SiCw compounded with ZrO2 / PyC composite coating as well as preparation method and application of SiCw

Abstract

The invention relates to SiCw compounded with a ZrO2 / PyC composite coating and a preparation method and application thereof, and belongs to the technical field of preparation of nonmetal powder materials. According to the preparation method, yttrium nitrate doped zirconium oxychloride is taken as a precursor of a ZrO2 coating, the ZrO2 coating is prepared on the surface of SiCw by adopting a sol-gel method, and ZrO2 is uniformly distributed on the surface of SiCw in a nanocrystalline form; and then preparing a pyrolytic carbon (PyC) coating on the surface of the whisker by adopting a chemical vapor deposition method, and grinding to obtain ZrO2 / PyC composite coating coated SiCw powder. According to the preparation method, the ZrO2 / PyC composite coating uniformly coating the surface of the SiCw can be efficiently obtained, the preparation method has the characteristics of low cost, simple process, uniform coating thickness and high controllable degree, the prepared SiCw can be used for reinforcing and toughening a ceramic-based composite material, and the preparation method is applied to preparation of the SiCw / SiC composite material.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of non-metal powder preparation, and particularly relates to SiCw with ZrO2 / PyC composite coating and a preparation method and application thereof. BACKGROUND

[0002] SiCw (silicon carbide whisker) is widely used in ceramic composite materials due to its high strength and good chemical stability, and realizes the toughening of materials through mechanisms such as pull-out, bridging and crack deflection. However, high-temperature preparation processes represented by liquid / gas silicon infiltration are prone to cause the coarsening of SiCw, which is not conducive to the reinforcing and toughening effect. PyC (pyrolytic carbon) has good high-temperature stability, and the deposition of PyC on the surface of SiCw by CVD (chemical vapor deposition) is conducive to improving the high-temperature stability. However, in the process of densifying ceramics by using the liquid silicon infiltration process, the PyC coating is prone to react with silicon to form SiC, and the generated SiC shell is prone to form strong interfacial bonding with SiCw, which is not conducive to the energy required for the whisker to dissipate crack propagation through pull-out. f / SiC and C f / SiC composite materials, ZrO2 is used to inhibit interfacial reaction and fiber oxidation, and is usually coated on the surface of the fiber by sol-gel method multiple times, but for application in the liquid / gas silicon infiltration process with a relatively high preparation temperature, how to inhibit the growth and agglomeration of ZrO2 nanoparticles on the surface of the whisker during the heating process should be considered, and there is currently no relevant research on this problem. SUMMARY

[0003] The application aims to overcome the shortcomings of the prior art, and provides SiCw with ZrO2 / PyC composite coating and a preparation method and application thereof, so as to solve the problem of easy growth and agglomeration of ZrO2 when applied in composite materials in the prior art.

[0004] To achieve the above-mentioned purpose, the following technical solutions are adopted in the application: A preparation method of SiCw with ZrO2 / PyC composite coating comprises the following steps: S1, mixing water and anhydrous ethanol, adding polyethylene glycol 600 and stirring uniformly, then adding ZrOCl2·8H2O and Y(NO3)3·6H2O, stirring uniformly, and then standing to obtain a ZrO2 precursor solution; S2, adding SiCw to the ZrO2 precursor solution, stirring, and then filtering to obtain whisker powder, and drying the whisker powder; dipping the dried whisker powder into the ZrO2 precursor solution, stirring, and then filtering and drying, and repeating the dipping, filtering and drying for several times to obtain process powder; S3, grinding the process powder after hot sintering to obtain SiCw@ZrO2 powder; S4, depositing PyC coating on the ZrO2 coating surface of the SiCw@ZrO2 powder by chemical vapor deposition method, and grinding to obtain SiCw powder with ZrO2 / PyC composite coating.

[0005] The further improvement of the present application is that: Preferably, in S1, the concentration of polyethylene glycol 600 in the ZrO2 precursor solution is 30-50 g / L, the concentration of ZrOCl2·8H2O is 65-85 g / L, and the concentration of Y(NO3)3·6H2O is 7.5-9.5 g / L.

[0006] Preferably, in S2, 0.2-0.5 g of SiCw is added to every 0.1 L of ZrO2 precursor solution.

[0007] Preferably, in S2, the diameter of the SiCw is 0.1-0.6 μm, and the length is 10-100 μm.

