A ternary boride composite ceramic, a preparation method thereof and application thereof as a composite ceramic drawing die

Abstract

The application belongs to the technical field of composite ceramics, and particularly relates to a ternary boride composite ceramic, a preparation method thereof and application of the ternary boride composite ceramic as a composite ceramic wire drawing die. The ternary boride composite ceramic die is prepared by using tungsten boride, boron carbide and cobalt boride as main raw materials, and adding a small amount of grain inhibitors, rare earth oxides, solid lubricants and silicon nitride whiskers, and has simple process and low cost. In the application, borides are used to replace traditional carbide raw materials, and appropriate solid lubricants are added, so that the material has excellent wear resistance and friction reduction. The grain inhibitors and the rare earth oxides have the effects of refining grains and enhancing material toughness, and the silicon nitride whiskers can increase the strength and toughness of the material. Therefore, the ternary boride composite ceramic wire drawing die prepared by the application has better high-temperature oxidation resistance and friction reduction performance than a hard alloy wire drawing die, and has better toughness than a polycrystalline diamond wire drawing die, so that the service life of the die can be significantly improved.

Description

Technical Field

[0001] This invention belongs to the field of composite ceramics technology, specifically relating to a ternary boride composite ceramic, its preparation method, and its application as a composite ceramic wire drawing die. Background Technology

[0002] A wire drawing die is a mold used to change the size of a metal wire. Under the action of external force, the metal wire is forced through the die, and the wire is compressed from thick to thin to obtain the desired size. Wire drawing dies are generally made of alloy steel, cemented carbide, natural diamond, polycrystalline diamond, CVD diamond, and ceramic. Among these, cemented carbide and polycrystalline diamond dies are the most widely used because cemented carbide dies have advantages such as good corrosion and wear resistance and low adhesion, while polycrystalline diamond dies have advantages such as good wear resistance and impact resistance.

[0003] However, the wire drawing process generates a large amount of heat, and cemented carbide is prone to oxidation at high temperatures, which reduces the hardness and wear resistance of the die and increases the coefficient of friction, thus shortening the die's service life. Polycrystalline diamond is quite brittle and is prone to cracking during continuous wire drawing. Therefore, it is necessary to further improve the oxidation resistance, hardness, and toughness of wire drawing dies, thereby increasing their service life. Summary of the Invention

[0004] The purpose of this invention is to provide a ternary boride composite ceramic, its preparation method, and its application as a composite ceramic wire drawing die. The ternary boride composite ceramic provided by this invention has the advantages of high hardness, good wear resistance and friction reduction, good corrosion resistance, high working temperature, good red hardness, and good toughness. As a wire drawing die, it can further extend its service life.

[0005] To achieve the above objectives, the present invention provides the following technical solution:

[0006] This invention provides a ternary boride composite ceramic comprising the following raw materials: 45.0–65.0 wt% tungsten boride, 10.0–20.0 wt% boron carbide, 5.0–15.0 wt% nickel, 5.0–10.0 wt% cobalt, 5.0–15.0 wt% cobalt boride, 1.0–5.0 wt% solid lubricant, 0.3–1.0 wt% rare earth oxides, 0.3–1.0 wt% silicon nitride whiskers, 0.3–1.0 wt% grain inhibitor, and 2.0–4.0 wt% forming agent.

[0007] Preferably, the grain inhibitor is a carbide, which includes one or more of molybdenum carbide, niobium carbide, and tantalum carbide; the purity of the grain inhibitor is greater than 99.0%, and the particle size is 0.2 to 5.0 μm.

[0008] Preferably, the solid lubricant includes one or more of molybdenum disulfide, tungsten sulfide, graphite, and fluorinated graphite, and the purity of the solid lubricant is greater than 99.0% and the particle size is 1-10 μm.

[0009] Preferably, the rare earth oxide includes one or more of cerium oxide, lanthanum oxide and yttrium oxide, and the purity of the rare earth oxide is greater than 99.0% and the particle size is 0.2 to 10.0 μm.

[0010] Preferably, the silicon nitride whiskers have a diameter of 100–300 nm and a length of 10–50 μm.

[0011] This invention also provides a method for preparing the ternary boride composite ceramic described in the above technical solution, comprising the following steps:

[0012] The raw materials contained in the boride composite ceramic are mixed and then ball-milled, dried and sieved in sequence to obtain alloy powder.

[0013] The alloy powder is pressed into shape and then sintered to obtain the ternary boride composite ceramic.

