The Investigation Of Pore Characteristic And Mechanical Property Of Porous Ti

Porous Ti with porosity of 5.8-62 vol.%, open/total porosity ratio of 60-99.5%, pore size of 5-420 m, Young's modulus of 0.8-37 GPa and compressive strength of 0.04-2.19 GPa was successfully prepared by powder metallurgy route. Microstructure of the porous Ti is observed using optical and scanning electron microscopy, and the phase structure was examined by X-ray diffraction (XRD). The distribution of the pore size is ascertained by quantitative metallurgy, the porosity is measured by liquid static balance, and the mechanical properties of the porous Ti were evaluated by compression test.Experimental results show that the microstructure of porous Ti consists of Widmanstaten a-Ti. The increasing in forming pressure reduces the pore size and porosity, but has little effect on the pore shape. With increasing sintering temperature and time, the pore size and porosity decrease, and the shape of the pore turns into sphere. As polymethyl methacrylate powders is added as pore maker, the porosity of the sintered porous Ti rises with increasing volume percent of the pore maker while particle size is unchanged. When the volume fraction of the pore maker is constant, the rise in particle size of the pore maker increases the porosity. The Young's modulus and compressive strength of the porous Ti are decreased with the increase in porosity. Besides, the mechanical behavior of porous Ti is affected by pore size and structure. When the porosity of the porous Ti is identical, the Young's modulus and compressive strength of the sample decrease with the increase in pore size.With the controlled sintering experiment using two kinds of pure Ti powders from Japan (99.9% purity) and China (99%), domestic Ti powder has larger shrinkage and porosity, lower relative density and higher plastic property. The nominal stress-strain curves of porous Ti using Japanese Ti powder have linear elastic stage, yield point, elongation and condensationstage. However, the porous Ti sintered by using domestic Ti powder presents elastic deformation, and brittle fracture occurs when the nominal strain is less than 2%.