Surface Treatment And Microstructure Of Biomedical Titanium Alloy

Titanium and titanium alloys are widely used in the biomedical fields owing to their excellent properties, such as low density, low toxicity, good biocompatibility, great corrosion resistance, et al. As an implant material, a rough surface can increase the contact area with human tissue and improve the biocompatibility. Consequently, the surface treatment of titanium implant has been an important studying direction. SLA technology is a new surface modification without coating involving Sandblasting with Large grit followed by Acid etching. In this work, the surface of titanium alloy was treated by SLA technology. The effect of different treatment method on surface microstructure and properties of titanium alloys was investigated. In addition, laser surface remelting was used for the preparation of a new implant surface. The results were shown as follows:The surface defects caused by sandblasting, such as dislocation and crack, leaded to fracture of passive film and outcrop of matrix metal. The activated areas dissolved preferentially and produced etch pits. With the increase of etching time, SLA surface showed a hierarchical structure of cavities with diameters of wider size (about10-40μm) completely superposed by smaller pores with micro sized. The SLA technology optimized the surface cellular structure and removed the residual sand particles.With the same technological parameters, there were small differences in SLA surfaces between TA2and TA4pure titanium. The shape of TA4second level micropore was irregular while TA2surface showed round-shaped second level micropores. TC20alloy had the similar SLA surface with TA2and TA4. Furthermore, there were lamellar structures existed in the second level micropores, which further improved the surface microstructure.The thermal shock of pulse laser on TA2surface leaded to the generation of pits and indentations. With the movement of laser beam, the indentation caused by single track overlapped. After several tracks of laser, the metal in melting zone was concave downward because of thermal contraction, and the metal pushed aside by the thermal shock overlapped. The overall appearance of laser remelting was fluctuating and the surface area was increased.