The development of P/M titanium-graphite triphasic composites for biomedical applications

摘要

The insidious wear of biomaterials in articulating implant devices has become the limiting factor in the long-term success of these devices. The presence of wear debris has led to adverse cellular activity resulting in osteolysis and, ultimately, loosening of total joint replacements [1]. Thus, the tribological concerns associated with traditional metallic bioma-terials like titanium have led to an earnest movement towards the use of ceramic biomaterials like alumina and zirconia in total joint prostheses. Ceramics have high wear resistance and good frictional properties. However, in long-term in vivo tests, they also fail by wear [2]. Another engineering issue is their propen-sity to fracture catastrophically. While every effort may be undertaken to ensure a defect-free material prior to implantation, shock loads or the initiation of defects/cracks during service can lead to detrimental consequences. A wear resistant biomaterial must therefore also be fracture resistant in terms of preventing uncontrolled, rapid and sudden failure. In this letter, a triphasic composite developed by the controlled heterogeneous sintering of titanium and graphite powders is presented as a candidate material for articulating orthopaedic implants [3]. The three phases are ductile pure titanium, hard and wear resistant titanium carbide and lubricating free graphite particles. The fracture toughness and tribological performance of the composite are reported.