1990 Volume 39 Issue 12 Pages 674-679
Titanium nitride has been used as corrosion-resistant films in recent years. In this investigation, the effect of nitrogen content of titanium nitrides on the corrosion resistance in H2SO4 was examined. Titanium nitride powders having various compositions were synthesized by the reaction of titanium hydride with nitrogen gas and used as specimens. X-ray diffraction showed that the nitrides of 17.5-29.0at% N had the mixed structure of α-Ti and Ti2N, those of 33.6-37.5at% N the mixed structure of Ti2N and TiN, and those of 40.5-48.9at% N the single phase of TiN. The relationship between the lattice parameter “a” of TiN and the nitrogen content was expressed as the equation a(nm)=1.74×10-4·N(at%)+0.4153. The change in the amount of dissolved titanium from the powders with time in 1kmol·m-3 H2SO4 at 373K fitted to the equation 1-(1-R)1/3=k·t, where R was the weight loss ratio of titanium. The rate constant k decreased with increasing nitrogen content and corrosion was apparently inhibited when the nitrogen content of titanium nitrides was more than 40at%. On specimens with nitrogen content less than 40at%, corrosion occured preferentially on Ti2N in the mixed structure.