Preparation And Characterization Of Biomedical Porous Titanium-based Suface Composites By Powder Metallurgy And Microarc-oxidation

Titanium is currently used as an implants material due to its excellent biocompatibility, good corrosion resistance and mechanical properties. However, its major questions presenced in the clinical application as following: firstly, it has poor biological mechanics compatibility due to its Young's modulus not match with the human hard tissue's. Secondly, it is a bio-inert and hard to form the chemical combination with the human hard tissue. Therefore, it is important scientific research value and good prospects for clinical application to reduce its Young's modulus in order to enhance its biological mechanical compatibility and surface modification research in order to enhance its biological activity. In recent years, it is one of the most researches in the field of biological materials. In this paper, porous titanium-based surface composite materials prepared by powder metallurgy and micro-oxidation accesses to the excellent biological mechanical compatibility, biological activity and good mechanical properties. The MAO film and the structure, composition, biological activity, mechanical and tribological properties of porous titanium-based composite surface materials were studied systemly.The results show that: the porous titanium prepared by powder metallurgy has no new phase form and good crystallization. With the forming pressure increasing, its density gradually increases, porosity gradually decreases, powder metallurgy pore diameter increased first and then decreases and the irregular shape gradually change to the circular. Controling porosity, Young's modulus of the porous titanium is able to lowing to 28.5GPa that closes to Young's modulus of human hard tissue. It is improveing the overall biomechanical compatibility.The results of MAO show that: under the conditions of the MAO processing of the 300 V-500V constant voltage and special allocation, porous titanium surface forms porous films including elements of Ca and P. Its porous film is the main feature that includes larger holes formed by powder metallurgy and smaller holes formed by micro-oxidation. In particular, smaller holes form in wall of the large holes. The film mainly contains the rutile and anatase titanium dioxide phase, the film also contains CaTiO₃ phase. With the voltage increasing, rutile titanium dioxide increases in the film, Ca content in the film increases and P content increases and then little change, Ca/P ratio increased. Scratch tests showed that bonding intensity is high between titanium oxide films and sintered, so the film has a shear capacity, but with the voltage increaseing, the shear capacity drops. A porous titanium-based surface composite material is prepared by process of combining PM and micro-oxidation. That porous film reduces the elasticity modulus of the material surface. Thereby, that morphology enhances biological mechanical compatibilityof composite materials.Simulation tests showed that the film of porous titanium-based composite material has a good biological activity in soak body fluids. The powder metallurgy pores and micro-oxidation porous structure and Ca and P contribute to bone-like apatite nuclear. Bone-like apatite growthes in the powder metallurgy pores and micro-oxidation pores, so it improves biological activity and mechanical fixed role of porous titanium-based composite materials.Porous titanium-based composite material prepared by 50MPa forming pressure o PM and 300V of MAO has good biomechanics compatibility, biological activity and biological characteristics of tribology; it may become human hard tissue replacement and repair materials.