Study Of The Porous Coating Of NiTi Shape Memory Alloy Prepared By Laser-Synthesized

Amongst the most interesting medical alloys developed in the last few years is NiTi shape memory alloy with nearly equiatiomic nickel and titanium distribution because of its shape memory effect, superelasticity and good biocompatibility. In clinical use, in the process of using NiTi alloy, there have a problem about the release of Ni element ion, Surface modification is to reduce the release of Ni ion, it is a effective way to improve their biocompatibility.NiTi coatings are deposited by a continuous wave Nd-YAG laser on NiTi alloy. Scanning electron microscopy (SEM), EDAX and X-ray diffraction (XRD) are used to investigate the composition, microstructure, components and phases of coatings. Using electrochemical Test System with potentiostat standard three-electrode evaluate the corrosion resistance, electrochemical corrosion and studies of the surface modification of NiTi shape memory alloy in simulated body fluid porous-coated Hank's solution.The mixed powder is prepare with different weight TiH₂ in NiTi alloy powder, synthesized by laser irradiation technology in dense NiTi shape memory alloy was successfully prepared with the matrix alloy showed good metallurgical bonding of porous coating. Optimize the coating composition, the coating performance porous, the coating surface composition of Ni content of only 12.5at%, significantly lower than the content of Ni substrate 49.2at%. Modified Porous coating has three-dimensional connectivity with 90% open The porous NiTi shape memory alloy possessed a high mechanical property and good biocompatibility, its unique pore structure confirmed the ingrowths of tissue and the transmission of body fluid, and made the combination of the implant and the body tissue much firmer.The electrochemical corrosion technique was employed to study their corrosion behaviours in Hank s simulated body fluid. Electrochemical test showed that the corrosion potential of NiTi was increased 38.6% while the corrosion current was reduce 73.7% which indicated that the corrosion reaction was inhabited effectively through TiN. The mechanical properties result is that: dense NiTi laser modification layer resulting in lower material tensile strength ductility. The tensile strength and elongation of the decline was 36.3%, 54.9%. Fracture mechanism is gathered for the fracture due to micro-ductil...