Environmental barrier coating material for SiC / SiC composites and method for producing same

Abstract

The application belongs to the technical field of silicon carbide-based composite materials, and discloses an environmental barrier coating material for SiC / SiC composite materials and a preparation method thereof; the preparation method is as follows: Al2O3 powder, HfO2 powder and SiO2 powder are uniformly mixed, then wet ball milling is performed to obtain a slurry; the slurry is dried and ground to obtain a mixed powder; the mixed powder is ground into powder after sintering treatment, and the environmental barrier coating material for SiC / SiC composite materials is obtained. The process flow of the application is simple, the process is highly feasible, raw materials are easy to obtain, the thermal expansion coefficient of the environmental barrier coating material prepared by the application is similar to that of SiC / SiC composite materials, the thermal expansion coefficient is adjustable, the anti-dry air oxidation resistance is excellent, and the water-oxygen corrosion resistance is high.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of silicon carbide-based composite materials, and particularly relates to an environmental barrier coating material for SiC / SiC composite materials and a preparation method thereof. BACKGROUND

[0002] Continuous silicon carbide fiber-reinforced silicon carbide-based (SiC / SiC) composite materials have excellent properties such as high specific strength, high specific modulus, creep resistance, oxidation resistance, and high-temperature resistance, and are ideal high-temperature structural materials for high-temperature components of gas turbine engines and aeroengines. It is reported that the use of SiC / SiC composite materials in turbine components can reduce weight by more than 50% and fuel consumption by 2%. However, under harsh environmental conditions such as high temperature, high gas flow, and chemical corrosion, the performance of SiC / SiC composite materials deteriorates sharply, which is a key factor for large-scale application of SiC / SiC composite materials in gas turbine engines and aeroengines.

[0003] To solve the above technical problems, the prior art proposes an environmental barrier coating (Environmental Barrier Coatings, EBCs), which can establish a barrier between the SiC / SiC composite material and the harsh environment of the engine, and as far as possible prevent or reduce the influence of the engine environment on the high-temperature structural material. A person skilled in the art proposes that the thermal expansion coefficient of HfSiO4 is extremely similar to that of SiC / SiC composite materials (4.5x10 -6 ~ 5x10 -6 K -1 ), which can be used as an environmental barrier coating material for SiC / SiC composite materials, but HfSiO4 has a defect, that is, insufficient water and oxygen corrosion resistance, and is easily reacted with high-temperature water vapor at high temperature to generate Si(OH)4 and residual porous HfO2. Although HfO2 can remain stable in a high-temperature water and oxygen environment and no longer reacts with high-temperature water vapor, HfO2 is a good conductor of oxygen, which is not conducive to the blocking of oxygen, and limits the potential of HfSiO4 as an environmental barrier coating for SiC / SiC composite materials.

[0004] Therefore, the present application provides an environmental barrier coating material for SiC / SiC composite materials and a preparation method thereof. SUMMARY

[0005] To solve the above technical problems, the present application provides an environmental barrier coating material for SiC / SiC composite materials and a preparation method thereof.

[0006] The environmental barrier coating material for SiC / SiC composite materials and the preparation method thereof are implemented through the following technical solutions:

[0007] The first object of the present application is to provide a preparation method of environmental barrier coating material for SiC / SiC composite material, comprising the following steps:

[0008] After mixing Al2O3 powder, HfO2 powder and SiO2 powder, wet ball milling is performed to obtain a slurry; the slurry is dried and ground to obtain a mixed powder.

[0009] Sintering treatment is performed on the mixed powder at 1350-1550℃, and then the powder is obtained by grinding, that is, the environmental barrier coating material for SiC / SiC composite material is obtained.

[0010] Preferably, the molar ratio of the Al2O3 powder, HfO2 powder and SiO2 powder is 1:1-1.5:0.8-1.8.

[0011] Preferably, the purity of the Al2O3 powder is ≥99.99wt.%, and the particle size of the Al2O3 powder is 0.2-0.6μm.

[0012] Preferably, the purity of the HfO2 powder is ≥99.99wt.%, and the particle size of the HfO2 powder is 3-6μm.

[0013] Preferably, the purity of the SiO2 powder is ≥99.99wt.%, and the particle size of the SiO2 powder is 1-2μm.

[0014] Preferably, after the sintering treatment, the sintered product obtained is ground to a particle size of 50-80μm.

[0015] Preferably, the sintering time of the sintering treatment is 1-2h.

[0016] Preferably, after the slurry is dried, the mixed powder is ground to a particle size of 30-60μm.

[0017] Preferably, the ball milling aid of the wet ball milling is anhydrous ethanol, and the ball milling rate is 20-60r / min, and the ball milling time is 12-24h.

