Fabrication Of Titanium Matrix/Hydroxyapatite Biocomposites

In recent years, Ti and its alloys are most widely used in orthopedic surgery.However, between Ti and bone there exists the mismatch of Young's modulus.Hydroxyapatite (HA) is one of the mineralcomponents in bone, so HAhas naturebiocompatibility. But HA is limited to artificial implants by its fragile. In thispaper, we try to combined the strong points of both making Timatrix/hydroxyapatite biocomposites by.using Mechanical Alloying (MA) andSparkPlasmaSintering (SPS).Four composites were produced: Ti-30vol%HA, Ti-50vol%HA, Ti15Mo-30vol%HA and Ti13Nb13Zr-44vol%HA. Results of mechanical alloying showedthat the composite particles are highly refined after 4 hours'mill, the particlessize is under 2 ?m. Elements distribute uniformly in particles and no reactionhappened during MA. Four components studied were sintered to dense bulkscompositesat 1000℃. During sintering, a reaction happened around 800℃, XRDanalyses showed that there appear some new phases: TiO, Ti2O and CaTiO3 inbulk composites. Porosity and pore size in bulk composites increased withdecreasingsintering pressure.Mechanical property test showed that composites with two components(Ti/HA) have high hardness, moderate compress strength and lower density.Lowest density of Ti/HA, TiMo/HA and Ti13Nb13Zr/HA is 3.34 g.cm-3, 4.56.g.cm-3 and 3.60 g.cm-3 respectively. The lowest hardness and compress strengthare 438HV, 655HV, 196HV and 278.9MPa, 1295.0MPa, 390.5MPa respectively.TiMo/HA. There exists a yield stage during compression. However, all materialspresentbrittle fractureunder compression.Surface treatment greatly changed the surface characteristic of the attainedcomposites. Samples treated with acid solution and Alkali solution showedmicroporous net work on surface,Pore size are around 100nm. Ca and Pelements were observed after immersed in SBF. After erode in 37% H3PO4,porous surface is found onBulk composites.