Corrosion-resistant aluminum oxide ceramic and method for producing the same

Abstract

The application discloses a kind of corrosion-resistant alumina ceramics and preparation method thereof, belong to ceramic technical field;Corrosion-resistant alumina ceramic of the application, by mass fraction, raw material component includes 75~85 mass parts alumina, 25~35 mass parts titanium carbide, 0.85~0.95 mass parts functionalized graphene, 0.091~0.092 mass parts aluminum powder, 4~6 mass parts binder aluminum dihydrogen phosphate, 1.4~1.8 mass parts zinc oxide, 3.9~4.1 mass parts magnesium oxide;Wherein functionalized graphene is obtained by mixed reaction of titanate coupling agent, hydrazine hydrate and graphene oxide;Corrosion-resistant alumina ceramic prepared by the application has good corrosion resistance and wear resistance.

Description

TECHNICAL FIELD

[0001] The present application relates to a kind of corrosion-resistant aluminum oxide ceramics and its preparation method. BACKGROUND

[0002] Aluminum oxide ceramics is widely used in important fields such as mechanical seal, cutting tool and aerospace heat-resistant components due to its excellent physical and chemical properties, such as high hardness, extremely high melting point, excellent wear resistance and chemical stability. However, the inherent brittleness, low fracture toughness and limited bending strength of aluminum oxide ceramics make it prone to crack propagation when facing impact load or thermal stress, especially in high temperature corrosion environment, grain boundary is easily eroded, grain growth leads to material performance degradation, showing insufficient corrosion resistance and sintering resistance.

[0003] To overcome these limitations, researchers have developed aluminum oxide-titanium carbide composites, which are a kind of multiphase structure material composed of aluminum oxide matrix and titanium carbide particles distributed therein. The composite not only inherits the excellent high temperature resistance, wear resistance and chemical stability of aluminum oxide ceramics, but also significantly improves the overall performance of the material by adding titanium carbide particles. Specifically, titanium carbide has very high hardness, which greatly enhances the wear resistance of the composite material, making it very suitable for manufacturing cutting tools; at the same time, the chemical inertness of titanium carbide in acid and alkali environment is stronger than that of pure aluminum oxide, further improving the corrosion resistance of the material. In addition, the presence of titanium carbide can also inhibit the growth of aluminum oxide grains, which helps to delay the high temperature creep process.

[0004] However, traditional aluminum oxide-titanium carbide composites still face some challenges, especially the difference in thermal expansion coefficient between titanium carbide and aluminum oxide may cause interfacial stress, thereby reducing the bending strength of the material. Therefore, how to effectively solve this problem and further improve the corrosion resistance, wear resistance and bending strength of aluminum oxide ceramics has become one of the key research directions.

[0005] The present application aims to propose a new type of corrosion-resistant aluminum oxide ceramic and its preparation method to solve the above problems. SUMMARY

[0006] The purpose of the present application is to provide a kind of corrosion-resistant aluminum oxide ceramics and its preparation method to solve the technical problems mentioned in the background.

[0007] The technical solution to achieve the purpose of the present application is:

[0008] In the first aspect, the application provides a kind of corrosion-resistant alumina ceramic, and the raw material components include 75-85 mass parts of alumina, 25-35 mass parts of titanium carbide, 0.85-0.95 mass parts of functional graphene, 0.091-0.092 mass parts of aluminum powder, 4-6 mass parts of binder aluminum dihydrogen phosphate, 1.4-1.8 mass parts of zinc oxide, 3.9-4.1 mass parts of magnesium oxide.

[0009] The application effectively improves the corrosion resistance, bending strength and wear resistance of alumina-titanium carbide ceramic by introducing functional graphene, aluminum powder, binder aluminum dihydrogen phosphate, zinc oxide and magnesium oxide into the alumina-titanium carbide-based alumina ceramic.

[0010] Further, the functional graphene is obtained by mixing and reacting titanate coupling agent, hydrazine hydrate and oxidized graphene.

[0011] In the alumina ceramic of the application, the functional graphene obtained by mixing and reacting titanate coupling agent, hydrazine hydrate and oxidized graphene is used. On the one hand, the functional graphene migrates to the surface of the alumina ceramic during friction and spreads to form a lubricating film, which significantly reduces the friction coefficient and wear rate, reduces the occurrence of adhesive wear, prevents large-scale wear caused by the occlusion of foreign substances and the alumina ceramic, and hinders crack propagation, prolongs crack path and consumes energy, thereby reducing crack generation. On the other hand, the functional graphene, with its high aspect ratio and surface wrinkle structure, extends the penetration path of the corrosion liquid as a physical barrier, prevents corrosion reaction or penetration by chemical inertness, and connects the two ends of the crack to prevent expansion and widening, relies on high strength to increase crack propagation resistance, and reduces the channel for the diffusion of corrosion liquid to the matrix, thereby significantly slowing down the corrosion rate. Through the modification reaction of titanate coupling agent and hydrazine hydrate, the functional graphene solves the defect of easy agglomeration of graphene and ensures its uniform dispersion in the alumina ceramic. This not only makes the alumina ceramic more dense and reduces the number of pores, but also avoids the problem of increased defects caused by graphene agglomeration, ultimately improving the wear resistance and corrosion resistance of the alumina ceramic.

