Titanium diboride-boron nitride-silicon carbide ceramic composite material prepared by spark plasma sintering and preparation method thereof
阅读说明：本技术 一种放电等离子烧结制备的二硼化钛-氮化硼-碳化硅陶瓷复合材料及其制备方法 (Titanium diboride-boron nitride-silicon carbide ceramic composite material prepared by spark plasma sintering and preparation method thereof ) 是由 田仕 李�浩 杨旺霖 廖泽林 何强龙 王为民 于 2020-09-04 设计创作，主要内容包括：本发明涉及一种放电等离子烧结制备的二硼化钛-氮化硼-碳化硅陶瓷复合材料及其制备方法,属于陶瓷材料技术领域。制备方法如下：将原料二硼化钛粉体、氮化硼粉体、碳化硅粉体球磨,得到混合粉体；将混合粉体置于60-100℃的真空干燥箱内干燥24-48h,研磨,过筛造粒,得到混合粉体；将混合粉体放入石墨模具,模具内衬有石墨纸,并且外面包裹一层有气孔的石墨绝缘层,置于等离子体活化烧结设备中,在惰性气氛下,施加压力,升温烧结,保温一段时间,然后自然冷却,即可得到TiB-2-BN-SiC陶瓷复合材料。该方法工艺简单,制备快速方便,可以制备出机械强度高且电阻率可控、热学性能可调的TiB-2-BN-SiC复合陶瓷。(The invention relates to a titanium diboride-boron nitride-silicon carbide ceramic composite material prepared by spark plasma sintering and a preparation method thereof, belonging to the technical field of ceramic materials. The preparation method comprises the following steps: ball-milling raw materials of titanium diboride powder, boron nitride powder and silicon carbide powder to obtain mixed powder; drying the mixed powder in a vacuum drying oven at 60-100 ℃ for 24-48h, grinding, sieving and granulating to obtain mixed powder; putting the mixed powder into a graphite mould, wherein the graphite mould is lined with graphite paper and is wrapped with a layer of porous graphite insulating layer, putting the graphite insulating layer into plasma activated sintering equipment, applying pressure under inert atmosphere, heating up for sintering, preserving heat for a period of time, and naturally cooling to obtain TiB 2 -BN-SiC ceramic composite material. The methodThe method has simple process, fast and convenient preparation, and can prepare the TiB with high mechanical strength, controllable resistivity and adjustable thermal property 2 -BN-SiC composite ceramic.)
1. TiB prepared by spark plasma sintering2-BN-SiC complex phase ceramic, characterized in that: from the starting material TiB2the-BN-SiC powder is sintered by a spark plasma sintering technology, and the raw material mixed powder comprises 21-25.8 percent of titanium diboride powder, 72 percent of boron nitride powder and 2.2-7 percent of silicon carbide powder by volume percentage.
2. The TiB of claim 12-BN-SiC complex phase ceramic, characterized in that: the average particle size of the titanium diboride powder in the mixed powder is 3-5 um; the average particle size of the boron nitride powder is 4-5 um; the grain diameter of the silicon carbide powder is 1-100 nm.
3. The TiB of claim 12-BN-SiC complex phase ceramic, characterized in that: the TiB2The elastic modulus of the-BN-SiC complex phase ceramic is kept between 83.5GPa and 85.5GPa, the bending strength is between 180 MPa and 190MPa, the relative density is between 93.5 percent and 94.5 percent, the resistivity is 4900-8050 mu omega-cm, the thermal conductivity is between 28.9 w/m-k and the thermal expansion coefficient is 7.5 multiplied by 10-3-10.8×10-3。
4. The TiB of claim 12The preparation method of the-BN-SiC ceramic composite material is characterized by comprising the following steps: the method comprises the following steps:
(1) ball-milling raw materials of titanium diboride powder, boron nitride powder and silicon carbide powder to obtain mixed powder;
(2) drying the mixed powder in a vacuum drying oven at 60-100 ℃ for 24-48h, grinding, sieving and granulating to obtain mixed powder;
(3) putting the mixed powder obtained in the last step into a graphite mould, wherein the graphite mould is lined with graphite paper and is wrapped with a layer of porous graphite insulating layer, putting the graphite insulating layer into plasma activated sintering equipment (PAS), applying pressure under inert atmosphere, heating up for sintering, preserving heat for a period of time, and naturally cooling to obtain TiB2-BN-SiC ceramic composite material.
