressure, but it does not improve the corrosion resistance of the matrix alloy and cannot meet the requirements of applications in corrosive environments. However, the inventors discovered by chance that adding tantalum powder to the corrosion-resistant matrix results in a relatively lower sintering temperature requirement and reduced difficulty in temperature control. Simultaneously, because tantalum forms Co-Ni-Ta and Co-Ni-Cr-Ta phases during sintering, the presence of this system can prevent WC grains from growing in the diamond layer. Furthermore, tantalum powder combines with C during sintering to form TaC, which enhances the chemical inertness and oxidation resistance of the resulting corrosion-resistant matrix.
[0017] In summary, the diamond composite sheet in this solution exhibits better chemical inertness and oxidation resistance. In non-oxidizing acidic, neutral, and alkaline media, a stable surface film can be formed on the corrosion-resistant substrate surface, thereby reducing the corrosion rate. Furthermore, the nickel in the Co-Ni-Cr, Co-Ni-Ta, and Co-Ni-Cr-Ta composite systems has good corrosion resistance to acidic substances. Actual testing shows that the corrosion weight loss of the diamond composite sheet in this solution in acidic drilling fluid is ≤0.3mg / cm²·24h, which is more than 30% lower than that of traditional diamond composite sheets. Attached Figure Description
[0018] Figure 1 This is a perspective view of the diamond composite sheet in an embodiment of the present invention. Detailed Implementation
[0019] The following detailed description illustrates the specific implementation method: The reference numerals in the accompanying drawings include: corrosion-resistant substrate 1, polycrystalline diamond layer 2.
[0020] Example This invention discloses a corrosion-resistant diamond composite sheet, comprising a corrosion-resistant matrix 1 and a polycrystalline diamond layer 2. The polycrystalline diamond layer 2 comprises cobalt, and 0.8-1.5 parts by weight of nickel and 0.05-0.5 parts by weight of tantalum, wherein the weight of cobalt is greater than zero and less than or equal to 6.0 parts. The corrosion-resistant matrix 1 comprises, by weight, 86.4-91.8 parts of tungsten carbide, 6.0-8.0 parts of cobalt, 2.0-4.0 parts of nickel, 0.1-0.8 parts of chromium, and 0.1-0.8 parts of tantalum; Specifically, in the embodiments of the present invention, the polycrystalline diamond layer 2 contains 3-5.5 parts by weight of cobalt, 0.2-0.6 parts by weight of chromium, and 0.1-0.3 parts by weight of tantalum. Furthermore, the bonding phase of the polycrystalline diamond layer 2 includes Co-Ni-Ta and Co-Ni-Cr-Ta.
[0021] This invention also discloses a corrosion-resistant diamond composite sheet, used to prepare the above-mentioned corrosion-resistant diamond composite sheet, comprising the following steps: Step 1: Preparation of corrosion-resistant matrix. Tungsten carbide powder, cobalt powder, nickel powder, chromium powder and tantalum powder are mixed by ball milling, pressed into shape and then vacuum hot pressing sintered. The sintering time is 40-120 min, the sintering temperature is 1400-1450℃ and the sintering pressure is 10-20 MPa to obtain the corrosion-resistant matrix. Step 2: Encapsulation. Diamond micro powder with an average particle size of 5-50 μm is mixed evenly with the catalyst and then placed into a high-temperature resistant metal cup. The above-mentioned corrosion-resistant matrix is then placed inside and encapsulated. Finally, it is placed into a high-temperature and high-pressure container. The catalyst in this invention uses existing cobalt, nickel, or iron-containing catalysts for sintering polygold diamond composite sheets. Specifically, the catalyst in this embodiment uses one or more of cobalt powder, nickel powder, chromium powder, and tantalum powder. Step 3: High temperature and high pressure synthesis and sintering. Place the high temperature and high pressure container into a six-sided top press until the pressure reaches 5.5-9.0 GPa and the temperature is 1350-1550℃. Hold the temperature for 30s-8min to obtain diamond composite sheets.
[0022] This invention discloses Examples 1-3 and Comparative Example 1. The amounts of tungsten carbide powder, cobalt powder, nickel powder, chromium powder, and tantalum powder used in Examples 1-3 and Comparative Example 1, the ratio of pre-alloyed binder powder to diamond micron powder, the particle size of the diamond micron powder, the sintering temperature, pressure, and sintering time in step 1, and the different heating temperatures, pressures, and holding times in step 3 are shown in the table below:
[0023] The present invention also discloses Comparative Example 2, wherein the matrix of Comparative Example 2 contains 9 parts by weight of cobalt powder, 2 parts by weight of nickel powder, and 89 parts by weight of tungsten carbide powder; the polycrystalline diamond layer contains 99 parts by weight of diamond micro powder and 1 part by weight of cobalt powder; and a diamond composite sheet is obtained by using the same preparation method as Comparative Example 1.
