Antioxidant compact compound tungsten carbide-based rare metal ceramic and preparation method thereof

Abstract

The invention discloses antioxidant compact compound tungsten carbide-based rare metal ceramic and a preparation method thereof, and relates to the field of metal ceramic. Firstly, a silicon carbide substance is introduced through polycarbosilane, ceramic pores are filled with metal zirconium through a metal infiltration reaction, compactness is improved, and meanwhile the oxidation resistance of a ceramic matrix is enhanced; and then, a tungsten carbide enrichment layer is formed on the surface of the ceramic in a mode of combining ion injection infiltration and spraying, and the high-temperature and high-speed tungsten carbide and the metal adhesive are combined with the originally injected tungsten carbide enrichment layer into a whole during spraying. Secondly, high-proportion rare metal nano rhenium is adopted, and material surface densification of the tungsten carbide-based metal ceramic compound coating in a high-temperature environment is achieved; finally, through hydrogen reduction treatment, the oxygen content of the powder is further reduced, and the high-activity low-oxygen compound carbide rare metal ceramic with the nanocrystalline structure is produced. The ceramic prepared by the invention has the effects of oxidation resistance and compactness.

Description

Technical Field

[0001] The invention relates to the technical field of ceramics, in particular to an oxidation-resistant, dense, composite tungsten carbide-based rare metal ceramic and a preparation method thereof. Background Art

[0002] Metal ceramics are a composite material composed of a ceramic hard phase and a metal bonding phase. It has good mechanical properties and performance, and is an ideal structural material for manufacturing cutting tools, molds, wear-resistant parts, etc. It is well known that high-performance metal ceramic materials are an important topic for research and development in industrially developed countries. They are the teeth of modern industry and an important basis for measuring a country's industrial level. Hard and super-hard materials are new materials that the country focuses on supporting and developing. As processing materials for hard and super-hard materials and difficult-to-process metal materials, their importance is obvious. my country's high-performance metal ceramic materials are now basically dependent on imports. Not only are they expensive, but they are also restricted in many aspects, which has a great impact on my country's industrial modernization process.

[0003] Tungsten carbide plays a vital role in modern industry. Its high hardness and heat resistance make it often used as cutting tool material in mechanical industry, high hardness armor or armor-piercing projectile core in military industry. Tungsten carbide has high wear resistance and corrosion resistance, so it is also used to manufacture wear-resistant thermal protective coatings for easily worn tools in aerospace industry and precision industry. How to combine tungsten carbide with metal ceramics to prepare highly resistant to oxidation is the research direction of this invention. The above problems are solved by introducing rare metals into sintering and process modification. Summary of the invention

[0004] The object of the present invention is to provide an oxidation-resistant and dense composite tungsten carbide-based rare metal ceramic and a preparation method thereof, so as to solve the problems existing in the prior art.

[0005] In order to solve the above technical problems, the present invention provides the following technical solutions: an oxidation-resistant dense composite tungsten carbide-based rare metal ceramic, wherein the ceramic is prepared by infiltrating metal zirconium as a matrix with tungsten carbide-silicon carbide composite porous ceramic as a matrix, and then spraying metal rhenium and tungsten carbide coating on its surface.

[0006] Furthermore, the matrix is ​​prepared by introducing silicon carbide into polycarbosilane, cracking it to generate tungsten carbide-silicon carbide composite porous ceramics, introducing metal zirconium through metal infiltration reaction, and nano-scale metal zirconium filling ceramic pores during the infiltration process.

[0007] Furthermore, the coating is formed by combining ion implantation and spraying, wherein tungsten carbide is implanted into the ceramic surface by ion implantation, and then a mixture of tungsten carbide powder and rhenium powder is sprayed.

[0008] Further, the method comprises the following preparation steps:

[0009] (1) Tungsten carbide is used as raw material, polycarbosilane precursor is used as binder, and the volume ratio of tungsten carbide and polycarbosilane precursor is 2-52:3. The prepared raw material powder is placed in a ball mill, the ball milling beads are carbide beads, and the ball-to-material ratio is 10:1; the ball milling medium is anhydrous ethanol, and the amount of anhydrous ethanol added is one-half of the volume of the ball mill; the ball mill used is a carbide ball mill, the ball milling speed is 200-300rpm, the total operation time of the equipment is 72h, and the ball mill stops for 1mi every 5min of operation. n, and at the same time, changing the rotation direction from clockwise to counterclockwise, continuing to run for 5 minutes, then stopping for 1 minute, and changing the running direction to counterclockwise, the ball milling time is 60 hours; after ball milling and mixing, a tungsten carbide blank containing a polycarbosilane precursor is prepared by molding; the obtained tungsten carbide blank containing a polycarbosilane precursor is placed in a high-temperature cracking furnace, and under the protection of an inert gas, the temperature is slowly raised to 800-1600° C., and the temperature is slowly lowered after being kept for 0.5-2 hours to prepare a tungsten carbide-silicon carbide porous ceramic.

