A method for preparing a highly wear-resistant water-sealing ceramic sheet

Abstract

The invention relates to the field of ceramic materials, and in particular to a method for preparing a high-wear-resistant water-sealing ceramic sheet. Alumina, lanthanum titanate pre-coated precursor fibers and a sintering aid are mixed and ball-milled, and then dried to obtain a mixed powder. The mixed powder is mixed with a binder to form granules, and then pressed into a blank. The obtained blank is transferred to a pressure sintering furnace, and the temperature is firstly increased to 600-800°C and kept for 1-3 hours, and then nitrogen is introduced and the pressure is increased to 1-5MPa. The temperature is secondarily increased to 1400-1500°C and kept for 1-3 hours, and then the pressure is restored to normal pressure and the blank is cooled to room temperature with the furnace. The high-wear-resistant water-sealing ceramic sheet prepared by the invention has excellent comprehensive performance and can meet various use requirements.

Description

Technical Field

[0001] The invention relates to the field of ceramic materials, in particular to a method for preparing a highly wear-resistant water-sealing ceramic sheet. Background Art

[0002] Water seal is a sealing component commonly used in kitchen and bathroom sanitary ware and plumbing equipment. Its main materials are rubber, metal and ceramic. Rubber water seal is easy to use and process, but has poor sealing performance and is easily affected by high temperature, pressure, corrosion and other factors. Metal water seal is suitable for high temperature and high pressure fluid media and has good sealing performance, but is not corrosion-resistant and has poor wear resistance. Ceramic water seal has high wear resistance, heat resistance, corrosion resistance and other characteristics, and is suitable for most acid and alkali solutions, high temperature solutions and other media. How to further improve the performance of ceramic water seal to expand its application prospects is currently a research hotspot for scientific researchers. 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 highly wear-resistant water-sealing ceramic sheet.

[0004] The technical solutions adopted are as follows:

[0005] A method for preparing a highly wear-resistant water-sealing ceramic sheet is as follows:

[0006] Alumina, lanthanum titanate pre-coated precursor fibers and sintering aids are mixed and ball-milled and then dried to obtain a mixed powder, the mixed powder is mixed with a binder to form granules, and then pressed into a green body, the green body obtained is transferred to a pressure sintering furnace, the temperature is first raised to 600-800°C and kept for 1-3 hours, then nitrogen is introduced and the pressure is increased to 1-5MPa, the temperature is secondly raised to 1400-1500°C and kept for 1-3 hours, then the pressure is restored to normal and the green body is cooled to room temperature with the furnace.

[0007] Furthermore, the weight ratio of the alumina, lanthanum titanate pre-coated precursor fiber and the sintering aid is 8-10:1-3:0.1-1.

[0008] Furthermore, the preparation method of the lanthanum titanate pre-coated precursor fiber is as follows:

[0009] Add soluble lanthanum salt and titanium sulfate to the precursor fiber dispersion, then add the precipitant, stir for 1-5 hours, seal and perform hydrothermal reaction, collect the precipitate, wash and dry.

[0010] Furthermore, the precursor fiber is pre-oxidized polyacrylonitrile fiber.

[0011] Furthermore, the precipitant is any one or more combinations of sodium hydroxide solution, potassium hydroxide solution or ammonia water.

[0012] Furthermore, the hydrothermal reaction temperature is 200-250°C and the time is 12-36h.

[0013] Furthermore, the sintering aid includes any one or more combinations of silicon dioxide, titanium dioxide, magnesium oxide, calcium oxide, yttrium oxide, and cerium oxide.

[0014] Furthermore, the binder is a polyvinyl alcohol solution and / or a polyvinyl butyral solution.

[0015] Furthermore, the pressure during pressing into the blank is 100-200 MPa.

[0016] Furthermore, the first stage heating rate is 10-50°C / min, and the second stage heating rate is 0.1-1°C / min.

