A single-crystal diamond composite material and its preparation method and application, a cobalt-based ceramic composite material and its preparation method and application

Abstract

The present invention belongs to the technical field of ceramic materials, and specifically relates to a single-crystal diamond composite material and its preparation method and application, as well as a cobalt-based ceramic composite material and its preparation method and application. The single-crystal diamond composite material provided by the present invention comprises single-crystal diamond and a functional layer coated on the surface of the single-crystal diamond; the material of the functional layer includes TiC, ZrH2 and Al. By coating with the functional layer, a protective layer is formed on the surface of the diamond, so that it is not affected by high temperature during sintering, effectively avoiding the occurrence of high-temperature carbonization phenomenon during the discharge sintering process, thereby maintaining its hardness and wear resistance; ZrH2 therein decomposes and releases hydrogen during the sintering process, effectively removing the pores in the material and promoting the densification of the material, while enhancing the bonding force between the diamond and the metal matrix, enabling a good interfacial bonding to be formed between the diamond and the metal matrix, thereby further improving the mechanical properties and wear resistance of the composite material.

Description

Technical Field

[0001] The present invention belongs to the technical field of ceramic materials, and particularly relates to a single-crystal diamond composite material, a preparation method and application thereof, a cobalt-based ceramic composite material, a preparation method and application thereof. Background Art

[0002] Cermet materials are composed of hard phases with high hardness and high melting points and binder phases with high toughness and relatively low melting points. Among them, cemented carbides based on Co, Ni, and Fe as the metal binder phase have been widely used in industry. Co has excellent wettability to WC and also has superior mechanical properties, making Co the most widely used metal in the binder phase. Diamond, as the hardest substance in nature, has extremely high hardness and wear resistance. Introducing it into cermet materials can significantly improve the hardness and wear resistance of the composite materials. This enhancement effect mainly comes from the uniform distribution of diamond particles in the composite materials, which can effectively resist external loads and friction, thereby extending the service life of the materials.

[0003] The traditional preparation method of cermet materials is mainly the spark plasma sintering process. During the sintering process, when discharging occurs at the voids of the grains, a local high temperature of up to several thousand degrees to ten thousand degrees will be generated. The formation of the local high temperature easily causes the surface of the diamond to be carbonized, thereby affecting the hardness and wear resistance of the cemented carbide. Summary of the Invention

[0004] The purpose of the present invention is to provide a single-crystal diamond composite material, a preparation method and application thereof, a cobalt-based ceramic composite material, a preparation method and application thereof. The single-crystal diamond composite material provided by the present invention can effectively prevent the diamond from being carbonized at high temperatures, and when applied to cermet materials, it can further improve their hardness and wear resistance.

[0005] In order to achieve the above purpose, the present invention provides the following technical solutions:

[0006] The present invention provides a single-crystal diamond composite material, including single-crystal diamond and a functional layer coated on the surface of the single-crystal diamond;

[0007] The material of the functional layer includes TiC, ZrH 2 and Al.

[0008] Preferably, the single-crystal diamond composite material includes the following components in mass percentage: 50-60% single-crystal diamond, 20-30% TiC, 5-15% ZrH 2 and 5-15% Al;

[0009] The particle size of the single-crystal diamond is 100-200 μm; the particle size of the TiC is 0.5-10 μm; the ZrH2 The particle size of which is 48 - 75 μm; the particle size of the Al is 48 - 75 μm.

[0010] The present invention also provides a preparation method of the single crystal diamond composite material described in the above technical solution, including the following steps:

[0011] Perform ball milling and mixing on the components included in the single crystal diamond composite material to obtain the single crystal diamond composite material.

[0012] Preferably, the rotation speed of the ball milling and mixing is 80 - 100 rpm, and the time is 48 h.

[0013] The present invention also provides the application of the single crystal diamond composite material described in the above technical solution or the single crystal diamond composite material prepared by the preparation method described in the above technical solution in the cermet composite material.

[0014] The present invention also provides a cobalt-based ceramic composite material, including the following raw materials for preparation by mass percentage: 70 - 80% of WC, 10 - 25% of Co, Yb 2 O 3 0 - 2% and the balance of modified diamond;

[0015] The modified diamond is the single crystal diamond composite material described in the above technical solution or the single crystal diamond composite material prepared by the preparation method described in the above technical solution.

[0016] Preferably, the particle size of the WC is 0.5 - 75 μm;

[0017] The particle size of the Co is 48 - 75 μm;

[0018] The particle size of the Yb 2 O 3 is 48 - 75 μm.

[0019] The present invention also provides a preparation method of the cobalt-based ceramic composite material described in the above technical solution, including the following steps:

[0020] Perform ball milling and mixing on the raw materials for preparation included in the cobalt-based ceramic composite material to obtain a mixture;

[0021] Sinter the mixture to obtain the cobalt-based ceramic composite material.

