Study On Preparation And Protective Mechanism Of Thermal Sprayed Coatings For High Temperature Oxidation Protection

Steel has a very high value for economic, it is currently the most widely used structural materials. However, in the high temperature environment, steel manufacturing equipment or part premature damage failure due to high temperature oxidation or corrosion problems, High temperature oxidation of steel problem, in this article, it improve resistance to high temperature oxidation properties of iron and steel materials, extending the life of their by using electric arc spraying technology in preparation of metal matrix composite coating on steel parts. Though the composite coating structure analysis and optimization of composite coating structural design, we discusse the high-temperature composite coating by thermal spraying protection mechanisms on this basis.With electric arc spraying technology, we prepared Fe-Cr-Al and SI-Al alloy and pure combination of aluminum alloy coating and its composite coating in low carbon steel substrate surface, and closed pore coated after using several processing methods. With the help of scanning electron microscope (SEM) and x-ray diffraction analysis we found that Aluminum-silicon layer in composite coatings have melted, part of it spreading into the internal coating, increased aluminum content in iron-chromium-aluminum, closed pore in the iron-chromium-aluminum, so as to slow the oxidation process under the condition of heating in 900℃. The Al-Si coating of Fe-Cr-Al coating formation diffusion layer thickness is about 0.4mm, 900℃3h. Fe-Cr-Al diffusion coating alloy elements in enter the matrix, Cr for the formation of diffusion layer depth is 20μm-25μm. Junction formation in Fe-Cr-Al coating and substrate transitional layer increased the bonding strength between coating and substrate. The combination mode of Fe-Cr-Al coating combined and low carbon steel has chananged from mechanical combination to combination of metallurgy. As the heating time extended, in-situ synthesis of oxide coating/substrate interface gradually increased, after 200 hours oxides with thickness is about 10μm-20μm Oxide layers effectively prevents the diffusion process of alloying elements, helps maintain composite coating in the antioxidant content of effective concentrations of alloying elements, also increasing the reliability of the metal coating and substrate binding.Though the high temperature oxidation test thermally sprayed composite coatings significantly improved the resistance of high temperature oxidation of steel, up to 2400h hanging piece of sponge titanium production environment test results proved effective antioxidant protection properties of composite coating, provides valuable reference for this practical application of the technology.