The effect of primary electroplated Nickel layer on aluminizing of AISI 316 stainless steel and study of its high temperature oxidation behavior

Surface alloying of aluminum into AISI 316 austenitic stainless steel was prepared by electroplating nickel layer followed by a single-step high-activity aluminizing process. After aluminization, the surface microstructure of stainless steel consist of β-(Fe, Ni)Al as matrix with β-FeAl+ α-(Fe, Cr) precipitates. Aluminized coating on specimens with 10 and 20 μm primary thickness of nickel layer made up of two layers; a thin layer of β-NiAl and a β-(Fe, Ni)Al layer. In the case of the nickel layer with thickness of 50 μm, the coating showed three layers: β-NiAl and Ni3Al phase and layer of remained Ni was also determined. Oxidation test at 950ºC was carried out for 157 hours to evaluate the coatings. By increasing primary electroplated nickel to 100μm, the weight gain of aluminized specimens decreased from 2.95 to 1.44g/cm2. Surface morphology of oxide scale on Th 100 after oxidation for 160 h at 950°C showed the stable α-Al2O3 and it can be confirmed from the XRD results.