5. The method of claim 4, wherein: the step (1) is as follows: weighing titanium diboride powder, boron nitride powder and silicon carbide powder as raw materials for later use; putting the weighed powder into a ball milling tank of a horizontal mixer, adding an ethanol solution as a dispersion medium to mix, and then sieving to remove grinding balls to obtain an ethanol solution of mixed powder; removing the ethanol solvent to obtain mixed powder.
6. The method of claim 4, wherein: the total volume of the titanium diboride powder, the boron nitride powder, the silicon carbide powder, the grinding balls and the ethanol is less than two thirds of the volume of the ball milling tank and more than one third of the volume of the ball milling tank; the rotating speed of the horizontal mixing instrument is 200-300r/min, the ball milling time is 2-3h, and the milling ball is a steel ball; the method for removing the ethanol solvent is rotary evaporation or suction filtration.
7. The method of claim 4, wherein: the purity of the titanium diboride powder in the mixed powder is more than 99 percent; the purity of the boron nitride powder is more than 99 percent; the grain diameter purity of the silicon carbide powder is more than 99 percent.
8. The method of claim 4, wherein: the sieve mesh number is 200 meshes.
9. The method of claim 4, wherein: the pressure range applied in the step (5) is 9.0-9.5Mpa, and the sintering temperature is 1800-1900 ℃.
10. The method of claim 4, wherein: in the step (5), the temperature rising rate is 100 +/-10 ℃/min, and the heat preservation time is 5-6 min.
Technical Field
The invention relates to a ceramic composite material and a preparation method thereof, in particular to TiB prepared by spark plasma sintering2-BN-SiC ceramic composite material and a preparation method thereof.
Background
TiB2the-BN complex phase ceramic has the excellent performances of titanium diboride and boron nitride, such as good electrical conductivity, thermal shock resistance, machinability, corrosion resistance and the like, and TiB with required resistivity can be obtained by controlling the proportion, the grain diameter ratio, the sintering temperature and the sintering system between the titanium diboride and the boron nitride2BN complex phase conductive ceramics are key materials for preparing evaporation sources in the metal evaporation industry due to appropriate resistivity and temperature coefficient of resistance. Titanium diboride has strong covalent bond and ionic bond characteristics and a high melting point, and is a material difficult to sinter; also boron nitride has a very high melting point and is a difficult material to sinter. The respective sintering temperatures exceed 1800 ℃ C, and it is expected that TiB2BN complex phase conductive ceramics are also very difficult to sinter. Therefore, if the normal pressure sintering method is adopted, not only the sintering temperature is high, the sintering time is long, and the power consumption is large, but also TiB with stable conductive network is difficult to obtain due to the sintering inertia of the surfaces of sample particles and the randomness of the arrangement of two-phase particles2-BN complex phase conductive ceramic.
Silicon carbide is also known as carborundum or refractory sand. The silicon carbide is prepared by smelting quartz sand, petroleum coke (or coal coke), wood chips (salt is required when green silicon carbide is produced) and other raw materials in a resistance furnace at high temperature. The silicon carbide material has semiconductor characteristics, the semiconductor is a substance with the resistivity between metal and an insulator and a negative temperature coefficient of resistance, and under a certain temperature, the generation and recombination of electron-hole pairs simultaneously exist and reach dynamic balance, so that the semiconductor has a certain carrier density and thus has certain conductivity. As the temperature increases, more electron-hole pairs are generated, the carrier density increases and the resistivity decreases.
Disclosure of Invention
Against the background of the above-mentioned research, the present invention provides a discharge deviceTiB prepared by ion sintering2-BN-SiC ceramic composite material and a preparation method thereof. The method has simple process, is rapid and convenient to prepare, and can prepare the TiB with high mechanical strength, controllable resistivity and adjustable thermal property2-BN-SiC composite ceramic.
In order to achieve the purpose, the invention adopts the following technical scheme to realize the purpose:
TiB prepared by spark plasma sintering2-BN-SiC complex phase ceramic made of TiB as raw material2the-BN-SiC powder is sintered by a spark plasma sintering technology, and the raw material mixed powder comprises 21-25.8 percent of titanium diboride powder, 72 percent of boron nitride powder and 2.2-7 percent of silicon carbide powder by volume percentage.
According to the scheme, the average particle size of the titanium diboride powder in the mixed powder is 3-5 um; the average particle size of the boron nitride powder is 4-5 um; the grain diameter of the silicon carbide powder is 1-100 nm.
According to the scheme, the purity of the titanium diboride powder in the mixed powder is more than 99 percent; the purity of the boron nitride powder is more than 99 percent; the grain diameter purity of the silicon carbide powder is more than 99 percent.
