Research on corrosion resistance of an Al-Si coating on a K4104 high-temperature alloy

In order to improve the high temperature corrosion performance of aero-engine blades,the Al-Si coating of a K4104 superalloy was prepared by the thermal diffusion method.After high temperature corrosion and oxidation experiments at 1 000 ℃ for 200 hrs,surface morphology,cross-sectional micrography and chemical composition testing of the Al-Si coating were done using SEM and EDS.Experimental results indicated that the Al-Si coating is transformed into three layers of α-Al2O3,Al-rich β-NiAl and Ni-rich β-NiAl,all of which have good adhesiveness with the basal body.The proper adding of Si and its reasonable distribution in the modified aluminum coating plays a significant role in suppressing the growth of the β-NiAl phase,accelerates the formation of M6C,puts a stay on the activity of elements of W and Mo,delays the degradation of the coating and gives the coating better corrosion and oxidation resistance at high temperatures.