[0010] (2) The obtained tungsten carbide-silicon carbide porous ceramic is used as a substrate and nano-metal zirconium is used as an infiltrant. The two are placed in a crucible and then placed in a high-temperature heat treatment device; under the protection of an inert gas, the temperature is slowly raised to 1000-2000°C, kept at this temperature for 1-10 hours, and then cooled at a cooling rate of 10°C / min; the obtained semi-finished product and the crucible are inverted and placed in a high-temperature heat treatment device again, and under the protection of an inert gas, the temperature is raised to 1600-2000°C, kept at this temperature for 1-2 hours, and then cooled at a cooling rate of 10°C / min, thereby obtaining a dense metal ceramic;

[0011] (3) placing the dense metal ceramic in a sealed can-shaped container with an inert gas as the medium, fixing a tungsten bar on the inner lining of the thermal insulation layer of the inner wall of the can body as the anode, and passing a high voltage current between the anode and the cathode to generate a glow discharge, and the discharge voltage is 50-1500V; as the discharge current continues to increase, the temperature in the container continues to increase to 900-1100°C, the tungsten metal at the anode is ionized, and injected into the ceramic at a high speed under the action of the electric field, and further diffuses into the interior of the workpiece and combines with the carbon element in the ceramic material to form tungsten carbide; then spraying tungsten carbide on it, the spraying method is a supersonic flame spraying method: the spraying raw material is a mixture of tungsten carbide powder and rhenium powder, the spraying thickness is 0.8-1.2mm, and a composite ceramic is obtained;

[0012] (4) The composite ceramic is placed in a high-temperature vacuum tube furnace, and the vacuum tube furnace is first evacuated to a vacuum, and then high-purity argon is introduced to balance the atmospheric pressure, and this step is repeated twice; then the heating process is started and high-purity hydrogen is introduced, and the purity of the hydrogen is ≥99.95%; the reduction process requires first raising the temperature to 600°C and keeping it warm for 3 hours, and then raising the temperature to 900°C and keeping it warm for 1 hour. The heating rate of the heating process is 10°C / min, and the hydrogen flow rate is 0.5L / min; after the insulation is completed, the heating is stopped, and the cooling process is cooling with the furnace to obtain an oxidation-resistant dense composite carbide-based rare metal ceramic.

[0013] Furthermore, the inert gas in the preparation process is helium.

[0014] Furthermore, the heating rate in step (1) is 10°C / min.

[0015] Furthermore, in the step (2), the tungsten carbide-silicon carbide porous ceramic and the nano-metal zirconium are mixed in a volume ratio of 4.5-6.5:5.

[0016] Furthermore, in step (3), the volume ratio of tungsten carbide powder to rhenium powder is 1:9-9.5.

[0017] Furthermore, the spraying process parameters in the step (3) are as follows: kerosene flow rate is 28-33 L / h, kerosene pressure is 1.6-1.8 MPa, oxygen flow rate is 850-920 L / min, oxygen pressure is 2.0-2.2 MPa, powder feeding rate is 60-80 g / min1 nitrogen flow rate is 12-14 L / min, nitrogen pressure is 1.0-1.4 MPa, and spraying distance is 380 mm-410 mm.

[0018] Furthermore, the vacuum degree in step (4) is -0.1 MPa.

[0019] The present invention uses tungsten carbide-silicon carbide composite porous ceramic as a matrix, infiltrates metal zirconium and then sprays metal rhenium and tungsten carbide on the surface to prepare a composite tungsten carbide-based rare metal ceramic to achieve anti-oxidation and dense effects.

[0020] Firstly, during the preparation process, silicon carbide is introduced into the material system through a polycarbosilane precursor, which acts as a cross-linking agent and a pore-forming agent, so that the ceramic matrix is ​​cracked at a relatively low temperature to generate a tungsten carbide-silicon carbide composite porous ceramic with sufficient strength; on this basis, metal zirconium is used as an infiltrant and introduced through a metal melt infiltration reaction. Nano-scale metal zirconium fills the ceramic pores during the melt infiltration process, thereby improving the density and strengthening the oxidation resistance of the ceramic matrix; then, ion implantation and spraying are combined to first inject tungsten carbide into the ceramic surface by an ion implantation method to form a tungsten carbide enriched layer on the ceramic surface. During spraying, the high-temperature and high-speed tungsten carbide and the metal adhesive are combined with the originally injected tungsten carbide enriched layer to form a transition surface, thereby greatly improving the bonding strength between the tungsten carbide spray layer and the ceramic matrix, thereby achieving the effect of improving the density and oxidation resistance.