[0012] Further, the titanate coupling agent includes titanate coupling agent 311W and titanate coupling agent TM-200S.

[0013] In the second aspect, the application provides a preparation method of the corrosion-resistant alumina ceramic according to the first aspect, which includes the following preparation steps:

[0014] (1) The raw material components are weighed and mixed according to the corresponding mass fraction;

[0015] (2) Mixing material A: the weighed binder aluminum dihydrogen phosphate in step (1) is warmed to 78-82 DEG C, then 0.25-0.38 mass parts of magnesium oxide is added and stirred for 55-65 min, then the temperature is increased to 108-112 DEG C, the temperature is decreased to 80 DEG C, 1.02-1.54 mass parts of zinc oxide is added and stirred for 55-65 min, then the remaining magnesium oxide and zinc oxide is added and stirred for 55-65 min, to obtain mixing material A;

[0016] The aluminum dihydrogen phosphate, magnesium oxide and zinc oxide are mixed first to form the aluminum magnesium zinc phosphate, magnesium oxide and zinc oxide mixture, the introduction of the aluminum magnesium zinc phosphate not only forms the granular magnesium metaphosphate crystal, but also generates the flaky zinc metaphosphate microcrystal, increases the degree of confusion of the system, and further generates the high-entropy effect, so that the crystal high-temperature stability of the system is improved, which helps to reduce the appearance of defects such as holes and cracks in the aluminum oxide ceramic, and enables the aluminum magnesium zinc phosphate in the aluminum oxide ceramic to be completely and closely coated with the remaining raw material powder, effectively improves the compactness of the aluminum oxide ceramic, and further improves the wear resistance and corrosion resistance of the aluminum oxide ceramic;

[0017] (3) Mixing material B: the weighed titanium carbide, functionalized graphene and aluminum powder in step (1) is put into a ball mill, then cyclohexane is added to completely immerse the titanium carbide, functionalized graphene and aluminum powder and the grinding balls in the ball mill, then ball milling is carried out for 49-51 h, after the ball milling, vacuum drying and sieving are carried out, to obtain the mixing material B; the titanium carbide, functionalized graphene and aluminum powder are mixed first, so that the titanium carbide, functionalized graphene and aluminum powder particles are significantly refined, the particles continuously collide and rub during the ball milling, so as to promote the mutual contact and uniform dispersion of the titanium carbide, functionalized graphene and aluminum powder, to provide more active sites and larger contact area for the subsequent reaction, and the ball milling enables the aluminum powder and the titanium dioxide on the surface layer of the functionalized graphene to form the "core-shell" agglomerates, i.e. the aluminum is the core and the functionalized graphene is the shell, the contact area of the structure is large, which is beneficial to the in-situ reaction of atoms through interface diffusion in the subsequent reaction, to provide the favorable interface structure between the composite materials for mutual contact and dispersion;

[0018] (4) the aluminum oxide, mixing material A and deionized water are put into a ball mill and ball milled for 71-73 h, then drying is carried out, then the mixing material B is added, dry mixing and ball milling are carried out for 23-25 h, so that all the raw materials are fully mixed and uniformly distributed, to create good conditions for the subsequent hot-pressing sintering reaction, the graphite mold is put into a hot-pressing furnace, then the vacuum degree is extracted to 1*10 -4When the pressure is 0.1 torr, the hot-pressing sintering is carried out, and after the furnace cooling, the corrosion-resistant alumina ceramic is obtained; under the vacuum hot-pressing condition, when the Al melting point is reached, the "nucleus-like" agglomerates are first reacted to generate TiAl3 and a small amount of TiO, and with the temperature rising, a large amount of fine alumina grains are precipitated on the TiAl3 grain boundaries to form a three-dimensional network structure of TiAl3 and alumina, and meanwhile, the C diffuses in the titanium carbide to obtain TiC x The compound and TiAl3 are dissolved and precipitated to generate part of Ti3AlC2, which tightly combines the phases in the alumina ceramic, improves the density and strength of the alumina ceramic, and further improves the corrosion resistance of the alumina ceramic. In addition, the generation of Ti3AlC2 enables the alumina ceramic to have good self-healing ability, and when a slight crack appears under stress, the material crack can be filled at a low temperature.

[0019] Further, the preparation step of the aluminum dihydrogen phosphate is as follows: 85% phosphoric acid is diluted into a 60% phosphoric acid solution in purified water, and the oil bath is heated to 78-82℃ to obtain a hot phosphoric acid solution; the aluminum hydroxide is dispersed in 10 times the mass of purified water, then added into the hot phosphoric acid solution at a speed of 1 drop / s, and stirred at a speed of 800-1200 rpm until it gradually becomes clear, to obtain the aluminum dihydrogen phosphate.

[0020] Further, the molar ratio of the phosphoric acid to the aluminum hydroxide is 3.1-3.3:1.