[0014] Preferably, the ball milling is a wet ball milling, wherein the ball milling media includes one or more of anhydrous ethanol, gasoline, acetone, heptane, hexane, carbon tetrachloride and benzene, the grinding balls used are cemented carbide balls, the ball-to-material ratio is (4-6):1, and the ball milling time is 24-96 hours.

[0015] The preferred drying method is vacuum drying, wherein the vacuum degree is 0.1-10 Pa, the temperature is 60-80°C, and the time is 4-8 hours.

[0016] The particle size of the alloy powder is 0.5–5 μm.

[0017] Preferably, the pressing pressure is 100-250 MPa;

[0018] The sintering temperature is 1300–1450℃, and the holding time is 0.5–1h.

[0019] The present invention also provides the application of the ternary boride composite ceramic described in the above technical solution or the ternary boride composite ceramic prepared by the preparation method described in the above technical solution as a composite ceramic wire drawing die.

[0020] This invention provides a ternary boride composite ceramic comprising the following raw materials: 45.0–65.0 wt% tungsten boride, 10.0–20.0 wt% boron carbide, 5.0–15.0 wt% nickel, 5.0–10.0 wt% cobalt, 5.0–15.0 wt% cobalt boride, 1.0–5.0 wt% solid lubricant, 0.3–1.0 wt% rare earth oxides, 0.3–1.0 wt% silicon nitride whiskers, 0.3–1.0 wt% grain inhibitor, and 2.0–4.0 wt% forming agent.

[0021] This invention uses tungsten boride (WB), boron carbide (B4C), and cobalt boride (CoB) as the main raw materials, and adds a small amount of grain inhibitors, rare earth oxides, solid lubricants, and silicon nitride whiskers. After drying, molding, and sintering, a ternary boride composite ceramic mold is obtained. The process is simple and the cost is low.

[0022] This invention uses borides instead of traditional carbide raw materials to prepare a ternary boride composite ceramic. The hard phase is mainly W₂CoB₂ with a small amount of WC, and the binder phase is a CoNi solid solution, giving the material better strength, hardness, wear resistance, corrosion resistance, friction reduction, and high-temperature oxidation resistance. The grain inhibitors and rare earth oxides added in this invention refine the grains and enhance the toughness of the material, while the addition of Si₃N₄ whiskers further increases the material's strength and toughness. Therefore, the ternary boride composite ceramic wire drawing die prepared by this invention has better high-temperature oxidation resistance and friction reduction performance compared to cemented carbide wire drawing dies, and better toughness than polycrystalline diamond wire drawing dies, which can significantly improve the die's service life.

[0023] The ternary boride composite ceramic wire drawing die prepared by this invention was tested and found to have the following properties: hardness of 91–93 HRA, flexural strength of 1600–1800 MPa, and fracture toughness of 9.2–9.8 MPa·m. 1 / 2 The coefficient of friction is 0.28 to 0.35, and the high-temperature hardness at a working temperature of 1200℃ is HV620 to 650.

[0024] Therefore, the present invention has low preparation cost and simple process, and the prepared ternary boride composite ceramic wire drawing die has the characteristics of high strength and hardness, good wear resistance and friction reduction, corrosion resistance, low coefficient of friction, low adhesion, low energy consumption and long service life. Attached Figure Description

[0025] Figure 1 The image shows the metallographic structure of the ternary boride composite ceramic obtained in Example 1. Detailed Implementation

[0026] This invention provides a ternary boride composite ceramic comprising the following raw materials: 45.0–65.0 wt% tungsten boride, 10.0–20.0 wt% boron carbide, 5.0–15.0 wt% nickel, 5.0–10.0 wt% cobalt, 5.0–15.0 wt% cobalt boride, 1.0–5.0 wt% solid lubricant, 0.3–1.0 wt% rare earth oxides, 0.3–1.0 wt% silicon nitride whiskers, 0.3–1.0 wt% grain inhibitor, and 2.0–4.0 wt% forming agent.

[0027] In this invention, unless otherwise specified, all raw materials used in the preparation are commercially available products well known to those skilled in the art.

