Preparation And Wear Resistance Of Ti-Sn Biomedical Alloys

New β shape memory Ti-7.5Nb-4Mo-2Sn alloy is important potential to find use as a bio-medical implant material due to the low elastic modulus, excellent super elastic property, good bio-compatibility and corrosion resistance. In order to improve the surface microhardness and wear resistance of Ti-7.5Nb-4Mo-2Sn alloy, in this thesis, Ti-Sn series alloys were developed through coating composition design, the effect of Sn content on microstructure and wear resistance were investigated. The most outstanding performance Ti-Sn alloy was select as cladding material with the form of preset alloy sheet, laser cladding were carried out without protective atmosphere, the resulting microstructure, microhardness, temperature distribution and wear resistance of the coatings under different scanning speed were investigated. The obtained results are as follows:(1)Ti-xSn series alloys were developed from the perspective of biomedical coating design, the result showed that, when the Sn content of Ti-xSn alloys is from 6at.% to 20 at.%, the microhardness and wear resistance is associated with the content of β-phase, that, the less of β-phase, the higher microhardness and the more excellent wear resistance. The main wear mechanism for Ti-Sn serial alloys are abrasive wear, showing good wear resistance, and Ti-10 Sn exhibit the most excellent surface property.(2)Ti-10 Sn composite coatings were successfully fabricated on Ti-7.5Nb-4Mo-2Sn substrate through laser cladding, A good metallurgical bond without any porosity or cracks was obtained at the substrate/coating interface. The hardness and wear resistance of Ti-7.5Nb-4Mo-2Sn alloy was significantly improved by cladding it with the Ti-10 Sn coating. The main wear mechanism for the Ti-7.5Nb-4Mo-2Sn substrate is dominant by abrasive and adhesive wear, while for the Ti-10 Sn coating specimens, it is the abrasive wear.(3)Laser scanning speed has a significant impact on the microstructure and mechanical properties of cladding layer. With the increase of the scanning speed, the cooling rate is faster and the temperature at the interface of substrate and coating is lower. Based on the investigation of microhardness and wear resistance,it is found that the coating with 10mm/s showing the best property. And coatings with different laser scanning speed show different wear mechanism. For 13mm/s, it is abrasive and adhesive wear; while for 10mm/s, it is obvious abrasive wear; when the speed is 7mm/s, the coating show surface cracks, so it is fatigue wear.