High temperature oxidation behaviour of autocatalytic Ni-P-BN(h) coatings

This paper investigates the high temperature oxidation behaviour of autocatalytic Ni-P-BN(h) coating when is applied directly on a carbon steel (AISI-1018) substrate and compares the results to when this coating layer is applied on an electroless Ni-P coated carbon steel substrate. For this purpose, high temperature oxidation tests were conducted at three temperatures (500, 600 and 700 °C) in air and for up to 96 h. Oxidation mass changes for each test condition and at each specific time interval were measured. Statistical techniques were used to calculate the oxidation rate constants (k) and growth-rate time constants (a) for all coatings and the results were used to formulate power equations for oxidation mass change as a function time. The confidence intervals associated with the tests were also calculated. The results showed an improvement in high temperature oxidation performance of the Ni-P-BN(h) coating when it was applied on a Ni-P coated carbon steel substrate as compared to when it was directly applied on the carbon steel substrate.