The Improvement Of Tribological Property With Diamond-like Carbon Film On The Artificial Joint

A series of multilayer diamond-like carbon films are deposited on Co-Cr alloy substrate by alternate soft (low sp~3 content) and hard (high sp~3 content) layers of tetrahedral amorphous carbon. The films surface are smooth and have many superior properties such as high hardness, high wear resistance, low coefficient of friction. Biasing of the substrate leads to a variation of the ion energy. The film properties, which are influenced by the ion energy, can be changed over a wide range.Using an alternating high- and low-bias voltage, we have formed hydrogen-free multilayers of hard and soft diamond-like carbon films.The hardness of multilayers was measured by Knoop micro-hardness and nano-indentation. The structure features of diamond-like carbon multilayer films were investigated by X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy. The interfacial adhesion was investigated using indentation method. Tribological properties of multilayers were investigated using pin-on-disk tribometer in ambient air and fetal bovine serum. Multilayer diamond-like carbon films of different structures are simulate deposited on the surface of simulate joint prosthesis, study on the improvement of tribological property of artificial joint.The results of XPS and Raman measurement indicated that, the sp~2 content increases with an increase in substrate-bias voltage. The multilayer films have typical diamond-like carbon characteristics. The hardness and elastic modulus of the films are strongly dependent on the alternate low sp~3 content and high sp~3 content layers of tetrahedral amorphous carbon.The surface hardness improved greatly after multilayer deposition. As the increasing of the ratio of soft layer in multilayer films, the micro hardness of multilayers has a tendency to decreasing. Microhardness of the film are about 357.1HV-485.5HV,the highest elastic modulus of the multilayer have high hardness (up to 35.7GPa) and elastic modulus up to398.7GPa.It become denser and more homogeneous than the one prepared with dual arcs. The interfacial adhesion was improved remarkably by adding a Ti transition layer. Some experiment results demonstrated that multilayer films have excellent tribological properties. The friction coefficient of multilayer films against SiC counter-face was only about 0.10.In general, diamond-like carbon multilayer films with high hardness, good adhesion, low friction efficient were successively prepared by FCVA technique. Our study suggests that multilayer diamond-like carbon films has a great potential for application in artificial joint prosthesis can be extended.