[0018] Preferably, the drying temperature of the drying is 70-80℃, and the drying time is 12-24h.

[0019] The second object of the present application is to provide an environmental barrier coating material for SiC / SiC composite material prepared by the above preparation method.

[0020] Compared with the prior art, the present application has the following beneficial effects:

[0021] The present application takes Al2O3 powder and HfO2 powder as raw materials to synthesize HfSiO4, so as to keep the environmental barrier coating material and SiC / SiC composite material in good thermal expansion matching performance by synthesizing a certain amount of HfSiO4, and on the basis of ensuring that the prepared environmental barrier coating material and SiC / SiC composite material are in good thermal expansion matching, the hindering effect of the environmental barrier coating material on oxygen diffusion is further improved by introducing Al2O3 powder. After introducing Al2O3 powder in the present application, the Al2O3 powder will partially react, and the thermal expansion coefficient (5.3*10 -6 K -1 ) of the mullite (3Al2O3*2SiO2) generated by the reaction is also not much different from that of SiC / SiC composite material, so that the overall thermal expansion coefficient of the environmental barrier coating material finally prepared by the present application still keeps good matching with SiC / SiC composite material.

[0022] The process flow of the present application is simple, the process feasibility is high, and the raw materials are easy to obtain. The thermal expansion coefficient of the environmental barrier coating material prepared by the present application is similar to that of SiC / SiC composite material, the thermal expansion coefficient is adjustable, the dry air oxidation resistance is excellent, and the water oxygen corrosion resistance is high. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1 It is the process flow chart of the preparation method of the present application.

[0024] Figure 2 It is the thermal expansion coefficient curve measured in Example 1.

[0025] Figure 3 It is the macroscopic morphology of Example 1 after water oxygen corrosion at 1300 DEG C for 100h. DETAILED DESCRIPTION

[0026] As described in the background, when HfSiO4 is used as the environmental barrier coating material for SiC / SiC composite material, the water oxygen corrosion resistance of HfSiO4 is insufficient, and HfSiO4 is easy to react with high-temperature water vapor to generate Si(OH)4 and residual porous HfO2 at high temperature. Although HfO2 can remain stable in a high-temperature water oxygen environment and no longer reacts with high-temperature water vapor, HfO2 is a good conductor of oxygen and is not conducive to the barrier of oxygen. Based on this, the present application takes HfO2 and SiO2 as raw materials to prepare HfSiO4, and introduces Al2O3 to improve the hindering effect of the coating raw material on oxygen diffusion. And the technical solutions in the examples of the present application will be described clearly and completely.

[0027] The present application provides an environmental barrier coating material for SiC / SiC composite material, and the preparation method is as follows:

[0028] Step 1, mix each preparation raw material:

[0029] After the Al2O3 powder, the HfO2 powder and the SiO2 powder are mixed, wet ball milling is performed to obtain a slurry; the slurry is dried and ground to obtain a mixed powder.

[0030] It should be noted that the Al2O3 powder and the HfO2 powder are used as raw materials to synthesize HfSiO4, so that the environmental barrier coating material and the SiC / SiC composite material are well matched in thermal expansion, and the Al2O3 powder is introduced to further improve the hindering effect of the environmental barrier coating material on oxygen diffusion.

[0031] It should be further noted that the Al2O3 powder introduced in the present application will partially react, and the thermal expansion coefficient (5.3×10 -6 K -1 ) of the mullite (3Al2O3·2SiO2) generated by the reaction is also not much different from that of the SiC / SiC composite material, so that the overall thermal expansion coefficient of the environmental barrier coating material ultimately prepared by the present application still maintains good matching with the SiC / SiC composite material.

[0032] In order to ensure that the content of the formed HfSiO4 can ensure that the environmental barrier coating material obtained has good performance in thermal expansion matching with the SiC / SiC composite material, and the Al2O3 powder added can improve the hindering effect of the environmental barrier coating material on oxygen diffusion, in a preferred embodiment of the present application, the molar ratio of the Al2O3 powder, the HfO2 powder and the SiO2 powder is 1:1-1.5:0.8-1.8.

[0033] In order to ensure that the overall thermal expansion coefficient of the environmental barrier coating material ultimately prepared by the present application still maintains good matching with the SiC / SiC composite material, in a preferred embodiment of the present application, the Al2O3 powder, the HfO2 powder and the SiO2 powder are premixed, anhydrous ethanol is used as a ball milling aid, and the mixture of the premixed Al2O3 powder, the HfO2 powder and the SiO2 powder is ball milled to mix the Al2O3 powder, the HfO2 powder and the SiO2 powder uniformly, the ball milling rate of the wet ball milling is 20-60 r / min, and the ball milling time is 12-24 h. It should be emphasized that the main purpose of the wet ball milling in the present application is to mix the Al2O3 powder, the HfO2 powder and the SiO2 powder uniformly, and the wet ball milling has no effect on the yield and purity of the final product.