[0008] Preferably, in S2, the drying temperature is 70℃, and the drying time is 1-3h.

[0009] Preferably, in S3, the specific process of the hot sintering is: heating to 900℃ at a heating rate of 3-5 ℃ / min, holding for 1-2 h, cooling to 600-700 ℃ at a cooling rate of 1-5 ℃ / min, and naturally cooling to room temperature.

[0010] Preferably, in S4, the temperature of the chemical vapor deposition process is 1050-1100 ℃, and the deposition time is 40-60 min.

[0011] A SiCw with ZrO2 / PyC composite coating prepared by any one of the above preparation methods, wherein the SiCw is wrapped by a ZrO2 coating, and the ZrO2 coating is wrapped by a PyC coating.

[0012] The SiCw with ZrO2 / PyC composite coating is used for preparing SiCw / SiC composite material.

[0013] Preferably, the method comprises the following steps: (1) grinding the mixed SiCw powder with ZrO2 / PyC composite coating and SiC powder to obtain a mixed powder, adding a mixed solution of phenolic resin and anhydrous ethanol dropwise to the mixed powder and grinding to obtain a mixed powder; (2) dry pressing the mixed powder to form a molding piece, and then sequentially performing solidification, carbonization and vapor siliconization to obtain SiCw / SiC composite material.

[0014] Compared with the prior art, the present application has the following beneficial effects: The application discloses a preparation method of SiCw coated with ZrO2 / PyC composite coating. The preparation method uses yttrium nitrate doped zirconium oxychloride as a precursor, and adopts a sol-gel method to prepare a ZrO2 coating on the surface of SiCw. The ZrO2 is uniformly distributed in the form of nanocrystals on the surface of SiCw and is uniformly distributed and well combined with SiCw. Then, a chemical vapor deposition method is used to prepare a pyrolytic carbon (PyC) coating on the surface of the whisker. After grinding, the SiCw powder coated with the ZrO2 / PyC composite coating can be obtained. The ZrO2 interface can block the contact between the whisker and liquid / gaseous silicon or siliconized PyC, thereby weakening the interface bonding between the whisker and the matrix. The outer PyC can maintain the stability of the morphology of the whisker and also inhibit the growth of the nanometer ZrO2 particles at high temperatures. The preparation method can efficiently obtain the ZrO2 / PyC composite coating uniformly coated on the surface of SiCw, and has the characteristics of low cost, simple process, uniform coating thickness and high controllability. The prepared SiCw can be used for the reinforcement and toughening of ceramic matrix composites, and the application is applied to the preparation of SiCw / SiC composite materials.

[0015] Further, the preparation method of the SiCw surface ZrO2 / PyC composite coating adopts a CVD method to prepare a PyC coating on the surface of the ZrO2 coating. The thickness of the coating can be controlled by adjusting the deposition time. The prepared coating is relatively uniform, and the deposited PyC coating is well combined with the ZrO2 coating.

[0016] Further, in the process of preparing the nanoscale ZrO2 coating on the surface of SiCw by the sol-gel method, the thickness of the coating can be controlled by adjusting the number of immersion-drying cycles. The preparation method is simple and low in cost.

[0017] Further, the preparation method of the SiCw surface ZrO2 / PyC composite coating can relieve the thermal mismatch between ZrO2 and SiC in the subsequent heating process of the heat treatment process by depositing a PyC coating on the surface of the ZrO2 coating. In addition, PyC has good high-temperature thermal stability, which can not only maintain the high-temperature morphology stability of SiCw, but also has a certain inhibitory effect on the growth of the coated ZrO2 nanoparticles. The existence of the ZrO2 layer can weaken the strong bonding between the whisker and the matrix after silicon infiltration, so that the whisker can more easily consume the energy required for crack propagation. The interaction of the two enables the entire whisker to maintain the morphology during the heating process and has a moderate bonding strength with the matrix after the gas phase silicon infiltration.

[0018] Brief Description of the Drawings, Figure 1It is a process flow chart of the present invention; Figure 2 The SiCw powder used in the present invention is gray-green; Figure 3 A powder with a ZrO2 coating on the surface of SiCw prepared in Example 1; Figure 4 This is a picture of PyC powder deposited on the surface of SiCw containing ZrO2 coating in Example 1; Figure 5 The SEM image and EDS results of the ZrO2 coating on the SiCw surface in Example 1; Figure 6 These are the low-magnification and high-magnification SEM images and EDS results of PyC deposited on the surface of SiCw containing ZrO2 coating in Example 1.