[0021] Further, the preparation step of the functionalized graphene is as follows: the pH of the 1 mg / mL graphene oxide solution is adjusted to 9-10 by adding 1M sodium hydroxide solution, then 1-3 times the mass of the graphene oxide is added into the solution, and 5-7 times the mass of the graphene oxide is added into the solution, and the mixture is reacted at 80-90℃ for 7-8h, then filtered while hot, and washed repeatedly with deionized water until the filtrate is neutral, to obtain the functionalized graphene.

[0022] Further, the ball milling tank and the grinding balls of the ball mill in step (3) are both made of alumina, the maximum diameter of the grinding balls is 10 mm, the minimum diameter is 3 mm, the ball-to-material ratio is 8:1, the rotation speed of the ball mill is 300 r / min, and the ball milling is carried out with the ball mill being stopped for 0.2h every 0.5h for the positive and negative rotation alternation.

[0023] Further, the grinding balls in step (4) are zirconia balls, and the mass ratio of the zirconia balls, deionized water, alumina and the mixed material A is 2:2:1.

[0024] Further, the sintering pressure of the hot-press sintering is 49-51 MPa, and the sintering process is as follows: first, the temperature is raised to 195-205 DEG C at a rate of 4-6 DEG C / min, then the temperature is raised to 655-665 DEG C at a rate of 18-22 DEG C / min, the temperature is raised to 755-765 DEG C at a rate of 1-3 DEG C / min, and then the temperature is raised to 1200-1300 DEG C at a rate of 20 DEG C / min, and calcination is carried out for 11-13 h, to obtain the corrosion-resistant aluminum oxide ceramic.

[0025] By adopting the technical scheme, the present application has the following beneficial effects:

[0026] (1) The present application effectively improves the corrosion resistance, bending strength and wear resistance of the aluminum oxide-titanium carbide ceramic by introducing functionalized graphene, aluminum powder, binder aluminum dihydrogen phosphate, zinc oxide and magnesium oxide into the aluminum oxide-titanium carbide ceramic.

[0027] (2) The functionalized graphene obtained by mixing and reacting titanate coupling agent, hydrazine hydrate and graphene oxide is used in the aluminum oxide ceramic. On the one hand, the functionalized graphene migrates to the surface of the aluminum oxide ceramic during friction and spreads to form a lubricating film, which significantly reduces the friction coefficient and wear rate, reduces the occurrence of adhesive wear, prevents large-scale wear caused by the occlusion of foreign substances and the aluminum oxide ceramic, and hinders crack propagation, prolongs the crack path and consumes energy, thereby reducing crack generation. On the other hand, the functionalized graphene, with its high aspect ratio and surface wrinkle structure, acts as a physical barrier to prolong the penetration path of the corrosion liquid and prevent corrosion reactions or penetration by virtue of its chemical inertness. The sheet structure can also connect the two ends of the crack to prevent expansion and widening, and rely on high strength to increase the resistance to crack propagation, thereby reducing the channels for the diffusion of the corrosion liquid to the matrix, significantly slowing down the corrosion rate. Through the modification reaction of the titanate coupling agent and the hydrazine hydrate, the functionalized graphene solves the defect of easy agglomeration of graphene, ensuring its uniform dispersion in the aluminum oxide ceramic. This not only makes the aluminum oxide ceramic more dense and reduces the number of pores, but also avoids the problem of increased defects caused by graphene agglomeration, ultimately improving the wear resistance and corrosion resistance of the aluminum oxide ceramic.

[0028] (3) The present application introduces aluminum dihydrogen phosphate into alumina ceramic, on the one hand, aluminum dihydrogen phosphate can effectively improve the viscosity and thixotropy of each raw material component in the wet grinding process, promote the uniform dispersion of the raw materials; it has good colloidal properties, can form a solvation film on the particle surface, reduce the solid-liquid interface energy, prevent the stratification of alumina and other components due to gravity; the ionized phosphate radical and the alumina surface hydroxyl group are combined, weakening the hydrogen bond effect and reducing the tendency of particle agglomeration; moreover, aluminum dihydrogen phosphate gives the wet grinding slurry good thixotropy, the slurry viscosity decreases under the action of ball mill shear force, which is beneficial to the rapid dispersion of the powder, and after the stirring stops, the high viscosity is restored to maintain the stability of the dispersion system; on the other hand, during sintering, when the temperature reaches above 1180℃, aluminum dihydrogen phosphate decomposes to form aluminum phosphate, forming an Al-O-P-O-Al bridge structure, so that the ceramic body obtains initial strength; further heating to above 1250℃, mullite phase is generated, which significantly improves the mechanical strength of the ceramic; at the same time, the introduction of aluminum phosphate significantly improves the high temperature performance of the ceramic, its thermal expansion coefficient is similar to that of alumina, reducing the sintering stress between them, and showing outstanding performance in improving thermal shock resistance and spalling resistance.

[0029] (4) The present application introduces magnesium oxide and zinc oxide into alumina ceramic, magnesium oxide and zinc oxide as common sintering aids, on the one hand, reduce the hot-pressing sintering temperature, on the other hand, increase the liquid phase content in the reaction process, which makes the diffusion process between particles easy to proceed, and the voids are also easy to be filled with liquid phase, so that the density increases, the density of alumina ceramic increases, and the corrosion resistance and mechanical properties of alumina ceramic are improved.

