Surface Hardening of Titanium by Using a Simplified Carbon and Nitrogen Diffusion Technique with Steel and Carbon Powders

Abstract

Commercially pure titanium plates were embedded in mixtures of steel and activated carbon powders and then heated at 1273 K for 3.6 ks in a nitrogen flow. During this simplified treatment, a Ti(C, N) layer with a thickness of approximately 10 µm formed on the titanium surface. The surface hardness of the titanium plates coated with the Ti(C, N) layer was more than HV = 1000 regardless of the steel powder ratio in the mixture. Although a Ti(C, N) layer formed upon heat treatment with the activated carbon powder alone, addition of the steel powder led to an increase in the surface hardness and layer thickness. From X-ray diffraction results, Ti(C, N) began to form on the titanium plate heat-treated at 1073 K and became a complete layer at higher heating temperatures. Instead of activated carbon, the use of graphite with added alumina as a reliable anti-sintering agent had no negative effects on the formation of the Ti(C, N) layer.