[0019] Figure 7 The XRD pattern of PyC deposited on the surface of SiCw containing ZrO2 coating in Example 1; Figure 8 is a morphological diagram; Among them, Figure (a) is the fracture morphology of the SiC / SiCw composite material prepared in Example 1; Figures (b) and (c) are the fracture morphologies of Example 1 and Comparative Example 1 after desiliconization by saturated NaOH, respectively, indicating that the whiskers containing the ZrO2 / PyC composite coating retain a longer whisker length after vapor siliconization. DETAILED DESCRIPTION

[0020] The present invention is described in further detail below with reference to the accompanying drawings: To facilitate understanding of the features and effects of the present invention by those skilled in the art, the following provides a general description and definition of the terms and expressions used in the specification and claims. Unless otherwise indicated, all technical and scientific terms used herein have the ordinary meanings as understood by those skilled in the art regarding the present invention. In the event of conflict, the definitions in this specification shall prevail.

[0021] In this document, unless otherwise specified, “include,” “including,” “contains,” “has” or similar terms cover the meanings of “consisting of” and “mainly consisting of,” for example, “A includes a” covers the meanings of “A includes a and other” and “A only includes a.”

[0022] Below in conjunction with specific embodiment, further set forth the present invention.Should be understood that these embodiments are only used to illustrate the present invention and are not used in limiting the scope of the present invention.In addition, should be understood that after reading the content taught by the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms fall equally within the scope limited by the appended claims of the application.

[0023] The following examples use apparatus and equipment that are conventional in the art. The experimental methods in the following examples, unless otherwise specified, are generally conducted under conventional conditions, or under conditions recommended by the manufacturer. The following examples use various raw materials, unless otherwise specified, and all use conventional commercially available products, which are of conventional specifications in the art. In the specification of the present application and in the following examples, unless otherwise specified, "%" means weight percent, "parts" means weight parts, and the ratio means weight ratio.

[0024] Disclosed is a method for preparing SiCw with a ZrO2 / PyC composite coating, comprising the following steps: S1, configuring a ZrO2 precursor solution, mixing deionized water and anhydrous ethanol in a volume ratio of 1.2:1-1:1.2, magnetically stirring for 0.5-1 h, then adding a certain amount of polyethylene glycol 600 and continuing to stir for 1-2 h, then adding a certain amount of ZrOCl2·8H2O and Y(NO3)3·6H2O, and continuing to stir for 10-15 h, and then standing for 2-4 h to obtain a ZrO2 precursor solution.

[0025] S2, adding a certain amount of SiCw to the above ZrO2 precursor solution, stirring for 10-30 min, and then filtering out the whisker powder, drying in a 70°C oven for 1-3 h; pouring the powder into the precursor solution, stirring for 1-5 min, and then filtering and drying, repeating this step 1-5 times.

[0026] In this process, after the Zr source and Y source are dissolved, colloidal particles are formed by hydrolysis and polycondensation and dispersed in the liquid phase. By controlling the ratio of whiskers to precursor solution, the whiskers are fully impregnated, and most of the solution and whiskers can be separated by filtration. During the drying process, polyethylene glycol helps to reduce the evaporation rate of the solvent to allow uniform polycondensation, and its steric hindrance effect can inhibit hard agglomeration during the drying process, so that the gel can be uniformly attached to the surface of the whisker.

[0027] S3, after heat treatment and sintering of the powder impregnated and dried multiple times under argon protection, ZrO2-coated SiCw is obtained; the powder after heat treatment is ground using a mortar to make the powder that is bonded into a block into loose powder.

[0028] S4, a PyC coating is further deposited on the surface of the ZrO2 coating using a chemical vapor deposition (CVD) method.

[0029] S5, the powder after deposition of PyC is ground to obtain SiCw powder with a ZrO2 / PyC composite coating on the surface.

[0030] In some embodiments of the present application, the concentration of polyethylene glycol 600 in the ZrO2 precursor solution in S1 is 30-50 g / L, the concentration of ZrOCl2·8H2O is 65-85 g / L, and the concentration of Y(NO3)3·6H2O is 7.5-9.5 g / L.