[0017] Beneficial effects of the present invention:

[0018] The present invention provides a method for preparing a highly wear-resistant water-sealed ceramic sheet. Currently, there are many studies on using carbon fiber to toughen ceramics and improve wear resistance. However, during ball milling, carbon fiber and ceramic powder will be bent or hit by grinding balls, resulting in defects in the carbon fiber, causing physical damage, and affecting the toughening and wear resistance of the carbon fiber. In the present invention, the precursor fiber can be converted into carbon fiber during high-temperature sintering of the ceramic, which has a toughening and wear resistance effect. In addition, lanthanum titanate is used to pre-coat the precursor fiber, which can prevent the precursor fiber from being damaged and broken during ball milling and improve its dispersion performance. On the other hand, lanthanum titanate has a perovskite structure and has a certain catalytic effect on the high-temperature cracking of the precursor fiber. The in-situ generated carbon fibers can reduce the crack propagation energy by sharing external loads, blocking crack propagation, increasing crack propagation paths, etc., thereby improving the ability of the ceramic matrix to resist crack propagation and the fracture toughness. In addition, due to the high thermal conductivity and low friction coefficient of carbon fibers, the heat generated by friction is more evenly dispersed, and the degree of friction and wear is correspondingly reduced, thereby improving the wear resistance of the ceramic matrix. The high wear-resistant water-sealing ceramic sheet prepared by the present invention has excellent comprehensive performance and can meet various usage requirements. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is a cross-sectional morphology of the highly wear-resistant water seal ceramic sheet prepared in Example 1. 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 a highly wear-resistant water-sealing ceramic sheet:

[0023] 10g of commercially available pre-oxidized polyacrylonitrile fiber was crushed and added to 500ml of deionized water, and then 0.5g of dispersant SDS was added. After ultrasonic oscillation for 30min, a dispersion was obtained. Then 3.25g of lanthanum nitrate and 2.4g of titanium sulfate were added respectively. After stirring for 30min, 0.1mol / L sodium hydroxide solution was added dropwise until the pH of the system reached 10. After stirring for 5h, the mixture was transferred to a hydrothermal reactor and sealed and heated to 240℃ for hydrothermal reaction for 24h. After the reaction was completed, the precipitate was filtered and collected, washed thoroughly with deionized water, and then dried to obtain lanthanum titanate pre-coated polyacrylonitrile fiber. The oxidized polyacrylonitrile fiber with a weight ratio of 9:1:0.5 was added. Aluminum, lanthanum titanate pre-coated polyacrylonitrile fiber and cerium oxide are added to a planetary ball mill, mixed and ball-milled for 5 hours with deionized water as the ball-milling medium, and then dried to obtain a mixed powder, a polyvinyl alcohol solution with a mass concentration of 8% is mixed with the mixed powder to form granules, the sieved granules are added to a mold, and pressed into a billet under a pressure of 150 MPa, and the obtained billet is transferred to a pressure sintering furnace, first heated to 650°C at a speed of 15°C / min and kept for 2 hours, then nitrogen is introduced and pressurized to 2.5 MPa, and then heated to 1450°C at a speed of 0.5°C / min in a second stage and kept for 2 hours, then restored to normal pressure and cooled to room temperature with the furnace.

[0024] Embodiment 2:

[0025] A method for preparing a highly wear-resistant water-sealing ceramic sheet:

