Preparation method of ZrB2 / ZrO2 gradient composite SiC ceramic-based material

Abstract

The invention provides a preparation method of a ZrB2 / ZrO2 gradient composite SiC ceramic-based material, and belongs to the field of ultrahigh-temperature ceramic materials. The preparation method comprises the following steps: firstly, adding ZrB2 powder and an inorganic adhesive according to a certain proportion to prepare ZrB2 slurry, brushing the slurry on the surface of the SiC ceramic-based material, and then drying and carrying out low-temperature heat treatment; zrO2 powder and an inorganic binder are added according to a certain proportion to prepare ZrO2 slurry, the slurry is brushed on the surface of the ZrB2-coated SiC ceramic-based material, and finally drying and high-temperature heat treatment are carried out, so that the ZrB2 / ZrO2 gradient composite SiC ceramic-based material with a certain size and anti-oxidation and heat-insulation performance can be obtained. The preparation method has the advantages that the preparation method is simple and feasible, and the prepared ZrB2 / ZrO2 gradient composite SiC ceramic-based material is uniform in surface structure, high in oxidation resistance and good in heat insulation performance.

Description

Technical Field

[0001] The invention belongs to the technical field of ultra-high temperature ceramic materials, and specifically relates to a method for preparing a ZrB2 / ZrO2 gradient composite SiC ceramic-based material. Technical Background

[0002] SiC ceramic-based composites are a new type of thermal structural functional integrated material that combines the performance advantages of metal materials, ceramic materials and carbon materials. It has the characteristics of material structure integration and multi-scale structure. Through the optimized design of each structural unit, a synergistic effect is produced, and high performance and a reasonable match of various performances can be achieved. It is one of the most promising key thermal structural materials for high-temperature components of high thrust-to-weight ratio aircraft engines. Studies have shown that the use of SiC ceramic-based composites in hot end components such as combustion chambers, turbines, afterburners and nozzles can increase the engine operating temperature by 300~500℃, reduce the structure weight by 50%~70%, and increase the thrust by 30%~100%.

[0003] Therefore, how to further improve the oxidation resistance and operating temperature of SiC ceramic-based composites is the premise and key to ensure their normal use. It is also a problem that needs to be solved urgently and the research focus of scholars and researchers around the world for better engineering applications. Summary of the invention

[0004] There are many studies on the modification of coatings of SiC ceramic-based composite materials, and the main means is to use the coating to block O2 from contacting the substrate and diffusing into the substrate; therefore, preparing antioxidant and heat-insulating coatings on the surface of SiC ceramic-based materials has become a major method and research hotspot; the purpose of the present invention is to provide a method for preparing a ZrB2 / ZrO2 gradient composite SiC ceramic-based material, the preparation method is simple and feasible, and the production efficiency is high. The prepared ZrB2 / ZrO2 gradient composite SiC ceramic-based material has a uniform surface structure, strong antioxidant performance and good thermal insulation performance.

[0005] The present invention adopts the following technical scheme to achieve the above-mentioned purpose: A method for preparing a ZrB2 / ZrO2 gradient composite SiC ceramic-based material, the specific process steps of the preparation method are: a. Preparation of ZrB2 coating slurry: Add ZrB2 powder and inorganic binder into a beaker at a mass ratio of 6-8:4-2, and then stir evenly on a magnetic stirrer to obtain ZrB2 coating slurry; b. Apply the prepared ZrB2 coating slurry to the surface of the SiC ceramic-based material, repeat this step 1 to 3 times, dry it, and perform low-temperature heat treatment at a temperature of 400 to 550°C to obtain a SiC ceramic-based composite material coated with a ZrB2 anti-oxidation coating; c. Preparation of ZrO2 coating slurry: Add ZrO2 powder and inorganic binder into a beaker at a slurry ratio of 8:8~2, and then stir evenly on a magnetic stirrer to obtain ZrO2 coating slurry; d. Then, the prepared ZrO2 coating slurry is brushed onto the surface of the SiC ceramic-based composite material coated with the ZrB2 anti-oxidation coating, and then dried and subjected to high-temperature heat treatment at a temperature of 800-1400°C to obtain a ZrB2 / ZrO2 gradient composite SiC ceramic-based material with anti-oxidation and heat-insulating properties.

[0006] The inorganic binder is one of silica sol, zirconium sol, aluminum dihydrogen phosphate and water glass.

[0007] The drying temperature is 80-120°C.

[0008] The drying time of the ZrB2 coating is 4 to 8 hours.