[0031] In some embodiments of the present application, the diameter of SiCw in S2 is 0.1-0.6 μm, and the length is 10-100 μm; 0.2-0.5 g of SiCw corresponds to 0.1 L of ZrO2 precursor solution.

[0032] In some embodiments of the present application, the heat treatment process for obtaining a ZrO2 coating uniformly coated on the surface of SiCw in S3 is as follows: heating at a rate of 3-5 ℃ / min to 900 ℃, holding for 1-2 h, cooling at a rate of 1-5 ℃ / min to 600-700 ℃, and then naturally cooling to room temperature.

[0033] In some embodiments of the present application, the specific process of chemical vapor deposition in S4 is as follows: placing SiCw@ZrO2 powder in an open graphite crucible, placing the graphite crucible in a CVD reaction chamber, heating to 1050-1100 ℃ under argon protection, maintaining the flow of 1.5-2.5 L / min of argon and 0.5-1.5 L / min of CH4 gas for a period of time, and then naturally cooling to room temperature.

[0034] In some embodiments of the present application, the substrate deposited in S4 is SiCw coated with ZrO2, and the reaction gas is flowed for 40-60 min.

[0035] The second aspect of the present application discloses a SiCw composite with a ZrO2 / PyC composite coating, which is mainly composed of SiCw, and the surface of which is sequentially attached with a ZrO2 coating and a PyC coating from inside to outside; the ZrO2 in the ZrO2 coating is in the form of a closely arranged nanocrystalline coating.

[0036] The third aspect of the present application discloses an application of SiCw composite with a ZrO2 / PyC composite coating, which is used for preparing SiCw / SiC composite materials, and the specific application includes the following steps: (1) weighing SiCw with a ZrO2 / PyC composite coating on the surface, phenolic resin and SiC powder according to a certain proportion, grinding and mixing SiCw with a ZrO2 / PyC composite coating on the surface and SiC powder to obtain a mixed powder; dissolving phenolic resin in anhydrous ethanol at a mass ratio of 1:3-1:6, adding the mixed powder in 2-3 times and grinding and mixing uniformly to obtain a mixed powder (2) 3-4 g of the mixed powder is weighed and dry-pressed to form a compact, which is then solidified, carbonized and subjected to vapor silicon infiltration to obtain the SiCw / SiC composite material.

[0037] The mass of the whisker powder and the phenolic resin is 3-5% and 8-10% of the mass of the SiC powder respectively, the particle size of the SiC powder is 1-3 μm, the solidification process is 2-10 h of heat preservation at 150 ℃, the carbonization process is 1-2 h of heat preservation at 900 ℃ under argon protection, and the vapor silicon infiltration temperature is 1800-2000 ℃.

[0038] The SiCw used in the application is a commercially available product, the diameter of the SiCw is 0.1-0.6 μm, and the length is 10-100 μm; and the other raw materials are commercially available products.

[0039] The application will be further described below in combination with specific examples.

[0040] Example 1 The preparation method of the SiCw surface ZrO2 / PyC composite coating in this example comprises the following steps: (1) A ZrO2 precursor solution is prepared, 40 ml of deionized water and 40 ml of anhydrous ethanol are mixed, magnetically stirred for 0.5 h, then 3.5 g of polyethylene glycol 600 is added and stirred for 1 h, then 6.44 g of ZrOCl2·8H2O and 0.75 g of Y(NO3)3·6H2O are added, and the stirring is continued for 12 h, and then the solution is left to stand for 2 h; (2) 0.4 g of SiCw is added to 80 ml of the precursor solution, stirred for 20 min, and then the whisker powder is filtered out using filter paper and dried in a 70 ℃ oven for 1 h; the powder is poured into the solution, stirred for 1 min, filtered and dried, and this step is repeated 5 times; (3) The powder after multiple dipping and drying is heat treated at 900 ℃ under argon atmosphere for 1 h, wherein the heating rate is 3.75 ℃ / min, the cooling rate is 3.3 ℃ / min, and the temperature is lowered to 700 ℃ and then naturally cooled, to obtain ZrO2-coated SiCw; the powder after heat treatment is ground using a mortar to make the powder that is bonded into blocks into loose powder, as shown in FIG. 1, wherein the gray color is derived from the carbonization product of the polyethylene glycol 600 and the generated ZrO2; Figure 3 (4) The powder is mixed with 3-4 g of phenolic resin, and then dry-pressed to form a compact, which is then solidified, carbonized and subjected to vapor silicon infiltration to obtain the SiCw / SiC composite material. Referring to Figure 5 The SEM image and the EDS result image show that the ZrO2 is uniformly distributed on the surface of the SiCw.

