A method for preparing high performance ceramic material

Abstract

The invention relates to the field of ceramic materials, and in particular to a method for preparing a high-performance ceramic material. Ethanol and alkali solution are mixed and stirred uniformly, and then vinyl siloxane and mercapto siloxane are added, and stirring is continued for 30-60 minutes to obtain a solution. The solution is mixed and stirred uniformly with ceramic powder, reinforcing fiber and a free radical initiator, and then injected into a mold. The mold is heated or exposed to light for reaction for 8-24 hours and then demoulded to obtain a green body. The green body is heated to 1000-1200°C in an inert atmosphere and sintered for 1-4 hours. The high-performance ceramic material prepared by the invention has both high porosity and certain mechanical properties.

Description

Technical Field

[0001] The invention relates to the field of ceramic materials, and in particular to a method for preparing a high-performance ceramic material. Background Art

[0002] As a new method for ceramic manufacturing, the preparation of ceramic materials by pyrolysis conversion of precursors has attracted much attention since its introduction because of its characteristics that are significantly different from traditional powder metallurgy processes. This approach to preparing ceramics through organic→inorganic, amorphous→crystallization transformation can regulate the composition and structure of the ceramic products through the molecular structure design of the precursor and the conversion conditions. It can achieve the preparation of ceramic materials with composition, phase structure, and function that are difficult to obtain by traditional powder metallurgy processes, and has the advantage of being able to be formed at lower temperatures and without pressure. However, it is currently difficult for ceramic materials prepared by pyrolysis conversion of precursors to have both mechanical properties and porosity, which limits their application. Summary of the invention

[0003] Purpose of the invention: In view of the above technical problems, the present invention proposes a method for preparing a high-performance ceramic material.

[0004] The technical solutions adopted are as follows:

[0005] A method for preparing high performance ceramic material:

[0006] After mixing and stirring ethanol and alkali solution evenly, vinyl siloxane and mercapto siloxane are added, and stirring is continued for 30-60 minutes to obtain a solution. The solution is mixed and stirred with ceramic powder, reinforcing fiber and free radical initiator, and then injected into a mold. The mold is heated or exposed to light for reaction for 8-24 hours, and then demolded to obtain a green body. The green body is heated to 1000-1200°C in an inert atmosphere and sintered for 1-4 hours.

[0007] Furthermore, the alkali solution is any one of ammonia water, sodium hydroxide solution or potassium hydroxide solution.

[0008] Furthermore, the weight ratio of the vinyl siloxane to the mercapto siloxane is 1-5:1-5.

[0009] Furthermore, the vinyl siloxane is any one or more combinations of vinyl trimethoxy silane, vinyl triethoxy silane, and vinyl tri(β-methoxyethoxy) silane.

[0010] Furthermore, the mercaptosiloxane is γ-mercaptopropyltrimethoxysilane and / or γ-mercaptopropyltriethoxysilane.

[0011] Furthermore, the ceramic powder includes aluminum oxide, yttrium oxide and magnesium oxide, and the weight ratio of aluminum oxide, yttrium oxide and magnesium oxide is 8-10:0.1-1:0.1-1.

[0012] Furthermore, the reinforcing fiber is lanthanum zirconate coated zirconia fiber.

[0013] Furthermore, the preparation method of the lanthanum zirconate coated zirconia fiber is as follows:

[0014] The zirconium oxide fiber is placed in a tubular furnace and heated to 800-1100°C in an inert atmosphere. Tri(2,2,6,6-tetramethyl-3,5-heptanedione)lanthanum and tri(2,2,6,6-tetramethyl-3,5-heptanedione)zirconium are used as precursors. Oxygen is introduced into the tubular furnace as a reaction gas, and an inert gas is used as a carrier gas for the precursor. The pressure is 500-1000 Pa, and the deposition time is 3-5 hours.

[0015] Furthermore, the free radical initiator is any one or more combinations of benzoyl peroxide, azobisisobutyronitrile, and benzoin dimethyl ether.

[0016] Furthermore, the weight ratio of the sum of the weight of vinyl siloxane and mercapto siloxane to the weight of the ceramic powder and the reinforcing fiber is 1-2:1-2:0.05-0.2.

