PRODUCTION OF TITANIUM CARBIDE FILMS BY REACTIVE ION PLATING AND EVALUATION OF FILM CORROSION-RESISTANCE

Transition metal carbide is expected to have a new application in the future as a corrosion resistant material against nonoxidizing acids. The purpose of this investigation is to evaluate the corrosion resistance of titanium carbide in sulfuric acid. For this purpose, titanium carbide films of various compositions were produced by reactive ion plating. The deposition rate and carbon content of the product films tended to increase with an increase in the flow rate of acetylene as a reactive gas at a constant electron beam current for evaporating titanium. The increase in the acetylene flow rate also led to great improvement in the corrosion resistance of the product films. The potential/current density curves showed that the maximum of the active dissolution current decreased exponentially with the rate increase in the range of 0-2.80 x 10(-7)m3.s-1. The most corrosion resistant titanium carbide film, produced at 6.20 x 10(-7)m3.s-1, has an extremely low current density, e.g., 3.6 x 10(-4)A.m-2 at 0.5 V vs. Ag/AgCl, which is less than 1/5000 of the titanium film current density. The corrosion of the titanium carbide film was apparently inhibited even in 1 kmol.m-3 H2SO4 at 373 K.