[0030] (5) The present application first mixes aluminum dihydrogen phosphate, magnesium oxide and zinc oxide to form an aluminum magnesium zinc phosphate, magnesium oxide and zinc oxide mixture, the introduction of aluminum magnesium zinc phosphate will form granular magnesium metaphosphate crystals and flaky zinc metaphosphate microcrystals, increasing the degree of disorder of the system, and further producing a high-entropy effect, which helps to reduce the occurrence of defects such as pores and cracks in the alumina ceramic, and enables the aluminum magnesium zinc phosphate in the alumina ceramic to be completely and tightly coated with the remaining raw material powder, effectively improving the density of the alumina ceramic, and further improving the wear resistance and corrosion resistance of the alumina ceramic.

[0031] (6)The present application first mixes titanium carbide, functionalized graphene, and aluminum powder, so that the titanium carbide, functionalized graphene, and aluminum powder particles are significantly refined. During ball milling, the particles continuously collide and rub against each other, promoting mutual contact and uniform dispersion of the titanium carbide, functionalized graphene, and aluminum powder, thereby providing more active sites and a larger contact area for subsequent reactions. Moreover, ball milling causes the aluminum powder and the titanium dioxide on the surface of the functionalized graphene to form a "nucleus-like" aggregate, i.e., the aluminum is the core and the functionalized graphene is the shell. This structure has a large contact area, which is conducive to in-situ reaction of atoms through interface diffusion in subsequent reactions, thereby providing a favorable interface structure for mutual contact and dispersion of the composite material.

[0032] (7)The present application uniformly ball-mills aluminum oxide, mixture A, and mixture B, which ensures uniform distribution of the components at the micro level, thereby creating good conditions for subsequent hot-pressing sintering reactions, and then obtaining corrosion-resistant aluminum oxide ceramic through vacuum hot-pressing sintering. Under vacuum hot-pressing conditions, when the Al melting point is reached, the "nucleus-like" aggregate first reacts to form TiAl3 and a small amount of TiO. As the temperature rises, a large number of fine aluminum oxide grains are precipitated on the TiAl3 grain boundaries, forming a three-dimensional network structure of TiAl3 and aluminum oxide that penetrates each other. At the same time, C diffuses in the titanium carbide to form TiC x compound, and dissolves and precipitates with TiAl3 to form part of Ti3AlC2, thereby tightly combining the phases in the aluminum oxide ceramic and improving the density and strength of the aluminum oxide ceramic, and further improving the corrosion resistance of the aluminum oxide ceramic. In addition, the generation of Ti3AlC2 enables the aluminum oxide ceramic to have good self-healing ability, so that when a slight crack occurs under stress, the material can fill the crack at a relatively low temperature. DETAILED DESCRIPTION

[0033] In order to better understand the above technical solutions, the above technical solutions will be described in detail below in combination with specific embodiments.

[0034] Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative labor fall within the scope of protection of the present application.

[0035] The following examples are only used to more clearly illustrate the technical solutions of the present application, and cannot be used to limit the protection scope of the present application.

[0036] Aluminum powder: purity 99.7%, particle size <50 μm.

[0037] Titanium dioxide powder: purity 99.9%, particle size <45 μm.

[0038] Magnesium oxide analytical pure produced by Shanghai Maikelin Company.

[0039] Zinc oxide was produced by Shanghai Maikelin Company.

[0040] Alumina: purity 99.9%, particle size 1-5 μm, produced by Guangzhou Jibisheng Science and Technology Industry Co., Ltd.

[0041] (Example 1)

[0042] A preparation method of a corrosion-resistant alumina ceramic comprises the following preparation steps:

[0043] (1) The raw material components are weighed and prepared according to the following mass fractions: 75 mass parts of alumina, 35 mass parts of titanium carbide, 0.85 mass parts of functionalized graphene, 0.091 mass parts of aluminum powder, 4 mass parts of binder aluminum dihydrogen phosphate, 1.4 mass parts of zinc oxide, and 3.9 mass parts of magnesium oxide;

[0044] (2) Mixing material A: the weighed binder aluminum dihydrogen phosphate in step (1) is heated to 78°C, then 0.25 mass parts of magnesium oxide is added and stirred for 55 min, then the temperature is increased to 108°C, and after the temperature is decreased to 80°C, 1.02 mass parts of zinc oxide is added and stirred for 55 min, then the remaining magnesium oxide and zinc oxide is continuously added and stirred for 55 min, to obtain mixing material A;

[0045] (3) Mixing material B: the weighed titanium carbide, functionalized graphene, and aluminum powder in step (1) are put into a ball mill, then cyclohexane is added to completely immerse the titanium carbide, functionalized graphene, aluminum powder, and grinding balls in the ball mill, then ball milling is performed for 49 h, and after the ball milling, vacuum drying is performed for 24 h and the mixture is sieved through a 200-mesh sieve to obtain mixing material B; wherein the ball mill jar and grinding balls are both made of alumina, the maximum diameter of the grinding balls is 10 mm, the minimum diameter of the grinding balls is 3 mm, the ball-to-material ratio is 8:1, the rotation speed of the ball mill is 300 r / min, and the ball mill is stopped for 0.2 h and then runs in the opposite direction for 0.2 h every 0.5 h during the ball milling;