[0041] (4) Further depositing PyC coating on the surface of ZrO2 coating by CVD method: placing SiCw@ZrO2 powder in an open graphite crucible, placing the graphite crucible in a CVD reaction chamber, heating to 1070 ℃ under argon protection, keeping 2 L / min of argon and 0.8 L / min of CH4 gas for 40 min, and then naturally cooling to room temperature; (5) Grinding the powder after depositing PyC to obtain SiCw powder with ZrO2 / PyC composite coating on the surface, as shown in FIG. 5, it can be seen from the figure that the powder is black, indicating that PyC is uniformly deposited on the surface of the whisker. Figure 4 As shown in FIG. 6, it can be seen from the figure that PyC is uniformly deposited on the surface of the whisker to form a coating structure; as shown in FIG. 7, which is an XRD pattern, indicating that the powder after heat treatment contains two phases of SiC and t-ZrO2, and PyC has no obvious characteristic diffraction peak due to low crystallinity.

[0042] As shown in FIG. 6, it can be seen from the figure that PyC is uniformly deposited on the surface of the whisker to form a coating structure; as shown in FIG. 7, which is an XRD pattern, indicating that the powder after heat treatment contains two phases of SiC and t-ZrO2, and PyC has no obvious characteristic diffraction peak due to low crystallinity. Figure 6 Figure 7 As shown in FIG. 6, it can be seen from the figure that PyC is uniformly deposited on the surface of the whisker to form a coating structure; as shown in FIG. 7, which is an XRD pattern, indicating that the powder after heat treatment contains two phases of SiC and t-ZrO2, and PyC has no obvious characteristic diffraction peak due to low crystallinity.

[0043] The whisker containing ZrO2 / PyC coating is used to prepare SiC / SiCw ceramic, including the following steps: (1) Taking 0.25 g of whisker powder, 7.5 g of SiC powder and 0.75 g of phenolic resin, grinding and mixing the whisker powder and SiC powder, dissolving the phenolic resin in 2.5 g of anhydrous ethanol, adding it into the mixed powder in 3 times and grinding to mix uniformly, to obtain a mixed powder; (2) Taking 3.5 g of the mixed powder obtained in the above process, dry pressing and forming, then placing it in a 150 ℃ oven for 6 h for curing, then heating to 900 ℃ under argon environment for 2 h to carbonize the phenolic resin, and then performing silicon vapor densification on the carbonized ceramic body at a temperature of 1860 ℃.

[0044] Example 2 (1) Configuring ZrO2 precursor solution, mixing 40 ml of deionized water and 40 ml of anhydrous ethanol, magnetically stirring for 0.5 h, then adding 3.5 g of polyethylene glycol 600 and continuing to stir for 1 h, then adding 6.44 g of ZrOCl2·8H2O and 0.75 g of Y(NO3)3·6H2O, continuing to stir for 10 h, and then standing for 4 h; (2) Adding 0.3 g of SiCw into 80 ml of precursor solution, stirring for 10 min, then filtering out the whisker powder using filter paper, and drying in a 70 ℃ oven for 3 h; pouring the powder into the solution, stirring for 2 min, then filtering and drying, and repeating this step for 3 times; ​(3) The multi-impregnation-dried powder is heat-treated at 900 °C under argon atmosphere for 2 h, wherein the heating rate is 3.75 °C / min, the cooling rate is 3.3 °C / min, and the temperature is cooled to 700 °C and then naturally cooled, to obtain ZrO2-coated SiCw; the heat-treated powder is ground using a mortar to make the agglomerated powder into loose powder; (4) A PyC coating is further deposited on the surface of the ZrO2 coating using a CVD method: the SiCw@ZrO2 powder is placed in an open graphite crucible, the graphite crucible is placed in a CVD reaction chamber, and the temperature is raised to 1070 °C under argon protection, 2 L / min of argon and 0.8 L / min of CH4 gas are introduced for 40 min, and then the temperature is naturally cooled to room temperature; (5) The powder after deposition of PyC is ground to obtain SiCw powder with a ZrO2 / PyC composite coating on the surface.