[0026] 10g of commercially available pre-oxidized polyacrylonitrile fiber was crushed and added to 500ml of deionized water, and then 0.5g of dispersant SDS was added. After ultrasonic oscillation for 30min, a dispersion was obtained. Then 3.25g of lanthanum nitrate and 2.4g of titanium sulfate were added respectively. After stirring for 30min, 0.1mol / L sodium hydroxide solution was added dropwise until the pH of the system reached 10. After stirring for 5h, the mixture was transferred to a hydrothermal reactor and sealed and heated to 240℃ for hydrothermal reaction for 24h. After the reaction was completed, the precipitate was filtered and collected, washed thoroughly with deionized water, and then dried to obtain lanthanum titanate pre-coated polyacrylonitrile fiber. Alumina with a weight ratio of 10:3:1 was added. , lanthanum titanate pre-coated polyacrylonitrile fiber and cerium oxide are added to a planetary ball mill, mixed and ball-milled with deionized water as the ball-milling medium for 5 hours and then dried to obtain a mixed powder, a polyvinyl alcohol solution with a mass concentration of 8% is mixed with the mixed powder to form granules, the sieved granules are added to a mold, and pressed into a billet under a pressure of 150 MPa, and the resulting billet is transferred to a pressure sintering furnace, first heated to 650°C at a rate of 15°C / min and kept warm for 2 hours, then nitrogen is introduced and pressurized to 2.5 MPa, and then heated to 1450°C in a second stage at a rate of 0.5°C / min and kept warm for 2 hours, then restored to normal pressure and cooled to room temperature with the furnace.

[0027] Embodiment 3:

[0028] A method for preparing a highly wear-resistant water-sealing ceramic sheet:

[0029] 10g of commercially available pre-oxidized polyacrylonitrile fiber was crushed and added to 500ml of deionized water, and then 0.5g of dispersant SDS was added. After ultrasonic oscillation for 30min, a dispersion was obtained. Then 3.25g of lanthanum nitrate and 2.4g of titanium sulfate were added respectively. After stirring for 30min, 0.1mol / L sodium hydroxide solution was added dropwise until the pH of the system reached 10. After stirring for 5h, the mixture was transferred to a hydrothermal reactor and sealed and heated to 240℃ for hydrothermal reaction for 24h. After the reaction was completed, the precipitate was filtered and collected, washed thoroughly with deionized water, and then dried to obtain lanthanum titanate pre-coated polyacrylonitrile fiber. The oxidized polyacrylonitrile fiber with a weight ratio of 8:1:0.1 was added. Aluminum, lanthanum titanate pre-coated polyacrylonitrile fiber and cerium oxide are added to a planetary ball mill, mixed and ball-milled for 5 hours with deionized water as the ball-milling medium, and then dried to obtain a mixed powder, a polyvinyl alcohol solution with a mass concentration of 8% is mixed with the mixed powder to form granules, the sieved granules are added to a mold, and pressed into a billet under a pressure of 150 MPa, and the obtained billet is transferred to a pressure sintering furnace, first heated to 650°C at a speed of 15°C / min and kept for 2 hours, then nitrogen is introduced and pressurized to 2.5 MPa, and then heated to 1450°C at a speed of 0.5°C / min in a second stage and kept for 2 hours, then restored to normal pressure and cooled to room temperature with the furnace.

[0030] Comparative Example 1:

[0031] The method is basically the same as Example 1, except that lanthanum titanate pre-coated polyacrylonitrile fiber is not added.

[0032] Comparative Example 2:

[0033] The method is basically the same as Example 1, except that the pre-oxidized polyacrylonitrile fiber is directly added without being pre-coated with lanthanum titanate.

[0034] Comparative Example 3:

[0035] The method is basically the same as Comparative Example 2, except that commercially available carbon fiber is used instead of pre-oxidized polyacrylonitrile fiber.

[0036] Comparative Example 4:

[0037] It is basically the same as Example 1, except that lanthanum titanate and pre-oxidized polyacrylonitrile fiber are added separately without coating treatment.

[0038] Comparative Example 5:

[0039] It is basically the same as Example 1, except that cerium oxide is not added.

[0040] Comparative Example 6:

[0041] The method is basically the same as Example 1, except that the sintering is performed under normal pressure in an air atmosphere in a common sintering furnace.