[0024] The diamond composite sheets prepared in Examples 1-2 and Comparative Examples 1-2 were ground and polished in the same manner to obtain samples. The corrosion weight loss, impact toughness, and wear ratio of the samples were tested, and the test results are shown in the table below:
[0025] The above tests show that: 1. The corrosion weight loss test results show that the diamond composite sheets prepared in Examples 1 and 2 have better corrosion resistance. In particular, comparing Examples 1 and 2, compared to Example 1, Example 2 increased chromium powder but reduced tantalum powder content. According to common technical principles, increasing the amount of tantalum powder (Example 1) should result in higher corrosion resistance of the diamond composite sheet. However, the tests on Examples 1 and 2 show that the corrosion resistance of Example 1 is actually lower than that of Example 2. Therefore, the Co-Ni-Cr-Ta composite system in this scheme has better corrosion resistance.
[0026] 2. In terms of impact toughness and wear ratio tests, although the impact toughness is slightly insufficient compared to Comparative Example 2, the diamond composite sheet in this solution is more wear-resistant. Therefore, the diamond composite sheet in this solution is more suitable for drilling operations in the presence of acidic liquids or corrosive gases.
[0027] The above descriptions are merely embodiments of the present invention, and common knowledge such as specific technical solutions and / or characteristics are not described in detail here. It should be noted that those skilled in the art can make various modifications and improvements without departing from the technical solutions of the present invention, and these should also be considered within the scope of protection of the present invention. These modifications and improvements will not affect the effectiveness of the implementation of the present invention or the practicality of the patent. The scope of protection claimed in this application should be determined by the content of its claims, and the specific embodiments described in the specification can be used to interpret the content of the claims.
Claims
1. A corrosion-resistant diamond composite sheet, characterized in that: It includes a corrosion-resistant substrate and a polycrystalline diamond layer, wherein the polycrystalline diamond layer comprises cobalt, and 0.8-1.5 parts by weight of nickel and 0.05-0.5 parts by weight of tantalum, wherein the cobalt comprises more than zero and less than or equal to 6.0 parts by weight; The corrosion-resistant matrix comprises, by weight, 86.4-91.8 parts of tungsten carbide, 4.0-8.0 parts of cobalt, 2.0-4.0 parts of nickel, and 0.1-0.8 parts of tantalum.
2. The corrosion-resistant diamond composite sheet according to claim 1, characterized in that: The bonding phases of the polycrystalline diamond layer include Co-Ni-Ta and Co-Ni-Cr-Ta.
3. The corrosion-resistant diamond composite sheet according to claim 1, characterized in that: The cobalt content in the polycrystalline diamond layer is 3-5.5 parts by weight.
4. The corrosion-resistant diamond composite sheet according to claim 1, characterized in that: The chromium content in the corrosion-resistant matrix is 0.1-0.8 parts by weight.
5. The corrosion-resistant diamond composite sheet according to claim 1, characterized in that: The tantalum content in the polycrystalline diamond layer is 0.1-0.3 parts by weight.
6. A method for preparing a corrosion-resistant diamond composite sheet, characterized in that: The method for preparing the corrosion-resistant diamond composite sheet according to any one of claims 1-5 comprises the following steps: Step 1: Preparation of corrosion-resistant matrix. Tungsten carbide powder is mixed with metal powder, including cobalt powder, nickel powder and tantalum powder. After pressing and molding, vacuum sintering is performed. The sintering time is 40-120 min, the sintering temperature is 1400-1450℃ and the sintering pressure is 10-20 MPa to obtain the corrosion-resistant matrix. Step 2: Encapsulation. After the diamond micro powder and catalyst are mixed evenly, they are placed into a high-temperature resistant metal cup, then the above-mentioned corrosion-resistant matrix is placed in and encapsulated. Finally, it is placed into a high-temperature and high-pressure container. Step 3: High temperature and high pressure synthesis and sintering. The high temperature and high pressure container is placed in a six-sided top press and pressurized and heated until the pressure reaches 5.5-9.0 GPa and the temperature is 1350-1550℃. The temperature is held for 30s-8min to obtain diamond composite sheets.
7. The method for preparing a corrosion-resistant diamond composite sheet according to claim 6, characterized in that: The average particle size of diamond powder is 5-50 μm.
8. The method for preparing a corrosion-resistant diamond composite sheet according to claim 6, characterized in that: The weight ratio of catalyst to diamond powder in step 2 is (0-3.0):(97-100).