According to the scheme, the TiB2The elastic modulus of the-BN-SiC complex phase ceramic is kept between 83.5GPa and 85.5GPa, the bending strength is between 180 MPa and 190MPa, the relative density is between 93.5 percent and 94.5 percent, the resistivity is 4900-8050 mu omega-cm, the thermal conductivity is between 28.9 w/m-k and the thermal expansion coefficient is 7.5 multiplied by 10-3-10.8×10-3。
The above TiB2The preparation method of the-BN-SiC ceramic composite material comprises the following steps:
(4) ball-milling raw materials of titanium diboride powder, boron nitride powder and silicon carbide powder to obtain mixed powder;
(5) drying the mixed powder in a vacuum drying oven at 60-100 ℃ for 24-48h, grinding, sieving and granulating to obtain mixed powder;
(6) placing the mixed powder obtained in the previous step into a graphite mold, wherein the mold is lined with graphite paper and is wrapped with a porous graphite insulating layer, placing the graphite insulating layer in a Plasma Activated Sintering (PAS) device, applying pressure in an inert atmosphere, and heatingSintering, keeping the temperature for a period of time, and then naturally cooling to obtain the TiB2-BN-SiC ceramic composite material.
According to the scheme, the step (1) is as follows: weighing titanium diboride powder, boron nitride powder and silicon carbide powder as raw materials for later use; putting the weighed powder into a ball milling tank of a horizontal mixer, adding an ethanol solution as a dispersion medium to mix, and then sieving to remove grinding balls to obtain an ethanol solution of mixed powder; removing the ethanol solvent to obtain mixed powder.
According to the scheme, the total volume of the titanium diboride powder, the boron nitride powder, the silicon carbide powder, the grinding balls and the ethanol is less than two thirds of the volume of the ball milling tank and more than one third of the volume of the ball milling tank.
According to the scheme, the rotating speed of the horizontal mixing instrument is 200-300r/min, the ball milling time is 2-3h, and the milling ball is a steel ball.
According to the scheme, the method for removing the ethanol solvent is rotary evaporation or suction filtration.
According to the scheme, the sieve mesh number is 200 meshes.
According to the scheme, the pressure range applied in the step (5) is 9.0-9.5Mpa, and the sintering temperature is 1800-1900 ℃.
According to the scheme, the temperature rising rate in the step (5) is 100 +/-10 ℃/min, and the heat preservation time is 5-6 min.
The silicon carbide has excellent semiconductor performance, and TiB can be well adjusted by adding a small amount of silicon carbide according to the requirement2The conductive performance of the BN composite ceramic meets the working requirements under different environments, and the purposes of adjustable resistivity and thermal performance can be achieved by changing the original volume ratio of the three components. Therefore, titanium diboride is introduced into the boron nitride matrix as a second phase, silicon carbide is used as an additive, and the characteristics of property superposition of the composite material are utilized to prepare the TiB with good processing performance and excellent mechanical, electrical and thermal conductivity2-BN-SiC ceramic composite material.
The invention has the beneficial effects that: the experiment adopts spark plasma sintering technology, so that the composite ceramic is prepared more quicklyConvenient and fast, and simultaneously selects silicon carbide with semiconductor characteristics as a third phase to prepare TiB2-BN-SiC composite ceramic to further improve TiB2The comprehensive performance of the-BN composite ceramic, and the TiB is adjusted by controlling the volume ratio of the titanium diboride to the silicon carbide2The conductive performance and the thermal performance of the BN-SiC composite ceramic are met so as to meet the working requirements under different environments.
Drawings
FIG. 1 shows TiB in example 1 of the present invention2SEM secondary electron image of the section of BN-SiC ceramic composite material.
FIG. 2 shows TiB in example 2 of the present invention2SEM secondary electron image of the section of BN-SiC ceramic composite material.
FIG. 3 shows TiB in example 3 of the present invention2SEM secondary electron image of the section of BN-SiC ceramic composite material.
FIG. 4 shows TiB in example 4 of the present invention2SEM secondary electron image of the section of BN-SiC ceramic composite material.
FIG. 5 shows a TiB prepared by spark plasma sintering according to the present invention2A process flow diagram of the-BN-SiC ceramic composite material.
FIG. 6 shows a TiB of the present invention2-BN-SiC ceramic resistivity four-probe test schematic.
Where U23 is the voltage (mV) received from the sample at probe 2 and 3, I14 is the current (mA) through the sample at probe 1 and 4, S is the length (cm) between the two probes, and the distance between the two probes in this laboratory is 0.2 cm.
