Powder Metallurgy Combines With Micro-arc Oxidation Preparing Medical Titanium-based Composites And Its Characterization

Titanium(Ti) is widely used as human bone substitute material for its excellent biocompatibility and corrosion resistance, but'stress-shielding'happens often after implantation for pure titanium has a high Young's modulus of elasticity(YME) and poor bioactivity.Medical titanium-based composites was prepared by powder metallurgy and micro-arc oxidation(MAO). Studied how isostatic pressing pressure has effected the density, tensile strength(TS) and YME and how contents of sponging agent have influenced density, bending strength(BS) and elasticity bending modulus(EBM); studied how MAO voltages and alkali treatment have affected the phase, morphologies and elements composition of the MAO films and what it would be of the MAO films'bioactivities if alkali treatment was executed.The results indicates lower the isostatic pressing pressure can reduce the TS and YME effectively and porous Ti with 20MPa and 30MPa compacting pressure have appropriate YME(about 26GPa) to match the YME(about 25GPa) of human cortical bone. EBM(23.44) of porous Ti with 20(wt%) sponging agent shows good mechanical compatibility for implantations and the microhardness is 2.24GPa, very closing to the microhardness of human cortical bone. EBM and microhardness of the Ti would drop rapidly if the sponging agent content is added. Rutile increase with improving of the MAO voltages and it in favor of nucleation of hydroxyapatite(HA). The MAO films with high voltages treated by alkali express good bioactivities as for OH- was added during the alkali treatment procedure and it accelerated the deposition of HA. Brushite is called the precursor of HA for it shows metastable phase and can be transformed to HA by alkali heat treatment. MAO could be conducted in pores of porous Ti with large bore diameter and the MAO pores emerged in pores of porous Ti and the porous Ti substrate with MAO pores as a whole formed a three-dimensional structure. Only OH- cannot induce nucleation of HA. Rutile, brushite and OH- provided strong driving force for the nucleation of HA and the MAO films show excellent bioactivities of rutile, brushite and OH" appear on the films simultaneously.Composites of excellent medical application with low YME and high bioactivity could be fabricated by powder metallurgy and micro-arc oxidation.