Oxidation Behavior of AISI ۳۱۶ Steel Coated with Ni-P-TiO۲-Al۲O۳ Composite Coating

Austenitic steels have numerous applications in high-temperature environments. The thermally-grown chromia scale on the steel surface may be-come unstable at high temperatures and as a result, oxidation resistance of steel will decrease. A potentially method for improving oxidation properties is the use of composite coatings using techniques such as electroplating. In the present study, Ni-P-TiO۲-Al۲O۳ composite coating was deposited on AISI ۳۱۶ steel sub-strate by electroplating. The as-coated samples were examined with scanning electron microscopy (SEM) with energy dispersive spectroscopy (EDS). X-Ray diffraction (XRD) was also used to identify the formed phases in the as-coated structures. In order to evaluate oxidation behavior, isothermal oxidation and cy-clic oxidation were conducted at ۸۰۰ ºC. Isothermal oxidation of uncoated steels revealed higher weight gain in comparison with Ni-P-TiO۲-Al۲O۳ composite-coated samples. The coating layer limited the outward diffusion of Cr cation and the inward diffusion of oxygen anion and resulted in better oxidation resistance. According to the results of cyclic oxidation, coated substrates demonstrated excel-lent resistance against spallation and cracking.