[0045] The whisker containing the ZrO2 / PyC coating is used to prepare SiC / SiCw ceramics, including the following steps: (1) 0.25 g of whisker powder, 7.5 g of SiC powder, and 0.75 g of phenolic resin are weighed, the whisker powder and SiC powder are ground and mixed, the phenolic resin is dissolved in 2.25 g of anhydrous ethanol, and then added dropwise to the mixed powder in two portions and ground to mix uniformly, to obtain a mixed powder; (2) 3.2 g of the mixed powder obtained in the above process is dry-pressed and shaped, and then placed in a 150 °C oven for 6 h of curing, and then heated to 900 °C under argon atmosphere for 2 h of heat preservation to carbonize the phenolic resin, and the carbonized ceramic blank is densified by vapor phase siliconization at a temperature of 1860 °C.

[0046] Example 3 (1) A ZrO2 precursor solution is prepared, 43.2 ml of deionized water and 36 ml of anhydrous ethanol are mixed, magnetically stirred for 1 h, then 3.5 g of polyethylene glycol 600 is added and stirred for 1 h, then 6.44 g of ZrOCl2·8H2O and 0.75 g of Y(NO3)3·6H2O are added, and the stirring is continued for 15 h, and then the solution is left to stand for 2 h; (2) 0.2 g of SiCw is added to 70 ml of the precursor solution, stirred for 30 min, and then the whisker powder is filtered out using filter paper and dried in a 70 °C oven for 1 h; the powder is poured into the solution, stirred for 5 min, filtered, and dried. (3) The multi-impregnation-dried powder is heat-treated at 900 °C under argon atmosphere for 2 h, wherein the heating rate is 3.75 °C / min, the cooling rate is 3.3 °C / min, and the temperature is cooled to 700 °C and then naturally cooled, to obtain ZrO2-coated SiCw; the heat-treated powder is ground using a mortar to make the agglomerated powder into loose powder; (4) A PyC coating is further deposited on the surface of the ZrO2 coating using a CVD method: the SiCw@ZrO2 powder is placed in an open graphite crucible, the graphite crucible is placed in a CVD reaction chamber, and the temperature is raised to 1050 °C under argon protection, 2.5 L / min of argon and 1.5 L / min of CH4 gas are introduced for 60 min, and then naturally cooled to room temperature; (5) The powder after deposition of PyC is ground to obtain SiCw powder with a ZrO2 / PyC composite coating on the surface.

[0047] The whisker containing the ZrO2 / PyC coating is used to prepare SiC / SiCw ceramics, including the following steps: (1) 0.25 g of whisker powder, 7.5 g of SiC powder, and 0.75 g of phenolic resin are weighed, the whisker powder and SiC powder are ground and mixed, the phenolic resin is dissolved in 3.75 g of anhydrous ethanol, and then added dropwise to the mixed powder in two portions and ground to mix uniformly, to obtain a mixed powder; (2) 4 g of the mixed powder obtained in the above process is dry-pressed and shaped, and then placed in a 150 °C oven for 10 h of curing, and then heated to 900 °C under argon atmosphere for 2 h of heat preservation to carbonize the phenolic resin, and the carbonized ceramic blank is densified by vapor phase siliconization at a temperature of 1800 °C.

[0048] Example 4 (1) A ZrO2 precursor solution is prepared, 36 ml of deionized water and 43.2 ml of anhydrous ethanol are mixed, magnetically stirred for 0.5 h, then 3.5 g of polyethylene glycol 600 is added and stirred for 2 h, then 6.73 g of ZrOCl2·8H2O and 0.75 g of Y(NO3)3·6H2O are added, and the stirring is continued for 12 h, and then the solution is left to stand for 3 h; (2) 0.2 g of SiCw is added to 70 ml of the precursor solution, stirred for 30 min, and then the whisker powder is filtered out using filter paper and dried in a 70 °C oven for 1 h; the powder is poured into the solution, stirred for 5 min, filtered, and dried. (3) The multi-impregnation-dried powder is heat-treated at 900 °C for 2 h under argon atmosphere, wherein the heating rate is 3 °C / min, and the cooling rate is 5 °C / min, and the temperature is cooled to 600 °C and then naturally cooled, to obtain ZrO2-coated SiCw; the heat-treated powder is ground using a mortar to make the agglomerated powder into loose powder; (4) A PyC coating is further deposited on the surface of the ZrO2 coating using a CVD method: the SiCw@ZrO2 powder is placed in an open graphite crucible, the graphite crucible is placed in a CVD reaction chamber, and the temperature is raised to 1050 °C under argon protection, 1.5 L / min of argon and 0.5 L / min of CH4 gas are introduced, and the temperature is maintained for 60 min, and then the temperature is naturally cooled to room temperature; (5) The powder after deposition of PyC is ground to obtain SiCw powder with a ZrO2 / PyC composite coating on the surface.