[0017] Beneficial effects of the present invention:

[0018] The invention provides a preparation method of a high-performance ceramic material. After vinyl siloxane and mercapto siloxane are hydrolyzed and self-polymerized, vinyl and mercapto groups react and cross-link with each other. The formed polymer has a density close to that of ceramics and can be fully mixed and coated with ceramic powder and reinforcing fibers. It is cracked during sintering in an inert atmosphere to generate free carbon, which plays an important role in the formation of the physical and chemical properties of ceramics. It can not only reduce cracks and defects of ceramics, but also improve its mechanical strength. Although zirconia fiber can improve the mechanical strength of ceramics, due to its poor bonding performance with ceramic powder and the difference in elastic modulus between the two, unevenly distributed defects will be generated in the transition zone. After lanthanum zirconate coating, the generation of defects can be reduced, and the dispersion and bonding performance of zirconia fiber in ceramics can be improved. This may be because the addition of lanthanum zirconate promotes sintering densification, so that more grains are generated on the fiber. After testing, the high-performance ceramic material prepared by the invention has both a higher porosity and maintains certain mechanical properties. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is a SEM image of the alumina ceramic prepared in Example 1 of the present invention. DETAILED DESCRIPTION

[0020] If the specific conditions are not specified in the examples, the experiments were carried out under conventional conditions or the conditions recommended by the manufacturer. If the manufacturer of the reagents or instruments is not specified, they are all conventional products that can be purchased commercially. The techniques not mentioned in the present invention are all referenced to the prior art. Unless otherwise specified, the following examples and comparative examples are parallel experiments, using the same processing steps and parameters.

[0021] Embodiment 1:

[0022] A method for preparing high performance ceramic material:

[0023] 500 mL of ethanol and 40 mL of 0.1 M sodium hydroxide solution were mixed and stirred for 30 min, and then 95 g of vinyl triethoxysilane and 98 g of γ-mercaptopropyl trimethoxysilane were added, and stirring was continued for 30 min to obtain a solution. Alumina, yttrium oxide and magnesium oxide with a weight ratio of 10:0.5:0.5 were added to a planetary ball mill and ball milled for 5 h and then dried to obtain a ceramic powder. 20 g of zirconia fiber was placed in a tube furnace and heated to 1000 ° C under an argon atmosphere. Tris(2,2,6,6-tetramethyl-3,5-heptanedione)lanthanum and tris(2,2,6,6-tetramethyl-3,5-heptanedione)zirconium with a molar ratio of 1:1 were used. Precursor, oxygen is introduced into the tubular furnace as a reaction gas with a flow rate of 160 mL / min, and argon is used as a carrier gas for the precursor with a flow rate of 50 mL / min. It is introduced into the interior of the tubular furnace cavity through different pipelines from a gas nozzle. The deposition pressure is 800 Pa and the deposition time is 5 h to obtain lanthanum zirconate-coated zirconia fiber. The above solution is mixed with 193 g of ceramic powder, 10 g of lanthanum zirconate-coated zirconia fiber and 0.5 g of benzoyl peroxide and stirred for 30 min, and then injected into a mold. The mold is heated to 100 ° C and reacted for 10 h before demolding to obtain a green body. The green body is heated to 1100 ° C at a rate of 20 ° C / min in an argon atmosphere and sintered for 2 h.

[0024] Embodiment 2:

[0025] A method for preparing high performance ceramic material:

[0026] 500 mL of ethanol and 40 mL of 0.1 M sodium hydroxide solution were mixed and stirred for 30 min, and then 95 g of vinyl triethoxysilane and 98 g of γ-mercaptopropyl trimethoxysilane were added, and stirring was continued for 60 min to obtain a solution. Alumina, yttrium oxide and magnesium oxide with a weight ratio of 10:1:1 were added to a planetary ball mill and ball milled for 5 h and then dried to obtain a ceramic powder. 20 g of zirconia fiber was placed in a tube furnace and heated to 1100 ° C under an argon atmosphere. Tris(2,2,6,6-tetramethyl-3,5-heptanedione)lanthanum and tris(2,2,6,6-tetramethyl-3,5-heptanedione)zirconium with a molar ratio of 1:1 were used as precursors. , oxygen was introduced into the tubular furnace as a reaction gas with a flow rate of 160 mL / min, and argon was used as a carrier gas for the precursor with a flow rate of 50 mL / min. It was introduced into the tubular furnace cavity through different pipelines from a gas nozzle. The deposition pressure was 1000 Pa and the deposition time was 5 h to obtain lanthanum zirconate-coated zirconia fiber. The above solution was mixed with 193 g of ceramic powder, 10 g of lanthanum zirconate-coated zirconia fiber and 0.5 g of azobisisobutyronitrile and stirred for 30 min, and then injected into a mold. The mold was heated to 100 ° C and reacted for 10 h before demolding to obtain a green body. The green body was heated to 1200 ° C at a rate of 20 ° C / min in an argon atmosphere and sintered for 2 h.

