Nickel-based alloys was widely used in many areas such as:aviation, aerospace, marine, petroleum, chemical and a variety of key structural components, because of the nature of high strength, corrosion resistance and other characteristics. As modern power plants of a variety of gas turbines, especially aero-engine turbine blades, heavy-duty gas turbine of the turbine blades, long-term withstand corrosion and high temperature oxidation of gas, usually the surface is damaged. the problem of hot corrosion and high temperature oxidation of hot end components are its basic and primary form of failure. The method to solve this problem is mainly coating on the alloy sueface in order to not only improve the corrosion resistance but also keep high mechanial properties. In this paper, X-ray diffraction (XRD), scanning electron microscopy (SEM), cydic oxidation and buried salt method has been used to investigate the microser corrosion properties phase constitution, oxidation and hot corrsion behaviors.The results show that there are not pores and cracks in the layer, and matrix interface is clear and smooth. The thickness of the layer thickening with the incresing time. the main phase of the layer changes gradually from Ni2Al3 to NiAl and then to Ni3Al phase at 1000 degrees. The cobalt-aluminum layer increases the CoAl phase than the aluminized layer. The interfrance between the layer and the matrix is clear and smooth.The hot corrosion results show that the K488 alloy is seriously corrosed in the 75%Na2SO4+25%NaCl at 900℃. The K488 alloy suffered from catas-trophic hot corrosion and serious internal oxidation and sulfidation; K488 alloy with Al coating was the general corrosion resistance, due to the presence of mixed oxide of Al2O3 and Co2Cr2O4; because of the formation of protec-tive Al2O3 scale, Co-Al coating had excellent resistance to hot corrosion.High-temperature oxidation results show that the oxidation kinetics curve of the K488 alloy was approximately linear within the 40 hours. After 40 hours, the oxide layer fell off. Porous oxide surface composed of of TiO2 and Cr2O3 shows poor oxidation resistance. After aluminizing and Co-Al co-infiltration, the kinetics curve of treated alloys was parabolic. Oxideproducts of K488 alloy with aluminizing coating were the mixtions of Al2O3 and TiO2. Oxide products of K488 alloy with Co-Al co-infiltration coating was a mixtureof Al2O3, Co2CrO4 and TiO2. |