High Temperature Performance And Antioxidant Protection Mechanism Of Metal Matrix Composite Coating

Stainless steel is the most widely used corrosion resistance engineering material.Stainless steel contains antioxidant element Cr, which can form a continuous oxide film onthe surface of the basic material, maintaining its using performance under high temperature.But when the temperature is higher than900℃, the Cr2O3film will loss by evaporation onsurface, which makes the basic metal expose to an oxidizing atmosphere, so stainless willloss antioxidant capacity. Aiming at the problem of high temperature oxidation of thestainless steel, by the way of electric arc spraying technology, the subject sprays the metalmatrix composite coating which is rich in Cr and Al elements on surface of06Cr18Ni10Nstainless steel, the composite coating specimen experienced1100℃,350h continuousoxidation. the high temperature oxidation of their performance, the microstructure ofcomposite coating, the high temperature protection mechanism will be investigated.The experimental results show that: the composite coating can effectively protect thebasic metal; the inner45CT coating provide enough Cr for the protection system. The outerAl coating not only increases the Al content in the system, but also helps to improve theability of self sealing holes in composite coating. Three kinds of composite coating can allensure adequate levels of Al, Cr elements in the surface coating system, form an oxideprotective film based on Al2O3on the coating, prevent oxidation medium inward invading;A laminar distribution of AlN diffusion barrier layer will be formed in the base metal,delaying the concentrations of Al, Cr antioxidant element reduce in the coating system, so that the composite coating can maintain a lasting protection ability in high temperatureoxidation atmosphere.Compare the three kinds of coating, in coating of45ct/AlSi, Si element can improvethe stability of oxide film. In coat of45ct/Mo/Al, Mo element is extremely to mobile,which play a role of diffusion barrier. Their protective effects on base metal is better thanpure Al coating, the coating thickness change is small, the diffusion layer develops slowly.However, the healing ability of45ct/Al coating is poor when cracks appear.