CN117658600A - Preparation method of high-hardness alumina composite ceramic - Google Patents
Preparation method of high-hardness alumina composite ceramic Download PDFInfo
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- 239000002131 composite material Substances 0.000 title claims abstract description 42
- 239000000919 ceramic Substances 0.000 title claims abstract description 38
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 title claims abstract description 23
- 238000002360 preparation method Methods 0.000 title claims abstract description 15
- 239000011812 mixed powder Substances 0.000 claims abstract description 34
- 229910018072 Al 2 O 3 Inorganic materials 0.000 claims abstract description 30
- 235000015895 biscuits Nutrition 0.000 claims abstract description 16
- 238000010438 heat treatment Methods 0.000 claims abstract description 16
- 239000000843 powder Substances 0.000 claims abstract description 14
- 238000001816 cooling Methods 0.000 claims abstract description 11
- 238000003825 pressing Methods 0.000 claims abstract description 11
- TWNQGVIAIRXVLR-UHFFFAOYSA-N oxo(oxoalumanyloxy)alumane Chemical compound O=[Al]O[Al]=O TWNQGVIAIRXVLR-UHFFFAOYSA-N 0.000 claims abstract description 10
- 238000000034 method Methods 0.000 claims description 20
- 239000000463 material Substances 0.000 claims description 19
- 238000002156 mixing Methods 0.000 claims description 15
- 238000000498 ball milling Methods 0.000 claims description 10
- 239000000956 alloy Substances 0.000 claims description 9
- 229910045601 alloy Inorganic materials 0.000 claims description 9
- 239000004033 plastic Substances 0.000 claims description 5
- 238000003756 stirring Methods 0.000 claims description 3
- 239000006185 dispersion Substances 0.000 claims description 2
- 238000005245 sintering Methods 0.000 abstract description 24
- 239000002994 raw material Substances 0.000 abstract description 11
- 239000002245 particle Substances 0.000 abstract description 6
- 230000003014 reinforcing effect Effects 0.000 abstract description 4
- 239000011159 matrix material Substances 0.000 abstract description 3
- 240000008866 Ziziphus nummularia Species 0.000 abstract 1
- 239000013078 crystal Substances 0.000 description 11
- 229910003460 diamond Inorganic materials 0.000 description 9
- 239000010432 diamond Substances 0.000 description 9
- 230000003247 decreasing effect Effects 0.000 description 8
- MCMNRKCIXSYSNV-UHFFFAOYSA-N ZrO2 Inorganic materials O=[Zr]=O MCMNRKCIXSYSNV-UHFFFAOYSA-N 0.000 description 7
- RVTZCBVAJQQJTK-UHFFFAOYSA-N oxygen(2-);zirconium(4+) Chemical compound [O-2].[O-2].[Zr+4] RVTZCBVAJQQJTK-UHFFFAOYSA-N 0.000 description 7
- 229910052751 metal Inorganic materials 0.000 description 6
- 239000002184 metal Substances 0.000 description 6
- 239000000126 substance Substances 0.000 description 5
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 description 4
- 229910052582 BN Inorganic materials 0.000 description 4
- PZNSFCLAULLKQX-UHFFFAOYSA-N Boron nitride Chemical compound N#B PZNSFCLAULLKQX-UHFFFAOYSA-N 0.000 description 4
- ZOKXTWBITQBERF-UHFFFAOYSA-N Molybdenum Chemical compound [Mo] ZOKXTWBITQBERF-UHFFFAOYSA-N 0.000 description 4
- 229910052750 molybdenum Inorganic materials 0.000 description 4
- 239000011733 molybdenum Substances 0.000 description 4
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 3
- 238000005520 cutting process Methods 0.000 description 3
- 238000011049 filling Methods 0.000 description 3
- 239000012535 impurity Substances 0.000 description 3
- 238000003754 machining Methods 0.000 description 3
- 238000004519 manufacturing process Methods 0.000 description 3
- 239000004570 mortar (masonry) Substances 0.000 description 3
- 238000000465 moulding Methods 0.000 description 3
- 230000003647 oxidation Effects 0.000 description 3
- 238000007254 oxidation reaction Methods 0.000 description 3
- 238000004321 preservation Methods 0.000 description 3
- 241001247821 Ziziphus Species 0.000 description 2
- 229910021529 ammonia Inorganic materials 0.000 description 2
- 230000015572 biosynthetic process Effects 0.000 description 2
- 229910010293 ceramic material Inorganic materials 0.000 description 2
- -1 iron group metals Chemical class 0.000 description 2
- 239000000203 mixture Substances 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 229910052903 pyrophyllite Inorganic materials 0.000 description 2
- 230000000630 rising effect Effects 0.000 description 2
- 150000003839 salts Chemical class 0.000 description 2
- 238000003786 synthesis reaction Methods 0.000 description 2