[0028] In this invention, the ternary boride composite ceramic preferably comprises the following raw materials: 50.0–60.0 wt% tungsten boride, 12.0–18.0 wt% boron carbide, 6.0–12.0 wt% nickel, 6.0–9.0 wt% cobalt, 6.0–12.0 wt% cobalt boride, 2.0–4.0 wt% solid lubricant, 0.4–0.9 wt% rare earth oxides, 0.4–0.9 wt% silicon nitride whiskers, 0.4–0.9 wt% grain inhibitor, and 2.2–3.5 wt%... The forming agent, preferably t%, comprises the following raw materials: 55.0–58.0 wt% tungsten boride, 15.0–16.0 wt% boron carbide, 8.0–10.0 wt% nickel, 7.0–8.0 wt% cobalt, 8.0–10.0 wt% cobalt boride, 2.0–3.0 wt% solid lubricant, 0.5–0.8 wt% rare earth oxides, 0.5–0.8 wt% silicon nitride whiskers, 0.5–0.8 wt% grain inhibitor and 2.5–3.0 wt% forming agent.

[0029] In this invention, the tungsten boride, boron carbide, nickel, cobalt, cobalt boride, and rare earth oxides are preferably used in powder form.

[0030] In this invention, the grain inhibitor is preferably a carbide, and the carbide is further preferably one or more of molybdenum carbide, niobium carbide and tantalum carbide; the purity of the grain inhibitor is preferably greater than 99.0%, and the particle size is preferably 0.2 to 5.0 μm.

[0031] In this invention, the solid lubricant preferably comprises one or more of molybdenum disulfide, tungsten sulfide, graphite, and fluorinated graphite, and the purity of the solid lubricant is preferably greater than 99.0%, with a particle size preferably of 1–10 μm. In this invention, the rare earth oxide preferably comprises one or more of cerium oxide, lanthanum oxide, and yttrium oxide, and the purity of the rare earth oxide is preferably greater than 99.0%, with a particle size preferably of 0.2–10.0 μm. In this invention, the diameter of the silicon nitride whiskers is preferably 100–300 nm, more preferably 200–300 nm; the length is preferably 10–50 μm, more preferably 30–50 μm.

[0032] In this invention, the molding agent preferably includes one or more of paraffin wax, machine oil, rubber, polyethylene glycol, zinc stearate, and polyvinyl alcohol.

[0033] This invention also provides a method for preparing the ternary boride composite ceramic described in the above technical solution, comprising the following steps:

[0034] The raw materials contained in the boride composite ceramic are mixed and then ball-milled, dried and sieved in sequence to obtain alloy powder.

[0035] The alloy powder is pressed into shape and then sintered to obtain the ternary boride composite ceramic.

[0036] In this invention, the raw materials contained in the boride composite ceramic are mixed and then ball-milled, dried, and sieved in sequence to obtain alloy powder.

[0037] In this invention, the ball milling is preferably wet ball milling, and the ball milling medium for wet ball milling preferably includes one or more of anhydrous ethanol, gasoline, acetone, heptane, hexane, carbon tetrachloride and benzene; the grinding balls used are preferably cemented carbide balls, the ball-to-material ratio is preferably (4-6):1, more preferably 5:1; and the ball milling time is preferably 24-96 hours.

[0038] In this invention, the drying method is preferably vacuum drying, wherein the vacuum degree is preferably 0.1 to 10 Pa, the temperature is preferably 60 to 80°C, and the time is preferably 4 to 8 hours.

[0039] The sieving process described in this invention is not particularly limited and can be any process well known to those skilled in the art. In this invention, the particle size of the alloy powder is preferably 0.5–5 μm.

[0040] After obtaining the alloy powder, the present invention presses the alloy powder into shape and then sinters it to obtain the ternary boride composite ceramic.

[0041] In this invention, the pressing pressure is preferably 100-250 MPa, more preferably 150-200 MPa. In this invention, the pressing method is preferably molding or isostatic pressing.

[0042] In this invention, the sintering temperature is preferably 1300–1450°C, more preferably 1350–1400°C; the heating rate to the sintering temperature is preferably 3–8°C / min; and the holding time is preferably 0.5–1 h. In this invention, the sintering is preferably one of vacuum sintering, hot pressing sintering, hot isostatic pressing sintering, and spark plasma sintering.

[0043] The present invention also provides the application of the ternary boride composite ceramic described in the above technical solution or the ternary boride composite ceramic prepared by the preparation method described in the above technical solution as a composite ceramic wire drawing die.

[0044] To further illustrate the present invention, the following detailed description, in conjunction with the accompanying drawings and embodiments, describes a ternary boride composite ceramic, its preparation method, and its application as a composite ceramic wire drawing die, but these descriptions should not be construed as limiting the scope of protection of the present invention.