[0009] The low-temperature heat treatment holding time of the ZrB2 coating is 30min~60min.

[0010] The present invention discloses a method for preparing a ZrB2 / ZrO2 gradient composite SiC ceramic-based material. An inorganic binder is selected to prepare a coating slurry. This is mainly because the ceramic coating in the present invention not only needs to be sintered and cured at high temperature, but also mostly needs to be used in high temperature environments. There are many varieties of binders with different components, and they are mainly divided into organic binders and inorganic binders. Among them, the poor heat resistance and anti-aging properties of organic binders limit their wide application. Therefore, organic binders are not suitable for binders of high-temperature ceramic coatings.

[0011] The advantages of first applying ZrB2 coating on the surface of SiC ceramic-based material and then applying ZrO2 coating are: first, the bonding strength between the interfaces. ZrB2 as the inner coating and the SiC substrate are both non-oxides and are compatible; ZrO2 as the outer coating and ZrB2 as the inner coating are both zirconium compounds and are compatible; second, with the increase of the operating temperature, the inner coating ZrB2 can self-generate ZrO2, which can not only tightly bond with the outer coating ZrO2 but also generate ZrSiO4 with the oxidation product SiO2 of the substrate SiC to improve the density of the anti-oxidation coating; third, the outer coating ZrO2 acts as a high-temperature thermal insulation coating, which can not only improve the thermal insulation performance of the SiC ceramic substrate but also serve as a dense layer to block oxygen. The inner coating ZrB2 acts as a high-temperature oxygen-consuming coating, which can consume the oxygen entering from the outside and prevent the substrate from being oxidized.

[0012] The preparation method of the invention is simple and feasible, and has high production efficiency. The prepared ZrB2 / ZrO2 gradient composite SiC ceramic-based material has uniform surface structure, strong antioxidant performance and good thermal insulation performance. DETAILED DESCRIPTION

[0013] The present invention is described in conjunction with the embodiments provided: Embodiment 1:

[0014] Preparation of ZrB2 coating: 21 g of ZrB2 powder and 9 g of silica sol were weighed and mixed according to a mass ratio of 7:3, and stirred evenly with a magnetic force. The prepared slurry was evenly applied to the surface of a 30 mm × 20 mm × 5.5 mm SiC ceramic-based sample with a brush, and placed in a constant temperature drying oven at 100 ° C for 4 hours to obtain a coating sample blank; the coating sample blank was then placed in a high-temperature re-firing furnace and kept at 450 ° C for 30 minutes to obtain a SiC ceramic-based composite material coated with a ZrB2 anti-oxidation coating; Preparation of ZrO2 coating: 16 g of ZrO2 powder and 4 ml of silica sol were weighed respectively in a slurry ratio of 8:2, mixed and stirred evenly with a magnetic force, then the prepared slurry was evenly applied to the surface of the SiC ceramic-based sample coated with the ZrB2 antioxidant coating with a brush, and placed in a constant temperature drying oven at 100°C for drying to obtain a coating sample blank; then the coating sample blank was placed in a high-temperature re-firing furnace and kept at 1000°C for 2h to obtain a ZrB2 / ZrO2 gradient composite SiC ceramic-based material with antioxidant and heat-insulating properties. Embodiment 2:

[0015] (1) Preparation of ZrB2 coating 16g of ZrB2 powder and 4g of silica sol were weighed and mixed according to a mass ratio of 8:2, and stirred evenly with magnetic force. The prepared slurry was evenly applied to the surface of the 30mm×20mm×5.5mm SiC ceramic-based sample with a brush, and placed in a constant temperature drying oven at 100℃ for 6h to obtain a coating sample blank. The coating sample blank was then placed in a high-temperature re-sintering furnace and kept at 450℃ for 60min to obtain a SiC ceramic-based composite material coated with a ZrB2 anti-oxidation coating.

[0016] (2) Preparation of ZrO2 coating: According to the slurry ratio of 8:2, 16g of ZrO2 powder and 4ml of silica sol were weighed and mixed with magnetic stirring, and then the prepared slurry was evenly applied to the surface of the SiC ceramic-based sample coated with ZrB2 anti-oxidation coating with a brush, and placed in a constant temperature drying oven at 100℃ for drying to obtain a coating sample blank. Then, the coating sample blank was placed in a high-temperature re-sintering furnace and kept at 1000℃ for 2h to obtain a ZrB2 / ZrO2 gradient composite SiC ceramic-based material with anti-oxidation and heat insulation properties. Embodiment 3:

[0017] (1) Preparation of ZrB2 coating Weigh 21g of ZrB2 powder and 9g of silica sol in a mass ratio of 7:3, mix them and stir them evenly with magnetic force, then brush the prepared slurry evenly on the surface of 30mm×20mm×5.5mm SiC ceramic-based sample with a brush, and put it in a constant temperature drying oven at 100℃ for 4h to obtain the coating sample blank. Then put the coating sample blank into a high-temperature re-sintering furnace and keep it at 500℃ for 30min to obtain the SiC ceramic-based composite material coated with ZrB2 anti-oxidation coating.