[0034] The present application further promotes the mixing of Al2O3, HfO2 and SiO2. In a preferred embodiment of the present application, Al2O3, HfO2 and SiO2 are preferably added in the form of high-purity powders, and the purity of the Al2O3 powder is ≥99.99 wt.%, and the particle size of the Al2O3 powder is 0.2-0.6 μm. The purity of the HfO2 powder is ≥99.99 wt.%, and the particle size of the HfO2 powder is 3-6 μm. The purity of the SiO2 powder is ≥99.99 wt.%, and the particle size of the SiO2 powder is 1-2 μm.

[0035] In order to facilitate subsequent sintering treatment, in a preferred embodiment of the present application, the slurry after wet ball milling is subjected to drying treatment to remove excess anhydrous ethanol, and the drying temperature is 70-80°C, and the drying time is 12-24 h.

[0036] In order to avoid agglomeration of the material during drying, which is not conducive to sintering treatment, the dried product is subjected to grinding treatment before sintering treatment, so as to facilitate the calcination of the mixed powder in air atmosphere during sintering treatment. However, in order to prevent other impurities from entering and affecting the subsequent high-temperature solid-phase reaction, the grinding time should not be too long. In a preferred embodiment of the present application, the mixed powder is ground in a corundum mortar for 20-40 min to obtain a mixed powder with a particle size of 30-60 μm. It should be noted that the grinding is performed to refine the particle size of the mixed powder, so as to facilitate the calcination of the mixed powder in air atmosphere during sintering treatment. The smaller the particle size of the mixed powder, the faster the reaction speed during calcination in air atmosphere. Large-sized particles will delay the completion of the reaction process, but have no effect on the purity and uniformity of the entire reaction product.

[0037] Step 2, sintering treatment:

[0038] The mixed powder is subjected to sintering treatment at 1350-1550°C, and is ground into powder to obtain an environmental barrier coating material for SiC / SiC composite materials.

[0039] It should be noted that the present application takes into account the factors that solid-phase reactions generally have low activity, must be activated before reaction, and the reaction rate is slow and requires sufficient time to react. Therefore, in a preferred embodiment of the present application, the sintering time of the sintering treatment is 1-2 h, so as to achieve high purity and uniform component distribution of the final product.

[0040] In a preferred embodiment of the present application, when the sintered product after sintering treatment is ground, corundum mortar is used for grinding for 30-50 minutes to obtain the environmental barrier coating material for SiC / SiC composite material with a particle size of 50-80 μm.

[0041] In the preparation process of the present application, during the sintering treatment, part of the silicon dioxide reacts with hafnium dioxide to form hafnium silicate, and part of the silicon dioxide reacts with aluminum oxide to form mullite, so that the silicon dioxide is completely reacted during the sintering treatment, and the main components in the obtained environmental barrier coating material for SiC / SiC composite material are HfSiO4 and mullite, as well as part of residual HfO2 and Al2O3. However, the thermal expansion coefficient of the sintered material of the environmental barrier coating material for SiC / SiC composite material obtained by the present application is still similar to that of SiC / SiC, and HfO2 and Al2O3 are difficult to continue to react with high-temperature water vapor at high temperature, that is, the water and oxygen corrosion resistance thereof is superior to that of HfSiO4 and mullite.

[0042] Example 1

[0043] The present embodiment provides an environmental barrier coating material for SiC / SiC composite material, and the preparation method thereof is as follows:

[0044] 1) Al2O3 powder with a particle size of 0.2 μm and a purity of 99.99 wt.%, HfO2 powder with a particle size of 3 μm and a purity of 99.99 wt.%, and SiO2 powder with a particle size of 1 μm and a purity of 99.99 wt.% are used as raw materials for preparation, and the corresponding mass of the above-mentioned Al2O3 powder, HfO2 powder and SiO2 powder is weighed according to the equal molar ratio, and is prepared for use.

[0045] 2) After mixing the weighed Al2O3 powder, HfO2 powder and SiO2 powder, a mixture is obtained; anhydrous ethanol with the same mass as the mixture is added as a ball milling aid, and the slurry is obtained by ball milling at a ball milling speed of 20 r / min for 12 h.

[0046] 3) The obtained slurry is dried in an oven at 70 °C for 12 h, and the dried slurry is ground in a corundum mortar for 20 min to obtain a mixed powder, and the particle size of the ground powder is 60 μm.