[0045] In the following embodiments:

[0046] The solid lubricant has a purity greater than 99.0% and a particle size of 2–5 μm;

[0047] The purity of the grain inhibitor is greater than 99.0%, and the particle size is 0.5–3 μm;

[0048] The rare earth oxide powder has a purity greater than 99.0% and a particle size of 1–5 μm;

[0049] The silicon nitride whiskers have a diameter of 200–300 nm and a length of 30–50 μm.

[0050] Example 1

[0051] Materials: 55.0 wt% tungsten boride powder, 15.0 wt% boron carbide powder, 10.0 wt% nickel powder, 5.0 wt% cobalt powder, 10.0 wt% cobalt boride powder, 3.5 wt% solid lubricant, 0.4 wt% rare earth oxide powder, 0.4 wt% silicon nitride whiskers, 0.7 wt% grain inhibitor and 2.9 wt% forming agent, wherein the grain inhibitor is molybdenum carbide, the solid lubricant is molybdenum sulfide, the rare earth oxide powder is cerium oxide, and the forming agent is liquid paraffin;

[0052] After mixing the raw materials, wet ball milling was performed, with anhydrous ethanol as the milling medium and a ball-to-material ratio of 5:1. After ball milling, the mixture was dried for 5 hours under a vacuum of 0.1 Pa and a temperature of 90 °C. The mixture was then sieved to obtain alloy powder with a particle size of 0.5–3 μm.

[0053] The obtained alloy powder was pressed into shape at 150 MPa, and then heated to 1400℃ at a heating rate of 5℃ / min for sintering, held at the temperature for 0.5h, and then machined to obtain a ternary boride composite ceramic wire drawing die.

[0054] Figure 1 The metallographic diagram of the ternary boride composite ceramic wire drawing die provided by the present invention is shown below. Figure 1 It can be seen that the hard phase of the prepared ternary boride composite ceramic is mainly composed of high-hardness W2CoB2 and WC, in which solid lubricant particles are dispersed. The binder phase is a CoNi solid solution with high strength and excellent oxidation resistance. This composite metallographic structure gives the material better strength, hardness, wear resistance, corrosion resistance, friction reduction and high-temperature oxidation resistance.

[0055] Example 2

[0056] Materials: 50.0 wt% tungsten boride powder, 17.0 wt% boron carbide powder, 13.5 wt% nickel powder, 6.0 wt% cobalt powder, 9.0 wt% cobalt boride powder, 3.0 wt% solid lubricant, 0.5 wt% rare earth oxide powder, 0.5 wt% silicon nitride whiskers, 0.5 wt% grain inhibitor and 3.0 wt% forming agent, wherein the grain inhibitor is niobium carbide, the solid lubricant is tungsten sulfide, the rare earth oxide powder is lanthanum oxide, and the forming agent is machine oil;

[0057] After mixing the raw materials, wet ball milling was performed, with gasoline as the milling medium and a ball-to-material ratio of 6:1. After ball milling, the mixture was dried for 8 hours under a vacuum of 1 Pa and a temperature of 70 °C. The mixture was then sieved to obtain alloy powder with a particle size of 0.5–2 μm.

[0058] The obtained alloy powder was pressed into shape at 200 MPa, and then sintered at 1350 °C with a heating rate of 3 °C / min. After holding at the temperature for 1 hour, it was machined to obtain a ternary boride composite ceramic wire drawing die.

[0059] Example 3

[0060] Materials: 60.0 wt% tungsten boride powder, 13.0 wt% boron carbide powder, 6.5 wt% nickel powder, 7.0 wt% cobalt powder, 8.0 wt% cobalt boride powder, 4.0 wt% solid lubricant, 0.6 wt% rare earth oxide powder, 0.6 wt% silicon nitride whiskers, 0.3 wt% grain inhibitor and 3.1 wt% forming agent, wherein the grain inhibitor is tantalum carbide, the solid lubricant is graphite, the rare earth oxide powder is yttrium oxide, and the forming agent is rubber;

[0061] After mixing the raw materials, wet ball milling was performed, with hexane as the milling medium and a ball-to-material ratio of 4:1. After ball milling, the mixture was dried for 6 hours under a vacuum of 5 Pa and a temperature of 80 °C, and then sieved to obtain alloy powder with a particle size of 1–3 μm.

