High Temperature Oxidation and Wear Resistance of Y-modified Hot Dipping Aluminized Coating on SCH12 Steel

摘要

Microstructures, high-temperature oxidation and wear resistance of hot dipping Al-Si-Y coating on SCH12 heat resistant cast steel were investigated in this study. The aluminized coating was characterized by scanning electron microscopy (SEM), energy dispersive X-ray spectrometry (EDX) and X-ray diffraction (XRD). The results showed that the coating was composed of the Al-rich outer layer and the intermetallics inner layer. In the Al-rich layer, some Y-rich precipitates and Fe-Al-Si-Cr precipitates could be observed. The intermetallics layer presented three layers induced by the increase of Fe, Cr, Ni content and the corresponding decrease of Al, Si content. The oxidation tests were conducted in still air at 850 °C for up to 100 h. After oxidation, a top oxide scale composed of mainly a-AI2O3, AI5Y3O12 was formed on the steel surface. The intermetallics beneath the oxide scale consisted of mainly FeAl and small amount of Fe2Al5 and Cr3Si phase. The mass gain of the coated and uncoated SCHlsteel is 0.45 mg/cm2 and 0.57 mg/cm2, respectively. The wear resistance was investigated using a high-temperature pin-on-disc tribometer at 650 °C. The wear rate for the coated and uncoated steel is 0.45 μmVμm-N and 3.01 μm3/μm-N, respectively. The high temperature wear tests and oxidation tests results demonstrated that the yttrium-modified aluminized specimen had significantly improved high-temperature wear resistance and equivalent oxidation resistance compared with the original SCH12 specimen.