Surface modification of CP-Ti and Ti–6Al–4V alloy by fluidised bed carburisation

Abstract

A fluidised bed carburising process was developed to see the effects on surface modification of CP-Ti and Ti–6Al–4V alloy. The performance of a patented molten salt carburising process was also cited in comparison. A mixture of diamond, graphite and rutile were identified to form on the outermost surface for both processes. The major product at the near surface layer for both processes was carbon deficient titanium carbide TiC_1−x. The lattice constants a_o of TiC_1−x and the associate stoichiometric ratios (1−x) were obtained by Nelson–Riley approach and interpolation respectively. Depth profiles used to quantitatively analysing the effects of processing parameters on the distribution of interstitial elements were achieved by the application of glow discharge optical spectrometry. The enhancement of surface hardness was more pronounced by employing fluidised bed carburising process.