Preparation And Characterization Of NiTi Occluder Coated With Ta

At present, occluder made of NiTi alloy has become the primarily medical instrument treating congenital heart disease.There is great significance for the preparation and surface modification of the nickel-titanium occluder device in the clinical medicine application.Tantalum hasn't any adverse reaction to human body as a metal with strong chemical stability. Tantalum has early applied in medical field, such as bone repair, vascular suturing. At present, tantalum has been widely used in clinical as a safe and reliable ideal contrast agent, due to its high density and good biocompatibility.In this paper, we got a tantalum film on the NiTi alloy and NiTi alloy wire by magnetron sputtering method.The microstructure, mechanical properties,corrosion resistance and biocompatibility have been investigated for the NiTi alloy coated with tantalum.When preparing tantalum films on NiTi alloy by magnetron sputtering, the main study is the influence of the magnetron sputtering power, sputtering work pressure and sputtering substrate temperature to the microstructure, mechanical properties and corrosion resistance and other properties of the tantalum coating. After the optimal sputtering technology is determined, the biocompatibility of the coatings are evaluated. In the experiments, the properties of tantalum coatings on NiTi alloys were characterized by means of the X-ray diffraction (XRD) phase analysis, scanning electron microscopy (SEM), atomic force microscope (AFM), contact angle measurement instrument, Nano-indentation technique, automatic scratch instrument, electrochemical corrosion test and biocompatibility test method. The surface properties,biocompatibility and X-ray visibility of NiTi silk and occluder were also investigated. The results show that, a-Ta films were successfully deposited on NiTi alloy surface by magnetron sputtering method. Mechanical property testing and corrosion resistance test results show that, the best sputtering technology is sputtering power of 100 W, substrate temperature of 300℃and sputtering pressure of 0.45 Pa in the same sputtering time 30 min. Tantalum coating has a better combination with NiTi alloy substrate as the critical load is more than 60 N, and the corrosion resistance is improved after tantalum depositing. After tantalum deposition, the surface roughness increases, the surface becomes hydrophobic from the hydrophilic, the biocompatibility of NiTi alloy is improved, additionally tantalum coating enhances the X-ray visibility of NiTi alloy. The most influential factor is the substrate temperature during sputtering, there is a large number of cracks on the tantalum films when the substrate is not heating up, due to the larger internal stress.