[0021] Secondly, by using a high proportion of rare metal nano-rhenium, the surface densification of the material under high temperature environment of the tungsten carbide-based metal ceramic composite coating is achieved. The particle size of rhenium and its addition amount have a great influence on the high temperature performance of the composite coating: the operating temperature of the rhenium-containing tungsten carbide rare metal ceramic composite coating is higher than that of ordinary tungsten carbide-based metal ceramic coating, which greatly improves the high temperature resistance of the tungsten carbide-based metal ceramic coating, making the prepared grains more stable and dense, thereby achieving an antioxidant effect; finally, through hydrogen reduction treatment, the oxygen content of the powder is further reduced, and a high-activity low-oxygen composite carbide rare metal ceramic with a nanocrystalline structure is produced. DETAILED DESCRIPTION

[0022] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0023] In order to more clearly illustrate the method provided by the present invention, the following examples are used to describe in detail the various index testing methods of an oxidation-resistant dense composite tungsten carbide-based rare metal ceramic prepared in the following examples are as follows:

[0024] Antioxidation property: The composite tungsten carbide-based rare metal ceramic samples of the embodiment and the comparative example were tested. The test was carried out using a ferric chloride solution with a concentration of 8.5±0.5 g / L. The ferric chloride solution was dropped on the ceramic substrate. No color change was observed after 15 minutes, indicating that the antioxidation effect met the standard.

[0025] Density: The composite tungsten carbide-based rare metal ceramic samples of the embodiment and the comparative example were tested for density in accordance with GB / T25995-2010.

[0026] Example 1

[0027] (1) Tungsten carbide is used as raw material, polycarbosilane precursor is used as binder, and the volume ratio of tungsten carbide and polycarbosilane precursor is 2:3. The prepared raw material powder is placed in a ball mill. The ball milling beads are carbide beads, and the ball-to-material ratio is 10:1. Anhydrous ethanol is used as the ball milling medium, and the amount of anhydrous ethanol added is one-half of the volume of the ball milling jar. The ball milling jar used is a carbide ball milling jar, the ball milling speed is 200 rpm, the total operation time of the equipment is 72 hours, and the ball mill stops for 1 minute after running for 5 minutes, and the speed is changed at the same time. The rotation direction is changed from clockwise to counterclockwise, and the operation is continued for 5 minutes, then it is stopped for 1 minute and the operation direction is changed to counterclockwise, and the ball milling time is 60 hours; after ball milling and mixing, a tungsten carbide blank containing a polycarbosilane precursor is prepared by molding; the obtained tungsten carbide blank containing a polycarbosilane precursor is placed in a high-temperature cracking furnace, and under the protection of inert gas helium, the temperature is slowly increased to 800°C at a heating rate of 10°C / min, and the temperature is slowly decreased after keeping the temperature for 0.5 hours to prepare tungsten carbide-silicon carbide porous ceramics.

[0028] (2) The obtained tungsten carbide-silicon carbide porous ceramic is used as a substrate, nano-metal zirconium is used as an infiltrant, and the tungsten carbide-silicon carbide porous ceramic and nano-metal zirconium are mixed in a volume ratio of 4.5:5 and placed in a crucible, and then placed in a high-temperature heat treatment device; under the protection of inert gas helium, the temperature is slowly raised to 1000°C, kept warm for 1 hour, and then cooled at a cooling rate of 10°C / min; the obtained semi-finished product and the crucible are inverted and placed in the high-temperature heat treatment device again, and under the protection of inert gas helium, the temperature is raised to 1600°C, kept warm for 1 hour, and then cooled at a cooling rate of 10°C / min, and a dense metal ceramic can be obtained;

[0029] (3) The dense metal ceramic is placed in a sealed can-shaped container with inert gas helium as the medium. A tungsten bar is fixed on the inner lining of the thermal insulation layer of the inner wall of the can as an anode and a high-voltage current is passed between the cathode to generate a glow discharge with a discharge voltage of 50V. As the discharge current increases, the temperature in the container increases to 900°C. The tungsten metal at the anode is ionized and injected into the ceramic at a high speed under the action of the electric field. It further diffuses into the workpiece and combines with the carbon element in the ceramic material to form tungsten carbide. Then, carbonized tungsten is sprayed on it. Tungsten, the spraying method is supersonic flame spraying: the spraying raw material is a mixture of tungsten carbide powder and rhenium powder, the volume ratio of the two is 1:9, the spraying thickness is 0.8mm, and a duplex ceramic is obtained; the spraying process parameters are: kerosene flow rate is 28L / h, kerosene pressure is 1.6MPa, oxygen flow rate is 850L / min, oxygen pressure is 2.0MPa, powder feeding rate is 60g / min1, nitrogen flow rate is 12L / min, nitrogen pressure is 1.0MPa, and spraying distance is 380mm;