FIG. 7 shows different TiB's in the present invention2The resistivity diagram of the TiB2-BN-SiC composite ceramic material at the volume ratio of SiC.
FIG. 8 shows different TiB's in the present invention2Thermal property diagram of TiB2-BN-SiC composite ceramic material in SiC volume ratio.
Detailed Description
In order to better understand the present invention, the following examples are further provided to illustrate the present invention, but the present invention is not limited to the following examples.
Example 1:
TiB described in this example2The preparation method of the-BN-SiC ceramic composite material comprises the following specific steps:
1) weighing 21% of titanium diboride powder, 72% of boron nitride powder and 7% of silicon carbide powder according to the volume percentage for later use;
2) putting the weighed powder into a ball milling tank of a horizontal mixer, adding an ethanol solution as a dispersion medium to mix, wherein the total volume of the powder, grinding balls and ethanol is one half of the volume of the ball milling tank, the rotating speed of the horizontal mixer is 300r/min, the ball milling time is 2 hours, the ball milling tank and the grinding balls are made of steel, and filtering to remove the grinding balls to obtain the ethanol solution of the mixed powder;
3) removing the ethanol solvent by adopting a rotary evaporation mode to obtain mixed powder;
4) drying the mixed powder in a vacuum drying oven at 60 ℃ for 24h, grinding, sieving with a 200-mesh sieve, and granulating to obtain mixed powder;
5) placing the mixed powder obtained in the previous step into a cylindrical graphite mold, lining graphite paper in the mold, wrapping a layer of graphite felt pad with a round hole outside, placing into a plasma activated sintering device (PAS), introducing argon to 80 KPa, applying pressure of 9.5Mpa, heating to sintering temperature of 1850 ℃ at 100 ℃/min, keeping the temperature for 5min, and naturally cooling to obtain TiB2-BN-SiC ceramic composite material.
The TiB obtained2The properties of the-BN-SiC ceramic composite are as follows: relative density 93.5%, resistivity 8053 [ mu ] omega-cm, bending strength 181.2MPa, elastic modulus 84GPa, thermal conductivity 28.9 w/m.k and thermal expansion coefficient 7.5X 10-3。
Example 2:
TiB described in this example2The preparation method of the-BN-SiC ceramic composite material comprises the following specific steps:
1) weighing 24% of titanium diboride powder, 72% of boron nitride powder and 4% of silicon carbide powder according to volume percentage for later use;
2) putting the weighed powder into a ball milling tank of a horizontal mixer, adding an ethanol solution as a dispersion medium to mix, wherein the total volume of the powder, grinding balls and ethanol is one half of the volume of the ball milling tank, the rotating speed of the horizontal mixer is 300r/min, the ball milling time is 2 hours, the ball milling tank and the grinding balls are made of steel, and filtering to remove the grinding balls to obtain the ethanol solution of the mixed powder;
3) removing the ethanol solvent by adopting a rotary evaporation mode to obtain mixed powder;
4) drying the mixed powder in a vacuum drying oven at 60 ℃ for 24h, grinding, sieving with a 200-mesh sieve, and granulating to obtain mixed powder;
5) putting the mixed powder obtained in the last step into a cylindrical graphite mould, wherein the inside of the mould is lined with graphite paper, a layer of graphite felt pad with a round hole is wrapped outside the mould, putting the mould into plasma activated sintering equipment (PAS), introducing argon to 80 KPa, applying pressure to 9.5MPa, heating to sintering temperature of 1850 ℃ at the speed of 100 ℃/min, preserving heat for 5min, and naturally cooling to obtain TiB2-BN-SiC ceramic composite material.
The TiB obtained2The properties of the-BN-SiC ceramic composite are as follows: relative density 93.6%, resistivity 6670 [ mu ] omega-cm, bending strength 189.9MPa, elastic modulus 83.5GPa, thermal conductivity 30.9 w/m.k, thermal expansion coefficient 8.3X 10-3。
Example 3:
TiB described in this example2The preparation method of the-BN-SiC ceramic composite material comprises the following specific steps:
1) weighing 25.2 percent of titanium diboride powder, 72 percent of boron nitride powder and 2.8 percent of silicon carbide powder according to volume percentage for later use;
2) putting the weighed powder into a ball milling tank of a horizontal mixer, adding an ethanol solution as a dispersion medium to mix, wherein the total volume of the powder, grinding balls and ethanol is one half of the volume of the ball milling tank, the rotating speed of the horizontal mixer is 300r/min, the ball milling time is 2 hours, the ball milling tank and the grinding balls are made of steel, and filtering to remove the grinding balls to obtain the ethanol solution of the mixed powder;
3) removing the ethanol solvent by adopting a rotary evaporation mode to obtain mixed powder;
4) drying the mixed powder in a vacuum drying oven at 60 ℃ for 24h, grinding, sieving with a 200-mesh sieve, and granulating to obtain mixed powder;
5) putting the mixed powder obtained in the last step into a cylindrical graphite mould, wherein the inside of the mould is lined with graphite paper, a layer of graphite felt pad with a round hole is wrapped outside the mould, putting the mould into plasma activated sintering equipment (PAS), introducing argon to 80 KPa, applying pressure to 9.5MPa, heating to sintering temperature of 1850 ℃ at the speed of 100 ℃/min, preserving heat for 5min, and naturally cooling to obtain TiB2-BN-SiC ceramic composite material.
