Microstructure And Properties Of Porous Sintered Titanium Powder

The influences of sintering temperature of porous titanium to the microstructure, to the appearance of the breakpoint, to the characters of holes, to the number of holes and the mechanical property were discussed in this paper by the method of optics microscope, SEM, EPMA and XRD. The influences of kind and content of pore-forming agent and compressive deformation were also discussed. The results were as follows:Sintering temperature influences the structure and mechanical property of porous titanium. The surface of titanium grain of porous titanium becomes less toughness and grains gets bigger as the sintering temperature increases. Further, the boundary of the holes gets smoother, the irregularly holes turns to circular and the pore rate decreases as the temperature increases. Sintering necks grows from thin to thick first, and then melted. With the sintering temperature rising, the hardness of final samples rises first, and then falls, reaching a peak around 1200℃. When the content of inorganic pore-form agent was 30%, the compressive strength increases and the modulus of elasticity increase first and then decrease as the sintering temperature increases. When the content of organic pore-form agent was 20%, the compressive strength increased and the modulus of elasticity decreased as the sintering temperature increases.Caking agent influences the aperture and pore rates of the porous titanium. The aperture turns bigger, pore rates increases and the connectivity of the holes becomes better as the content of caking agent increases. When the caking agent content was 3% the aperture and pore rates gets a better outcome.The kind and content of pore-form agent affect the structure of the holes, compose phase and mechanical property of porous titanium. The holes of the porous titanium made by inorganic pore-form agent have the same shape with pore-form agent, while the holes of the porous titanium made by organic pore-form agent have the different shape and size with pore-form agent. Specimens with porous titanium made by inorganic pore-form agent were made up with the phase of Ti, rutile TiO₂ and Na₄Ti O₄. Specimens with porous titanium made by organic pore-form agent were basically made up with Ti phase and seldom TiO₂ of rutile phase. The compressive strength of porous titanium has 20% organic pore-form agent was 510.26Mpa.It was only 21.79Mpa when the titanium was made with inorganic pore-form agent. The compressive strength of the porous titanium made with organic pore-form agent was observably higher than that made with inorganic pore-form agent. But it has a lower modulus of elasticity. With the increase of inorganic pore-form agent, the pore rates increases, connectivity of the holes gets better, the compressive strength and modulus of elasticity go down.Compressive deformation can change the shape and structure of the holes. The holes have different deformation rate after the compression. Some holes were elongated and staved along the vertical direction, some with only small deformation, still some one without any deformation. As result of different plastic deformation rates, the grain's slippage line density is different too.