Gradient ceramic coating on steel substrate and its preparation process

Abstract

The present invention relates to one kind of gradient Fe / Al2O3 material coating on steel substrate part and its preparation process. The coating consists of one inner layer, one middle layer and one outer layer, and has Al2O3 content gradually raised from 10-20 wt% in the inner layer to 100 wt% in the outer layer, Fe content gradually lowered from 65-85 wt% in the inner layer to 0 wt% in the outer layer, and Al content gradually lowered from 5-15 wt% in the inner layer to 0 wt% in the outer layer. The coating is prepared through spraying process to form the inner layer and the middle layer, and sol-gel process to form the outer layer with painted Al(OH)3 sol. The coating is wear resistant, corrosion resistant, high in high temperature oxidation resistance and high in high temperature heat stability, may be well matched physically and chemically with steel base in less macrostress and moderated interface combining strength.

Description

(1) Technical field [0001] The invention relates to a steel-based ceramic gradient material coating, in particular to a method for coating Fe-Al / Al on the surface of steel-based components. 2 o 3 Gradient material coatings, and methods for their preparation. (2) Background technology [0002] At present, steel is one of the most widely used materials in engineering, but due to its limitations in high temperature resistance, corrosion resistance, wear resistance, etc., many steel parts in metallurgy, chemical industry, machinery and other industries have been exposed to high temperature, wear and tear for a long time. When used in a severely corrosive working environment, the entire component often fails due to local wear and corrosion damage on the surface, resulting in hundreds of millions of dollars in economic losses every year. Ceramics have excellent properties such as high hardness, wear resistance, and stable chemical properties, but their toughness is low. It can b...

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Problems solved by technology

However, the plasma spraying and laser cladding plasma spraying processes are complex and not suitable for large-scale production. Explosive spraying is expensive and the deposition rate is low. Therefore, the application is limited to a certain extent, and there is unstable γ-Al 2 o 3 Crystal form and difficulty in densification, etc., and because the thermal expansion coefficient and elastic modulus of metal and ceramics do not match, the bonding strength between the substrate and the coating is low, and cracking or peeling often occurs during use.

Therefore, the thermal stress at the interface between ceramics and metals has not been fundamentally eliminated or eased, and the examples of successful application in engineering have not yet been reported.

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