Silicon carbide fiber reinforced tantalum boride ceramic and preparation method thereof

Abstract

The present invention provides a silicon carbide fiber reinforced tantalum boride ceramic and a preparation method thereof, which belongs to the field of tantalum boride ceramics. The preparation method of the silicon carbide fiber reinforced tantalum boride ceramics consists of the following steps: preparing a composite powder, preparing a modified fiber material, mixing and molding, and multi-stage sintering. The silicon carbide fiber reinforced tantalum boride ceramics and the preparation method thereof of the present invention can achieve the effective reinforcement of the silicon carbide fiber on the tantalum boride ceramics, effectively improve the bonding performance of the silicon carbide fiber and the tantalum boride ceramic matrix, and reduce the occurrence of the interface reaction between the silicon carbide fiber and other raw materials of the tantalum boride ceramics, improve the structural stability of the tantalum boride ceramics, and effectively improve the toughness of the tantalum boride ceramics; at the same time, it alleviates the thermal matching problem between the silicon carbide fiber and the tantalum boride ceramic matrix, improves the stability of the tantalum boride ceramics under rapid temperature change conditions, and improves the durability of the tantalum boride ceramics.

Description

Technical Field

[0001] The invention relates to the field of tantalum boride ceramics, in particular to a silicon carbide fiber reinforced tantalum boride ceramic and a preparation method thereof. Background Art

[0002] With the continuous development of science and technology, human society has never stopped pursuing speed and energy. The maximum speed of the hypersonic aircraft currently developed can reach ten times the speed of sound. During the flight, the surface and air produce strong compression and friction, which can make the local temperature reach 2000℃. The surface materials of the aircraft are in a very extreme working environment, and the performance requirements for the surface materials are getting higher and higher; similarly, in the fields of high-speed cutting tools, spacecraft recovery, nuclear energy utilization, etc., due to their special working environment, there is also a great demand for materials that can work stably in extreme special environments.

[0003] In the existing technology, traditional single materials can no longer meet the above-mentioned usage requirements. With the continuous deepening of the study of high entropy effect, the exploration and expansion of high entropy materials are also continuing. In 2015, American scholars first reported a rock salt structure oxide high entropy ceramic. Since then, various high entropy ceramic materials, such as borides, carbides, nitrides, etc. have been discovered; high entropy ceramic materials generally refer to ceramic materials with multiple components. The solid solution coupling effect between the multiple components can make the material have a higher entropy value, thereby effectively improving the phase stability of the ceramic material; at the same time, the significant solid solution strengthening effect can make the ceramic material have the characteristics of high hardness. Among high entropy ceramic materials, transition metal borides with high conductivity, high melting point, high hardness and high stability have received more and more attention and research in the field of high entropy ceramics. Due to its excellent performance, boride high entropy ceramics have good application prospects in extreme special working conditions such as aerospace, high-speed cutting tools, and nuclear energy utilization.

[0004] During the preparation of boride high entropy ceramics, the hardness can be improved due to lattice distortion, but the high entropy effect cannot change the brittle characteristics of boride ceramics. The inherent brittle defects of boride high entropy ceramic materials are one of the main obstacles limiting their application in extreme environments. In order to improve the brittle defects of high entropy ceramic materials, the prior art discloses the technical idea of ​​using fiber toughening. It uses fiber as the toughening phase of high entropy ceramic materials to suppress the volume effect of its matrix defects, and improves the fracture toughness of high entropy ceramic materials through toughening mechanisms such as fiber pull-out, fiber debonding, crack deflection, crack bridging and crack branching.

[0005] However, in the process of using fibers to toughen boride high entropy ceramics, the bonding performance between the fibers and the boride high entropy ceramic material matrix is ​​poor; and in the process of sintering the fibers in contact with other raw materials of the boride high entropy ceramics, interfacial reactions are prone to occur, affecting the structural stability of the boride high entropy ceramics; specifically, under the action of external force, the fibers are prone to break or pull out in the boride high entropy ceramic material matrix, which not only limits its effect on improving the toughness of the material, but also affects the original mechanical properties of the boride high entropy ceramic material.

[0006] At the same time, there is also the problem of thermal expansion mismatch between fibers and boride high entropy ceramics. Under rapid temperature changes, cracks can easily appear inside the boride high entropy ceramic matrix, which not only affects the durability of the boride high entropy ceramics, but may also form diffusion channels for oxidizing gases, further reducing the structural stability of the boride high entropy ceramics, accelerating the deterioration of its overall performance, and making it impossible to maintain good mechanical properties for a long time. Summary of the invention

[0007] In order to solve the technical problems existing in the prior art, the present invention provides a silicon carbide fiber reinforced tantalum boride ceramic and a preparation method thereof, which can achieve effective reinforcement of the tantalum boride ceramic by silicon carbide fiber, effectively improve the bonding performance of the silicon carbide fiber and the tantalum boride ceramic matrix, reduce the occurrence of interface reaction between the silicon carbide fiber and other raw materials of the tantalum boride ceramic, improve the structural stability of the tantalum boride ceramic, and effectively improve the toughness of the tantalum boride ceramic; at the same time, alleviate the thermal matching problem between the silicon carbide fiber and the tantalum boride ceramic matrix, improve the stability of the tantalum boride ceramic under rapid temperature change conditions, and improve the durability of the tantalum boride ceramic.