[0062] The obtained alloy powder was pressed into shape at 180 MPa, and then sintered at 1420 °C with a heating rate of 8 °C / min. After holding at the temperature for 1 hour, it was machined to obtain a ternary boride composite ceramic wire drawing die.

[0063] Performance testing

[0064] The performance of the ternary boride composite ceramic wire drawing dies obtained in Examples 1-3 was tested, and the test results are shown in Table 1.

[0065] Table 1 shows the performance results of the ternary boride composite ceramic wire drawing dies obtained in the examples.

[0066] Example 1 Example 2 Example 3 Test standard Hardness / HRA 92 93 91 GB / T3323-2015 Bending strength / MPa 1680 1620 1780 GB / T3323-2015 Fracture toughness / MPa-m 1 / 2 ]] 9.2 9.8 9.2 JB / T12616-2016 Friction coefficient 0.28 0.31 0.35 GB / T34501-2017 Hardness at 1200℃ / HV 620 650 638 GB / T4340.1-2009

[0067] As shown in Table 1, the ternary boride composite ceramic wire drawing die prepared in this invention was tested and found to have the following properties: hardness of 91–93 HRA, flexural strength of 1600–1800 MPa, and fracture toughness of 9.2–9.8 MPa·m. 1 / 2 The coefficient of friction is 0.28 to 0.35, and the high-temperature hardness at a working temperature of 1200℃ is HV620 to 650.

[0068] Although the above embodiments have provided a detailed description of the present invention, they are only some embodiments of the present invention, and not all embodiments. Other embodiments can be obtained based on these embodiments without creative effort, and these embodiments all fall within the protection scope of the present invention.

Claims

1. A ternary boride composite ceramic, characterized by, The raw materials include: 45.0~65.0wt% of tungsten boride WB, 10.0~20.0wt% of boron carbide, 5.0~15.0wt% of nickel, 5.0~10.0wt% of cobalt, 5.0~15.0wt% of cobalt boride CoB, 1.0~5.0wt% of solid lubricant, 0.3~1.0wt% of rare earth oxide, 0.3~1.0wt% of silicon nitride whisker, 0.3~1.0wt% of grain inhibitor and 2.0~4.0wt% of forming agent.

2. The ternary boride composite ceramic of claim 1, wherein, The grain inhibitor is carbide, which includes one or more of molybdenum carbide, niobium carbide and tantalum carbide; the purity of the grain inhibitor is greater than 99.0% and the particle size is 0.2~5.0μm.

3. The ternary boride composite ceramic of claim 1, wherein, The solid lubricant includes one or more of molybdenum disulfide, tungsten sulfide, graphite and fluorinated graphite, the purity of the solid lubricant is greater than 99.0% and the particle size is 1~10μm.

4. The ternary boride composite ceramic of claim 1, wherein, The rare earth oxide includes one or more of cerium oxide, lanthanum oxide and yttrium oxide, the purity of the rare earth oxide is greater than 99.0% and the particle size is 0.2~10.0μm.

5. The ternary boride composite ceramic of claim 1, wherein, The silicon nitride whisker has a diameter of 100~300nm and a length of 10~50μm.

6. The method of producing ternary boride composite ceramics according to any one of claims 1 to 5, characterized by, The method includes the following steps: After the raw materials included in the boride composite ceramic are mixed, ball milling, drying and sieving are sequentially performed to obtain alloy powder; After the alloy powder is press-formed, sintering is performed to obtain the ternary boride composite ceramic.

7. The preparation method according to claim 6, characterized in that, The ball milling is wet ball milling, the ball milling medium of the wet ball milling includes one or more of anhydrous ethanol, gasoline, acetone, heptane, hexane, carbon tetrachloride and benzene, the grinding balls used are hard alloy balls, the ball-to-material ratio is (4~6):1 and the ball milling time is 24~96h.

8. The preparation method according to claim 6, characterized in that, The drying is performed by vacuum drying, the vacuum degree of the vacuum drying is 0.1~10Pa, the temperature is 60~80℃ and the time is 4~8h; The particle size of the alloy powder is 0.5~5μm.

9. The preparation method according to claim 6, characterized in that, The pressure of the press-forming is 100~250MPa; The sintering temperature is 1300~1450℃ and the holding time is 0.5~1h.

10. Use of the ternary boride composite ceramic of any one of claims 1~5 or the ternary boride composite ceramic prepared by the preparation method of any one of claims 6~9 as a composite ceramic wire drawing die.

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