Preparation And Properties Of Al₂O₃、Ti-Al-O Thin Films By R.F. Magnetron Sputtering

The heart stents material316L stainless steel has been widely used because of its excellent mechanics, corrosion resistance. But naked316L stainless steel stent still has two majorproblems:It will lead thrombosis on the surface of stent. It is will be corroded in body after a long time, then Ni2+, Cr3+and Cr6+released by316L stainless steel. Al2O3and Ti-Al-O composite oxides, which possess excellent biocompatibility and hemocompatibility and strong corrosion resistance. In order to improve the316L heart stent biocompatibility and hemocompatibility, and improve the corrosion resistance and drug carrying characteristics, and prevent the releasing of Ni2+, Cr3+and Cr6+, the author has coated Al2O3and Ti-Al-O composite oxides films on316L stainless steel by RF magnetron sputtering.Al2O3thin films were successfully coated on316L stainless steel substrates by using RF magnetron sputtering. Thin films’ morphology, phase, adhesion were been studied, by using FESEM, XRD and the scratch adhesion test. Research shows that lower pressure, longer deposition time and lower target power contribute to the formation of dense, less defect of membrane structure, and improve the adhesion between film and substrate. The optimum process for preparation of Al2O3thin films is P=400W, Ptotal=0.2Pa, T=300℃, t=12h, tTi=4min. In this condition, the film is composed of a and yAl2O3phase. The surface morphology was fiber structure of arched. The fiber grain size is about150nm. the adhesion between film and substrate is11.60N.For studying the Al2TiO3ceramic can be used as a corrosion resistant coating or not, Ti-Al-O composite oxides thin films were successfully coated on316L stainless steel substrates by using RF reaction magnetron sputtering. To study the influence of temperature, deposition time, target power on the film structure, phase composition and corrosion resistance. Thin films’morphology, phase, corrosion resistance were been studied, by using FESEM, XRD and electrochemical workstation. Research shows that longer deposition time, higher target power and higher temperature have a positive impact on the thin films microstructure and corrosion resistance. The optimum process for preparation of Al2O3thin films is P=600W, Ptotal=0.2Pa, PO2=0.01Pa, T=300℃, t=172min, tTi=4min. In this condition, Ti-Al-O composite oxides thin films had a higher degree of crystallinity. The films is composed of Al2TiO5and Alo.64TiOo.36phase. The films have the best corrosion resistance with the corrosion current and corrosion potential respectively1.318×10-6A/cm2and-0.1405V.