Method for preparing high-temperature composite coating on niobium-based surface by utilizing sol-gel method

Abstract

The invention discloses a method for preparing a high-temperature composite coating on a niobium-based surface by utilizing a sol-gel method. The method comprises the following steps: step 1, pretreating a niobium-based alloy specimen; step 2, preparing an intermediate bonding layer of the niobium-based alloy specimen in a chemical treatment manner; step 3, preparing Al2O sol-gel; step 4, performing dip-coating and drying; and step 5, performing vacuum heat treatment, thereby obtaining the high-temperature-resistant oxidation coating containing the intermediate bonding layer. The method has the advantages that 1, the process equipment is simple and easy to operate; the components of the coating are uniform and are controllable in thickness; the influence of the high temperature on the tissue property of a niobium substrate is avoided due to the adoption of a low heat treatment temperature; 2, the internal stress caused by the difference of thermal expansion coefficients between the substrate and the coating is effectively reduced under the action of the intermediate bonding layer, so that the combination between the coating with the substrate is improved; the capability of the coating for protecting the substrate from being oxidized is improved.

Description

technical field [0001] The invention belongs to the technology of preparing a high-temperature anti-oxidation coating on an alloy substrate. Specifically, it is a method for preparing a composite high-temperature coating by a niobium-based surface sol-gel method. The method uses the preparation of an intermediate binding layer to improve the sol-gel process. [0002] The glue method is used to prepare the combination between the coating and the substrate, so as to achieve the purpose of improving the oxidation resistance of the coating. Background technique [0003] With the further development of aerospace technology and the continuous improvement of the thrust-to-weight ratio of aerospace vehicles, the operating temperature of aircraft engines can reach more than 1200 ° C, and rockets can reach higher temperatures. Traditional superalloys can no longer meet people's needs. The excellent properties of niobium alloy make it one of the important candidate materials for high...

AI Technical Summary

Problems solved by technology

Al 2 o 3 The coefficient of thermal expansion is 8.3~9.3×10 -6 K -1 , the thermal expansion coefficient of the niobium-based alloy is 7.2×10 ﹣6 K ﹣1 , due to the difference in the thermal expansion coefficient of the coating and the niobium alloy and the different lattice structure, internal stress will be generated at high temperature, which will cause the coating to crack and fall off and lose the role of protecting the substrate

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