[0030] (4) The composite ceramic is placed in a high-temperature vacuum tube furnace. The vacuum tube furnace is first evacuated to a vacuum degree of -0.1 MPa, and then high-purity argon is introduced to balance the atmospheric pressure. This step is repeated twice. Then the heating process is started and high-purity hydrogen is introduced, and the purity of the hydrogen is ≥99.95%. The reduction process requires first raising the temperature to 600°C and keeping it warm for 3 hours, and then raising the temperature to 900°C and keeping it warm for 1 hour. The heating rate of the heating process is 10°C / min, and the hydrogen flow rate is 0.5L / min. After the insulation is completed, the heating is stopped, and the cooling process is cooling with the furnace to obtain an oxidation-resistant dense composite carbide-based rare metal ceramic.

[0031] Example 2

[0032] (1) Tungsten carbide is used as raw material, polycarbosilane precursor is used as binder, and the volume ratio of tungsten carbide and polycarbosilane precursor is 27:3. The prepared raw material powder is placed in a ball mill, the ball milling beads are carbide beads, and the ball-to-material ratio is 10:1; the ball milling medium is anhydrous ethanol, and the amount of anhydrous ethanol added is one-half of the volume of the ball mill; the ball mill used is a carbide ball mill, the ball milling speed is 250 rpm, the total operation time of the equipment is 72 hours, and the ball mill stops for 1 minute after running for 5 minutes, and the rotation speed is changed at the same time. The ball milling time is 60 hours. After ball milling and mixing, a tungsten carbide blank containing a polycarbosilane precursor is prepared by molding. The obtained tungsten carbide blank containing a polycarbosilane precursor is placed in a high-temperature cracking furnace, and the temperature is slowly increased to 1200°C under the protection of inert gas helium, with a heating rate of 10°C / min. After keeping the temperature for 1.25 hours, the temperature is slowly decreased to prepare tungsten carbide-silicon carbide porous ceramics.

[0033] (2) The obtained tungsten carbide-silicon carbide porous ceramic is used as a substrate, nano-metal zirconium is used as an infiltrant, and the tungsten carbide-silicon carbide porous ceramic and nano-metal zirconium are mixed in a volume ratio of 5.5:5 and placed in a crucible, and then placed in a high-temperature heat treatment device; under the protection of inert gas helium, the temperature is slowly raised to 1500°C, kept warm for 5 hours, and then cooled at a cooling rate of 10°C / min; the obtained semi-finished product and the crucible are inverted and placed in the high-temperature heat treatment device again, and under the protection of inert gas helium, the temperature is raised to 1800°C, kept warm for 1.5 hours, and then cooled at a cooling rate of 10°C / min, and a dense metal ceramic can be obtained;

[0034] (3) The dense metal ceramic is placed in a sealed can-shaped container with inert gas helium as the medium. A tungsten bar is fixed on the inner wall of the can body as the thermal insulation layer. A high-voltage current is passed between the anode and the cathode to generate a glow discharge. The discharge voltage is 725V. As the discharge current continues to increase, the temperature in the container continues to increase to 1000°C. The tungsten metal at the anode is ionized and injected into the ceramic at a high speed under the action of the electric field. It further diffuses into the workpiece and combines with the carbon element in the ceramic material to form tungsten carbide. Then, carbon is sprayed on it. Tungsten carbide, the spraying method is supersonic flame spraying: the spraying raw material is a mixture of tungsten carbide powder and rhenium powder, the volume ratio of the two is 1:9.25, the spraying thickness is 1mm, and the composite ceramic is obtained; the spraying process parameters are: kerosene flow rate is 31L / h, kerosene pressure is 1.7MPa, oxygen flow rate is 885L / min, oxygen pressure is 2.1MPa, powder feeding rate is 70g / min1, nitrogen flow rate is 13L / min, nitrogen pressure is 1.2MPa, and spraying distance is 395mm;

[0035] (4) The composite ceramic is placed in a high-temperature vacuum tube furnace. The vacuum tube furnace is first evacuated to a vacuum degree of -0.1 MPa, and then high-purity argon is introduced to balance the atmospheric pressure. This step is repeated twice. Then the heating process is started and high-purity hydrogen is introduced, and the purity of the hydrogen is ≥99.95%. The reduction process requires first raising the temperature to 600°C and keeping it warm for 3 hours, and then raising the temperature to 900°C and keeping it warm for 1 hour. The heating rate of the heating process is 10°C / min, and the hydrogen flow rate is 0.5L / min. After the insulation is completed, the heating is stopped, and the cooling process is cooling with the furnace to obtain an oxidation-resistant dense composite carbide-based rare metal ceramic.