[0042] Performance Testing:

[0043] Prepare samples and perform performance tests according to the methods in Examples 1-3 and Comparative Examples 1-6 of the present invention;

[0044] The fracture toughness of the sample was tested on a universal testing machine using the single-sided notched beam method. The sample size was 4×6×30mm and the span was 24mm. The sample surface was ground and polished before testing, and all edges were chamfered at 45°. An internal circular cutting machine was used to prefabricate a crack in the middle of the sample. The crack depth was less than half of the sample height (i.e. <3mm) and the width was less than 0.2mm. The sample was loaded using the three-point bending method, and the indenter moving rate was 0.05mm / min. The fracture toughness of the sample was calculated based on the applied load when the sample broke and the crack depth accurately measured by a vernier caliper and a reading microscope (with an accuracy of 0.01mm).

[0045] The dry friction and wear test was carried out on the sample at room temperature using a ring friction tester. The friction ring was a 12% Co-WC carbide grinding ring, the sample size was 10×15×10mm, the load was 200N, the friction and wear test was carried out at a speed of 480r / min, the wear time was 20min, and the sample before and after wear was weighed using an electronic balance with a measurement accuracy of 0.0001g. The volume wear rate of the sample was used to represent the wear resistance of the material. The volume wear rate calculation formula is shown as follows:

[0046]

[0047] Where W is the volume wear rate, m1 is the mass of the sample before wear, m2 is the mass of the sample after wear, ρ is the density of the sample, and t is the wear time;

[0048] The test results are shown in Table 1 below:

[0049] Table 1:

[0050]

[0051]

[0052] It can be seen from Table 1 above that the highly wear-resistant water-sealing ceramic sheet prepared by the present invention has excellent comprehensive performance and can meet various usage requirements.

[0053] 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 highly wear-resistant water-sealing ceramic sheet, characterized in that: The details are as follows: Alumina, lanthanum titanate pre-coated precursor fibers and sintering aids are mixed and ball-milled and then dried to obtain a mixed powder, the mixed powder is mixed with a binder to form granules, and then pressed into a green body, the green body is transferred to a pressure sintering furnace, the temperature is first raised to 600-800°C and kept for 1-3 hours, then nitrogen is introduced and the pressure is increased to 1-5MPa, the temperature is secondly raised to 1400-1500°C and kept for 1-3 hours, then the pressure is restored to normal and the green body is cooled to room temperature with the furnace; The weight ratio of the alumina, lanthanum titanate pre-coated precursor fiber and the sintering aid is 8-10:1-3:0.1-1; The preparation method of the lanthanum titanate pre-coated precursor fiber is as follows: Add soluble lanthanum salt and titanium sulfate to the precursor fiber dispersion, then add the precipitant, stir for 1-5 hours, seal and perform hydrothermal reaction, collect the precipitate, wash and dry it; The precursor fiber is pre-oxidized polyacrylonitrile fiber.

2. The method for preparing a highly wear-resistant water-sealing ceramic sheet according to claim 1, characterized in that: The precipitant is any one or more combinations of sodium hydroxide solution, potassium hydroxide solution or ammonia water.

3. The method for preparing a highly wear-resistant water-sealing ceramic sheet according to claim 1, characterized in that: The hydrothermal reaction temperature is 200-250°C and the time is 12-36h.

4. The method for preparing a highly wear-resistant water-sealing ceramic sheet according to claim 1, characterized in that: The sintering aid includes any one or more combinations of silicon dioxide, titanium dioxide, magnesium oxide, calcium oxide, yttrium oxide, and cerium oxide.

5. The method for preparing a highly wear-resistant water-sealing ceramic sheet according to claim 1, characterized in that: The binder is a polyvinyl alcohol solution and / or a polyvinyl butyral solution.

6. The method for preparing a highly wear-resistant water-sealing ceramic sheet according to claim 1, characterized in that: The pressure during pressing into billets is 100-200 MPa.

7. The method for preparing a highly wear-resistant water-sealing ceramic sheet according to claim 1, characterized in that: The heating rate of the first stage is 10-50℃ / min, and the heating rate of the second stage is 0.1-1℃ / min.

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