[0008] In order to solve the above technical problems, the technical solution adopted by the present invention is as follows:

[0009] A method for preparing silicon carbide fiber reinforced tantalum boride ceramics comprises the following steps: preparing composite powder material, preparing modified fiber material, mixing and molding, and multi-stage sintering.

[0010] The method for preparing the composite powder is to put tantalum diboride powder, zirconium diboride powder, titanium carbide powder, aluminum oxide powder, zirconium oxide powder and neodymium oxide powder into a high-energy ball mill, control the ball-to-material mass ratio to be 11-11.5:1, the ball milling speed to be 400-450rpm, and perform ball milling for 13-15h to obtain the composite powder.

[0011] In the preparation of the composite powder, the mass ratio of tantalum diboride powder, zirconium diboride powder, titanium carbide powder, aluminum oxide powder, zirconium oxide powder and neodymium oxide powder is 115-118:22-23:48-50:10-10.5:6.8-7:3.1-3.3;

[0012] The average particle size D50 of tantalum diboride powder, zirconium diboride powder, titanium carbide powder, aluminum oxide powder, zirconium oxide powder and neodymium oxide powder is 2-6 μm.

[0013] The modified fiber material is prepared by the following steps: fiber pretreatment, impregnation and curing.

[0014] The fiber pretreatment method comprises the following steps: completely immersing silicon carbide fibers with a diameter of 13-15 μm into a pretreatment liquid, heating the fibers to 30-35° C., and heat-insulating and immersing the fibers for 70-90 minutes, separating the silicon carbide fibers, washing the fibers with deionized water until they are neutral, and drying the fibers at 100-110° C. until they are constant weight; and then transferring the fibers into a treatment chamber of a low-temperature plasma device, introducing a pretreatment gas, adjusting the pressure in the treatment chamber of the low-temperature plasma device to 70-80 Pa (gauge pressure), controlling the low-temperature plasma treatment power to 400-500 W, and performing low-temperature plasma treatment for 20-30 minutes to obtain pretreated fibers.

[0015] In the fiber pretreatment, the pretreatment liquid is a deionized water solution in which hydrochloric acid and nitric acid are dissolved; the concentration of hydrochloric acid in the pretreatment liquid is 0.12-0.13 mol / L, and the concentration of nitric acid is 0.04-0.05 mol / L; the weight ratio of silicon carbide fiber to pretreatment liquid is 1:8-9;

[0016] The pretreatment gas is a mixture of nitrogen and argon, and the volume ratio of nitrogen to argon is 1:2.5-3.

[0017] The impregnation and curing method comprises the following steps: chopping the pretreated fibers into pieces of 0.9-1.2 cm to obtain chopped pretreated fibers; then putting the chopped pretreated fibers into an impregnation treatment liquid, and impregnating them at room temperature under negative pressure for 50-60 minutes under a vacuum degree of 0.03-0.04 MPa, and then pressurizing them to 1.5-1.8 MPa, and then pressurizing them at room temperature for 50-60 minutes to obtain solid matter; transferring the solid matter into a roasting furnace, and then heat-treating them at 70-75° C. for 10-12 hours, and then heating them to 180-200° C. for 1-1.5 hours, and then cooling them naturally to obtain a modified fiber material.

[0018] In the impregnation and curing, the weight ratio of the chopped pretreated fibers to the impregnation treatment liquid is 1:4-5.

[0019] The preparation method of the impregnation treatment liquid is as follows: n-butyl titanate, tetrabutyl zirconate and hafnium n-butoxide are added into ethylene glycol in an ice bath, stirred for 10-20 minutes, and then diethylamine and acetylacetone are added. After stirring and reacting in an ice bath for 12-13 hours, the impregnation treatment liquid is obtained.

[0020] In the preparation of the impregnation treatment solution, the molar ratio of n-butyl titanate, tetrabutyl zirconate, hafnium n-butoxide, diethylamine, and acetylacetone is 10-10.5:10-10.5:10-10.5:0.01-0.02:2-3;

[0021] The added amount of ethylene glycol is 1.95-2 times the total weight of n-butyl titanate, tetrabutyl zirconate and hafnium n-butoxide.

[0022] The mixing and molding method comprises the following steps: putting the composite powder and the modified fiber material into a high-speed mixer, controlling the mixing speed to be 1200-1500 rpm, mixing them evenly, and obtaining a mixture; then transferring the mixture into a mold, sealing it, placing it in a cold isostatic pressing molding machine, controlling the cold isostatic pressing molding pressure to be 240-250 MPa, performing cold isostatic pressing molding for 15-25 minutes, and demolding to obtain a green body.

