EFFECT OF Al_2O_3 COATING ON HOT CORROSION OF SUPERALLOY K38G
Al_2O_3涂层对高温合金K38G热腐蚀的影响

Hot corrosion behavior of Ni-base superalloy K38G with Al_2O_3 coating was investigated in air at 1123K by applying (Na,K)_2SO_4 salt deposit. The Al_2O_3 coating was prepared by means of DC reactive sputtering, which improved the corrossion resistance of superalloy K38G. Both the basic fluxing and the oxidation-sulfidation occurred during the incubation period of the uncoated specimensm whereas they were alleviated by the application of the Al_2O_3 coating. For example, the depth of internal salfidation layer was minimized 3 times. It was also observed that the Al_2O_3 coating was scarcely thinned during corrosion. Some (Al,Cr)_2O_3 pillars and the TiO_2 needles were found at the coating / salt interface for the coated specimen. The mechanisms of the influence of the Al_2O_3 coating on hot corrosion of K38G alloy was discussed.