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- 230000002159 abnormal effect Effects 0.000 description 1
- 239000000654 additive Substances 0.000 description 1
- 230000000996 additive effect Effects 0.000 description 1
- 229910052782 aluminium Inorganic materials 0.000 description 1
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 230000001276 controlling effect Effects 0.000 description 1
- 239000002826 coolant Substances 0.000 description 1
- 230000002939 deleterious effect Effects 0.000 description 1
- 238000001514 detection method Methods 0.000 description 1
- 238000009792 diffusion process Methods 0.000 description 1
- 239000010459 dolomite Substances 0.000 description 1
- 229910000514 dolomite Inorganic materials 0.000 description 1
- 238000001035 drying Methods 0.000 description 1
- 230000008030 elimination Effects 0.000 description 1
- 238000003379 elimination reaction Methods 0.000 description 1
- 229910002804 graphite Inorganic materials 0.000 description 1
- 239000010439 graphite Substances 0.000 description 1
- 238000000227 grinding Methods 0.000 description 1
- 238000009776 industrial production Methods 0.000 description 1
- 238000009413 insulation Methods 0.000 description 1
- 229910052574 oxide ceramic Inorganic materials 0.000 description 1
- 239000011224 oxide ceramic Substances 0.000 description 1
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- 230000000704 physical effect Effects 0.000 description 1
- 230000008569 process Effects 0.000 description 1
- 239000003870 refractory metal Substances 0.000 description 1
- 230000001105 regulatory effect Effects 0.000 description 1
- 238000001878 scanning electron micrograph Methods 0.000 description 1
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- 239000002345 surface coating layer Substances 0.000 description 1
- 230000009466 transformation Effects 0.000 description 1
- 230000007704 transition Effects 0.000 description 1
- 238000005303 weighing Methods 0.000 description 1
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- Compositions Of Oxide Ceramics (AREA)
Abstract
The invention provides a preparation method of high-hardness aluminum oxide composite ceramic, which comprises the following steps: step 1: taking the mixed Al 2 O 3 And cBN mixed powder is treated for 0.1 to 10 hours at the temperature of 500 to 1600 ℃; step 2: prepressing and forming the heat-treated mixed powder to obtain a biscuit, wherein the compactness of the biscuit formed by prepressing is more than 30%; step 3: heating the biscuit under high pressure at 800-1600 deg.c for 1-30min, and cooling to obtain the superhard alumina ceramic composite material. The invention uses Al with specific size 2 O 3 And cBN powder as raw material, al 2 O 3 cBN is used as a reinforcing phase and Al is used as a matrix 2 O 3 And cBNThe powder is mixed according to a specific volume ratio, and then Al is added 2 O 3 After pre-pressing and forming the mixed powder composed of cBN powder, sintering at a proper high temperature and high pressure to form Al 2 O 3 The 'jujube cake model' structure of the coated cBN particles can effectively improve the hardness of the alumina ceramic.
Description
Technical Field
The invention belongs to the field of materials, and particularly relates to a preparation method of high-hardness aluminum oxide composite ceramic.
Background
Superhard materials are known as "industrial teeth" and have good high hardness, fracture toughness, wear resistance and low coefficient of friction, and are the most desirable physical properties of cutting tools. Diamond and cubic boron nitride (cBN) are the two most widely used superhard materials, but both also have significant drawbacks in the field of material processing. For example, diamond is known as the most hard substance in nature, with vickers hardness as high as 60-120GPa. However, it is inferior in thermal stability and chemical inertness at normal temperature and pressure, has an oxidation temperature of about 600 ℃ in air, and diamond is liable to chemically react with iron group metals and their alloys during processing to fail. In comparison, cBN is superior to diamond in thermal stability and chemical inertness, has an oxidation temperature of about 1100 ℃ in air and is not susceptible to chemical reaction with iron group metals and their alloys, but has a hardness of only about half that of diamond. In addition, the conditions for preparing diamond and cBN are very severe, and taking diamond as an example, the diamond is prepared under the complicated and severe conditions of high temperature and high pressure of about 15-18GPa and 1500-2300 ℃ so as to obtain good diamond.