[0023] In the mixed material forming, the weight ratio of the composite powder material to the modified fiber material is 10:0.9-1.1.

[0024] The multi-stage sintering method comprises the following steps: placing the green body in a calcining furnace, heating the green body to 1200-1300°C at a heating rate of 2-3°C / min, and maintaining the temperature for primary sintering for 40-60min; using argon to completely replace the air in the calcining furnace, heating the green body to 1500-1600°C at a heating rate of 5-6°C / min, and maintaining the temperature for secondary sintering for 40-60min; adjusting the pressure in the calcining furnace to 22-25MPa by using argon, heating the green body to 1900-2000°C at a heating rate of 10-12°C / min, and maintaining the temperature for tertiary sintering for 40-60min, and cooling the green body with the furnace to obtain silicon carbide fiber reinforced tantalum boride ceramics.

[0025] A silicon carbide fiber reinforced tantalum boride ceramic is prepared by adopting the above-mentioned preparation method.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] (1) The preparation method of silicon carbide fiber reinforced tantalum boride ceramics of the present invention comprises the following steps: in the step of preparing composite powder, tantalum diboride and zirconium diboride are combined with titanium carbide, aluminum oxide, zirconium oxide and neodymium oxide to form composite powder; in the step of preparing modified fiber material, a pretreatment liquid is first used to perform surface etching treatment on silicon carbide fiber, and on the basis of etching with the pretreatment liquid, a low-temperature plasma is further used to perform surface treatment on silicon carbide fiber to obtain pretreated fiber, further improve the surface roughness of silicon carbide fiber, realize surface activation of silicon carbide fiber, and improve the binding performance of silicon carbide fiber with effective components in subsequent impregnation treatment liquid; then, an impregnation treatment liquid is obtained by hydrolysis condensation of n-butyl titanate, tetrabutyl zirconate and hafnium n-butoxide, and the pretreated fiber is impregnated with the impregnation treatment liquid. After the fiber is impregnated into the impregnation treatment liquid for treatment, a modified fiber material is obtained; in the mixing and molding step, the aforementioned composite powder and the modified fiber material are mixed to form a green body, and then multi-stage sintering is performed to obtain silicon carbide fiber reinforced tantalum boride ceramics; the aforementioned technical means cooperate and synergize with each other to achieve the effective reinforcement of tantalum boride ceramics by silicon carbide fibers, effectively improve the bonding performance of silicon carbide fibers and tantalum boride ceramic matrix, reduce the occurrence of interface reaction between silicon carbide fibers and other raw materials of tantalum boride ceramics, improve the structural stability of tantalum boride ceramics, and effectively improve the toughness of tantalum boride ceramics; at the same time, the thermal matching problem between silicon carbide fibers and tantalum boride ceramic matrix is ​​alleviated, the stability of tantalum boride ceramics under rapid temperature change conditions is improved, and the durability of tantalum boride ceramics is improved.

[0028] (2) The silicon carbide fiber reinforced tantalum boride ceramic of the present invention has an open porosity of 0.17-0.20%, a Vickers hardness HV of 34.2-34.6 GPa, and a fracture toughness of 6.40-6.45 MPa·m 1 / 2 The three-point bending strength at 1600℃ is 851-853MPa, and the bonding strength between the fiber and the ceramic matrix is ​​6.5-6.7MPa.

[0029] (3) After 30 rapid temperature changes from room temperature to 1900°C, the silicon carbide fiber reinforced tantalum boride ceramic of the present invention has a Vickers hardness HV of 32.5-32.9 GPa and a fracture toughness of 6.14-6.18 MPa·m 1 / 2 The three-point bending strength at 1600℃ is 803-806MPa, and no cracking or deformation occurs.

[0030] (4) The method for preparing silicon carbide fiber reinforced tantalum boride ceramics of the present invention has a simple process flow and is easy to control during the preparation process, which is conducive to industrial-scale production. DETAILED DESCRIPTION

[0031] In order to have a clearer understanding of the technical features, purposes and effects of the present invention, the specific implementation methods of the present invention are now described.

[0032] Example 1

[0033] This embodiment provides a method for preparing silicon carbide fiber reinforced tantalum boride ceramics, which comprises the following steps:

[0034] 1. Preparation of composite powder

[0035] Tantalum diboride powder, zirconium diboride powder, titanium carbide powder, aluminum oxide powder, zirconium oxide powder and neodymium oxide powder were put into a high-energy ball mill, the ball-to-material mass ratio was controlled to be 11:1, the ball milling speed was 400 rpm, and the ball milling treatment was carried out for 13 hours to obtain a composite powder.

[0036] Among them, the mass ratio of tantalum diboride powder, zirconium diboride powder, titanium carbide powder, aluminum oxide powder, zirconium oxide powder and neodymium oxide powder is 115:22:48:10:6.8:3.1.

[0037] The average particle size D50 of the tantalum diboride powder, zirconium diboride powder, titanium carbide powder, aluminum oxide powder, zirconium oxide powder, and neodymium oxide powder used is 5 μm.