[0022] Preferably, the rotation speed of the ball milling and mixing is 160 - 180 rpm, and the time is 48 h;

[0023] The sintering includes performing first sintering, second sintering and third sintering in sequence;

[0024] The temperature of the first sintering is 550 - 650 °C, the heat preservation time is 2 - 3 min, and the pressure is 12 - 15 kN;

[0025] The temperature of the second sintering is 850 - 950 °C, the heat preservation time is 2 - 3 min, and the pressure is 23 - 25 kN;

[0026] The temperature of the third sintering is 1340 - 1360 °C, the heat preservation time is 0 - 6 min, and the pressure is 30 - 33 kN;

[0027] The sintering is carried out under vacuum conditions, and the vacuum degree ≤ 8×10 0 Pa.

[0028] The present invention also provides an application of the cobalt-based ceramic composite material described in the above technical solution or the cobalt-based ceramic composite material prepared by the preparation method described in the above technical solution as a tool.

[0029] The present invention provides a single-crystal diamond composite material, including single-crystal diamond and a functional layer coated on the surface of the single-crystal diamond; the material of the functional layer includes TiC, ZrH 2 and Al.

[0030] In the present invention, by adding TiC, the wettability of the functional layer to diamond can be further improved, and the holding force of the bonding phase matrix to diamond can be increased; ZrH therein 2 releases hydrogen during the sintering process, effectively removing pores in the material and promoting densification of the material. At the same time, the bonding force between diamond and the metal matrix is enhanced, enabling a good interfacial bond to be formed between diamond and the metal matrix, thereby further improving the wear resistance, flexural strength and impact toughness of the alloy structure; the addition of aluminum can improve the effect of wrapping diamond, improve the holding of the bonding phase to diamond, and the low melting point of aluminum can improve the densification of the alloy structure by its interstitial effect, while inhibiting the growth of WC grains and having the effect of refining grains. In the present invention, through the coating of the functional layer, a protective layer is formed on the surface of diamond, making it not affected by high temperature during sintering, effectively avoiding the occurrence of high-temperature carbonization phenomenon during the discharge sintering process, thereby maintaining its hardness and wear resistance.

[0031] The present invention also provides a cobalt-based ceramic composite material, including the following raw materials for preparation in mass percentage: WC 70 - 80%, Co 10 - 25%, Yb 2 O 30 to 2% and modified diamond; the modified diamond is the single crystal diamond composite material described in the above technical solution or the single crystal diamond composite material prepared by the preparation method described in the above technical solution. In the present invention, during the specific sintering process, a new phase of tungsten aluminum carbide (W-Al-C) can be formed. The generation of this new phase greatly improves the hardness and wear resistance of the composite material, enabling the material to exhibit better mechanical properties under high-temperature and high-stress environments, effectively resisting external loads and friction, and extending the service life. Description of the Drawings

[0032] Figure 1 SEM image with a scale of 50 μm of the cobalt-based ceramic composite material obtained in Example 1;

[0033] Figure 2 SEM image with a scale of 200 μm of the cobalt-based ceramic composite material obtained in Example 1;

[0034] Figure 3 SEM image with a scale of 1 mm of the cobalt-based ceramic composite material obtained in Example 1;

[0035] Figure 4 SEM image with a scale of 100 μm of the cobalt-based ceramic composite material obtained in Example 1;

[0036] Figure 5 EDS energy spectrum diagram of the cobalt-based ceramic composite material obtained in Example 1;

[0037] Figure 6 SEM image with a scale of 100 μm of the cobalt-based ceramic composite material obtained in Example 2;

[0038] Figure 7 SEM image with a scale of 20 μm of the cobalt-based ceramic composite material obtained in Example 2;

[0039] Figure 8 XRD diagram of the cobalt-based ceramic composite material obtained in Example 4;

[0040] Figure 9 SEM image of the cobalt-based ceramic composite material obtained in Comparative Example 1;

[0041] Figure 10 SEM image of the cobalt-based ceramic composite material obtained in Comparative Example 1;

[0042] Figure 11 Three-dimensional contour diagram of the cobalt-based ceramic composite material obtained in Example 1 after the friction and wear test;

[0043] Figure 12 Three-dimensional contour diagram of the cobalt-based ceramic composite material obtained in Example 1 after the friction and wear test;

[0044] Figure 13 The electrochemical polarization curve of the cobalt-based ceramic composite material obtained in Example 1. Detailed implementation mode

[0045] The present invention provides a single crystal diamond composite material, comprising single crystal diamond and a functional layer coated on the surface of the single crystal diamond;

[0046] The material of the functional layer includes TiC, ZrH 2 and Al.

[0047] In the present invention, the single crystal diamond composite material preferably comprises the following components in mass percentage: 50-60% single crystal diamond, 20-30% TiC, 5-15% ZrH 2 and 5-15% Al.

[0048] In terms of mass percentage, the single crystal diamond composite material provided by the present invention preferably comprises 50-60% single crystal diamond, specifically 50%, 51%, 52%, 53%, 54%, 55%, 56%, 57%, 58%, 59%, 60%. In the present invention, the particle size of the single crystal diamond is preferably 100-200 μm.