Currently, there is no universal material available for use as a cutting blade for all machining applications. The machining tools for high-speed cutting, high feed rates, dry machining (without deleterious coolant) and efficient finishing operations (elimination of grinding operations) are still based on oxide-based ceramic materials. Their basic component is usually alumina (Al 2 O 3 ) Or zirconium dioxide (ZrO) 2 )。Al 2 O 3 The ceramic has the excellent performances of high heat resistance, high wear resistance, good chemical stability, high mechanical strength and the like. Against the increasing demands of parts and components in use performance, the alloy is made of Al 2 O 3 The mechanical properties of ceramics are subject to more stringent requirements. Thus, al is also produced 2 O 3 Novel Al with high heat resistance and high hardness of cBN 2 O 3 Composite materials are becoming increasingly important to researchers in the field of superhard materials.
With the development, it is based on the addition of hard particles to increase Al 2 O 3 The idea of ceramic composite material hardness is to try to prepare Al under the conditions of high temperature and high pressure 2 O 3 Composite materialSuperhard ceramics, e.g. Al 2 O 3 The composite material with cBN prepares ceramic which has high hardness and high wear resistance of additive and Al 2 O 3 Is improved in heat stability. Wherein P.Klimczyk et Al sintered Al by SPS (75 MPa,1300 ℃,4 min) and high temperature and high pressure (7.5 GPa,1170 ℃ C.) method 2 O 3 The hardness of +30vol.% cBN composite is 18.6 and 21.8GPa (published under Journal of the European Ceramic Society (2016) 1783-1789), respectively. Al sintered by Jiakun Wu et Al under high temperature and high pressure conditions of 5.5GPa and 850 DEG C 2 O 3 The hardness of +40vol% cBN was 30GPa (published under International Journal of Refractory Metals and Hard Materials 109 (2022) 105969). The hardness of commercial cBN polycrystalline material is about 35GPa, and Al prepared by the method 2 O 3 Although the hardness of the composite material is improved, the hardness of the composite material is still different from that of the common cBN polycrystalline material. Al (Al) 2 O 3 The hardness of the composite material is to be further increased.
Disclosure of Invention
The invention provides a preparation method of high-hardness aluminum oxide composite ceramic, which is used for preparing Al with higher hardness and higher wear resistance 2 O 3 A ceramic material.
The invention provides a preparation method of high-hardness aluminum oxide composite ceramic, which comprises the following steps:
step 1: taking the mixed Al 2 O 3 And cBN mixed powder is treated for 0.1 to 10 hours at the temperature of 500 to 1600 ℃;
step 2: prepressing and forming the heat-treated mixed powder to obtain a biscuit, wherein the compactness of the biscuit formed by prepressing is more than 30%;
step 3: heating the biscuit under high pressure at 800-1600 deg.c for 1-30min, and cooling to obtain the superhard alumina ceramic composite material.
Further, the Al 2 O 3 And cBN are micron-sized micro-powders.
Further, the preparation method of the mixed powder in the step 1 comprises the following steps:
step 1: by volumeSpecific Al 2 O 3 70% -100% of cBN and 0% -30% of Al are weighed 2 O 3 Mixing with cBN micropowder, and mechanically stirring for 20min to obtain Al 2 O 3 Preliminary dispersion and mixing of cBN micro powder are obtained;
step 2: adding hard ZrO 2 In a plastic ball milling tank of the alloy ball, the rotating speed is set to be 60-150 revolutions per minute according to the mass ratio of the ball materials to be 2:1, and the ball milling time is 0.5-3h.
Further, the mixed powder in the step 1 has a vacuum degree of 1X 10-1 to 1X 10 -5 Heating is performed under Pa conditions.
Further, the temperature rising and reducing rate in the step 1 is 5-30 ℃/min.
Further, the mixed powder in the step 2 is pre-pressed and molded under 100-600 MPa.