[0038] 2. Preparation of modified fiber materials

[0039] (1) Fiber pretreatment

[0040] The silicon carbide fiber with a diameter of 15 μm was completely immersed in the pretreatment liquid, heated to 30°C, and kept warm for 70 minutes. The silicon carbide fiber was separated, washed with deionized water until neutral, and dried at 100°C to constant weight; then transferred to the treatment chamber of the low-temperature plasma device, the pretreatment gas was introduced, and the pressure in the treatment chamber of the low-temperature plasma device was adjusted to 70Pa (gauge pressure), the low-temperature plasma treatment power was controlled to 400W, and the low-temperature plasma treatment was carried out for 20 minutes to obtain the pretreated fiber.

[0041] The pretreatment liquid is a deionized water solution in which hydrochloric acid and nitric acid are dissolved; the concentration of hydrochloric acid in the pretreatment liquid is 0.12 mol / L, and the concentration of nitric acid is 0.04 mol / L; and the weight ratio of silicon carbide fiber to the pretreatment liquid is 1:8.

[0042] The pretreatment gas is a mixture of nitrogen and argon, and the volume ratio of nitrogen to argon is 1:2.5.

[0043] (2) Impregnation and curing

[0044] The pretreated fibers were chopped into 1.1 cm to obtain chopped pretreated fibers; the chopped pretreated fibers were then put into an impregnation treatment liquid, and were impregnated at negative pressure at room temperature for 50 minutes under a vacuum degree of 0.03 MPa, and then pressurized to 1.5 MPa, and impregnated at room temperature for 50 minutes, and then solid matter was separated; the solid matter was transferred into a roasting furnace, and after a heat preservation treatment at 70°C for 10 hours, the temperature was continuously raised to 180°C, and the heat preservation treatment was performed for 1 hour, and the modified fiber material was obtained by natural cooling.

[0045] The weight ratio of the chopped pretreated fibers to the impregnated treatment liquid is 1:4.

[0046] The preparation method of the impregnation treatment liquid is as follows: n-butyl titanate, tetrabutyl zirconate, and hafnium n-butoxide are added into ethylene glycol in an ice bath, stirred for 10 minutes, and then diethylamine and acetylacetone are added. After stirring and reacting in an ice bath for 12 hours, the impregnation treatment liquid is obtained.

[0047] The molar ratio of n-butyl titanate, tetrabutyl zirconate, hafnium n-butoxide, diethylamine and acetylacetone is 10:10:10:0.01:2.

[0048] The added amount of ethylene glycol is 1.95 times the total weight of n-butyl titanate, tetrabutyl zirconate and hafnium n-butoxide.

[0049] 3. Mixing and molding

[0050] The composite powder and modified fiber material are put into a high-speed mixer, the mixing speed is controlled to be 1200rpm, and the mixture is evenly mixed to obtain a mixture; then the mixture is transferred into a mold and sealed, and then placed in a cold isostatic pressing machine, the cold isostatic pressing pressure is controlled to be 240MPa, and after cold isostatic pressing for 15 minutes, demolding is carried out to obtain a green body.

[0051] Among them, the weight ratio of the composite powder material to the modified fiber material is 10:0.9.

[0052] 4. Multi-stage sintering

[0053] The green body was placed in a calcining furnace, heated to 1200°C at a heating rate of 2°C / min, and kept warm for primary sintering for 40 minutes; the air in the calcining furnace was completely replaced by argon, the temperature was raised to 1500°C at a heating rate of 5°C / min, and kept warm for secondary sintering for 40 minutes, the pressure in the calcining furnace was adjusted to 22MPa by argon, the temperature was raised to 1900°C at a heating rate of 10°C / min, and kept warm for tertiary sintering for 40 minutes, and then cooled with the furnace to obtain silicon carbide fiber reinforced tantalum boride ceramics.

[0054] This embodiment also provides silicon carbide fiber reinforced tantalum boride ceramics prepared by the above method.

[0055] Example 2

[0056] This embodiment provides a method for preparing silicon carbide fiber reinforced tantalum boride ceramics, which comprises the following steps:

[0057] 1. Preparation of composite powder

[0058] Tantalum diboride powder, zirconium diboride powder, titanium carbide powder, aluminum oxide powder, zirconium oxide powder and neodymium oxide powder were put into a high-energy ball mill, the ball-to-material mass ratio was controlled to be 11.2:1, the ball milling speed was 420 rpm, and the ball milling treatment was carried out for 14 hours to obtain a composite powder.

[0059] Among them, the mass ratio of tantalum diboride powder, zirconium diboride powder, titanium carbide powder, aluminum oxide powder, zirconium oxide powder and neodymium oxide powder is 117:22.5:49:10.3:6.9:3.2.

[0060] The average particle size D50 of the tantalum diboride powder, zirconium diboride powder, titanium carbide powder, aluminum oxide powder, zirconium oxide powder, and neodymium oxide powder used is 5 μm.