The TiB obtained2The properties of the-BN-SiC ceramic composite are as follows: 94.5% relative density, 6292 [ mu ] omega-cm resistivity, 185.2MPa bending strength, 83.8GPa elastic modulus, 31.8 w/m.k thermal conductivity and 9.7X 10 thermal expansion coefficient-3。
Example 4:
TiB described in this example2The preparation method of the-BN-SiC ceramic composite material comprises the following specific steps:
1) weighing 25.85 percent of titanium diboride powder, 72 percent of boron nitride powder and 2.15 percent of silicon carbide powder according to volume percentage for later use;
2) putting the weighed powder into a ball milling tank of a horizontal mixer, adding an ethanol solution as a dispersion medium to mix, wherein the total volume of the powder, grinding balls and ethanol is one half of the volume of the ball milling tank, the rotating speed of the horizontal mixer is 300r/min, the ball milling time is 2 hours, the ball milling tank and the grinding balls are made of steel, and filtering to remove the grinding balls to obtain the ethanol solution of the mixed powder;
3) removing the ethanol solvent by adopting a rotary evaporation mode to obtain mixed powder;
4) drying the mixed powder in a vacuum drying oven at 60 ℃ for 24h, grinding, sieving with a 200-mesh sieve, and granulating to obtain mixed powder;
5) putting the mixed powder obtained in the last step into a cylindrical graphite mould, wherein the mould is lined with graphite paper and is coated with a layer of graphite paperPlacing a graphite felt pad with a round hole in a plasma activated sintering equipment (PAS), introducing argon to 80 KPa, heating to sintering temperature of 1850 ℃ at 100 ℃/min, keeping the temperature for 5min, and naturally cooling to obtain TiB2-BN-SiC ceramic composite material.
The TiB obtained2The properties of the-BN-SiC ceramic composite are as follows: relative density 94.3%, resistivity 4923 [ mu ] omega-cm, bending strength 189.7MPa, elastic modulus 85.5GPa, thermal conductivity 34.2 w/m.k and thermal expansion coefficient 10.8X 10-3。
The TiB of the present invention will be described in detail with reference to the following drawings2Phase composition, compactness and microstructure of the-BN-SiC ceramic composite material.
FIG. 1, FIG. 2, FIG. 3 and FIG. 4 are TiB in example 1, example 2, example 3 and example 4, respectively2SEM secondary electron image of the cross section of the BN-SiC ceramic composite material shows that the main part of the material is a sheet product, and large and small crystal grains are uniformly distributed around the material, and partial air holes exist. FIG. 7 shows different TiB2TiB in volume ratio of-SiC2Resistivity diagram of-BN-SiC composite ceramic Material, as TiB2Increase in volume proportion of-SiC, i.e. conductive phase TiB2The increase of the components and the gradual decrease of the resistivity of the composite ceramic material lead to the proper increase of TiB2The components can regulate and control the resistivity of the composite ceramic material to meet the industrial requirements. FIG. 8 shows different TiB2TiB in proportion of-SiC2Thermal conductivity and thermal expansion coefficient of-SiC-BN composite ceramic, along with TiB2The volume ratio of SiC is increased, the resistivity is changed, and the thermal conductivity and the thermal expansion coefficient of the composite ceramic are increased to different degrees. As can be seen from the above examples, the elastic modulus of the prepared composite ceramic material is kept between 83.5GPa and 85.5GPa, and the bending strength is in the range of 180 MPa and 190 MPa. Therefore, the resistance characteristic of the product meets the requirement of adjustable resistance, the thermal property can be adjusted, the mechanical strength is good, the mechanical processing is facilitated, and the technical route has good reference significance for preparing the composite conductive ceramic.