[0047] 4) The obtained mixed powder is sintered at a temperature of 1400 °C for 1 h under air atmosphere, and the sintered product is placed in a corundum mortar and ground for 30 min, and the particle size of the ground powder is 80 μm, that is, the environmental barrier coating material for SiC / SiC composite material is obtained.

[0048] Example 2

[0049] The embodiment provides an environmental barrier coating material for SiC / SiC composite materials, and a preparation method thereof is as follows:

[0050] 1) Al2O3 powder with a particle size of 0.3 μm and a purity of 99.99 wt.%, HfO2 powder with a particle size of 4 μm and a purity of 99.99 wt.%, and SiO2 powder with a particle size of 1 μm and a purity of 99.99 wt.% are used as preparation raw materials, and corresponding masses of the Al2O3 powder, the HfO2 powder and the SiO2 powder are respectively taken according to an equimolar ratio, for standby.

[0051] 2) After the Al2O3 powder, the HfO2 powder and the SiO2 powder are mixed, a mixture is obtained; anhydrous ethanol with the same mass as the mixture is added as a ball milling aid, and ball milling is performed at a ball milling speed of 30 r / min for 16 h to obtain a slurry.

[0052] 3) The obtained slurry is dried in an oven at 70 °C for 16 h, and the dried slurry is ground in a corundum mortar for 30 min to obtain a mixed powder, and the particle size of the ground powder is 50 μm.

[0053] 4) The obtained mixed powder is sintered at a temperature of 1400 °C for 2 h under an air atmosphere, and the sintered mixed powder is ground in a corundum mortar for 40 min, and the particle size of the ground powder is 70 μm, thereby obtaining an environmental barrier coating material for SiC / SiC composite materials.

[0054] Embodiment 3

[0055] The embodiment provides an environmental barrier coating material for SiC / SiC composite materials, and a preparation method thereof is as follows:

[0056] 1) Al2O3 powder with a particle size of 0.4 μm and a purity of 99.99 wt.%, HfO2 powder with a particle size of 5 μm and a purity of 99.99 wt.%, and SiO2 powder with a particle size of 1 μm and a purity of 99.99 wt.% are used as preparation raw materials, and corresponding masses of the Al2O3 powder, the HfO2 powder and the SiO2 powder are respectively taken according to a molar ratio of 1:1:1.3, for standby.

[0057] 2) After the Al2O3 powder, the HfO2 powder and the SiO2 powder are mixed, a mixture is obtained; anhydrous ethanol with the same mass as the mixture is added as a ball milling aid, and ball milling is performed at a ball milling speed of 40 r / min for 20 h to obtain a slurry.

[0058] 3) The obtained slurry is dried in an oven at 70 °C for 20 h, and the dried slurry is ground in a corundum mortar for 40 min to obtain a mixed powder, and the particle size of the ground powder is 30 μm.

[0059] 4) The mixed powder obtained above is sintered at a temperature of 1400°C for 2h under an air atmosphere, and the mixed powder after sintering is placed in a corundum mortar and ground for 50min, and the particle size of the ground powder is 50μm, thereby obtaining the environmental barrier coating material for SiC / SiC composite material.

[0060] Example 4

[0061] The present example provides an environmental barrier coating material for SiC / SiC composite material, and the preparation method is as follows:

[0062] 1) Al2O3 powder with a particle size of 0.5μm and a purity of 99.99wt.%, HfO2 powder with a particle size of 6μm and a purity of 99.99wt.%, and SiO2 powder with a particle size of 1μm and a purity of 99.99wt.% are used as raw materials for preparation, and the corresponding mass of the above-mentioned Al2O3 powder, HfO2 powder and SiO2 powder is weighed according to a molar ratio of 1:1:1.6, and is ready for use.

[0063] 2) The weighed Al2O3 powder, HfO2 powder and SiO2 powder are mixed to obtain a mixture; anhydrous ethanol with the same mass as the mixture is added as a ball milling aid, and the mixture is ball milled at a ball milling speed of 50r / min for 24h to obtain a slurry.

[0064] 3) The slurry obtained above is dried in an oven at 70°C for 24h, and the dried slurry is ground in a corundum mortar for 20min to obtain a mixed powder, and the particle size of the ground powder is 50μm.

[0065] 4) The mixed powder obtained above is sintered at a temperature of 1400°C for 2h under an air atmosphere, and the mixed powder after sintering is placed in a corundum mortar and ground for 35min, and the particle size of the ground powder is 60μm, thereby obtaining the environmental barrier coating material for SiC / SiC composite material.