[0036] Example 3

[0037] (1) Tungsten carbide is used as raw material, polycarbosilane precursor is used as binder, and the volume ratio of tungsten carbide and polycarbosilane precursor is 52:3. The prepared raw material powder is placed in a ball mill. The ball milling beads are carbide beads, and the ball-to-material ratio is 10:1. Anhydrous ethanol is used as the ball milling medium, and the amount of anhydrous ethanol added is one-half of the volume of the ball mill. The ball mill used is a carbide ball mill, the ball milling speed is 300 rpm, the total operation time of the equipment is 72 hours, and the ball mill stops for 1 minute after running for 5 minutes, and changes The rotation direction is changed from clockwise to counterclockwise, and it continues to run for 5 minutes, then stops for 1 minute, and changes the running direction to counterclockwise, and the ball milling time is 60 hours; after ball milling and mixing, a tungsten carbide blank containing a polycarbosilane precursor is prepared by molding; the obtained tungsten carbide blank containing a polycarbosilane precursor is placed in a high-temperature cracking furnace, and under the protection of inert gas helium, the temperature is slowly increased to 1600°C, the heating rate is 10°C / min, and after keeping warm for 2 hours, the temperature is slowly reduced to prepare tungsten carbide-silicon carbide porous ceramics.

[0038] (2) The obtained tungsten carbide-silicon carbide porous ceramic is used as a substrate, nano-metal zirconium is used as an infiltrant, and the tungsten carbide-silicon carbide porous ceramic and nano-metal zirconium are mixed in a volume ratio of 6.5:5 and placed in a crucible, and then placed in a high-temperature heat treatment device; under the protection of inert gas helium, the temperature is slowly raised to 2000°C, kept at this temperature for 10 hours, and then cooled at a cooling rate of 10°C / min; the obtained semi-finished product and the crucible are inverted and placed in the high-temperature heat treatment device again, and under the protection of inert gas helium, the temperature is raised to 2000°C, kept at this temperature for 2 hours, and then cooled at a cooling rate of 10°C / min, so that a dense metal ceramic can be obtained;

[0039] (3) The dense metal ceramic is placed in a sealed can-shaped container with inert gas helium as the medium. A tungsten bar is fixed on the inner lining of the thermal insulation layer of the inner wall of the can as an anode and a high-voltage current is passed between the cathode to generate a glow discharge with a discharge voltage of 1500V. As the discharge current continues to increase, the temperature in the container continues to increase to 1100°C. The tungsten metal at the anode is ionized and injected into the ceramic at a high speed under the action of the electric field. It further diffuses into the interior of the workpiece and combines with the carbon element in the ceramic material to form tungsten carbide. Then, carbon is sprayed on it. Tungsten carbide, the spraying method is supersonic flame spraying: the spraying raw material is a mixture of tungsten carbide powder and rhenium powder, the volume ratio of the two is 1:9.5, the spraying thickness is 1.2mm, and the composite ceramic is obtained; the spraying process parameters are: kerosene flow rate is 33L / h, kerosene pressure is 1.8MPa, oxygen flow rate is 920L / min, oxygen pressure is 2.2MPa, powder feeding rate is 80g / min1, nitrogen flow rate is 14L / min, nitrogen pressure is 1.4MPa, and spraying distance is 410mm;

[0040] (4) The composite ceramic is placed in a high-temperature vacuum tube furnace. The vacuum tube furnace is first evacuated to a vacuum degree of -0.1 MPa, and then high-purity argon is introduced to balance the atmospheric pressure. This step is repeated twice. Then the heating process is started and high-purity hydrogen is introduced, and the purity of the hydrogen is ≥99.95%. The reduction process requires first raising the temperature to 600°C and keeping it warm for 3 hours, and then raising the temperature to 900°C and keeping it warm for 1 hour. The heating rate of the heating process is 10°C / min, and the hydrogen flow rate is 0.5L / min. After the insulation is completed, the heating is stopped, and the cooling process is cooling with the furnace to obtain an oxidation-resistant dense composite carbide-based rare metal ceramic.

[0041] Comparative Example 1

[0042] The difference between Comparative Example 1 and Example 2 lies in step (1), in which step (1) is modified as follows: tungsten carbide is used as raw material, polycarbosilane precursor is used as binder, tungsten carbide and polycarbosilane precursor are mixed in a volume ratio of 27:3, and a tungsten carbide blank containing polycarbosilane precursor is prepared by molding; the obtained tungsten carbide blank containing polycarbosilane precursor is placed in a high-temperature cracking furnace, and the temperature is slowly increased to 1200°C under the protection of inert gas helium, the temperature is increased at a rate of 10°C / min, and the temperature is slowly decreased after being kept for 1.25 hours to prepare tungsten carbide-silicon carbide porous ceramics; the remaining steps are the same as those in Example 2.

