Study On High-Temperature Property And Principle Of 45CT Coating

Currently the study on high temperature oxidation and corrosion resistant coating focused on the surface of the coating mechanism of high temperature oxidation and high temperature corrosion, but the issue about combination of coating and substrate is not specifically studied. Transition layer exists or not, the performance and role of transition layer is no specific analysis. The subject is the use the way of electric arc spraying spraying 45CT and Ni-Cr coating, doing the experiment of high temperature oxidation and corrosion at 900℃,1000℃,1100℃, and measurement of quality of weight gain, the oxidation and corrosion kinetics analysis. Using scanning electron microscopy, X-ray diffraction, optical microscopy to observe the surface morphology, structure, existing specific phase, then studying the mechanism of high temperature oxidation resistance and high temperature corrosion resistance, compared 45CT and Ni-Cr coating high temperature oxidation resistance and high temperature corrosion resistance. On the coating for hole sealing processing, analyze the function of the hole sealing agent. The emphasis is observing combination between the coating and the substrate, the existence of transition layer, the performance of transition layer.The results showed that 45CT coating and Ni-Cr coatings have good high temperature oxidation resistance and high temperature corrosion resistance, because the Cr content of 45CT is higher than ordinary Ni-Cr, formation of Cr₂O₃ is dense uniform, fine grain size, So 45CT coating is greenish, the performance of oxidation resistance and corrosion resistance is better than ordinary Ni-Cr coating, and compared to Ni-Cr alloy coating, it has certain advantages; the mechanism 45CT coating and Ni-Cr coating high temperature oxidation and high temperature corrosion resistance is the formation of Cr₂O₃ coating and NiCr₂O₄ has excellent high temperature oxidation and corrosion resistance and protect the substrate; the high temperature oxidation resistance and high temperature corrosion resistance of the hole sealing coating At the same time, formation of transition layer between the coating and the substrate, it mostly contain Ni-Cr-Fe,[Fe,Ni],Fe-Cr, not only proved it is metallurgically bonded between the coating and substrate to improve the binding force between the matrix and the coating, and it is raising capability of the high temperature oxidation resistance and high temperature corrosion resistance. And with time, increasing the diffusion that the coating goes to the substrate, transition layer thickness increases, the bonding force between the matrix and the coating is raising,and capability of the high temperature oxidation resistance and high temperature corrosion resistance is better. it is of great significance to the combination of coating and the bonding.