Further, the pre-pressing time in the step 2 is 5-20s.
Further, the high pressure condition in the step 3 is 3-7GPa.
Further, the step-up and step-down rate in the step-up and step-down method is 1-3GPa/min.
Further, the temperature rising and reducing rate in the step 3 is 50-300 ℃/min.
Compared with the prior art, the invention uses Al with specific size 2 O 3 And cBN powder as raw material, al 2 O 3 cBN is used as a reinforcing phase and Al is used as a matrix 2 O 3 Mixing with cBN powder according to a specific volume ratio, and adding Al 2 O 3 After pre-pressing and forming the mixed powder composed of cBN powder, sintering at a proper high temperature and high pressure to form Al 2 O 3 The 'jujube cake model' structure of the coated cBN particles can effectively improve the hardness of the alumina ceramic.
Drawings
FIG. 1 is Al 2 O 3 -cBN composite high temperature high pressure schematic;
FIG. 2 is Al 2 O 3 -cBN ceramic superhard composite material physical map;
FIG. 3 is Al 2 O 3 SEM image of cBN ceramic superhard composite material.
Detailed Description
In order that those skilled in the art will better understand the present invention, a technical solution of the embodiments of the present invention will be clearly and completely described below, and it is apparent that the described embodiments are only some embodiments of the present invention, not all embodiments.
In both conventional SPS and HPHT production processes there is a softening of cBN, i.e. a transition from high strength cBN phase to soft hBN phase, and an initial nano/sub-micron Al 2 O 3 The grains grow up. Both problems occur to cause Al 2 O 3 The hardness of the composite material is reduced. The invention selects micron-sized Al singly 2 O 3 And cBN micropowder is used as raw material, and a skillfully designed gradient cooling and depressurization method is adopted in a proper cBN phase stabilization temperature and pressure interval, so that the residual stress of the composite material is effectively reduced, and the Al with high hardness, high toughness and high wear resistance is obtained 2 O 3 A preparation method of composite ceramic.
The scheme of the embodiment of the invention is as follows:
weighing Al 2 O 3 And the required mass of each initial raw material of cBN, uniformly mixing the initial raw materials by using a ball mill, performing vacuum heat treatment in a vacuum furnace to remove impurities, and compressing the uniformly mixed initial mixed materials into a biscuit; and assembling the biscuit and the high-temperature high-pressure assembly into a synthetic block, placing the synthetic block into a large-cavity high-temperature high-pressure device, and carrying out high-temperature high-pressure phase transformation and sintering under the conditions of the temperature of 800-1600 ℃ and the pressure of 3-7GPa. By accurately regulating and controlling the pressure, the temperature, the sintering time and the chemical components, the mixed raw materials are sintered under the high-temperature and high-pressure conditions, so that the alumina ceramic composite material with high strength and hardness and excellent comprehensive mechanical properties is prepared. The hardness of the alumina ceramic composite material prepared by the method is improved to 35GPa.
The experimental process adopts the method for preparing Al under the high-temperature and high-pressure conditions generated by a domestic hexahedral top large cavity press 2 O 3 Ceramic superhard composite material.
