Simultaneous Boronizing and Carburizing of Titanium via Spark Plasma Sintering

Abstract

This study focused on a diffusion coating method for the formation of a hard layer with excellent adhesion through the formation of an interlayer and a gradient layer on titanium materials. A limitation of conventional diffusion coating methods is the deterioration of the mechanical properties of the matrix resulting from the long-term, high-temperature processing. Therefore, spark plasma sintering (SPS) was used to form a ceramic layer, as it allows the suppression of the growth of crystal grains via rapid heating and enables low temperature and short processing time. The purpose of this study is to simultaneously form borides and carbides on a titanium surface using the SPS method and evaluate their properties. Commercially pure titanium (CP-Ti) was used as the substrate, and B₄C powder was utilized as both the boronizing and carburizing source. An analysis of the sample surface subjected to SPS processing indicated the formation of TiC, TiB₂, and TiB. As a ceramic layer was formed on the titanium surface, a surface hardness of ∼1700 HV was obtained, and the wear resistance was improved compared with that of untreated CP-Ti.

Fig. 1 Cross-sectional SEM image and EPMA elemental mapping images of titanium, boron, and carbon for SPS-treated samples for 180 min at 1273 K.