[0046] (4) The alumina, mixing material A, and deionized water are put into a ball mill for ball milling for 71 h, and then the mixing material B is added and dry-mixed and ball-milled for 23 h to fully mix and uniformly distribute all the raw materials, so as to create good conditions for subsequent hot-pressing sintering reaction, wherein the grinding balls are made of zirconia, the mass ratio of the zirconia grinding balls, deionized water, and the mass of the alumina and mixing material A is 2:2:1, and then the mixture is put into a graphite mold, and then the graphite mold is put into a hot-pressing furnace, and when the vacuum degree is extracted to 1×10 -4 torr, hot-pressing sintering is performed, and after the furnace is cooled, a corrosion-resistant alumina ceramic is obtained; wherein the sintering pressure of the hot-pressing sintering is 49 MPa, and the sintering process is as follows: first, the temperature is increased to 195°C at a rate of 4°C / min, then the temperature is increased to 655°C at a rate of 18°C / min, the temperature is increased to 755°C at a rate of 1°C / min, and then the temperature is increased to 1200°C at a rate of 20°C / min for calcination for 11 h.

[0047] The preparation steps of the aluminum dihydrogen phosphate are as follows: 85% phosphoric acid is added to pure water to dilute into a 60% phosphoric acid solution, heated to 78℃ in an oil bath to obtain a hot phosphoric acid solution; aluminum hydroxide is dispersed in 10 times its mass of pure water, then added to the hot phosphoric acid solution at a rate of 1 drop / s, and stirred at 800 rpm until it gradually becomes clear, to obtain aluminum dihydrogen phosphate; wherein the molar ratio of phosphoric acid to aluminum hydroxide is 3.1:1.

[0048] The preparation steps of the functionalized graphene are as follows: 1M sodium hydroxide solution is added to a 1mg / mL graphene oxide solution to adjust the pH to 9, then 1 times the mass of the graphene oxide of hydrazine hydrate and 7 times the mass of the graphene oxide of titanium ester coupling agent TM-200S are added, and after 8h of reaction at 80℃, hot filtration is performed, and repeated washing with deionized water is performed until the filtrate is neutral, to obtain functional graphene.

[0049] (Example 2)

[0050] A preparation method of a corrosion-resistant aluminum oxide ceramic, comprising the following preparation steps:

[0051] (1) The raw material components are weighed and prepared according to the following mass fractions: 80 parts by mass of aluminum oxide, 30 parts by mass of titanium carbide, 0.9 parts by mass of functionalized graphene, 0.0916 parts by mass of aluminum powder, 5 parts by mass of binder aluminum dihydrogen phosphate, 1.6 parts by mass of zinc oxide, and 4 parts by mass of magnesium oxide;

[0052] (2) Mixing material A: the weighed binder aluminum dihydrogen phosphate of step (1) is warmed to 80℃, then 0.32 parts by mass of magnesium oxide is added and stirred for 60min, then it is warmed to 110℃, cooled to 80℃, 1.28 parts by mass of zinc oxide is added and stirred for 60min, then the remaining magnesium oxide and zinc oxide are added and stirred for 60min, to obtain mixing material A;

[0053] (3) Mixing material B: the weighed titanium carbide, functionalized graphene, and aluminum powder of step (1) are placed in a ball mill, then cyclohexane is added to completely immerse the titanium carbide, functionalized graphene, aluminum powder, and grinding balls in the ball mill, then ball milling is performed for 50h, after ball milling, vacuum drying is performed for 24h, and sieving is performed through a 200 mesh sieve, to obtain mixing material B; wherein the ball mill jar and grinding balls are both made of aluminum oxide, the maximum diameter of the grinding balls is 10mm, the minimum diameter is 3mm, and the ball-to-material ratio is 8:1; the rotation speed of the ball mill is 300r / min, and during ball milling, it is stopped for 0.2h every 0.5h for alternating forward and reverse rotation;

[0054] (4) Put the alumina, mixture A, deionized water into the ball mill and ball mill for 72h, dry, then add mixture B, dry mix ball mill for 24h, mix all raw materials evenly, ensure that each component is evenly distributed at the micro level, create good conditions for subsequent hot-pressing sintering reaction, wherein the grinding ball is zirconium oxide ball, the mass ratio of zirconium oxide ball, deionized water, alumina and mixture A is 2:2:1, put into a graphite mold, then put the graphite mold into a hot-pressing furnace, when the vacuum degree is 1x10 -4 torr, hot-pressing sintering is carried out, and after cooling in the furnace, the corrosion-resistant alumina ceramic is obtained; wherein the sintering pressure of hot-pressing sintering is 50MPa, and the sintering process is as follows: first, increase the temperature to 200℃ at 5℃ / min, then increase the temperature to 660℃ at 20℃ / min, increase the temperature to 760℃ at 2℃ / min, then increase the temperature to 1250℃ at 20℃ / min and calcine for 12h.