[0049] In terms of mass percentage, the single crystal diamond composite material provided by the present invention preferably comprises 20-30% TiC, specifically 20%, 21%, 22%, 23%, 24%, 25%, 26%, 27%, 28%, 29%, 30%. In the present invention, the particle size of the TiC is preferably 0.5-10 μm.

[0050] In terms of mass percentage, the single crystal diamond composite material provided by the present invention preferably comprises 5-15% ZrH 2 , specifically 5%, 10%, 15%. In the present invention, the ZrH 2 has a particle size preferably of 48-75 μm.

[0051] In terms of mass percentage, the single crystal diamond composite material provided by the present invention preferably comprises 5-15% Al, specifically 5%, 10%, 15%. In the present invention, the particle size of the Al is preferably 48-75 μm.

[0052] The present invention also provides a preparation method of the single crystal diamond composite material according to the above technical solution, comprising the following steps:

[0053] Mix the components included in the single crystal diamond composite material by ball milling to obtain the single crystal diamond composite material.

[0054] Before the ball milling and mixing, the present invention preferably further includes cleaning the single crystal diamond. The cleaning method is preferably ultrasonic cleaning with anhydrous ethanol. Through ultrasonic cleaning, the pollutants on the surface of the single crystal diamond can be removed, enabling the diamond surface energy to truly and completely contact with TiC, ZrH 2 , Al, and making the bonding force of the encapsulated diamond more excellent.

[0055] In the present invention, the rotation speed of the ball milling and mixing is preferably 80 - 100 rpm, and the time is preferably 48 h. In the present invention, the ball milling and mixing is preferably carried out in a planetary ball mill. The tank body of the planetary ball mill is preferably a vacuum ceramic tank, and the grinding balls used are preferably ceramic balls. In the present invention, using a vacuum ceramic tank and ceramic balls for ball milling and mixing can prevent Al from being oxidized during the ball milling process.

[0056] The present invention also provides the application of the single crystal diamond composite material described in the above technical solution or the single crystal diamond composite material prepared by the preparation method described in the above technical solution in a cermet composite material.

[0057] The present invention also provides a cobalt-based ceramic composite material, which includes the following raw materials for preparation in mass percentage: WC 70 - 80%, Co 10 - 25%, Yb 2 O 3 0 - 2% and modified diamond;

[0058] The modified diamond is the single crystal diamond composite material described in the above technical solution or the single crystal diamond composite material prepared by the preparation method described in the above technical solution.

[0059] Calculated by mass percentage, the raw materials for preparing the cobalt-based ceramic composite material provided by the present invention include WC 70 - 80%, specifically 70%, 71%, 72%, 73%, 74%, 75%, 76%, 77%, 78%, 79%, 80%. In the present invention, the particle size of the WC is preferably 0.5 - 75 μm, specifically 0.5 - 1 μm or 48 - 75 μm.

[0060] Calculated by mass percentage, the raw materials for preparing the cobalt-based ceramic composite material provided by the present invention include Co 10 - 25%, specifically 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, 20%, 21%, 22%, 23%, 24%, 25%. In the present invention, the particle size of the Co is preferably 48 - 75 μm.

[0061] Calculated by mass percentage, the raw materials for preparing the cobalt-based ceramic composite material provided by the present invention include Yb 2 O 30 to 2%, specifically it can be 0% (i.e., without adding Yb 2 O 3 ), 1%, 2%. In the present invention, the particle size of the Yb 2 O 3 is preferably 48 to 75 μm. In the present invention, by adding Yb 2 O 3 the tissue performance can be enhanced, and the holding force between the diamond and the matrix tissue can be further enhanced.

[0062] The present invention also provides a preparation method of the cobalt-based ceramic composite material described in the above technical solution, including the following steps:

[0063] Ball-mill and mix the preparation raw materials included in the cobalt-based ceramic composite material to obtain a mixed material;

[0064] Sinter the mixed material to obtain the cobalt-based ceramic composite material.

[0065] In the present invention, the rotation speed of the ball-milling and mixing is preferably 160 to 180 rpm, and the time is preferably 48 h. In the present invention, the ball-milling and mixing is preferably carried out in a planetary ball mill, the tank body of the planetary ball mill is preferably a vacuum stainless steel tank, and the grinding balls used are preferably stainless steel balls; using a vacuum stainless steel tank and stainless steel balls for ball-milling in the present invention can further ensure that the raw materials are mixed evenly.

[0066] In the present invention, the sintering preferably includes first sintering, second sintering and third sintering in sequence; the temperature of the first sintering is preferably 550 to 650 °C, specifically it can be 550 °C, 600 °C, 650 °C, the heat preservation time is preferably 2 to 3 min, and the pressure is preferably 12 to 15 kN; the temperature of the second sintering is preferably 850 to 950 °C, specifically it can be 850 °C, 900 °C, 950 °C, the heat preservation time is preferably 2 to 3 min, and the pressure is preferably 23 to 25 kN; the temperature of the third sintering is preferably 1340 to 1360 °C, the heat preservation time is preferably 0 to 6 min, and the pressure is preferably 30 to 33 kN; the heating rate during the first sintering, second sintering and third sintering is independently preferably 80 to 100 °C / min. In the present invention, the sintering method is preferably spark plasma sintering. In the present invention, the sintering is preferably carried out under vacuum conditions, and the vacuum degree ≤ 8×10 0 Pa. In the present invention, the sintering is preferably carried out in a sintering furnace, and the pulse ratio of the sintering furnace is preferably 14, and the heating voltage is preferably 5 to 6 V.