[0061] 2. Preparation of modified fiber materials

[0062] (1) Fiber pretreatment

[0063] The silicon carbide fiber with a diameter of 15 μm was completely immersed in the pretreatment liquid, heated to 32°C, and kept warm for 80 minutes. The silicon carbide fiber was separated, washed with deionized water until neutral, and dried at 105°C to constant weight; then transferred to the treatment chamber of the low-temperature plasma device, the pretreatment gas was introduced, and the pressure in the treatment chamber of the low-temperature plasma device was adjusted to 73 Pa (gauge pressure), the low-temperature plasma treatment power was controlled to 460 W, and the low-temperature plasma treatment was carried out for 25 minutes to obtain the pretreated fiber.

[0064] The pretreatment liquid is a deionized water solution in which hydrochloric acid and nitric acid are dissolved; the concentration of hydrochloric acid in the pretreatment liquid is 0.13 mol / L, and the concentration of nitric acid is 0.04 mol / L; and the weight ratio of silicon carbide fiber to the pretreatment liquid is 1:8.5.

[0065] The pretreatment gas is a mixture of nitrogen and argon, and the volume ratio of nitrogen to argon is 1:2.8.

[0066] (2) Impregnation and curing

[0067] The pretreated fibers were chopped into 1.1 cm to obtain chopped pretreated fibers; the chopped pretreated fibers were then put into an impregnation treatment liquid, and impregnated at negative pressure at room temperature for 55 minutes under a vacuum degree of 0.04 MPa, and then pressurized to 1.7 MPa, and impregnated at room temperature for 55 minutes to obtain a solid; the solid was transferred into a roasting furnace, and after a heat preservation treatment at 73°C for 11 hours, the temperature was continued to be raised to 190°C, and the heat preservation treatment was carried out for 1.3 hours, and the modified fiber material was obtained by natural cooling.

[0068] The weight ratio of the chopped pretreated fibers to the impregnated treatment liquid is 1:4.5.

[0069] The preparation method of the impregnation treatment liquid is as follows: n-butyl titanate, tetrabutyl zirconate, and hafnium n-butoxide are added into ethylene glycol in an ice bath, stirred for 15 minutes, and then diethylamine and acetylacetone are added. After stirring and reacting in an ice bath for 12.5 hours, the impregnation treatment liquid is obtained.

[0070] The molar ratio of n-butyl titanate, tetrabutyl zirconate, hafnium n-butoxide, diethylamine and acetylacetone is 10.3:10.3:10.3:0.015:2.4.

[0071] The added amount of ethylene glycol is 1.97 times the total weight of n-butyl titanate, tetrabutyl zirconate, and hafnium n-butoxide.

[0072] 3. Mixing and molding

[0073] The composite powder and modified fiber material are put into a high-speed mixer, the mixing speed is controlled to be 1400rpm, and the mixture is mixed evenly to obtain a mixture; then the mixture is transferred into a mold and sealed, and then placed in a cold isostatic pressing machine, the cold isostatic pressing pressure is controlled to be 245MPa, and after cold isostatic pressing for 20 minutes, demolding is carried out to obtain a green body.

[0074] Among them, the weight ratio of the composite powder material to the modified fiber material is 10:1.

[0075] 4. Multi-stage sintering

[0076] The green body was placed in a calcining furnace, heated to 1250°C at a heating rate of 2.5°C / min, and kept warm for primary sintering for 50 minutes; the air in the calcining furnace was completely replaced by argon, and the temperature was increased to 1550°C at a heating rate of 5.5°C / min, and kept warm for secondary sintering for 50 minutes. The pressure in the calcining furnace was adjusted to 24MPa by argon, and the temperature was increased to 1950°C at a heating rate of 11°C / min, and kept warm for tertiary sintering for 50 minutes. The green body was cooled in the furnace to obtain silicon carbide fiber reinforced tantalum boride ceramics.

[0077] This embodiment also provides silicon carbide fiber reinforced tantalum boride ceramics prepared by the above method.

[0078] Example 3

[0079] This embodiment provides a method for preparing silicon carbide fiber reinforced tantalum boride ceramics, which comprises the following steps:

[0080] 1. Preparation of composite powder

[0081] Tantalum diboride powder, zirconium diboride powder, titanium carbide powder, aluminum oxide powder, zirconium oxide powder and neodymium oxide powder were put into a high-energy ball mill, the ball-to-material mass ratio was controlled to be 11.5:1, the ball milling speed was 450 rpm, and the ball milling treatment was carried out for 15 hours to obtain a composite powder.

[0082] Among them, the mass ratio of tantalum diboride powder, zirconium diboride powder, titanium carbide powder, aluminum oxide powder, zirconium oxide powder and neodymium oxide powder is 118:23:50:10.5:7:3.3.

[0083] The average particle size D50 of the tantalum diboride powder, zirconium diboride powder, titanium carbide powder, aluminum oxide powder, zirconium oxide powder, and neodymium oxide powder used is 5 μm.