[0066] Example 5

[0067] The present example provides an environmental barrier coating material for SiC / SiC composite material, and the preparation method is as follows:

[0068] 1) Al2O3 powder with a particle size of 0.6μm and a purity of 99.99wt.%, HfO2 powder with a particle size of 3μm and a purity of 99.99wt.%, and SiO2 powder with a particle size of 2μm and a purity of 99.99wt.% are used as raw materials for preparation, and the corresponding mass of the above-mentioned Al2O3 powder, HfO2 powder and SiO2 powder is weighed according to a molar ratio of 1:1:1.8, and is ready for use.

[0069] 2) The Al2O3 powder, HfO2 powder and SiO2 powder are mixed to obtain a mixture, and anhydrous ethanol is added to the mixture as a ball milling aid, and the mixture is ball milled at a speed of 20 r / min for 12 h to obtain a slurry.

[0070] 3) The slurry is dried in an oven at 80°C for 12 h, and the dried slurry is ground in a corundum mortar for 30 min to obtain a mixed powder, and the particle size of the ground powder is 40 μm.

[0071] 4) The mixed powder is sintered at a temperature of 1400°C for 2 h in an air atmosphere, and the sintered mixed powder is ground in a corundum mortar for 30 min, and the particle size of the ground powder is 70 μm, thereby obtaining an environmental barrier coating material for SiC / SiC composite materials.

[0072] Example 6

[0073] The present embodiment provides an environmental barrier coating material for SiC / SiC composite materials, and the preparation method is as follows:

[0074] 1) Al2O3 powder with a particle size of 0.3 μm and a purity of 99.99 wt.%, HfO2 powder with a particle size of 4 μm and a purity of 99.99 wt.%, and SiO2 powder with a particle size of 2 μm and a purity of 99.99 wt.% are used as raw materials, and the corresponding amounts of the Al2O3 powder, HfO2 powder and SiO2 powder are weighed according to a molar ratio of 1:1.5:1.

[0075] 2) The Al2O3 powder, HfO2 powder and SiO2 powder are mixed to obtain a mixture, and anhydrous ethanol is added to the mixture as a ball milling aid, and the mixture is ball milled at a speed of 30 r / min for 16 h to obtain a slurry.

[0076] 3) The slurry is dried in an oven at 80°C for 16 h, and the dried slurry is ground in a corundum mortar for 40 min to obtain a mixed powder, and the particle size of the ground powder is 30 μm.

[0077] 4) The mixed powder is sintered at a temperature of 1500°C for 2 h in an air atmosphere, and the sintered mixed powder is ground in a corundum mortar for 45 min, and the particle size of the ground powder is 60 μm, thereby obtaining an environmental barrier coating material for SiC / SiC composite materials.

[0078] Example 7

[0079] The present embodiment provides an environmental barrier coating material for SiC / SiC composite materials, and the preparation method is as follows:

[0080] 1) Al2O3 powder with a particle size of 0.4 μm and a purity of 99.99 wt.%, HfO2 powder with a particle size of 5 μm and a purity of 99.99 wt.%, and SiO2 powder with a particle size of 2 μm and a purity of 99.99 wt.% are used as raw materials for preparation, and the corresponding amounts of the above-mentioned Al2O3 powder, HfO2 powder and SiO2 powder are weighed according to a molar ratio of 1:1.5:1.3, respectively, for standby.

[0081] 2) The above-mentioned Al2O3 powder, HfO2 powder and SiO2 powder are mixed to obtain a mixture; anhydrous ethanol with the same mass as the mixture is added as a ball milling aid, and the mixture is ball milled at a ball milling speed of 40 r / min for 20 h to obtain a slurry.

[0082] 3) The above-mentioned slurry is dried in an oven at 80 °C for 20 h, and the dried slurry is ground in a corundum mortar for 40 min to obtain a mixed powder, and the particle size of the ground powder is 30 μm.

[0083] 4) The above-mentioned mixed powder is sintered at a temperature of 1500 °C for 2 h under an air atmosphere, and the sintered mixed powder is ground in a corundum mortar for 50 min, and the particle size of the ground powder is 50 μm, thereby obtaining an environmental barrier coating material for SiC / SiC composite material.

[0084] Example 8

[0085] The present embodiment provides an environmental barrier coating material for SiC / SiC composite material, and the preparation method thereof is as follows:

[0086] 1) Al2O3 powder with a particle size of 0.5 μm and a purity of 99.99 wt.%, HfO2 powder with a particle size of 6 μm and a purity of 99.99 wt.%, and SiO2 powder with a particle size of 2 μm and a purity of 99.99 wt.% are used as raw materials for preparation, and the corresponding amounts of the above-mentioned Al2O3 powder, HfO2 powder and SiO2 powder are weighed according to a molar ratio of 1:1.5:1.3, respectively, for standby.

