Preparation method for forming spinel coating on surface of alloy

Abstract

The invention relates to a preparation method for forming a spinel coating on the surface of an alloy. Mn and Cr alloy elements are infiltrated into the surface of the alloy by adopting the elemental co-infiltration process, the concentration of the surface elements, especially Mn, is increased, and then the surface of the material is subjected to in-situ oxidation through the low oxygen partial pressure method, to preferentially generate a dense manganese chrome spinel protective film. The protective film can effectively improve the high temperature oxidation resistant, anti-carburizing and anti-coking performances of the material, thereby prolonging the service life or coke cleaning period of the material.

Description

[0001] 【Technical field】 [0002] The invention relates to the technical field of coatings, in particular to a preparation method for forming a spinel coating on the surface of an alloy. [0003] 【Background technique】 [0004] Alloys with high Cr and Ni content are commonly used in high-temperature environments. Cr can improve oxidation resistance and thermal strength, and Ni can improve the strength of steel while maintaining good plasticity and toughness. Rust and heat resistance. But at higher than 1000 ° C and in the presence of CO, CO 2 、H 2 O, CH 4 、H 2 In high-temperature environments such as gases, Cr on the surface of Cr-containing alloys 2 o 3 The protective oxide layer is prone to volatilization and peeling, and serious carburizing reactions can occur in the carburizing atmosphere, thereby deteriorating the performance of the substrate. In addition, at high temperatures, petroleum hydrocarbons in chemical processes tend to interact with catalytic elements Ni,...

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Problems solved by technology

[0006] The spinel protective layer prepared by the above-mentioned patent can protect the substrate to a certain extent, but it has the following disadvantages: the Mn element content of the alloy material substrate is about 1%, while the Mn content in the ideal spinel layer formed on the surface is as high as 24% or 34% (without considering the O element), the spinel coating prepared solely by the outward diffusion of the Mn element in the matrix is ​​relatively thin, and it is not an ideal stoichiometric ratio of MnCr 2 o 4 ; There is a big difference between the performance of the ceramic coating and the furnace tube material, and the coating life is short; the rare earth is easy to burn, and the relatively high Al, Si and other elements inside the matrix affect the mechanical properties and welding performance of the furnace tube

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