[0084] 2. Preparation of modified fiber materials

[0085] (1) Fiber pretreatment

[0086] The silicon carbide fiber with a diameter of 15 μm was completely immersed in the pretreatment liquid, heated to 35°C, and kept warm for 90 minutes. The silicon carbide fiber was separated, washed with deionized water until neutral, and dried at 110°C to constant weight; then transferred to the treatment chamber of the low-temperature plasma device, the pretreatment gas was introduced, and the pressure in the treatment chamber of the low-temperature plasma device was adjusted to 80 Pa (gauge pressure), the low-temperature plasma treatment power was controlled to 500 W, and the low-temperature plasma treatment was carried out for 30 minutes to obtain the pretreated fiber.

[0087] The pretreatment liquid is a deionized water solution containing hydrochloric acid and nitric acid; the concentration of hydrochloric acid in the pretreatment liquid is 0.13 mol / L, and the concentration of nitric acid is 0.05 mol / L; and the weight ratio of silicon carbide fiber to the pretreatment liquid is 1:9.

[0088] The pretreatment gas is a mixture of nitrogen and argon, and the volume ratio of nitrogen to argon is 1:3.

[0089] (2) Impregnation and curing

[0090] The pretreated fibers were chopped into 1.2 cm to obtain chopped pretreated fibers; the chopped pretreated fibers were then put into an impregnation treatment liquid, and were impregnated at negative pressure at room temperature for 60 minutes under a vacuum degree of 0.04 MPa, and then pressurized to 1.8 MPa, and impregnated at room temperature for 60 minutes to obtain solid matter; the solid matter was transferred into a roasting furnace, and after being heat-treated at 75°C for 12 hours, the temperature was continued to be raised to 200°C, and the temperature was kept for 1.5 hours, and naturally cooled to obtain a modified fiber material.

[0091] The weight ratio of the chopped pretreated fibers to the impregnated treatment liquid is 1:5.

[0092] The preparation method of the impregnation treatment liquid is as follows: n-butyl titanate, tetrabutyl zirconate, and hafnium n-butoxide are added into ethylene glycol in an ice bath, stirred for 20 minutes, and then diethylamine and acetylacetone are added. After stirring and reacting in an ice bath for 13 hours, the impregnation treatment liquid is obtained.

[0093] The molar ratio of n-butyl titanate, tetrabutyl zirconate, hafnium n-butoxide, diethylamine and acetylacetone is 10.5:10.5:10.5:0.02:3.

[0094] The added amount of ethylene glycol is twice the total weight of n-butyl titanate, tetrabutyl zirconate and hafnium n-butoxide.

[0095] 3. Mixing and molding

[0096] The composite powder and modified fiber material are put into a high-speed mixer, the mixing speed is controlled to be 1500rpm, and the mixture is evenly mixed to obtain a mixture; then the mixture is transferred into a mold and sealed, and then placed in a cold isostatic pressing machine, the cold isostatic pressing pressure is controlled to be 250MPa, and after cold isostatic pressing for 25 minutes, demolding is carried out to obtain a green body.

[0097] Among them, the weight ratio of the composite powder material to the modified fiber material is 10:1.1.

[0098] 4. Multi-stage sintering

[0099] The green body was placed in a calcining furnace, heated to 1300°C at a heating rate of 3°C / min, and kept warm for primary sintering for 60 minutes; the air in the calcining furnace was completely replaced by argon, the temperature was raised to 1600°C at a heating rate of 6°C / min, and kept warm for secondary sintering for 60 minutes, the pressure in the calcining furnace was adjusted to 25MPa by argon, the temperature was raised to 2000°C at a heating rate of 12°C / min, and kept warm for tertiary sintering for 60 minutes, and then cooled with the furnace to obtain silicon carbide fiber reinforced tantalum boride ceramics.

[0100] This embodiment also provides silicon carbide fiber reinforced tantalum boride ceramics prepared by the above method.

[0101] Comparative Example 1

[0102] The technical solution of Example 2 is adopted, but the differences are: 1) in the preparation of the composite powder, zirconium diboride powder, zirconium oxide powder and neodymium oxide powder are omitted; 2) the fiber pretreatment step is omitted, and the silicon carbide fiber is directly chopped and used in the impregnation and curing step.

[0103] Comparative Example 2

[0104] The technical solution of Example 2 is adopted, but the differences are: 1) in the fiber pretreatment step, the low-temperature plasma treatment is omitted, and the silicon carbide fiber treated with the pretreatment liquid is used as the pretreated fiber; 2) the impregnation and curing step is omitted, and the pretreated fiber prepared above is directly used in the mixing and molding step.

