Surface transformation of TiC-316L cermets by boriding
PLUCKNETT K. 1, GRIFFIN D. 1, KIMURA A. 2, CRAIG O. 1, MORITA M. 2, GAIER M. 1, LIN H. 3, SEKI T. 2
1 Dalhousie University, Halifax, Canada; 2 University of Tokyo, Tokyo, Japan; 3 Guangdong University of Technology, Guangzhou, China
Ceramic-metal composites, or cermets, are employed for a wide range of applications, in both bulk material and coating forms. This is largely due to their high wear and corrosion resistance. In the current study, a ‘pack boriding’ diffusion treatment has been applied to TiC-316L cermets, to further harden their surface. Boriding is achieved by heating the cermet samples within a packed powder-bed, containing a boron source, between 950 and 1150 °C, for a period of four hours. The surface transition for these materials is complex. A semi-continuous borided layer can be developed, with transformation of the steel binder to high hardness iron borides (i.e., FeB and Fe2B). Fine TiBx nanocrystals are also shown to form on the surface TiC during boriding, while the core of the TiC ‘core-rim’ structure is also preferentially attacked/removed. While the boriding treatment increases the surface roughness, it is also shown to increase both the cermet Vickers hardness and scratch hardness, highlighting the potential benefits of this such diffusion-based surface treatments.