[0049] The whisker containing the ZrO2 / PyC coating is used to prepare SiC / SiCw ceramics, including the following steps: (1) 0.375 g of whisker powder, 7.5 g of SiC powder, and 0.75 g of phenolic resin are weighed, the whisker powder and SiC powder are ground and mixed, the phenolic resin is dissolved in 4.5 g of anhydrous ethanol, and then added dropwise to the mixed powder in three portions and ground to mix uniformly, to obtain a mixed powder; (2) 3 g of the mixed powder obtained in the above process is dry-pressed and shaped, and then placed in a 150 °C oven for 2 h for curing, and then heated to 900 °C under argon protection for 1 h to carbonize the phenolic resin, and the carbonized ceramic body is densified by vapor phase siliconization at a temperature of 2000 °C.

[0050] Example 5 (1) A ZrO2 precursor solution is prepared, 40 ml of deionized water and 40 ml of anhydrous ethanol are mixed, and then 4 g of polyethylene glycol 600 is added and stirred for 0.5 h, and then 5.2 g of ZrOCl2·8H2O and 0.6 g of Y(NO3)3·6H2O are added, and the stirring is continued for 12 h, and then the solution is left to stand for 2 h; (2) 0.16 g of SiCw is added to 80 ml of the precursor solution, and stirred for 30 min, and then the whisker powder is filtered out using filter paper, and dried in a 70 °C oven for 1 h; the powder is poured into the solution, stirred for 2 min, filtered and dried, and the step is repeated 3 times. (3) The powder after multiple impregnation and drying was heat treated at 900 °C in an argon environment for 2 h, with a heating rate of 5 °C / min and a cooling rate of 1 °C / min. The powder was cooled to 700 °C and then naturally cooled to obtain ZrO2-coated SiCw. The heat-treated powder was ground in a mortar to make the powder that was stuck into a block become loose powder. (4) PyC coating was further deposited on the surface of ZrO2 coating by CVD method: SiCw@ZrO2 powder was placed in an open graphite crucible, and the graphite crucible was placed in a CVD reaction chamber. The temperature was raised to 1100 °C under argon protection, and 2 L / min of argon and 0.8 L / min of CH4 gas were kept flowing for 40 min, and then naturally cooled to room temperature; (5) Grinding the powder after PyC deposition to obtain SiCw powder with a ZrO2 / PyC composite coating on the surface.

[0051] The whiskers containing ZrO2 / PyC coating are used to prepare SiC / SiCw ceramics, comprising the following steps: (1) Weigh 0.225 g of whisker powder, 7.5 g of SiC powder, and 0.6 g of phenolic resin, grind and mix the whisker powder and SiC powder, dissolve the phenolic resin in 3 g of anhydrous ethanol, add it dropwise to the mixed powder twice, grind and mix evenly, and obtain a mixed powder; (2) Weigh 4 g of the mixed powder obtained in the above process, dry-press it into shape, and place it in a 150 °C oven for curing for 2 h. Then, heat it to 900 °C in an argon environment and keep it at that temperature for 2 h to carbonize the phenolic resin. The carbonized ceramic body is densified by vapor siliconization at a temperature of 1900 °C.