[0105] The open porosity, Vickers hardness HV, fracture toughness, 1600°C three-point bending strength, and fiber-ceramic matrix bonding strength of the tantalum boride ceramics of Examples 1-3 and Comparative Examples 1-2 were tested. Among them, the open porosity was measured by the Archimedes drainage method with reference to the relevant provisions of ASTMC373. The Vickers hardness HV was measured by a micro-Vickers hardness tester on 10 test points at the same position of each tantalum boride ceramic, and the minimum value was taken. The fracture toughness was measured by a micro-Vickers hardness tester through the indentation method, and the test loading force was controlled to 49N and the loading time was 15s; after the loading was completed, the diagonal length of the crack was measured using a scanning electron microscope to obtain the corresponding fracture toughness. The 1600°C three-point bending strength is the three-point bending strength of tantalum boride ceramics at a temperature of 1600°C. The bonding strength between the fiber and the ceramic matrix was tested 20 times by the pull-out method, and the average value was taken.

[0106] The specific results are shown in the following table:

[0107]

[0108] Furthermore, the tantalum boride ceramics of Examples 1-3 and Comparative Examples 1-2 were placed in a calcining furnace, heated to 1900°C at a heating rate of 30°C / min in an air atmosphere, and kept warm for 7 hours; then cooled to room temperature within 1 hour; the aforementioned heating and cooling process was a rapid temperature change cycle, and after 30 consecutive times, the Vickers hardness HV, fracture toughness, and 1600°C three-point bending strength of each tantalum boride ceramic were tested, and whether each tantalum boride ceramic had cracking or deformation was observed. The specific results are shown in the following table:

[0109]

[0110] It can be seen that the preparation method of silicon carbide fiber reinforced tantalum boride ceramics of the present invention, in the step of preparing the composite powder, tantalum diboride, zirconium diboride and titanium carbide, aluminum oxide, zirconium oxide, and neodymium oxide are combined to form the composite powder; in the step of preparing the modified fiber material, the silicon carbide fiber is firstly etched on the surface by a pretreatment liquid, and on the basis of the etching by the pretreatment liquid, the silicon carbide fiber is further surface treated by a low-temperature plasma to obtain a pretreated fiber, so as to further improve the surface roughness of the silicon carbide fiber, and achieve The surface of the silicon carbide fiber is activated to improve the binding performance of the silicon carbide fiber with the effective ingredients in the subsequent impregnation treatment solution; then, the impregnation treatment solution is prepared by hydrolysis and condensation of n-butyl titanate, tetrabutyl zirconate, and hafnium n-butoxide, and the pretreated fiber is impregnated into the impregnation treatment solution to obtain a modified fiber material; in the mixing and molding step, the aforementioned composite powder and the modified fiber material are mixed to form a green body, and then multi-stage sintering is performed to obtain silicon carbide fiber reinforced tantalum boride ceramics; wherein, tantalum diboride and zirconium diboride are used as the main raw materials, and the pretreated fiber is impregnated into the green body. Titanium carbide is used as a reinforcing phase, and is combined with aluminum oxide, zirconium oxide and neodymium oxide to adjust the tantalum boride ceramics; then a modified fiber material is introduced as a toughening phase, and the hydrolysis condensation products of n-butyl titanate, tetrabutyl zirconate and hafnium n-butoxide bound to the fiber surface improve its bonding performance with the ceramic matrix while achieving a barrier effect, reducing the occurrence of interface reactions between silicon carbide fibers and other raw materials of tantalum boride ceramics, and achieving thermal expansion transition between the fiber and the ceramic matrix, thereby improving the thermal matching of silicon carbide fibers and tantalum boride ceramic matrix. The aforementioned technical means cooperate and work synergistically with each other to achieve the effective reinforcement of tantalum boride ceramics by silicon carbide fibers, effectively improve the bonding performance between silicon carbide fibers and tantalum boride ceramic matrix, reduce the occurrence of interface reaction between silicon carbide fibers and other raw materials of tantalum boride ceramics, improve the structural stability of tantalum boride ceramics, and effectively improve the toughness of tantalum boride ceramics; at the same time, alleviate the thermal matching problem between silicon carbide fibers and tantalum boride ceramic matrix, improve the stability of tantalum boride ceramics under rapid temperature change conditions, and improve the durability of tantalum boride ceramics.

[0111] Unless otherwise specified, all percentages used in the present invention are by mass.

[0112] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments or replace some of the technical features therein by equivalents. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for preparing silicon carbide fiber reinforced tantalum boride ceramics, characterized in that: The method comprises the following steps: preparing composite powder, preparing modified fiber material, mixing and molding, and multi-stage sintering; The method for preparing the composite powder is to uniformly ball-mill tantalum diboride powder, zirconium diboride powder, titanium carbide powder, aluminum oxide powder, zirconium oxide powder and neodymium oxide powder to obtain the composite powder; The modified fiber material is prepared by the following steps: fiber pretreatment, impregnation and curing; The fiber pretreatment method comprises: dipping the silicon carbide fiber into a pretreatment liquid, heating it to 30-35° C., and separating the silicon carbide fiber after heat preservation and dipping treatment, washing it to neutrality, and drying it; then transferring it into a treatment chamber of a low-temperature plasma device, introducing a pretreatment gas, and performing low-temperature plasma treatment to obtain pretreated fiber; The pretreatment liquid is a deionized water solution dissolved with hydrochloric acid and nitric acid; The impregnation and curing method comprises the following steps: chopping the pretreated fibers to obtain chopped pretreated fibers; placing the chopped pretreated fibers into an impregnation treatment liquid, performing negative pressure impregnation and pressure impregnation, and separating to obtain solids; heat-treating the solids at 70-75° C. and then continuing to heat-treat at 180-200° C. to obtain a modified fiber material; The preparation method of the impregnation treatment liquid is as follows: n-butyl titanate, tetrabutyl zirconate, and hafnium n-butoxide are added to ethylene glycol in an ice bath, mixed evenly, and then diethylamine and acetylacetone are added to react in an ice bath to obtain the impregnation treatment liquid; The composite powder and modified fiber material are mixed, molded, and multi-stage sintered to obtain silicon carbide fiber reinforced tantalum boride ceramics.