[0043] Comparative Example 2

[0044] The difference between Comparative Example 2 and Example 2 is that there is no step (2), and step (3) is changed to: the tungsten carbide-silicon carbide porous ceramic is placed in a closed can-shaped container with inert gas helium as the medium, a tungsten bar is fixed on the inner lining of the thermal insulation layer of the inner wall of the can body as an anode and a high-voltage current is passed between the cathode to generate glow discharge, and the discharge voltage is 1500V; as the discharge current continues to increase, the temperature in the container continues to increase to 1100°C, the tungsten metal at the anode is ionized, and is injected into the ceramic at a high speed under the action of the electric field, and further diffuses into the workpiece and combines with the carbon element in the ceramic material to generate to carbonize tungsten; and then spray tungsten carbide on it, the spraying method is supersonic flame spraying: the sprayed raw material is a mixture of tungsten carbide powder and rhenium powder, the volume ratio of the two is 1:9.5, the spraying thickness is 1.2mm, and a duplex ceramic is obtained; the spraying process parameters are: kerosene flow rate is 33L / h, kerosene pressure is 1.8MPa, oxygen flow rate is 920L / min, oxygen pressure is 2.2MPa, powder feeding rate is 80g / min1 nitrogen flow rate is 14L / min, nitrogen pressure is 1.4MPa, and spraying distance is 410mm; the remaining steps are the same as Example 2.

[0045] Comparative Example 3

[0046] The difference between Comparative Example 3 and Example 2 is that step (2) is different. Step (3) is changed to: spray tungsten carbide on the dense metal ceramic, and the spraying method is supersonic flame spraying: the sprayed raw material is a mixture of tungsten carbide powder and rhenium powder, the volume ratio of the two is 1:9.25, the spraying thickness is 1 mm, and a composite ceramic is obtained; the spraying process parameters are: kerosene flow rate is 31 L / h, kerosene pressure is 1.7 MPa, oxygen flow rate is 885 L / min, oxygen pressure is 2.1 MPa, powder feeding rate is 70 g / min1 nitrogen flow rate is 13 L / min, nitrogen pressure is 1.2 MPa, and spraying distance is 395 mm; the remaining steps are the same as Example 2.

[0047] Comparative Example 4

[0048] The difference between Comparative Example 4 and Example 2 is that step (3) is different. Step (3) is changed to: the dense metal ceramic is placed in a closed can-shaped container with inert gas helium as the medium, a tungsten bar is fixed on the inner lining of the thermal insulation layer on the inner wall of the can body as an anode and a high-voltage current is passed between the cathode to generate glow discharge, and the discharge voltage is 725V; as the discharge current continues to increase, the temperature in the container continues to increase to 1000°C, the tungsten metal at the anode is ionized, and is injected into the ceramic at a high speed under the action of the electric field, and further diffuses into the workpiece and combines with the ceramic The carbon element in the material is combined to form tungsten carbide; then tungsten carbide is sprayed on it, and the spraying method is supersonic flame spraying: the raw material for spraying is tungsten carbide powder, the spraying thickness is 1 mm, and a duplex ceramic is obtained; the spraying process parameters are: kerosene flow rate is 31 L / h, kerosene pressure is 1.7 MPa, oxygen flow rate is 885 L / min, oxygen pressure is 2.1 MPa, powder feeding rate is 70 g / min1 nitrogen flow rate is 13 L / min, nitrogen pressure is 1.2 MPa, and spraying distance is 395 mm; the remaining steps are the same as Example 2.

[0049] Comparative Example 5

[0050] The difference between Comparative Example 5 and Example 2 is that step (4) is different, and step (3) is changed to: the dense metal ceramic is placed in a closed can-shaped container with inert gas helium as the medium, a tungsten bar is fixed on the inner lining of the thermal insulation layer on the inner wall of the can body as the anode and a high-voltage current is passed between the cathode to generate glow discharge, and the discharge voltage is 725V; as the discharge current continues to increase, the temperature in the container continues to increase to 1000°C, the tungsten metal at the anode is ionized, and is injected into the ceramic at a high speed under the action of the electric field, and further diffuses into the interior of the workpiece and combines with the carbon element in the ceramic material to form tungsten carbide; then it is sprayed Coating tungsten carbide, the spraying method is supersonic flame spraying: the spraying raw material is a mixture of tungsten carbide powder and rhenium powder, the volume ratio of the two is 1:9.25, the spraying thickness is 1mm, and the obtained antioxidant dense compound carbide-based rare metal ceramic is obtained; the spraying process parameters are: kerosene flow rate is 31L / h, kerosene pressure is 1.7MPa, oxygen flow rate is 885L / min, oxygen pressure is 2.1MPa, powder feeding rate is 70g / min1 nitrogen flow rate is 13L / min, nitrogen pressure is 1.2MPa, and spraying distance is 395mm; the remaining steps are the same as Example 2.