[0052] Comparative Example 1 (1) Weigh 0.25 g of SiCw powder, 7.5 g of SiC powder, and 0.75 g of phenolic resin, grind and mix the SiCw powder and SiC powder, dissolve the phenolic resin in 3 g of anhydrous ethanol, add it dropwise to the mixed powder three times, grind and mix evenly, and obtain a mixed powder; (2) Weigh 3 g of the mixed powder obtained in the above process, dry-press it into shape, and place it in a 150 °C oven for curing for 6 h. Then, heat it to 900 °C in an argon environment and keep it at that temperature for 2 h to carbonize the phenolic resin. The carbonized ceramic body is densified by vapor siliconization at a temperature of 1860 °C.

[0053] See also Figure 8, (a) is a fracture morphology of SiC / SiCw composite material prepared in Example 1; (b) and (c) are fracture morphologies of Example 1 and Comparative Example 1 after silicon removal by saturated NaOH respectively, it can be seen from the figures that the whisker length of the ZrO2 / PyC composite coating containing whisker is larger after gas phase silicon infiltration.

[0054] The above merely describes preferred embodiments of the present application and is not used to limit the present application, any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A method for producing a SiCw composite with a Zr02 / PyC composite coating, characterized by, The method comprises the following steps: S1, mixing water and anhydrous ethanol, adding polyethylene glycol 600, stirring until uniform, adding ZrOCl2.8H2O and Y(NO3)3.6H2O, stirring until uniform, and standing to obtain a ZrO2 precursor solution; S2, adding SiCw to the ZrO2 precursor solution, stirring, filtering to obtain a whisker powder, and drying the whisker powder; dipping the dried whisker powder into the ZrO2 precursor solution, stirring, filtering, and drying, repeating the dipping, filtering, and drying for several times, and obtaining a process powder; S3, grinding the process powder after heat sintering, and obtaining a SiCw@ZrO2 powder; S4, depositing a PyC coating on the surface of the ZrO2 coating of the SiCw@ZrO2 powder by using a chemical vapor deposition method, and grinding to obtain a SiCw powder with a ZrO2 / PyC composite coating.

2. The method for preparing SiCw composite with ZrO2 / PyC composite coating according to claim 1, characterized in that: In S1, the concentration of polyethylene glycol 600 in the ZrO2 precursor solution is 30-50 g / L, the concentration of ZrOCl2.8H2O is 65-85 g / L, and the concentration of Y(NO3)3.6H2O is 7.5-9.5 g / L.

3. The method for preparing SiCw composite with ZrO2 / PyC composite coating according to claim 1, characterized in that: In S2, 0.2-0.5 g of SiCw is added to every 0.1 L of the ZrO2 precursor solution.

4. The method for preparing SiCw composite with ZrO2 / PyC composite coating according to claim 1, characterized in that: In S2, the diameter of the SiCw is 0.1-0.6 μm, and the length is 10-100 μm.

5. The method for preparing SiCw composite with ZrO2 / PyC composite coating according to claim 1, characterized in that: In S2, the drying temperature is 70 ℃, and the drying time is 1-3 h.

6. The method for preparing SiCw composite with ZrO2 / PyC composite coating according to claim 1, characterized in that: In S3, the specific process of the heat sintering is as follows: increasing the temperature to 900 ℃ at a temperature increasing rate of 3-5 ℃ / min, keeping the temperature for 1-2 h, decreasing the temperature to 600-700 ℃ at a temperature decreasing rate of 1-5 ℃ / min, and naturally cooling to room temperature.

7. The method for preparing SiCw composite with ZrO2 / PyC composite coating according to claim 1, characterized in that: In S4, the temperature of the chemical vapor deposition process is 1050-1100 ℃, and the deposition time is 40-60 min.

8. SiCw with ZrO2 / PyC composite coating prepared by the method according to any one of claims 1 to 7, characterized in that The SiCw is wrapped by the ZrO2 coating, and the ZrO2 coating is wrapped by the PyC coating.

9. The use of SiCw coated with a ZrO2 / PyC composite coating according to claim 8, characterized in that The SiCw / SiC composite material is prepared.

10. Use according to claim 9, characterized in that, The method comprises the following steps: (1) grinding the mixed SiCw powder with the ZrO2 / PyC composite coating and the SiC powder to obtain a mixed powder, adding a mixed solution of phenolic resin and anhydrous ethanol dropwise to the mixed powder, and grinding the mixed powder to obtain a mixed powder material; (2) dry pressing the mixed powder material, sequentially passing the pressed piece through solidification, carbonization, and gas-phase silicon infiltration, and obtaining a SiCw / SiC composite material.

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