[0067] In the present invention, ZrH 2Decompose at high temperature, release hydrogen, effectively reduce the pores in the sintering process, increase the density of the material, and reduce the generation of cracks. At the same time, ZrH 2 can also enhance the wettability of the binder phase to diamond, form high-strength chemical bonds between the coating and diamond, and promote the uniform dispersion of diamond particles in the alloy matrix, thereby further improving the mechanical properties and wear resistance of the material, realizing the efficient application of diamond in tungsten-cobalt alloy. In the present invention, Yb 2 O 3 addition also promotes the fluidity of WC and Co, and improves the overall density and structural strength of the composite material.

[0068] In the present invention, the eutectic temperature of WC-Co is 1340 °C. The sintering temperature is close to the eutectic temperature, and WC diffuses and dissolves into Co to generate a liquid phase. The sintering temperature is slightly higher than the eutectic temperature, combined with a rapid cooling process, effectively inhibits grain growth and forms a denser tissue structure. In addition, during the sintering process, due to the interaction of elements such as tungsten and aluminum, a new phase of tungsten aluminum carbide (W-Al-C) is generated. The formation of this new phase not only increases the hardness of the material, but also enhances its wear resistance and high-temperature stability.

[0069] The present invention also provides the application of the cobalt-based ceramic composite material described in the above technical solution or the cobalt-based ceramic composite material prepared by the preparation method described in the above technical solution as a tool.

[0070] Unless otherwise specified, the materials and equipment used in the present invention are all commercially available products in the art.

[0071] Next, the technical solutions in the present invention will be clearly and completely described in conjunction with the embodiments in the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments in the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts belong to the scope of protection of the present invention.

[0072] Example 1

[0073] Ultrasonically clean single-crystal diamond with absolute ethanol to strip and disperse the surface dirt to achieve the cleaning purpose, and then dry it for standby;

[0074] Prepare a single-crystal diamond composite material: by mass percentage, uniformly mix 55% of the cleaned single-crystal diamond, 25% of TiC, 10% of ZrH 2 and 10% of Al using a planetary ball mill; the particle size of the single-crystal diamond is 180 μm, the particle size of TiC is 10 μm, and the particle size of ZrH 2The particle size of is 48 μm, and the particle size of Al is 48 μm; During ball milling, a vacuum ceramic pot and ceramic balls are used. The ball milling speed is 80 rpm, and the ball milling time is 48 h. After uniform mixing, a single crystal diamond composite material is obtained and stored in a vacuum seal for later use;

[0075] Prepare a cobalt-based ceramic composite material: By mass percentage, take 5% of the single crystal diamond composite material, 80% of WC, 13% of Co, and 2% of Yb 2 O 3 Use a planetary ball mill for uniform mixing. Among them, the particle size of WC powder is 0.5 μm, the particle size of Co is 48 μm, and the particle size of Yb 2 O 3 is 48 μm; The ball milling is carried out using a stainless steel pot and stainless steel balls. The ball milling speed is 180 rpm, and the ball milling time is 48 hours to obtain a mixed material;

[0076] Uniformly spread the above-obtained mixed material in a cylindrical graphite mold, place it in a sintering furnace, adjust the process parameters, and carry out the first sintering, the second sintering, and the third sintering in sequence to obtain a cobalt-based ceramic composite material; Among them, the sintering parameters are: the pressure of the first sintering is 13 kN, the heating rate is 100 °C / min, the temperature reaches 600 °C, and the holding time is 2 min; the pressure of the second sintering is 25 kN, the heating rate is 100 °C / min, the temperature reaches 900 °C, and the holding time is 2 min; the pressure of the third sintering is 30 kN, the heating rate is 100 °C / min, the temperature reaches 1360 °C, and the holding time is 6 min. During the sintering process, control the vacuum degree ≤ 8×10 0 Pa, the pulse ratio of the sintering furnace is 14, and the heating voltage is 5 - 6 V.