[0055] The preparation steps of the aluminum dihydrogen phosphate are as follows: 85% phosphoric acid is diluted into a 60% phosphoric acid solution with pure water, and the hot phosphoric acid solution is obtained by heating the oil bath to 80℃; the aluminum hydroxide is dispersed in 10 times the mass of pure water, then added to the hot phosphoric acid solution at a rate of 1 drop / s, and stirred at 1000rpm until it gradually becomes clear, to obtain aluminum dihydrogen phosphate; wherein the molar ratio of phosphoric acid to aluminum hydroxide is 3.2:1.

[0056] The preparation steps of the functionalized graphene are as follows: adjust the pH of the 1mg / mL graphene oxide solution to 9.5 by adding 1M sodium hydroxide solution, then add 2 times the mass of hydrazine hydrate and 7 times the mass of titanium ester coupling agent TM-200S of the graphene oxide, react at 80℃ for 8h, filter while hot, and wash repeatedly with deionized water until the filtrate is neutral to obtain functional graphene.

[0057] (Example 3)

[0058] A preparation method of a corrosion-resistant alumina ceramic, comprising the following preparation steps:

[0059] (1) The raw material components are weighed and prepared according to the following mass fractions: 85 parts by mass of alumina, 25 parts by mass of titanium carbide, 0.95 parts by mass of functionalized graphene, 0.092 parts by mass of aluminum powder, 6 parts by mass of binder aluminum dihydrogen phosphate, 1.8 parts by mass of zinc oxide, and 4.1 parts by mass of magnesium oxide;

[0060] (2) Mixing material A: the weighed binder aluminum dihydrogen phosphate in step (1) is warmed to 82℃, then 0.38 parts by mass of magnesium oxide is added and stirred for 65 min, then it is warmed to 112℃, cooled to 80℃, 1.54 parts by mass of zinc oxide is added and stirred for 65 min, then the remaining magnesium oxide and zinc oxide is added and stirred for 65 min, to obtain mixing material A;

[0061] (3) Mixing material B: the weighed titanium carbide, functionalized graphene and aluminum powder in step (1) is put into a ball mill, then cyclohexane is added to completely immerse the titanium carbide, functionalized graphene, aluminum powder and grinding balls in the ball mill, then ball milling is performed for 51 h, after the ball milling, vacuum drying is performed for 24 h, and then it is passed through a 200-mesh sieve to obtain mixing material B; wherein the ball mill jar and grinding balls are both made of aluminum oxide, the maximum diameter of the grinding balls is 10 mm, the minimum diameter is 3 mm, and the ball-to-material ratio is 8:1; the rotation speed of the ball mill is 300 r / min, and during the ball milling, the ball mill is stopped for 0.2 h every 0.5 h and then runs in the opposite direction for 0.2 h.

[0062] (4) The aluminum oxide, mixing material A and deionized water are put into a ball mill and ball milled for 73 h, then dried, then the mixing material B is added and dry-mixed and ball milled for 25 h to fully mix and uniformly distribute all the raw materials, so as to create good conditions for subsequent hot-pressing sintering reaction, wherein the grinding balls are made of zirconia, the mass ratio of the zirconia grinding balls, deionized water, and the sum of the mass of the aluminum oxide and mixing material A is 2:2:1, then it is put into a graphite mold, then the graphite mold is put into a hot-pressing furnace, and when the vacuum degree is extracted to 1x10 -4 torr, hot-pressing sintering is performed, and after the furnace is cooled, the corrosion-resistant aluminum oxide ceramic is obtained; wherein the sintering pressure of the hot-pressing sintering is 51 MPa, and the sintering process is as follows: first, it is warmed to 205℃ at a rate of 6℃ / min, then warmed to 665℃ at a rate of 22℃ / min, warmed to 765℃ at a rate of 3℃ / min, then warmed to 1300℃ at a rate of 20℃ / min, and calcined for 13 h.

[0063] The preparation steps of the aluminum dihydrogen phosphate are as follows: 85% phosphoric acid is diluted with pure water to obtain a 60% phosphoric acid solution, the solution is heated to 82℃ by oil bath to obtain a hot phosphoric acid solution; aluminum hydroxide is dispersed in 10 times its mass of pure water, then added to the hot phosphoric acid solution at a rate of 1 drop / s, and stirred at a speed of 1200 rpm until it gradually becomes clear, to obtain aluminum dihydrogen phosphate; wherein the molar ratio of phosphoric acid to aluminum hydroxide is 3.3:1.

[0064] The preparation steps of the functionalized graphene are as follows: 1M sodium hydroxide solution is added to the graphene oxide solution with a concentration of 1mg / mL to adjust the pH to 10, then 3 times the mass of the graphene oxide of hydrazine hydrate and 5 times the mass of the graphene oxide of titanate coupling agent 311W are added, and after 7h of reaction at 90℃, hot filtration is performed, and repeated washing with deionized water is performed until the filtrate is neutral to obtain functional graphene.

[0065] (Comparative Example 1)

[0066] The difference between Comparative Example 1 and Example 2 is that the raw material components of the corrosion-resistant alumina ceramic include, by mass fraction: 80 parts of alumina, 30 parts of titanium carbide, 0.9 parts of graphene, 0.0916 parts of aluminum powder, 5 parts of binder aluminum dihydrogen phosphate, 1.6 parts of zinc oxide, 4 parts of magnesium oxide; the remaining steps and components are the same as those of Example 2.