Example 1
Specifically, embodiment 1 of the present invention includes the following steps:
step 1: al (Al) 2 O 3 And cBN according to 70:30 volume ratio mixing;
step 2: mixing the initial raw materials in the proportion in an agate mortar for 20min, primarily dispersing the initial mixed powder, and uniformly mixing the initial mixed powder by using a ball mill, wherein the rotating speed of the ball mill is 150 revolutions per minute for 0.5h; then, pouring in hard ZrO 2 In a plastic ball milling tank of the alloy ball, the ball material mass ratio is 2:1, the rotating speed is set to 150 revolutions per minute, and the ball milling time is 0.5h;
step 3. The preparation method of the alumina ceramic superhard composite material is characterized in that the vacuum degree of the vacuum heat treatment of the mixed powder is 1 multiplied by 10 -1 Pa, the temperature is 500-600 ℃, and the treatment time is 10 hours; wherein the heating rate of the temperature from room temperature to the treatment temperature and the cooling rate of the temperature from the treatment temperature to the room temperature are both 30 ℃/min;
step 4, carrying out prepressing molding on the mixed powder, wherein the pressure of the mixed powder in a mold is 100-200MPa during prepressing molding, and the prepressing time is 20s, so that the compactness of a biscuit formed by prepressing is more than 30%;
step 5, sintering the biscuit at high temperature and high pressure at the pressure of 4GPa and the temperature of 800-1600 ℃ for 30min, and cooling to obtain the alumina ceramic of the embodiment of the invention; wherein the pressure increasing rate of increasing the pressure from the normal pressure to the sintering pressure and the pressure decreasing rate of decreasing the pressure from the sintering pressure to the normal pressure are 3GPa/min, and the temperature increasing rate of increasing the temperature from the room temperature to the sintering temperature and the temperature decreasing rate of decreasing the temperature from the sintering temperature to the room temperature are 50 ℃/min;
example 2
Specifically, embodiment 1 of the present invention includes the following steps:
step 1: al (Al) 2 O 3 And cBN according to 70:30 volume ratio mixing;
step 2: mixing the initial raw materials in the proportion in an agate mortar for 20min, primarily dispersing the initial mixed powder, and uniformly mixing the initial mixed powder by using a ball mill, wherein the rotating speed of the ball mill is 60 revolutions per minute for 3h; then, pour intoInto hard ZrO 2 In a plastic ball milling tank of the alloy ball, the ball material mass ratio is 2:1, the rotating speed is set to be 60 revolutions per minute, and the ball milling time is 3 hours;
step 3. The preparation method of the alumina ceramic superhard composite material is characterized in that the vacuum degree of the vacuum heat treatment of the mixed powder is 1 multiplied by 10 -5 Pa, the temperature is 1500-1600 ℃, and the treatment time is 0.1h; wherein the heating rate of the temperature from room temperature to the treatment temperature and the cooling rate of the temperature from the treatment temperature to the room temperature are both 30 ℃/min;
step 4, pre-pressing and forming the mixed powder, wherein the pressure of the mixed powder in a mold is 500-600MPa during pre-pressing and forming, and the pre-pressing time is 5s, so that the compactness of a biscuit formed by pre-pressing is more than 30%;
step 5, performing high-temperature high-pressure sintering on the biscuit at the pressure of 7GPa and the temperature of 1600 ℃ for 1min, and cooling to obtain the alumina ceramic of the embodiment of the invention; wherein the pressure increasing rate of increasing the pressure from the normal pressure to the sintering pressure and the pressure decreasing rate of decreasing the pressure from the sintering pressure to the normal pressure are 1GPa/min, and the temperature increasing rate of increasing the temperature from the room temperature to the sintering temperature and the temperature decreasing rate of decreasing the temperature from the sintering temperature to the room temperature are 50 ℃/min;
example 3
The embodiment 2 of the invention comprises the following steps:
step 1, mixing initial powder: in volume ratio of Al 2 O 3 70% of cBN and 30% of Al are respectively weighed by volume 2 O 3 And cBN micropowder, dispersing into agate mortar, mechanically stirring for 20min to obtain Al 2 O 3 And the cBN micropowder is primarily dispersed and mixed. Then, pouring in hard ZrO 2 In a plastic ball milling tank of the alloy ball, the ball material mass ratio is 2:1, the rotating speed is set to be 60-150 revolutions per minute, and the ball milling time is 0.5-3 hours;
step 2, analyzing the microcosmic appearance of the mixed materials: SEM detection is carried out on the mixed powder mixed by the ball mill, and the uniformity, the size and the hard ZrO of the mixed powder are analyzed 2 Analyzing the content of impurities possibly introduced into the alloy ball;