[0077] Example 2

[0078] Ultrasonically clean the single crystal diamond with absolute ethanol to peel and disperse the surface dirt to achieve the cleaning purpose, and then dry it for later use;

[0079] Prepare a single crystal diamond composite material: By mass percentage, take 55% of the cleaned single crystal diamond, 25% of TiC, 10% of ZrH 2 and 10% of Al and use a planetary ball mill for uniform mixing; Among them, the particle size of the single crystal diamond is 180 μm, the particle size of TiC is 10 μm, the particle size of ZrH 2 is 48 μm, and the particle size of Al is 48 μm; During ball milling, a vacuum ceramic pot and ceramic balls are used. The ball milling speed is 80 rpm, and the ball milling time is 48 h. After uniform mixing, a single crystal diamond composite material is obtained and stored in a vacuum seal for later use;

[0080] Preparation of cobalt-based ceramic composite materials: By mass percentage, 5% of single-crystal diamond composite materials, 75% of WC, and 20% of Co are uniformly mixed using a planetary ball mill. Among them, the particle size of WC powder is 48 μm, and the particle size of Co is 48 μm; the ball milling is carried out using a vacuum stainless steel tank and stainless steel balls; the ball milling speed is 180 rpm, and the ball milling time is 48 h to obtain a mixed material;

[0081] The above-obtained mixed material is evenly spread and powdered in a cylindrical graphite mold, placed in a sintering furnace, and the process parameters are adjusted to carry out the first sintering, the second sintering, and the third sintering in sequence to obtain a cobalt-based ceramic composite material; the sintering parameters are: the pressure of the first sintering is 13 kN, the heating rate is 100 °C / min, the temperature reaches 600 °C, and the holding time is 2 min; the pressure of the second sintering is 25 kN, the heating rate is 100 °C / min, the temperature reaches 900 °C, and the holding time is 2 min; the pressure of the third sintering is 30 kN, the heating rate is 100 °C / min, the temperature reaches 1360 °C, and the holding time is 3 min. During the sintering process, the vacuum degree is controlled ≤8×10 0 Pa, the pulse ratio of the sintering furnace is 14, and the heating voltage is 5 - 6 V.

[0082] Example 3

[0083] The single-crystal diamond is ultrasonically cleaned with absolute ethanol to peel and disperse the surface dirt to achieve the cleaning purpose, and then it is dried and reserved;

[0084] Preparation of single-crystal diamond composite materials: By mass percentage, 50% of the cleaned single-crystal diamond, 30% of TiC, 10% of ZrH 2 and 10% of Al are uniformly mixed using a planetary ball mill; among them, the particle size of the single-crystal diamond is 180 μm, the particle size of TiC is 10 μm, ZrH 2 has a particle size of 48 μm, and the particle size of Al is 48 μm; the ball milling is carried out using a vacuum ceramic tank and ceramic balls, the ball milling speed is 80 rpm, and the ball milling time is 48 h. After mixing evenly, a single-crystal diamond composite material is obtained and stored in a vacuum and sealed for later use;

[0085] Preparation of cobalt-based ceramic composite materials: By mass percentage, 5% of single-crystal diamond composite materials, 70% of WC, and 25% of Co are uniformly mixed using a planetary ball mill. Among them, the particle size of WC powder is 48 μm, and the particle size of Co is 48 μm; the ball milling is carried out using a vacuum stainless steel tank and stainless steel balls; the ball milling speed is 180 rpm, and the ball milling time is 48 h to obtain a mixed material;

[0086] The obtained mixture is evenly spread and powdered in a cylindrical graphite mold, placed in a sintering furnace, and the process parameters are adjusted. The first sintering, the second sintering, and the third sintering are carried out in sequence to obtain a cobalt-based ceramic composite material. The sintering parameters are as follows: the pressure of the first sintering is 12 kN, the heating rate is 80 °C / min, the temperature reaches 600 °C, and the holding time is 2 min; the pressure of the second sintering is 23 kN, the heating rate is 80 °C / min, the temperature reaches 900 °C, and the holding time is 2 min; the pressure of the third sintering is 30 kN, the heating rate is 80 °C / min, the temperature reaches 1360 °C, and the holding time is 0 min. During the sintering process, the vacuum degree is controlled ≤ 8×10 0 Pa, the pulse ratio of the sintering furnace is 14, and the heating voltage is 5 - 6 V.

[0087] Example 4

[0088] The single-crystal diamond is ultrasonically cleaned with absolute ethanol to peel and disperse the surface dirt to achieve the cleaning purpose, and then it is dried for standby.

[0089] Prepare a single-crystal diamond composite material: By mass percentage, 55% of the cleaned single-crystal diamond, 25% of TiC, 10% of ZrH 2 and 10% of Al are evenly mixed using a planetary ball mill. The particle size of the single-crystal diamond is 180 μm, the particle size of TiC is 10 μm, and the particle size of ZrH 2 is 48 μm, and the particle size of Al is 48 μm. The ball milling is carried out using a vacuum ceramic pot and ceramic balls. The ball milling speed is 80 rpm, and the ball milling time is 48 h. After mixing evenly, a single-crystal diamond composite material is obtained and stored in a vacuum seal for standby.

[0090] Prepare a cobalt-based ceramic composite material: By mass percentage, 5% of the single-crystal diamond composite material, 75% of WC, and 20% of Co are evenly mixed using a planetary ball mill. Among them, the particle size of the WC powder is 48 μm, and the particle size of Co is 48 μm. The ball milling is carried out using a vacuum stainless steel pot and stainless steel balls. The ball milling speed is 180 rpm, and the ball milling time is 48 h to obtain a mixture.