[0067] (Comparative Example 2)

[0068] The difference between Comparative Example 2 and Example 2 is that the raw material components of the corrosion-resistant alumina ceramic include, by mass fraction: 80 parts of alumina, 30 parts of titanium carbide, 0.9 parts of functionalized graphene, 5 parts of binder aluminum dihydrogen phosphate, 1.6 parts of zinc oxide, 4 parts of magnesium oxide, and the remaining steps and components are the same as those of Example 2.

[0069] (Comparative Example 3)

[0070] The difference between Comparative Example 3 and Example 2 is that the raw material components of the corrosion-resistant alumina ceramic include, by mass fraction: 80 parts of alumina, 30 parts of titanium carbide, 0.9 parts of functionalized graphene, 0.0916 parts of aluminum powder, 5 parts of binder aluminum dihydrogen phosphate, 5.6 parts of magnesium oxide, and the remaining steps and components are the same as those of Example 2.

[0071] (Comparative Example 4)

[0072] The difference between Comparative Example 4 and Example 2 is that the raw material components of the corrosion-resistant alumina ceramic include, by mass fraction: 80 parts of alumina, 30 parts of titanium carbide, 0.9 parts of functionalized graphene, 0.0916 parts of aluminum powder, 5 parts of binder aluminum dihydrogen phosphate, 5.6 parts of zinc oxide, and the remaining steps and components are the same as those of Example 2.

[0073] (Comparative Example 5)

[0074] The difference between Comparative Example 5 and Example 2 is that the corrosion-resistant alumina ceramic is prepared by directly ball milling and hot pressing sintering of alumina, titanium carbide, functionalized graphene, aluminum powder, binder aluminum dihydrogen phosphate, zinc oxide, and magnesium oxide, and the remaining steps and components are the same as those of Example 2.

[0075] (Effect Example)

[0076] Corrosion resistance: The corrosion-resistant alumina ceramics prepared from Examples 1-3 and Comparative Examples 1-5 were made into 10 cm*10 cm*2 cm samples, washed with clean water, drained, and the mass m1 of the samples was recorded. Then the samples were immersed in seawater for 90 days, taken out, washed with clean water, drained, and the mass m2 of the samples was recorded again. The mass loss rate was calculated as (m1-m2)*100% / m1.

[0077] Wear resistance: The friction and wear properties of the corrosion-resistant alumina ceramics prepared from Examples 1-3 and Comparative Examples 1-5 were detected using a MDW-02 type friction and wear tester, with a load of 30 N, a test time of 40 min under load, and a zirconia ball as the friction pair. The samples before and after the test were weighed using an electronic balance with a precision of 10-6, and the wear rate was calculated.

[0078] Flexural strength: The flexural strength of the corrosion-resistant alumina ceramics prepared from Examples 1-3 and Comparative Examples 1-5 was tested according to GB / T5593-2015.

[0079] Self-healing ability: The corrosion-resistant alumina ceramics prepared from Examples 1-3 and Comparative Examples 1-5 were polished to have no obvious scratches, and a 0.2 mm*1.5 mm notch was pre-prepared in the middle. A universal testing machine was used to load at a rate of 0.05 mm / min until the crack occurred, and then the load was reduced to 80% of the maximum value. The change in bending strength after heat treatment at 1200°C in air for 60 min showed that the crack reduced the toughness of the composite. The bending strength after 0 min and 60 min of heat treatment was tested according to GB / T6569-2006.

[0080] Table 1 below shows the performance test results of the corrosion-resistant alumina ceramics prepared from Examples 1-3 and Comparative Examples 1-5:

[0081] Table 1

[0082]

[0083] As shown in Table 1 above, the corrosion-resistant alumina ceramics prepared from Examples 1-3 have good flexural strength, wear resistance, corrosion resistance, and self-healing ability.

[0084] The difference between Comparative Example 1 and Example 2 is that ordinary graphene is used instead of functionalized graphene. The corrosion-resistant alumina ceramics prepared from Examples 1-3 have better flexural strength, wear resistance, corrosion resistance, and self-healing ability than those prepared from Comparative Example 1.

[0085] The difference between Comparative Example 2 and Example 2 is that the corrosion-resistant alumina ceramic does not add aluminum powder, and the corrosion-resistant alumina ceramic prepared in Examples 1-3 has better bending strength, wear resistance, corrosion resistance and self-healing property than that prepared in Comparative Example 2.

[0086] The difference between Comparative Example 3 and Example 2 is that the corrosion-resistant alumina ceramic does not add zinc oxide, and the corrosion-resistant alumina ceramic prepared in Examples 1-3 has better bending strength, wear resistance, corrosion resistance than that prepared in Comparative Example 2.

[0087] The difference between Comparative Example 4 and Example 2 is that the corrosion-resistant alumina ceramic does not add magnesium oxide; and the corrosion-resistant alumina ceramic prepared in Examples 1-3 has better bending strength, wear resistance, corrosion resistance than that prepared in Comparative Example 2.

