材料期刊网

A Cr0.50Al0.50N coating has been prepared by a reactive-magnetron-sputtering method on alloy K38G. The coating possesses mainly the B1 type with a small amount of B4-type crystal structure phase. Isothermal oxidation tests were performed at 900-1,100 degrees C for 20 h by thermogravimetric analysis (TGA) in air. The results reveal that the coated samples have much lower mass gain than that of the bare alloy. The parabolic rate constants of the coated samples decrease by 2 orders of magnitude compared with the bare alloy at 1,000 and 1,100 degrees C. During the oxidation of the coated samples below 1,000 degrees C, the main oxide is Cr2O3, but above 1,000 degrees C, the scale changes to alpha-Al2O3. The observed oxidation behaviors demonstrate that the Cr0.50Al0.50N coating can provide good protection against corrosion over a wide temperature range.