[0091] The obtained mixture is evenly spread and powdered in a cylindrical graphite mold, placed in a sintering furnace, and the process parameters are adjusted. The first sintering, the second sintering, and the third sintering are carried out in sequence to obtain a cobalt-based ceramic composite material. The sintering parameters are as follows: the pressure of the first sintering is 13 kN, the heating rate is 100 °C / min, the temperature reaches 600 °C, and the holding time is 2 min; the pressure of the second sintering is 25 kN, the heating rate is 100 °C / min, the temperature reaches 900 °C, and the holding time is 2 min; the pressure of the third sintering is 30 kN, the heating rate is 100 °C / min, the temperature reaches 1350 °C, and the holding time is 3 min. During the sintering process, the vacuum degree is controlled ≤ 8×10 0 Pa, the pulse ratio of the sintering furnace is 14, and the heating voltage is 5 - 6 V.

[0092] Comparative Example 1

[0093] The single-crystal diamond is ultrasonically cleaned with absolute ethanol to peel and disperse the surface dirt to achieve the cleaning purpose, and then it is dried for standby.

[0094] Prepare a single-crystal diamond composite material: By mass percentage, 70% of the cleaned single-crystal diamond, 10% of TiC, 10% of ZrH 2 and 10% of Al are uniformly mixed using a planetary ball mill. The particle size of the single-crystal diamond is 180 μm, the particle size of TiC is 10 μm, and the particle size of ZrH 2 is 48 μm, and the particle size of Al is 48 μm. During ball milling, a vacuum ceramic pot and ceramic balls are used. The ball milling speed is 180 rpm, and the ball milling time is 48 h. After uniform mixing, a single-crystal diamond composite material is obtained and stored in a vacuum seal for standby.

[0095] Prepare a cobalt-based ceramic composite material: By mass percentage, 5% of the single-crystal diamond composite material, 70% of WC, and 25% of Co are uniformly mixed using a planetary ball mill. Among them, the particle size of the WC powder is 48 μm, and the particle size of Co is 48 μm. Ball milling is carried out using a vacuum stainless steel pot and stainless steel balls. The ball milling speed is 180 rpm, and the ball milling time is 48 h to obtain a mixture.

[0096] The obtained mixture is evenly spread as powder in a cylindrical graphite mold, placed in a sintering furnace, and the process parameters are adjusted to conduct the first sintering, the second sintering, and the third sintering in sequence to obtain a cobalt-based ceramic composite material; the sintering parameters are as follows: the pressure for the first sintering is 12 kN, the heating rate is 80 °C / min, the temperature reaches 600 °C, and the holding time is 2 min; the pressure for the second sintering is 25 kN, the heating rate is 80 °C / min, the temperature reaches 900 °C, and the holding time is 2 min; the pressure for the third sintering is 30 kN, the heating rate is 80 °C / min, the temperature reaches 1360 °C, and the holding time is 1.5 min. During the sintering process, the vacuum degree is controlled ≤ 8×10 0 Pa, the pulse ratio of the sintering furnace is 14, and the heating voltage is 5 - 6 V.

[0097] Performance Test

[0098] Test Example 1

[0099] Figures 1 - 4 It is the SEM image of the cobalt-based ceramic composite material obtained in Example 1, where Figure 1 is the SEM image with a scale of 50 μm, Figure 2 is the SEM image with a scale of 200 μm, Figure 3 is the SEM image with a scale of 1 mm, Figure 4 is the SEM image with a scale of 100 μm. It can be seen from Figures 1 - 4 that the diamond is tightly combined with the binder, the binder phase evenly wraps around the diamond, and the diamond has a good transition with the matrix.

[0100] Figure 5 It is the EDS spectrum of the cobalt-based ceramic composite material obtained in Example 1. It can be seen from Figure 5 that the diamond has not been carbonized and is tightly combined with the binder, and the main elements of the binder phase are Yb, W, Co, and Ti.

[0101] Figures 6 - 7 It is the SEM image of the cobalt-based ceramic composite material obtained in Example 2, where Figure 6 is the SEM image with a scale of 100 μm, Figure 7 is the SEM image with a scale of 20 μm. It can be seen from Figures 6 - 7 that in the alloy composition obtained by the experimental scheme of Example 2, the high-particle-size matrix structure also has a good binding effect on the diamond.

[0102] Figure 8 It is the XRD pattern of the cobalt-based ceramic composite material obtained in Example 4. It can be seen from Figure 8 that new phases are formed after sintering (Al 0.5 W 0.5 C).

[0103] Figures 9 - 10 SEM images of different positions of the cobalt-based ceramic composite material obtained in Comparative Example 1, where Figure 9 and Figure 10 both have a scale of 50 μm. As can be seen from Figures 9 - 10 after sintering using the process of Comparative Example 1, the diamond undergoes carbonization and is not densely combined with the binder, the porosity of the alloy structure is relatively high, and the overall performance is poor.