step 3, vacuum heat treatment of the mixed materials: will oxidizeCleaning and drying the aluminum crucible, and filling the Al with relatively uniform mixture 2 O 3 And cBN micropowder mixture, and covering an alumina crucible cover. Firstly, coarse vacuumizing until the air pressure in the furnace reaches 5 multiplied by 10 -2 Heating to 300 deg.C below Pa, maintaining for 10-20min, and vacuumizing to air pressure of 3×10 -5 Heating to 800 deg.C below Pa, maintaining for 10-30min, stopping vacuumizing, charging mixed gas of CO, ammonia and Ar, uniformly mixing CO, ammonia and Ar at a ratio of 0.5:0.5:1, maintaining for 2 hr, and vacuumizing to 3×10 in-furnace air pressure -5 Under Pa, obtaining an initial mixed material for purifying and removing impurities;
step 4, assembling a mixed powder block: subjecting the vacuum heat treated Al to 2 O 3 Filling the mixed powder of cBN into a metal molybdenum cup, compacting and shaping in a layered manner, and sleeving the metal molybdenum cup from right above by using a larger metal molybdenum cup to obtain an assembled block of mixed powder of alumina and cubic boron nitride;
step 5, pre-pressing mixed powder: prepressing the assembly block in the step 4 on a hydraulic press, wherein the pressure of the mixed powder in the die is 100-600MPa, and the prepressing time is 5-20s, so that the compactness of a biscuit formed by prepressing is more than 30%;
step 6, assembling a synthesis block: filling Al after the pre-pressing of the molybdenum cup in the steps 4 and 5 2 O 3 And cBN mixed powder, sequentially placing the mixed powder into pyrophyllite blocks by using a salt sheet, a salt pipe, a dolomite sheet, a graphite pipe, a metal gasket, a plug and the like according to the assembly sequence shown in figure 1 (the assembly is the prior art and is not repeated here);
step 7, sintering at high temperature and high pressure: and placing the pyrophyllite block into high-temperature high-pressure equipment, setting pressure boosting, heating, heat preservation, cooling and pressure relief procedures in a pressure temperature control system, and performing high-temperature high-pressure sintering. During sintering, the sintering pressure is raised to 3-7GPa at the speed of 0.8GPa/min, then the high-temperature sintering is carried out at the temperature raising speed of 36 ℃/S, after the heat preservation is carried out at the temperature of 800-1500 ℃ for 1-30min, the temperature is reduced to 600 ℃ at the speed of 21 ℃/S after the 4 sintering is finished, the temperature is reduced to room temperature after the heat preservation is carried out for 20min, and the pressure is reduced to normal pressure at the pressure reducing speed of 0.8 GPa/min. The assembly blocks are pressed by a hexahedral top pressTaking out, removing the surface coating layer to obtain sintered Al as shown in figure 2 2 O 3 And cBN compact ceramic.
Compared with the prior art, the embodiment of the invention has the following advantages:
1. al used in the present invention 2 O 3 Compared with the traditional SPS preparation method which takes a plurality of hours, the preparation method has higher production efficiency, wherein the sintering time of the preparation method of the cBN ceramic superhard composite material is 1-30 min;
2. the aluminum oxide ceramic composite material prepared by the method has the advantages of improved hardness, up to 35GPa, and high hardness with Al sintered at the temperature of 7.5GPa and 1170 DEG C 2 O 3 +30vol.% cBN, 21.8GPa and 5.5GPa, sintered Al at 850 DEG C 2 O 3 The hardness of +40vol% cBN is greatly improved by 30GPa, which is equivalent to that of commercial cBN;
3. the equipment used in the invention is common equipment for industrial production of superhard materials, and the preparation method is simple and is convenient for commercial production.
Alumina (Al) 2 O 3 ) The ceramic has the advantages of high hardness, high temperature resistance, wear resistance, electric insulation, oxidation resistance, abundant raw materials, low price and the like, and is the earliest and most widely applied fine ceramic. Al (Al) 2 O 3 The crystal has stronger ionic bond, larger lattice energy and low diffusion coefficient, and the existing Al 2 O 3 The discharge plasma (SPS) sintering of ceramic mainly has the problems of high sintering temperature (over 1700 ℃) and long sintering time (over several hours), high cost, easy abnormal growth of crystal grains and influence on the performance of the ceramic.
As the functional ceramic, the hardness was Al 2 O 3 Ceramic has important basic properties, and attempts have been made to prepare Al by high-temperature and high-pressure methods 2 O 3 However, the Vickers hardness of the ceramic cannot break through 30GPa so far, and the ceramic needs to be further improved. The invention introduces cubic boron nitride (cBN) as a reinforcing phase and makes the cubic boron nitride (cBN) and Al under the conditions of high temperature and high pressure 2 O 3 Forming an inter-crystalline/intra-crystalline mixed structure, the crack propagates from inter-crystalline to intra-crystalline to inter-crystalline paths, and is consumed moreMultiple fracture energy forms a fracture mode of mixed crystal/crystal penetration, improves the comprehensive mechanical property of the alumina ceramic composite material from the microstructure source, and can lead Al to be mixed with 2 O 3 The hardness of the ceramic is improved to 35GPa.