2. The method for preparing silicon carbide fiber reinforced tantalum boride ceramics according to claim 1, characterized in that: In the preparation of the composite powder, the ball-to-material mass ratio is 11-11.5:1, the ball milling speed is 400-450rpm, and the ball milling time is 13-15h; The mass ratio of tantalum diboride powder, zirconium diboride powder, titanium carbide powder, aluminum oxide powder, zirconium oxide powder and neodymium oxide powder is 115-118:22-23:48-50:10-10.5:6.8-7:3.1-3.

3.

3. The method for preparing silicon carbide fiber reinforced tantalum boride ceramics according to claim 1, characterized in that: In the fiber pretreatment, the concentration of hydrochloric acid in the pretreatment solution is 0.12-0.13 mol / L, and the concentration of nitric acid is 0.04-0.05 mol / L; The weight ratio of silicon carbide fiber to pretreatment liquid is 1:8-9; The diameter of silicon carbide fibers is 13-15 μm.

4. The method for preparing silicon carbide fiber reinforced tantalum boride ceramics according to claim 1, characterized in that: In the fiber pretreatment, the low-temperature plasma treatment pressure is 70-80Pa, the treatment power is 400-500W, and the treatment time is 20-30min; The pretreatment gas is a mixture of nitrogen and argon, and the volume ratio of nitrogen to argon is 1:2.5-3.

5. The method for preparing silicon carbide fiber reinforced tantalum boride ceramics according to claim 1, characterized in that: In the impregnation curing, the weight ratio of the chopped pretreated fibers to the impregnation treatment liquid is 1:4-5; The vacuum degree of negative pressure impregnation is 0.03-0.04MPa, the negative pressure impregnation time is 50-60min, and the negative pressure impregnation temperature is room temperature; The pressure of the pressurized impregnation is 1.5-1.8 MPa, the pressurized impregnation time is 50-60 min, and the pressurized impregnation temperature is room temperature.

6. The method for preparing silicon carbide fiber reinforced tantalum boride ceramics according to claim 1, characterized in that: In the preparation of the impregnation treatment solution, the ice bath reaction time is 12-13 hours; The molar ratio of n-butyl titanate, tetrabutyl zirconate, hafnium n-butoxide, diethylamine and acetylacetone is 10-10.5:10-10.5:10-10.5:0.01-0.02:2-3; The added amount of ethylene glycol is 1.95-2 times the total weight of n-butyl titanate, tetrabutyl zirconate and hafnium n-butoxide.

7. The method for preparing silicon carbide fiber reinforced tantalum boride ceramics according to claim 1, characterized in that: The mixing molding method comprises the following steps: uniformly mixing the composite powder material and the modified fiber material to obtain a mixture; transferring the mixture into a mold and sealing it, controlling the cold isostatic pressing pressure to be 240-250MPa, performing cold isostatic pressing, and demolding to obtain a green body.

8. The method for preparing silicon carbide fiber reinforced tantalum boride ceramics according to claim 1, characterized in that: The multi-stage sintering method comprises the following steps: placing the green body obtained by mixed material molding in a calcining furnace, heating it to 1200-1300° C., and maintaining the temperature for primary sintering; in an inert gas environment, continuing to heat it to 1500-1600° C., and maintaining the temperature for secondary sintering; adjusting the pressure in the calcining furnace to 22-25 MPa, continuing to heat it to 1900-2000° C., and maintaining the temperature for third-stage sintering to obtain silicon carbide fiber reinforced tantalum boride ceramics.

9. The method for preparing silicon carbide fiber reinforced tantalum boride ceramics according to claim 8, characterized in that: In the multi-stage sintering, the heating rate to 1200-1300°C is 2-3°C / min, and the first-stage sintering time is 40-60min; The heating rate to 1500-1600°C is 5-6°C / min, and the secondary sintering time is 40-60min; The heating rate to 1900-2000°C is 10-12°C / min, and the three-stage sintering time is 40-60min.

10. A silicon carbide fiber reinforced tantalum boride ceramic, characterized in that: The method is prepared by the method according to any one of claims 1 to 9.

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