[0087] 2) The above-mentioned Al2O3 powder, HfO2 powder and SiO2 powder are mixed to obtain a mixture; anhydrous ethanol with the same mass as the mixture is added as a ball milling aid, and the mixture is ball milled at a ball milling speed of 50 r / min for 24 h to obtain a slurry.

[0088] 3) The above-mentioned slurry is dried in an oven at 80 °C for 24 h, and the dried slurry is ground in a corundum mortar for 30 min to obtain a mixed powder, and the particle size of the ground powder is 50 μm.

[0089] 4) sintering the mixed powder obtained above under an air atmosphere at a temperature of 1400°C for 2h, and grinding the mixed powder after sintering in a corundum mortar for 40min, the particle size of the ground powder being 80μm, to obtain an environmental barrier coating material for SiC / SiC composite material.

[0090] Example 9

[0091] The present example provides an environmental barrier coating material for SiC / SiC composite material, and the preparation method thereof is as follows:

[0092] 1) taking Al2O3 powder with a particle size of 0.6μm and a purity of 99.99wt.%, HfO2 powder with a particle size of 6μm and a purity of 99.99wt.%, and SiO2 powder with a particle size of 2μm and a purity of 99.99wt.% as raw materials for preparation, and taking the corresponding mass of the above-mentioned Al2O3 powder, HfO2 powder and SiO2 powder according to a molar ratio of 1:1.5:1.6, respectively, for standby.

[0093] 2) mixing the above-mentioned Al2O3 powder, HfO2 powder and SiO2 powder after weighing, to obtain a mixture; adding anhydrous ethanol with the same mass as the mixture as a ball milling aid, and ball milling at a ball milling speed of 50r / min for 18h to obtain a slurry.

[0094] 3) drying the slurry obtained above in an oven at 80°C for 18h, and grinding the dried slurry in a corundum mortar for 35min to obtain a mixed powder, the particle size of the ground powder being 40μm.

[0095] 4) sintering the mixed powder obtained above under an air atmosphere at a temperature of 1550°C for 2h, and grinding the mixed powder after sintering in a corundum mortar for 50min, the particle size of the ground powder being 50μm, to obtain an environmental barrier coating material for SiC / SiC composite material.

[0096] Comparative Example 1

[0097] The present example provides an environmental barrier coating material for SiC / SiC composite material, and the preparation method thereof is as follows:

[0098] 1) taking HfO2 powder with a particle size of 6μm and a purity of 99.99wt.%, and SiO2 powder with a particle size of 2μm and a purity of 99.99wt.% as raw materials for preparation, and taking the corresponding mass of the above-mentioned HfO2 powder and SiO2 powder according to an equal molar ratio, respectively, for standby.

[0099] 2) The HfO2 powder and the SiO2 powder are mixed to obtain a mixture, and anhydrous ethanol is added to the mixture as a ball milling aid in an amount equal to that of the mixture, and the mixture is ball milled at a speed of 20 r / min for 12 h to obtain a slurry.

[0100] 3) The slurry obtained above is dried in an oven at 70°C for 12 h, and the dried slurry is ground in a corundum mortar for 30 min to obtain a mixed powder, and the particle size of the ground powder is 40 μm.

[0101] 4) The mixed powder obtained above is sintered at a temperature of 1500°C for 2 h in an air atmosphere, and the sintered mixed powder is ground in a corundum mortar for 40 min, and the particle size of the ground powder is 60 μm, thereby obtaining an environmental barrier coating material for SiC / SiC composite materials.

[0102] Test Part

[0103] In order to verify the feasibility of the synthesized powder raw material for the environmental barrier coating of SiC / SiC composite materials, and considering that the thermal expansion coefficient of the powder material is difficult to determine, the powder-like environmental barrier coating material in the present application is made into a block ceramic with a fixed size, and the thermal expansion coefficient obtained by determining the block ceramic material is taken as the thermal expansion coefficient of the corresponding Examples 1-9 and Comparative Example 1. The powder-like environmental barrier coating material in the present application is made into a block ceramic with a fixed size by the following steps: 20 g of the environmental barrier coating material prepared in Examples 1-9 and Comparative Example 1 is respectively placed in a graphite mold, and is hot-pressed and sintered in a vacuum hot-pressing sintering furnace at a temperature of 1500°C and a pressure of 35 MPa for 2 h, thereby preparing the corresponding block ceramic of Examples 1-9 and Comparative Example 1.