[0051] Effect example

[0052] Table 1 below shows the performance analysis results of an oxidation-resistant, dense, composite tungsten carbide-based rare metal ceramic using Examples 1 to 3 of the present invention and Comparative Examples 1 to 5.

[0053] Table 1

[0054] Antioxidant properties (discoloration) Density(%) Example 1 No discoloration 98.25 Example 2 No discoloration 98.41 Example 3 No discoloration 98.28 Comparative Example 1 Slight discoloration 97.52 Comparative Example 2 Slight discoloration 92.36 Comparative Example 3 Slight discoloration 90.21 Comparative Example 4 Slight discoloration 92.68 Comparative Example 5 Slight discoloration 98.10

[0055] From the comparison of the experimental data of the compactness of the embodiment and the comparative example, it can be found that in the preparation process of the present invention, silicon carbide material is introduced into the material system through a polycarbosilane precursor, and the polycarbosilane precursor acts as a cross-linking agent and a pore-forming agent, which allows the ceramic matrix to crack at a relatively low temperature to generate a tungsten carbide-silicon carbide composite porous ceramic with sufficient strength; on this basis, metal zirconium is used as an infiltrant and introduced through a metal melt infiltration reaction. Nano-scale metal zirconium fills the ceramic pores during the melt infiltration process, thereby improving the compactness and strengthening the oxidation resistance of the ceramic matrix; then, a combination of ion implantation and spraying is adopted, and tungsten carbide is first injected into the ceramic surface by an ion implantation method to form a tungsten carbide enriched layer on the ceramic surface. During spraying, the high-temperature and high-speed tungsten carbide and the metal adhesive are combined with the originally injected tungsten carbide enriched layer as a whole to form a transition surface, thereby greatly improving the bonding strength between the tungsten carbide spray layer and the ceramic matrix, thereby achieving the effect of improving the compactness and oxidation resistance. From the comparison of the experimental data of the oxidation resistance of the embodiment and the comparative example, it can be found that the present invention adopts a high proportion of rare metal nano-rhenium to achieve the densification of the material surface of the tungsten carbide-based metal ceramic composite coating under high temperature environment, and the particle size of rhenium and its addition amount have a great influence on the high temperature performance of the composite coating: the operating temperature of the rhenium-containing tungsten carbide rare metal ceramic composite coating is higher than that of the ordinary tungsten carbide-based metal ceramic coating, which greatly improves the high temperature resistance of the tungsten carbide-based metal ceramic coating, so that the prepared grains are more stable and dense, thereby achieving the antioxidant effect; finally, the oxygen content of the powder is further reduced by hydrogen reduction treatment, and a high-activity low-oxygen composite carbide rare metal ceramic with a nanocrystalline structure is produced.

[0056] It will be apparent to those skilled in the art that the invention is not limited to the details of the exemplary embodiments described above and that the invention can be implemented in other specific forms without departing from the spirit or essential features of the invention. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description, and it is intended that all variations within the meaning and scope of the equivalent elements of the claims be included in the invention. Any marking in a claim should not be considered as limiting the claim to which it relates.

Claims

1. An oxidation-resistant, dense, composite tungsten carbide-based rare metal ceramic. It is characterized in that The ceramic is prepared by using tungsten carbide-silicon carbide composite porous ceramic as a matrix, infiltrating metal zirconium as a matrix, and then spraying metal rhenium and tungsten carbide coating on the surface.

2. The oxidation-resistant, dense, composite tungsten carbide-based rare metal ceramic according to claim 1, It is characterized in that The matrix is ​​prepared by introducing silicon carbide into polycarbosilane, cracking it to generate tungsten carbide-silicon carbide composite porous ceramics, introducing metal zirconium through metal infiltration reaction, and nano-scale metal zirconium filling ceramic pores during the infiltration process.

3. The oxidation-resistant, dense, composite tungsten carbide-based rare metal ceramic according to claim 1, It is characterized in that The coating is formed by combining ion implantation and spraying, wherein tungsten carbide is implanted into the ceramic surface by ion implantation, and then a mixture of tungsten carbide powder and rhenium powder is sprayed.