[0027] Embodiment 3:

[0028] A method for preparing high performance ceramic material:

[0029] 500 mL of ethanol and 40 mL of 0.1 M sodium hydroxide solution were mixed and stirred for 30 min, and then 95 g of vinyl triethoxysilane and 98 g of γ-mercaptopropyl trimethoxysilane were added, and stirring was continued for 30 min to obtain a solution. Alumina, yttrium oxide and magnesium oxide with a weight ratio of 8:0.5:0.5 were added to a planetary ball mill and ball milled for 5 h and then dried to obtain a ceramic powder. 20 g of zirconia fiber was placed in a tube furnace and heated to 1100 ° C under an argon atmosphere. Tris(2,2,6,6-tetramethyl-3,5-heptanedione)lanthanum and tris(2 ,2,6,6-tetramethyl-3,5-heptanedione) zirconium as a precursor, oxygen as a reaction gas is introduced into the tubular furnace at a flow rate of 160mL / min, argon is used as a carrier gas for the precursor at a flow rate of 50mL / min, and is introduced into the tubular furnace cavity through different pipelines from a gas nozzle. The deposition pressure is 500Pa and the deposition time is 5h to obtain lanthanum zirconate-coated zirconia fiber. The above solution is mixed with 193g of ceramic powder, 10g of lanthanum zirconate-coated zirconia fiber and 0.5g of benzoin dimethyl ether and stirred for 30min, then injected into a mold and heated at room temperature with an intensity of 400mW / cm 2The mold was irradiated with ultraviolet light for 24 hours and then demolded to obtain a green body. The distance between the ultraviolet light source and the mold was 5 cm. The green body was heated to 1200° C. at a rate of 20° C. / min in an argon atmosphere and sintered for 4 hours.

[0030] Comparative Example 1:

[0031] The method is substantially the same as Example 1, except that vinyltriethoxysilane is replaced by γ-mercaptopropyltrimethoxysilane of the same weight.

[0032] Comparative Example 2:

[0033] The method is substantially the same as Example 1, except that γ-mercaptopropyltrimethoxysilane is replaced by the same weight of vinyltriethoxysilane.

[0034] Comparative Example 3:

[0035] The method is basically the same as Example 1, except that lanthanum zirconate-coated zirconia fibers are not added.

[0036] Comparative Example 4:

[0037] It is basically the same as Example 1, except that the zirconium oxide fiber is directly added without being coated with lanthanum zirconate.

[0038] Performance Test:

[0039] The high performance ceramic materials prepared in Examples 1-3 and Comparative Examples 1-4 of the present invention are used as samples;

[0040] The porosity of the samples was measured using the Archimedes method;

[0041] The three-point bending method was used to test the bending strength of the specimen, with a span of 20 mm and a pressing rate of 0.5 mm / min.

[0042] The test results are shown in Table 1 below:

[0043] Table 1:

[0044]

[0045] It can be seen from Table 1 above that the high-performance ceramic material prepared by the present invention has both a relatively high porosity and maintains certain mechanical properties.

[0046] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing a high performance ceramic material, characterized in that: After mixing and stirring ethanol and alkali solution evenly, vinyl siloxane and mercapto siloxane are added, and stirring is continued for 30-60 minutes to obtain a solution, and the solution is mixed and stirred with ceramic powder, reinforcing fiber and free radical initiator evenly, and then injected into a mold, and the mold is heated or exposed to light for reaction for 8-24 hours, and then demolded to obtain a green body, and the green body is heated to 1000-1200° C. and sintered for 1-4 hours in an inert atmosphere; The weight ratio of the vinyl siloxane to the mercapto siloxane is 1-5:1-5; The vinyl siloxane is any one or more combinations of vinyl trimethoxy silane, vinyl triethoxy silane, and vinyl tri(β-methoxyethoxy) silane; The mercaptosiloxane is γ-mercaptopropyltrimethoxysilane and / or γ-mercaptopropyltriethoxysilane; The ceramic powder comprises aluminum oxide, yttrium oxide and magnesium oxide, and the weight ratio of aluminum oxide, yttrium oxide and magnesium oxide is 8-10: 0.1-1：0.1-1； The reinforcing fiber is lanthanum zirconate coated zirconium oxide fiber; The preparation method of the lanthanum zirconate-coated zirconia fiber is as follows: placing the zirconia fiber in a tube furnace, heating it to 800-1100° C. in an inert atmosphere, using tri(2,2,6,6-tetramethyl-3,5-heptanedione) lanthanum and tri(2,2,6,6-tetramethyl-3,5-heptanedione) zirconium as precursors, introducing oxygen into the tube furnace as a reaction gas, using an inert gas as a carrier gas for the precursor, the pressure is 500-1000 Pa, and the deposition time is 3-5 hours; The weight ratio of the sum of the weight of vinyl siloxane and mercapto siloxane to the weight of ceramic powder and reinforcing fiber is 1-2:1-2:0.05-0.

2.

2. The method for preparing a high performance ceramic material according to claim 1, characterized in that: The alkali solution is any one of ammonia water, sodium hydroxide solution or potassium hydroxide solution.

3. The method for preparing a high performance ceramic material according to claim 1, characterized in that: The free radical initiator is any one or more combinations of benzoyl peroxide, azobisisobutyronitrile, and benzoin dimethyl ether.

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