[0018] (2) Preparation of ZrO2 coating According to the slurry ratio of 8:2, 16g of ZrO2 powder and 4ml of silica sol were weighed and mixed, and stirred evenly with magnetic force. Then, the prepared slurry was evenly applied to the surface of the SiC ceramic-based sample coated with ZrB2 anti-oxidation coating with a brush, and placed in a constant temperature drying oven at 100°C for drying to obtain a coating sample blank. Then, the coating sample blank was placed in a high-temperature re-firing furnace and kept at 800°C for 2h to obtain a ZrB2 / ZrO2 gradient composite SiC ceramic-based material with anti-oxidation and heat-insulating properties. Embodiment 4:

[0019] (1) Preparation of ZrB2 coating 12g of ZrB2 powder and 8g of silica sol were weighed and mixed according to the mass ratio of 6:4, and stirred evenly with magnetic force. Then, the prepared slurry was evenly applied to the surface of 30mm×20mm×5.5mm SiC ceramic-based sample with a brush, and placed in a constant temperature drying oven at 80℃ for 6h to obtain the coating sample blank. Then, the coating sample blank was placed in a high-temperature re-sintering furnace and kept at 400℃ for 60min to obtain the SiC ceramic-based composite material coated with ZrB2 anti-oxidation coating.

[0020] (2) Preparation of ZrO2 coating Weigh 16g of ZrO2 powder and 8ml of silica sol in a slurry ratio of 8:4, mix them and stir them evenly with magnetic force, then brush the prepared slurry evenly on the surface of the SiC ceramic-based sample coated with ZrB2 anti-oxidation coating, and put it into a constant temperature drying oven at 120℃ for drying to obtain the coating sample blank. Then put the coating sample blank into a high-temperature re-firing furnace and keep it at 1200℃ for 2h to obtain the ZrB2 / ZrO2 gradient composite SiC ceramic-based material with anti-oxidation and heat insulation properties.

Claims

1. A method for preparing a ZrB2 / ZrO2 gradient composite SiC ceramic-based material, characterized in that: The specific process steps of the preparation method are: a. Preparation of ZrB2 coating slurry: Add ZrB2 powder and inorganic binder into a beaker at a mass ratio of 6-8:4-2, and then stir evenly on a magnetic stirrer to obtain ZrB2 coating slurry; b. Apply the prepared ZrB2 coating slurry to the surface of the SiC ceramic-based material, repeat this step 1 to 3 times, dry it, and perform low-temperature heat treatment at a temperature of 400 to 550°C to obtain a SiC ceramic-based composite material coated with a ZrB2 anti-oxidation coating; c. Preparation of ZrO2 coating slurry: Add ZrO2 powder and inorganic binder into a beaker at a slurry ratio of 8:8~2, and then stir evenly on a magnetic stirrer to obtain ZrO2 coating slurry; d. Then, the prepared ZrO2 coating slurry is brushed onto the surface of the SiC ceramic-based composite material coated with the ZrB2 anti-oxidation coating, and then dried and subjected to high-temperature heat treatment at a temperature of 800-1400°C to obtain a ZrB2 / ZrO2 gradient composite SiC ceramic-based material with anti-oxidation and heat-insulating properties.

2. The method for preparing a ZrB2 / ZrO2 gradient composite SiC ceramic-based material according to claim 1, characterized in that: The inorganic binder is one of silica sol, zirconium sol, aluminum dihydrogen phosphate and water glass.

3. The method for preparing a ZrB2 / ZrO2 gradient composite SiC ceramic-based material according to claim 1, characterized in that: The drying temperature is 80-120°C.

4. The method for preparing a ZrB2 / ZrO2 gradient composite SiC ceramic-based material according to claim 1, characterized in that: The drying time of the ZrB2 coating is 4 to 8 hours.

5. The method for preparing a ZrB2 / ZrO2 gradient composite SiC ceramic-based material according to claim 1, characterized in that: The low-temperature heat treatment holding time of the ZrB2 coating is 30min~60min.