[0104] Test Example 2

[0105] The wear resistance and surface average hardness of the cobalt-based ceramic composite materials obtained in Examples 1 to 4 and Comparative Example 1 were tested. The test process for wear resistance was as follows: Using Si 3 N 4 abrasive balls, applying a load of 100 N, a reciprocating frequency of 500 times / min, a test time of 30 min, and weighing the wear amount under dry friction after cleaning with absolute ethanol. The test results are shown in Table 1;

[0106] Among them, Figure 11 and Figure 12 are the three-dimensional contour maps after the friction and wear tests of the cobalt-based ceramic composite material obtained in Example 1; As can be seen from Figures 11 - 12 the wear scar contour of Example 1 is relatively shallow, and there is no obvious material adhesion phenomenon around the wear scar. The wear behavior during dry friction is mainly plastic deformation.

[0107] Table 1 Performance test results of the cobalt-based ceramic composite materials obtained in Examples 1 to 4 and Comparative Example 1

[0108]

[0109] It can be seen from Table 1 that the hardness and wear resistance of Example 1 are much higher than those of the other three examples. Due to the different WC content and particle size in Example 1, the structure of the sintered ceramic tool material is highly dense and the combination is closer. And a part of Yb 2 O 3 was added alone. The addition of Yb 2 O 3 makes the hard phase more evenly distributed inside the alloy during the sintering process. The holding time of the sintering parameters is extended, so that during the sintering of the cemented carbide, when WC-Co is at the eutectic temperature, more WC dissolves into the liquid phase. The increase in the liquid phase process time makes more solid solutions generated in the alloy structure, strengthening the tissue performance, but it is necessary to prevent the grains from growing too large, reduce the total area of grain boundaries in the crystal, and reduce the interfacial energy.

[0110] The present invention passes through TiC, ZrH 2, Al coats single-crystal diamond, protecting the microstructure and properties of diamond during sintering, while forming chemical bonds around the diamond to create a suitable transition between the diamond and the metal bonding phase. As Figure 1 shown, the diamond is effectively and tightly combined with the surrounding structure, and the diamond has its original morphology and properties, enhancing the overall hardness and wear resistance. According to Figure 2 and Figure 7 , Figure 10 shown by comparison, by adjusting the WC particle size in the present invention, the atoms are rearranged more closely during the sintering process, improving the tissue compactness, Figure 10 with obvious intergranular cracks and obvious gaps between the components. As one of the most important parameters of the process, different holding times result in different reaction times of each component during the sintering process, and different holding times at the eutectic temperature lead to different intermolecular binding forces. According to Figure 1 and Figure 6 , Figure 9 shown by comparison, increasing the holding time promotes grain growth while increasing the retention force of the diamond, Figure 9 due to the short holding time, obvious diamond shedding occurs.

[0111] Test Example 3

[0112] Test the electrochemical corrosion performance of the cobalt-based ceramic composite material obtained in Example 1;

[0113] Step 1: Sample preparation: For the samples of the example, first ultrasonically clean them with deionized water and absolute ethanol to remove surface oil stains and impurities. During the cleaning process, the frequency of the ultrasonic cleaner used is set to 40 kHz, and the duration is 15 minutes. The cleaned samples are dried in clean air, the drying temperature is 60 °C, and the drying time is 30 minutes. After that, the samples are sealed for standby.

[0114] Step 2: Preparation for electrochemical corrosion test: Use a three-electrode system for the electrochemical corrosion test. The test electrolyte is 5% NaCl solution. The prepared cobalt-based WC-diamond composite ceramic tool material sample is used as the working electrode, a platinum sheet is used as the counter electrode, and a calomel electrode is used as the reference electrode. The exposed area of the working electrode is 1 cm² to ensure full contact between the material sample surface and the electrolyte. To reduce external interference, the entire test process is carried out in an electrochemical cell at room temperature (25 °C), and the open circuit potential (OCP) is kept stable for 20 minutes before the corrosion test to ensure a stable electrochemical state.

[0115] Step 3: Polarization curve measurement: After stabilizing the open-circuit potential, a potentiodynamic polarization curve test is carried out. The potential scanning range starts from the open-circuit potential (Eocp) and scans in the range of ±1V, and the scanning rate is set to 0.5mV / s. By measuring the potentiodynamic polarization curve, the self-corrosion potential (Ecorr) and the self-corrosion current density (Icorr) are calculated. According to the Tafel slope method, the anodic slope (βa) and the cathodic slope (βc) are obtained respectively through the linear fitting of the anodic and cathodic regions of the polarization curve, and the polarization resistance (Rp) is calculated according to the Stern-Geary equation. Figure 13 It is the electrochemical polarization curve diagram of the cobalt-based ceramic composite material obtained in Example 1.