[0088] The difference between Comparative Example 5 and Example 2 is that the corrosion-resistant alumina ceramic is directly prepared by ball milling and hot-pressing sintering of alumina, titanium carbide, functionalized graphene, aluminum powder, binder aluminum dihydrogen phosphate, zinc oxide and magnesium oxide, and the corrosion-resistant alumina ceramic prepared has better bending strength, wear resistance, corrosion resistance and better self-healing property.

[0089] The above specific examples further illustrate the purpose, technical solutions and advantages of the present application. It should be understood that the above description is only a specific embodiment of the present application and is not intended to limit the present application. Any modification, equivalent replacement, improvement, etc. within the spirit and principles of the present application should be included in the protection scope of the present application.

Claims

1. A method for preparing corrosion-resistant alumina ceramic, characterized in that, The preparation steps include the following: (1) Weigh and mix each raw material component according to the corresponding mass parts; by mass parts, the raw material components include 75~85 parts alumina, 25~35 parts titanium carbide, 0.85~0.95 parts functionalized graphene, 0.091~0.092 parts aluminum powder, 4~6 parts aluminum dihydrogen phosphate binder, 1.4~1.8 parts zinc oxide, and 3.9~4.1 parts magnesium oxide; (2) Mixture A: Heat the aluminum dihydrogen phosphate binder weighed in step (1) to 78~82℃, then add 0.25~0.38 parts by mass of magnesium oxide and stir for 55~65min. Then continue to heat to 108~112℃, cool down to 80℃ and add 1.02~1.54 parts by mass of zinc oxide and continue to stir for 55~65min. Then continue to add the remaining magnesium oxide and zinc oxide and continue to stir for 55~65min to obtain mixture A; (3) Mixture B: Put the weighed titanium carbide, functionalized graphene, and aluminum powder from step (1) into a ball mill, then add cyclohexane to completely submerge the titanium carbide, functionalized graphene, aluminum powder, and grinding balls in the ball mill, and then ball mill for 49~51h. After ball milling, vacuum dry and sieve to obtain mixture B. (4) Place alumina, mixture A, and deionized water into a ball mill and ball mill for 71-73 hours. Dry the mixture, then add mixture B and dry-mix and ball mill for 23-25 ​​hours. Place the mixture into a graphite mold, then place the graphite mold into a hot press furnace and wait for the vacuum degree to reach 1×10⁻⁶. -4 During the torr process, hot pressing and sintering are carried out, and after cooling in the furnace, corrosion-resistant alumina ceramics are obtained. The preparation steps of the functionalized graphene are as follows: 1M sodium hydroxide solution is added to a graphene oxide solution with a concentration of 1mg / mL to adjust the pH to 9-10. Then, 1-3 times the mass of hydrazine hydrate and 5-7 times the mass of titanate coupling agent are added. After reacting at 80-90℃ for 7-8h, the mixture is filtered while hot and repeatedly washed with deionized water until the filtrate is neutral to obtain the functionalized graphene.

2. The method for preparing corrosion-resistant alumina ceramic according to claim 1, characterized in that, The titanate coupling agents include titanate coupling agent 311W and titanate coupling agent TM-200S.

3. The method for preparing corrosion-resistant alumina ceramic according to claim 1, characterized in that, The preparation steps of aluminum dihydrogen phosphate are as follows: 85% phosphoric acid is diluted with pure water to make a 60% phosphoric acid solution, and heated in an oil bath to 78~82℃ to obtain a hot phosphoric acid solution; aluminum hydroxide is dispersed in 10 times its mass of pure water, and then added to the hot phosphoric acid solution at a rate of 1 drop / s, and stirred at a rate of 800~1200 rpm until it gradually becomes clear to obtain aluminum dihydrogen phosphate.

4. The method for preparing corrosion-resistant alumina ceramic according to claim 3, characterized in that, The molar ratio of phosphoric acid to aluminum hydroxide is 3.1~3.3:

1.

5. The method for preparing corrosion-resistant alumina ceramic according to claim 1, characterized in that, The ball mill jar and grinding balls in step (3) are made of alumina. The maximum diameter of the grinding balls is 10mm and the minimum diameter is 3mm. The ball-to-material ratio is 8:

1. The ball mill speed is 300r / min. During ball milling, the mill stops for 0.2h every 0.5h and runs in both forward and reverse directions alternately.

6. The method for preparing corrosion-resistant alumina ceramic according to claim 1, characterized in that, The grinding balls in step (4) are zirconia balls, and the ratio of the mass of the zirconia balls, the mass of deionized water, the mass of alumina and the mass of mixture A is 2:2:

1.

7. The method for preparing corrosion-resistant alumina ceramic according to claim 1, characterized in that, The sintering pressure of the hot pressing sintering is 49~51MPa, and the sintering process is as follows: first, the temperature is raised to 195~205℃ at 4~6℃ / min, then raised to 655~665℃ at 18~22℃ / min, then raised to 755~765℃ at 1~3℃ / min, and then calcined at 1200~1300℃ at 20℃ / min for 11~13h to obtain corrosion-resistant alumina ceramic.

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