[0104] The thermal expansion coefficient a (25-1600°C), the mass change rate Δm1 after 100 h of dry air treatment at 1500°C, and the mass change rate Δm2 after 100 h of water-oxygen corrosion at 1300°C of the block ceramic corresponding to Examples 1-9 and Comparative Example 1 obtained above are respectively tested, and the test results are shown in Table 1, Figure 2 and Figure 3 .

[0105] Table 1 Test results of the thermal expansion coefficient a, the mass change rate Δm1 after 100 h of dry air treatment at 1500°C, and the mass change rate Δm2 after 100 h of water-oxygen corrosion at 1300°C

[0106]

[0107]

[0108] Among them, Figure 2The curve of the coefficient of thermal expansion of Example 1 is shown. Figure 3 This is a photograph of the sample from Example 1 after 100 hours of water-oxygen corrosion at 1300℃.

[0109] As shown in Table 1, compared with the HfSiO4 prepared in Comparative Example 1, the environmental barrier coating materials prepared in Examples 1-9, by adding Al2O3 while synthesizing HfSiO4 using HfO2 and SiO2, improved the oxygen diffusion barrier effect of the coating raw materials while maintaining good thermal expansion matching between HfSiO4 and the SiC / SiC composite material. Even with the addition of Al2O3 during the synthesis of HfSiO4 using HfO2 and SiO2, the thermal expansion coefficient of the mullite (3Al2O3·2SiO2) generated in the reaction was not significantly different from that of the SiC / SiC composite material. Therefore, the thermal expansion coefficient of the environmental barrier coating material finally prepared in this invention still shows good matching with that of the SiC / SiC composite material.

[0110] And by Figures 2-3 As can be seen from the test results in Table 1, compared with HfSiO4, the thermal expansion coefficient of the environmental barrier coating material in Example 1 still matches well with that of the SiC / SiC composite material; the mass change after 100h of dry air treatment at 1500℃ is minimal, almost zero, indicating that Example 1 has excellent resistance to drying oxidation; the mass change rate after 100h of water-oxygen corrosion at 1300℃ is 0.105%, which is 62% lower than that of HfSiO4, indicating that the resistance to water-oxygen corrosion has been greatly improved.

[0111] The test results in Table 1 also show that, compared with HfSiO4, the thermal expansion coefficient of the environmental barrier coating material in Example 2 is still well matched with that of the SiC / SiC composite material; the mass change after 100 hours of dry air treatment at 1500℃ is minimal, almost zero, indicating excellent resistance to drying oxidation; the mass change rate after 100 hours of water-oxygen corrosion at 1300℃ is 0.110%, which is 58.6% lower than that of HfSiO4, indicating a significant improvement in resistance to water-oxygen corrosion.

[0112] Compared with HfSiO4, the thermal expansion coefficient of the environmental barrier coating material in Example 3 still matches well with that of the SiC / SiC composite material; the mass change after 100 hours of dry air treatment at 1500℃ is minimal, almost zero, indicating excellent resistance to drying oxidation; the mass change rate after 100 hours of water-oxygen corrosion at 1300℃ is 0.102%, which is 62.6% lower than that of HfSiO4, indicating a significant improvement in resistance to water-oxygen corrosion.

[0113] Compared with HfSiO4, the environmental barrier coating material of Example 4 has a good thermal expansion coefficient matching with SiC / SiC composite material; the mass change after 100h dry air treatment at 1500℃ is extremely small, almost zero, indicating excellent dry oxidation resistance; the mass change rate after 100h water and oxygen corrosion at 1300℃ is 0.125%, which is 54.2% lower than that of HfSiO4, indicating that the water and oxygen corrosion resistance has been greatly improved.

[0114] Compared with HfSiO4, the environmental barrier coating material of Example 5 has a good thermal expansion coefficient matching with SiC / SiC composite material; the mass change after 100h dry air treatment at 1500℃ is extremely small, almost zero, indicating excellent dry oxidation resistance; the mass change rate after 100h water and oxygen corrosion at 1300℃ is 0.092%, which is 66.3% lower than that of HfSiO4, indicating that the water and oxygen corrosion resistance has been greatly improved.

[0115] Compared with HfSiO4, the environmental barrier coating material of Example 6 has a good thermal expansion coefficient matching with SiC / SiC composite material; the mass change after 100h dry air treatment at 1500℃ is extremely small, almost zero, indicating excellent dry oxidation resistance; the mass change rate after 100h water and oxygen corrosion at 1300℃ is 0.111%, which is 59.3% lower than that of HfSiO4, indicating that the water and oxygen corrosion resistance has been greatly improved.