[0116] Step 4: The self-corrosion potential ((E corr =-0.614V) and the self-corrosion current density (I corr =4.313×10 -6 A / cm 2 ) are obtained through the Tafel fitting curve. A low self-corrosion current density indicates a low corrosion rate, showing that the material has excellent corrosion resistance in the corrosive medium. The anodic branch of the polarization curve reflects the dissolution process of the Co-based binder phase, while the cathodic branch indicates the behavior of the reduction of dissolved oxygen on the material surface. The passivation film formed on the material surface effectively inhibits the further corrosion process, and the calculation result of the polarization resistance (Rp = 35292 Ω·cm 2 ) verifies this. The self-corrosion potential (E corr ), the self-corrosion current density (I corr ), the anodic Tafel constant (β a ) and the cathodic Tafel constant (β c ) are calculated from the dynamic polarization potential curve by using the Tafel fitting method. The polarization resistance Rp can be calculated by the Stern-Geary equation.

[0117]

[0118] The self-corrosion current density I corr reflects the corrosion rate of the material, and the smaller the value, the slower the corrosion rate. The measured self-corrosion potential (E corr ) is -0.614V, the self-corrosion current density (I corr ) is 4.313×10 -6 A / cm 2 , and the polarization resistance (Rp) is 35292 Ω·cm 2 , indicating that the sample has good corrosion resistance.

[0119] Conclusion:

[0120] The electrochemical polarization curve test shows that the cobalt-based ceramic composite material provided by the present invention has excellent electrochemical corrosion resistance in a 5% NaCl solution, showing a high polarization resistance and a low corrosion rate. The analysis of the corrosion products further verifies the corrosion resistance of the material, especially in the cobalt binder phase region. Although corrosion has a certain impact on the hardness and wear resistance of the material, the material still exhibits high mechanical properties and is suitable for use in highly corrosive environments.

[0121] Although the above embodiments have described the present invention in detail, they are only a part of the embodiments of the present invention, rather than all the embodiments. Other embodiments can also be obtained based on these embodiments without creative efforts, and these embodiments all fall within the protection scope of the present invention.

Claims

1. A cobalt-based ceramic composite material, characterized in that: The preparation raw materials include the following mass percentages: WC 70-80%, Co 10-25%, Yb2O3 0-2% and the remainder modified diamond; The particle size of the WC is 0.5-1 μm; The modified diamond comprises a single crystal diamond and a functional layer coated on the surface of the single crystal diamond; The material of the functional layer includes TiC, ZrH2 and Al; The modified diamond comprises the following components in percentage by mass: 50-60% single crystal diamond, 20-30% TiC, 5-15% ZrH2 and 5-15% Al; The method for preparing the cobalt-based ceramic composite material comprises the following steps: Ball-milling and mixing the raw materials for preparing the cobalt-based ceramic composite material to obtain a mixed material; sintering the mixture to obtain the cobalt-based ceramic composite material; The sintering includes sequentially performing a first sintering, a second sintering and a third sintering; The first sintering temperature is 550-650°C, the holding time is 2-3 minutes, and the pressure is 12-15 kN; The second sintering temperature is 850-950°C, the holding time is 2-3 minutes, and the pressure is 23-25 ​​kN; The third sintering process is performed at a temperature of 1340-1360° C., a holding time of 3-6 min, and a pressure of 30-33 kN.

2. The cobalt-based ceramic composite material according to claim 1, characterized in that: The particle size of the single crystal diamond is 100-200 μm; the particle size of the TiC is 0.5-10 μm; the particle size of the ZrH2 is 48-75 μm; and the particle size of the Al is 48-75 μm.

3. The cobalt-based ceramic composite material according to claim 1, characterized in that: The preparation method of the modified diamond comprises the following steps: The components included in the single crystal diamond composite material are ball-milled and mixed to obtain the modified diamond.

4. The cobalt-based ceramic composite material according to claim 3, characterized in that: The ball milling mixing was performed at a rotation speed of 80-100 rpm for 48 h.

5. The cobalt-based ceramic composite material according to claim 1, characterized in that: The particle size of the Co is 48-75 μm; The particle size of the Yb2O3 is 48~75μm.

6. The method for preparing the cobalt-based ceramic composite material according to any one of claims 1 to 5, characterized in that: The following steps are involved: Ball-milling and mixing the raw materials for preparing the cobalt-based ceramic composite material to obtain a mixed material; sintering the mixture to obtain the cobalt-based ceramic composite material; The sintering includes sequentially performing a first sintering, a second sintering and a third sintering; The first sintering temperature is 550-650°C, the holding time is 2-3 minutes, and the pressure is 12-15 kN; The second sintering temperature is 850-950°C, the holding time is 2-3 minutes, and the pressure is 23-25 ​​kN; The third sintering process is performed at a temperature of 1340-1360° C., a holding time of 3-6 min, and a pressure of 30-33 kN.

7. The preparation method according to claim 6, characterized in that: The ball milling mixing speed is 160-180 rpm, and the time is 48 h; the sintering is carried out under vacuum conditions, and the vacuum degree is ≤8×10 0 Pa.

8. Use of the cobalt-based ceramic composite material according to any one of claims 1 to 5 or the cobalt-based ceramic composite material prepared by the preparation method according to claim 6 or 7 as a cutting tool.

Images