Synthesis And Property Investigation Of Si-N(O) Thin Films On The Surface Of Ti6Al4V Alloy

With the population aging accelerated day by day, the incidence of cardiovascular diseases increased and the demand quantity of the artificial heart valve, stent, etc. increased continuously. However, the key problem to be solved is the durability and the anti-thrombus capability of the cardiovascular implant materials to be developed. Surface modification technology is the common method to improve the bloodcompatibility of metallic biomaterials. The preliminary result showed that the anti-thrombus capability of Si-N(O) films was equivalent to Low Temperature Isotropic Pyrolitic Carbon(LTIC), so researchers attempt to use the Si-N(O)films to modify the biomedical metallic materials.In this paper, the chemical composition, structure, mechanical properties and the blood compatibility of Si-N(O) films were systematical studied, and the effect of equipment optimization and deposition condition on the chemical composition, structure and properties of the films was evaluated. In addition, the in vivo test of the titanium alloy modified by the Si-N(O) films was performed.Si-N(O) films with different composition, microstructure, mechanical properties were synthesized on Ti6Al4V alloy and monocrystalline silicon wafer by unbalanced magnetron sputtering technique, by optimazing the equipment and deposition condition. The chemical composition and structure were characterized with X-ray photoelectron spectrometry (XPS) and Fourier transform infrared spectroscopy (FTIR). The films thickness was tested by AMBIOS XP-2 profile meter and the hydrophilic-hydrophobic property was tested by JY-82 contact angle measurement. The mechanical properties were characterized with HXD-1000 microhardness meter, CSEM pin-on-disk wear test apparatus and WS-97 scratch tester. Platelet adhesion and animal experiments were used to evaluate the anticoagulation property of the films.After four rounds optimization, the O atom content was reduced effectively by taking out the unnecessary accessories and improving vacuum degree. The N atom content was increased with the increasing of N₂ flow rate and the decreasing of the background pressure. The analysis of microstructure showed that the bonding structure of Si was dominated by Si and SiO_x(x≤2) bonding structure when N atom content was lower and Si₃N₄ bonding structure in the films was increased significantly to the dominant bonding structure with the increasing of N atom content.The mechanical result of Si-N(O) films showed that: the films with lower oxygen atom content had bigger composite hardness, and better wear resistance accordingly.. With the increasing of N atom content, more and more Si₃N₄ bonding structure formed in the films. The formation of Si₃N₄ bonding structure was beneficial to the film composite hardness, and improved the films wear resistance. The blood compatibility of Si-N(O) films was equivalent to LTIC, but some difference existed among the films. The in vivo test indicated that the Si-N(O) films had certain anticoagulation property.