4. A method for preparing an oxidation-resistant, dense, composite tungsten carbide-based rare metal ceramic. It is characterized in that The method comprises the following preparation steps: (1) Tungsten carbide is used as raw material, polycarbosilane precursor is used as binder, and the volume ratio of tungsten carbide and polycarbosilane precursor is 2-52:

3. The prepared raw material powder is placed in a ball mill, the ball milling beads are carbide beads, and the ball-to-material ratio is 10:1; the ball milling medium is anhydrous ethanol, and the amount of anhydrous ethanol added is one-half of the volume of the ball mill; the ball mill used is a carbide ball mill, the ball milling speed is 200-300rpm, the total operation time of the equipment is 72h, and the ball mill stops for 1mi every 5min of operation. n, and at the same time, changing the rotation direction from clockwise to counterclockwise, continuing to run for 5 minutes, then stopping for 1 minute, and changing the running direction to counterclockwise, the ball milling time is 60 hours; after ball milling and mixing, a tungsten carbide blank containing a polycarbosilane precursor is prepared by molding; the obtained tungsten carbide blank containing a polycarbosilane precursor is placed in a high-temperature cracking furnace, and under the protection of an inert gas, the temperature is slowly raised to 800-1600° C., and the temperature is slowly lowered after being kept for 0.5-2 hours to prepare a tungsten carbide-silicon carbide porous ceramic. (2) The obtained tungsten carbide-silicon carbide porous ceramic is used as a substrate and nano-metal zirconium is used as an infiltrant. The two are placed in a crucible and then placed in a high-temperature heat treatment device; under the protection of an inert gas, the temperature is slowly raised to 1000-2000°C, kept at this temperature for 1-10 hours, and then cooled at a cooling rate of 10°C / min; the obtained semi-finished product and the crucible are inverted and placed in a high-temperature heat treatment device again, and under the protection of an inert gas, the temperature is raised to 1600-2000°C, kept at this temperature for 1-2 hours, and then cooled at a cooling rate of 10°C / min, thereby obtaining a dense metal ceramic; (3) placing the dense metal ceramic in a sealed can-shaped container with an inert gas as the medium, fixing a tungsten bar on the inner lining of the thermal insulation layer of the inner wall of the can body as the anode, and passing a high voltage current between the anode and the cathode to generate a glow discharge, and the discharge voltage is 50-1500V; as the discharge current continues to increase, the temperature in the container continues to increase to 900-1100°C, the tungsten metal at the anode is ionized, and injected into the ceramic at a high speed under the action of the electric field, and further diffuses into the interior of the workpiece and combines with the carbon element in the ceramic material to form tungsten carbide; then spraying tungsten carbide on it, the spraying method is a supersonic flame spraying method: the spraying raw material is a mixture of tungsten carbide powder and rhenium powder, the spraying thickness is 0.8-1.2mm, and a composite ceramic is obtained; (4) The composite ceramic is placed in a high-temperature vacuum tube furnace, and the vacuum tube furnace is first evacuated to a vacuum, and then high-purity argon is introduced to balance the atmospheric pressure, and this step is repeated twice; then the heating process is started and high-purity hydrogen is introduced, and the purity of the hydrogen is ≥99.95%; the reduction process requires first raising the temperature to 600°C and keeping it warm for 3 hours, and then raising the temperature to 900°C and keeping it warm for 1 hour. The heating rate of the heating process is 10°C / min, and the hydrogen flow rate is 0.5L / min; after the insulation is completed, the heating is stopped, and the cooling process is cooling with the furnace to obtain an oxidation-resistant dense composite carbide-based rare metal ceramic.

5. A method for preparing an oxidation-resistant, dense, composite tungsten carbide-based rare metal ceramic according to claim 4, It is characterized in that The inert gas in the preparation process is helium.

6. A method for preparing an oxidation-resistant, dense, composite tungsten carbide-based rare metal ceramic according to claim 4, It is characterized in that The heating rate in step (1) is 10°C / min.

7. A method for preparing an oxidation-resistant, dense, composite tungsten carbide-based rare metal ceramic according to claim 4, It is characterized in that In the step (2), the tungsten carbide-silicon carbide porous ceramic and the nano-metal zirconium are mixed in a volume ratio of 4.5-6.5:

5.

8. The method for preparing an oxidation-resistant and dense composite tungsten carbide-based rare metal ceramic according to claim 4, It is characterized in that In the step (3), the volume ratio of tungsten carbide powder to rhenium powder is 1:9-9.

5.

9. The method for preparing an oxidation-resistant and dense composite tungsten carbide-based rare metal ceramic according to claim 4, It is characterized in that The spraying process parameters in the step (3) are as follows: kerosene flow rate is 28-33 L / h, kerosene pressure is 1.6-1.8 MPa, oxygen flow rate is 850-920 L / min, oxygen pressure is 2.0-2.2 MPa, powder feeding rate is 60-80 g / min, nitrogen flow rate is 12-14 L / min, nitrogen pressure is 1.0-1.4 MPa, and spraying distance is 380 mm-410 mm.

10. The method for preparing an oxidation-resistant and dense composite tungsten carbide-based rare metal ceramic according to claim 4, It is characterized in that The vacuum degree in step (4) is -0.1 MPa.