In conclusion, the invention uses Al with specific size 2 O 3 And cBN powder as raw material, al 2 O 3 cBN is used as a reinforcing phase and Al is used as a matrix 2 O 3 Mixing with cBN powder according to a specific volume ratio, and adding Al 2 O 3 After pre-pressing and molding, the mixed powder composed of cBN powder is sintered at a proper high temperature and high pressure to form Al as shown in figure 1 2 O 3 A "jujube cake model" structure surrounding the cBN particles; cBN and Al 2 O 3 Forming an intra-crystal/inter-crystal mixed structure, changing and expanding a crack propagation path from inter-crystal to intra-crystal to inter-crystal, wherein a fracture mode comprises two forms of along-crystal fracture and through-crystal fracture, more fracture energy is consumed, and meanwhile, high-strength cBN particles can also block crack propagation, so that Al is greatly improved 2 O 3 The comprehensive mechanical properties of the ceramic composite material, and the particle size, the proportion and the temperature and pressure synthesis conditions of the raw materials are key factors for improving the performance.
Finally, it should be noted that the above-mentioned embodiments are only for illustrating the technical solution of the present invention and not for limiting the same, and although the present invention has been described in detail with reference to the above-mentioned embodiments, it should be understood by those skilled in the art that modifications and equivalents may be made to the specific embodiments of the present invention after reading the present specification, and these modifications and variations do not depart from the scope of the invention as claimed in the pending claims.
Claims (10)
1. The preparation method of the high-hardness aluminum oxide composite ceramic is characterized by comprising the following steps of:
step 1: taking the mixed Al 2 O 3 And cBN mixed powder is treated for 0.1 to 10 hours at the temperature of 500 to 1600 ℃;
step 2: prepressing and forming the heat-treated mixed powder to obtain a biscuit, wherein the compactness of the biscuit formed by prepressing is more than 30%;
step 3: heating the biscuit under high pressure at 800-1600 deg.c for 1-30min, and cooling to obtain the superhard alumina ceramic composite material.
2. The method for preparing high-hardness alumina composite ceramic according to claim 1, wherein the Al 2 O 3 And cBN are micron-sized micro-powders.
3. The method for preparing the high-hardness aluminum oxide composite ceramic according to claim 1, wherein the method for preparing the mixed powder in the step 1 is as follows:
step 1: according to the volume ratio of Al 2 O 3 70% -100% of cBN and 0% -30% of Al are weighed 2 O 3 Mixing with cBN micropowder, and mechanically stirring for 20min to obtain Al 2 O 3 Preliminary dispersion and mixing of cBN micro powder are obtained;
step 2: adding hard ZrO 2 In a plastic ball milling tank of the alloy ball, the rotating speed is set to be 60-150 revolutions per minute according to the mass ratio of the ball materials to be 2:1, and the ball milling time is 0.5-3h.
4. The method for preparing high-hardness alumina composite ceramic according to claim 1, wherein the degree of vacuum of the mixed powder in step 1 is 1 x 10-1 to 1 x 10 -5 Heating is performed under Pa conditions.
5. The method for preparing the high-hardness aluminum oxide composite ceramic according to claim 1, wherein the heating and cooling rate in the step 1 is 5-30 ℃/min.
6. The method for preparing high-hardness alumina composite ceramic according to claim 1, wherein the mixed powder in the step 2 is pre-pressed and molded under 100-600 MPa.
7. The method for preparing high-hardness alumina composite ceramic according to claim 1, wherein the pre-pressing time in the step 2 is 5-20s.
8. The method for preparing high-hardness alumina composite ceramic according to claim 1, wherein the high-pressure condition in the step 3 is 3-7GPa.
9. The method for preparing the high-hardness aluminum oxide composite ceramic according to claim 1, wherein the step-up and step-down rates in the step-3 are 1-3GPa/min.
10. The method for preparing the high-hardness aluminum oxide composite ceramic according to claim 1, wherein the heating and cooling rate in the step 3 is 50-300 ℃/min.
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