Abstract
Titanium cermet combining metallic toughness with ceramic wear resistance has been proven to be a potential candidate for implanted joint material. In this work, titanium cermet was synthesized by means of the elevated temperature solid carburizing technology. The Ti13Nb13Zr alloy surface was found to be converted into TiC ceramic layer combined with a carbon strengthened diffusion zone underneath. The overall thickness of the carburized region grew to about 100 µm after 120 min carburization at 1,500 K. In order to clarify the growth behaviors of TiC ceramic layer, a growth mechanism is proposed. At the beginning of carburizing process, carbonaceous gas decomposed from carburizer due to high temperature and then converted to free atomic carbons through reduction reaction. Then, in-situ generated TiC ceramic layer possessing certain thickness formed on the surface, meanwhile, the inner carbon diffusion zone also grew inwards due to physical diffusion of carbon, and finally forming a gradient carbon distribution. In addition, the tribological behaviors of the new materials were evaluated through reciprocating ball-on-plate sliding wear tests in bovine calf serum. Although there was an increase in friction coefficient, the wear rate decreased by 59.6% due to the formation of the wear-resistant TiC ceramic layer. The wear mechanisms evolved from severe abrasive wear for bare Ti13Nb13Zr alloy to mild adhesive wear for titanium cermet.
Highlights
Total hip arthroplasty (THA) surgery is one of the most successful operations for patients suffered from degenerative joints diseases [1, 2]
In order to explore the growth mechanism of titanium cermet, the elevated temperature solid carburization with varied holding time was employed for Ti13Nb13Zr alloy
As the holding time increased, the overall thickness of carburized region involving TiC ceramic layer and carbon diffusion zone reached to 100 μm, and the surface hardness increased to 758 HV, approximately four times higher than that of the reference sample
Summary
Total hip arthroplasty (THA) surgery is one of the most successful operations for patients suffered from degenerative joints diseases [1, 2]. With the advances in prosthesis design and manufacture, the success rate of THA has been increased significantly. Since articulating surfaces have to undergo dynamic loading, multidirectional sliding friction, and severe tribo-corrosion for a long time, the wear is inevitable in in-vivo. Up to now numerous postoperative complications have been confirmed to be related to the accumulative wear debris and cytotoxic metal ions, especially for traditional materials such as CoCrMo alloy and stainless steel [3, 4]. Medical titanium alloys exhibit beneficial mechanical properties and outstanding corrosion resistance, which render them the competitive candidates for implanted joint materials [5]
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