The oxidation of electroless Ni-B and Ni-P coatings in air at 800 to 1000�C

Abstract

The oxidation of electroless Ni-B coatings in air at 800 to 1000°C has been determined by kinetic, X-ray diffraction, and microscopical methods. Some data have also been obtained on the oxidation of Ni-P coatings, the oxidation of nickel, and the effect of Na2SO4 on the oxidation process. All kinetics followed the parabolic oxidation law and the rate increased in the order spectrographically pure nickel, commercially pure nickel, Ni-B, and Ni-P, with the Ni-P oxidizing approximately 1000 times faster than the spectrographically pure nickel. Fine surface deposits of Na2SO4 greatly increase the oxidation rate of all materials except the Ni-P coatings which appear to be immune to hot-corrosion. The nature of the oxidation processes are discussed.