[0116] Compared with HfSiO4, the environmental barrier coating material of Example 7 has a good thermal expansion coefficient matching with SiC / SiC composite material; the mass change after 100h dry air treatment at 1500℃ is extremely small, almost zero, indicating excellent dry oxidation resistance; the mass change rate after 100h water and oxygen corrosion at 1300℃ is 0.108%, which is 60.4% lower than that of HfSiO4, indicating that the water and oxygen corrosion resistance has been greatly improved.

[0117] Compared with HfSiO4, the environmental barrier coating material of Example 8 has a good thermal expansion coefficient matching with SiC / SiC composite material; the mass change after 100h dry air treatment at 1500℃ is extremely small, almost zero, indicating excellent dry oxidation resistance; the mass change rate after 100h water and oxygen corrosion at 1300℃ is 0.097%, which is 64.5% lower than that of HfSiO4, indicating that the water and oxygen corrosion resistance has been greatly improved.

[0118] Compared with HfSiO4, the thermal expansion coefficient of the environmental barrier coating material of Example 9 is still well matched with the SiC / SiC composite material; the mass change after 100h of dry air treatment at 1500 DEG C is extremely small, almost zero, which indicates that the dry oxidation resistance performance is excellent; the mass change rate after 100h of water and oxygen corrosion at 1300 DEG C is 0.101%, which is 63% lower than the mass change rate of HfSiO4, which indicates that the water and oxygen corrosion resistance has been greatly improved.

[0119] Based on the above, the molar ratio of the Al2O3 powder, the HfO2 powder and the SiO2 powder and the sintering temperature and the sintering time in the application are the key steps for the performance of the prepared powder raw material. All of them determine the content of the final product HfSiO4, Mullite, HfO2 and Al2O3, wherein the more the content of the residual HfO2 is, the greater the mass loss rate of the block-shaped ceramic after the hot-pressing sintering in the next step is under the water and oxygen corrosion at 1300 DEG C. Al2O3 plays a role in improving the density, and the more the content of the residual Al2O3 is relative to HfO2, the more excellent the oxidation resistance performance of the block-shaped ceramic is under the dry air treatment at 1500 DEG C. The content of HfSiO4 and Mullite is a key factor affecting the thermal expansion coefficient of the block-shaped ceramic prepared in the next step, because the thermal expansion coefficient of the mixture of the two changes slightly, but the thermal expansion coefficient still remains good match with the SiC / SiC composite material. It should be noted that the thermal expansion coefficient in some literature is written as a fixed value, which is not a precise statement. When measuring the thermal expansion coefficient, the test result of the thermal expansion coefficient is a curve (as shown in Figure 2 ) with the increase of the test temperature. That is to say, the thermal expansion coefficient is a range, rather than an exact fixed value, and the thermal expansion coefficient of the ceramic material will change at different temperatures.

[0120] Obviously, the above-mentioned examples are only part of the examples of the application, rather than all the examples. Based on the examples in the application, all other examples obtained by those skilled in the art without creative labor belong to the protection scope of the application.

Claims

1. A method for preparing an environmental barrier coating material for SiC / SiC composite materials, characterized in that, Includes the following steps: Al2O3 powder, HfO2 powder and SiO2 powder are mixed and then wet ball milled to obtain a slurry. The slurry is dried and then ground to obtain a mixed powder; The mixed powder is sintered at 1350~1550℃ and then ground into powder to obtain an environmental barrier coating material for SiC / SiC composite materials. The molar ratio of Al2O3 powder, HfO2 powder, and SiO2 powder is 1:1~1.5:0.8~1.8; The sintering time for the sintering treatment is 1 to 2 hours.

2. The preparation method according to claim 1, characterized in that, The purity of the Al2O3 powder is ≥99.99 wt.%; and the particle size of the Al2O3 powder is 0.2~0.6 μm.

3. The preparation method according to claim 1, characterized in that, The purity of the HfO2 powder is ≥99.99 wt.%; and the particle size of the HfO2 powder is 3~6 μm.

4. The preparation method according to claim 1, characterized in that, The purity of the SiO2 powder is ≥99.99 wt.%; and the particle size of the SiO2 powder is 1~2 μm.

5. The preparation method according to claim 1, characterized in that, After the sintering treatment, the obtained sintered product is ground to a particle size of 50~80μm.

6. The preparation method according to claim 1, characterized in that, After the slurry is dried, it is ground until the particle size of the mixed powder is 30~60μm.

7. The preparation method according to claim 1, characterized in that, The ball milling aid used in the wet ball milling process is anhydrous ethanol, and the ball milling rate is 20~60 r / min, with a ball milling time of 12~24 h.

8. An environmental barrier coating material for SiC / SiC composite materials prepared by the preparation method according to any one of claims 1-7.

Images