Processing of an ultrafine-grained titanium by high-pressure torsion: An evaluation of the wear properties with and without a TiN coating

作者：Wang Chuan Ting; Gao Nong^*; Gee Mark G; Wood Robert J K; Langdon Terence G

来源：Journal of the Mechanical Behavior of Biomedical Materials, 2013, 17: 166-175.

DOI：10.1016/j.jmbbm.2012.08.018

• Bio-implants
• High-pressure torsion
• Titanium
• TiN coatings
• Wear

A commercial purity (CP) Grade 2 Ti was processed by high-pressure torsion (HPT) using an imposed pressure of 3.0 GPa at room temperature. The HPT processing reduced the grain size from similar to 8.6 mu m in the as-received state to ultra-fine grains (UFG) of similar to 130 nm after HPT. Tensile testing showed the HPT-processed Ti exhibited a good combination of high ultimate tensile strength (similar to 940 MPa) and a reasonable elongation to failure (similar to 23%). Physical vapour deposition was used to deposit TiN coatings, with a thickness of 2.5 mu m, on Ti samples both with and without HPT processing. Scratch tests showed the TiN coating on UFG Ti had a critical failure load of 22.5 N whereas the load was only similar to 12.7 N for the coarse-grained Ti. The difference is explained using a simple composite hardness model. Wear tests demonstrated an improved wear resistance of TiN coating when using UFG Ti as the substrate. The results suggest that CP Ti processed by HPT and subsequently coated with TiN provides a potentially important material for use in bio-implants.

• 出版日期2013-1