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

316L stainless steel has been widely used to make the heart stent because of its excellent corrosion resistance and superior mechanical properties.But the heart stent generates thrombosis on its surface and releases toxic metal ions,such as Ni2+,Cr3+ and Cr6+.Ti-O and Ti-Al-O composite oxides possess good biocompatibility and very strong corrosion resistance.Ti-O and Ti-Al-O composite oxides films were coated on the 316L stainless steel by radio frequency(R.F.)reactive magnetron sputtering to prevent the release of toxic metal ions and improve its biocompatibility and drug loading capability.Ti-O thin films were coated on the substrate of 316L stainless steel by RF magnetron sputtering changing the sputtering temperature,pressure,oxygen flowing rate,sputtering power and sputtering time.The morphology,phase and film-substrate binding force of the thin films were studied by SEM,XRD and tensile test respectively.Corrosion resistance of the thin films was studied by electrochemical workstation and salt spray test.The contact angles between films and water were measured by the contact angle meter,and the micro-mechanical properties of the films were studied by the nanoindentor.The results showed that the film-substrate binding force was the best when the transition layer of Ti was added by depositing 5min,and the corrosion resistance and binding force of the thin films increased with the increase of temperature.Especially when T=300?,the Ti-O thin film had a high degree of crystallinity of rutile type.The elastic modulus(E)and nano-indentation hardness(H)of the Ti-O film were the maximum when the sputtering power was 500W.The ratio of H/E was the maximum when the sputtering power was 600W,that were the best friction and wear properties.The optimum process for preparation of Ti-O thin films was tTi=5min?T=300??P=400W?P?=0.2Pa?tTi-O=90min.Under this condition,the tensile test of the substrate of 5%and 8%showed that it had the best film-substrate binding force.The Ti-O thin film also had great corrosion resistance with the corrosion current 3.5632�10-8A/cm2,which can block the release of toxic metal ions.To study the corrosion resistance of the Ti-Al-O composite oxide,it was coated on 316L stainless steel by RF reactive magnetron sputtering.The morphology and phase of the films were studied by SEM and XRD respectively and the corrosion resistance was studied by electrochemical workstation.The optimal process for the preparation of the films of Ti-AI-l composite oxide was tTi-Al-O=100min,T=300?,P=400W,P?=0.2Pa,tTi=5min.Under this condition,the film was mainly composed of Al2TiO5 phase.The Ti-Al-O thin film also had good corrosion resistance with the corrosion current 4.8779�10-8A/cm2.