Preparation Of Amorphous Carbon Based Multilayer Film And Its Wear-resistance,Anti-corrosion,and Biocompatibility

Amorphous carbon(a-C)films have many attractive properites,for example high chemical inert,good biocompatibility and excellent tribological properites,and hence exhibit a potential in improving the wear resistance of Ti6A14V medical implant.However,drawbacks such as high intrinsic stress,low toughness,low load bearing capability,and low adhesion strength restrict their practical application.In this present paper,the modification method of a-C films are investigated in detail.The a-C based nanomultilayer film is compared with a-C base nanocomposite film.The microstructure and properites of a-CTM/a-C multilayer films are optimized.(TM=Ti,Ta,Zr)The novel ZrN/Zr/a-C multilayer films are designed,prepared and detailedly studied.In addition,a biological analysis is carried out for the a-C based nanomultilayer films in this paper.1)Compared with a-C film,the nanostructured a-C based film process higher hardness and toughness.By tribo-tests in Hank's solution,it can be found that at applied load of 1 N,both a-C based nanocompsite film and nanomultilayer film show low friction coefficient and wear rate;at applied load of 3 N,partially delamination occers for a-C based nanocompsite film,while the wear resistance of a-C based nanomultilayer film remains high.Additionally,both a-C based nanocompsite film and nanomultilayer film exhibit high corrosion resistance and show no dinstinct difference compared to each other.2)The a-C:Ti/a-C nanomultilayer films with various Ti content are successfully prepared by an industrial closed field unbalanced magnetron sputtering.It is demonstrated trough studying the influence of Ti content on microstructure and properties that the a-C:Ti/a-C nanomultilayer film with 22%Ti content process the highest harness(25.2 GPa),the lowest residual stress(-0.55 GPa),high adhesion strength(80N),and excellent tribological properties in both air and Hank's solution.3)The substrate bias and duty cycle have a significant effect on the microstructure,mechanical,tribological and electrochemical properites of a-C:Ti/a-C nanomultilayer films.The sp3 content in the films increase with the increment of substrate bias and duty cycle.The properties of a-C:Ti/a-C nanomultilayer films can be optimized by controlling the substrate bias and duty cycle.4)a-C:Ta/a-Cand a-C:T i/a-Cnanomultilayer films exhibits excellent tribo-corrosion performance in Hank's solution.For example,after tribo-corrosion tests,a-C:Ta/a-C nanomultilayer films has low wear rate of 7.6×10-17m3 N-1 m-1,and meanwhile the corrosion current density almost keeps constant with and without mechanical wear.The enhanced tribo-corrosion performance of a-C:Ta/a-Cand a-C:Ti/a-Cnanomultilayer films is mainly attributed to the multilayered structure.5)The novel ZrN/Zr/a-C nanomultilayer films are successfully designed and deposited,and the microstructure and properites of them are explored.The introduction of Zr monolayer significantly reduces the intrinsic stress and improved the adhesion between a-C and ZrN monolayers.ZrN/Zr/a-C nanomultilayer films exhibit excellent tribological properties in fetal bovine serum(FBS).The friction coefficient and wear rate of the ZrN/Zr/a-C nanomultilayer film keep a low value of 0.1 and 1?2×10-17 m3 N-1m-1 respectively at applied load of 2 N after sliding over 8000 m,indicating an excellent long-term wear resistance.At the edge load(contact stress over 1 GPa),the ZrN/Zr/a-C nanomultilayer film also shows low friction coefficient of 0.15 and wear rate of 4.7×10-17 m3 N-1m-1.6)Taking ZrN/Zr/a-C nanomultilayer as interlayer and a-C as top-layer,excellent mechanical properties and tribological performance in FBS can be simultaneously realized for a-C-ZrN/Zr/a-C nanomultilayer films if the thickness ratio of interlayer and top-layer is optimized.7)A biological analysis is carried out for the a-C based nanomultilayer films in this paper.It is found that the a-C based nanomultilayer films in this paper has no cytotoxic,no genotoxicity,no acute sustemic toxicity,no subchronic systemic toxicity and no sensitization response.Moreover,no contraindications in rabbit bone implant are found.The a-C based nanomultilayer films show high biocompatibility.