The Study On The Properties Of TiB Reinfoced Porous Titanium By Spark Plasma Sintering

Titanium and titanium alloys are widely used in hard tissue implant materials due to their high specific strength,good corrosion resistance and good biocompatibility.However,the elastic moduli of traditional titanium materials are still higher compared with that of human bone,which can result in stress shielding,and implant failure.It has been studied that the porous structure can effectively reduce the elastic modulus of the alloy,but at the same time the strength is also reduced.In this paper,a new discharge plasma sintering technology was performed,and the porous structure and TiB enhancement were combined in order to maintain low elastic modulus and enhance the trength.Up to now,the research on the preparation of TiB reinforced porous titanium by spark plasma sintering has not been reported yet.The research in this paper can provide a theoretical basis for the design and development of new porous titanium matrix composites with low modulus,high strength and proper porosity.In this paper,two kinds of pure titanium powder were chosen as raw materials,and NH4HCO3 was chosen as the pore forming agent(30?70%),and TiB2 powder with different contents(0.5?8%)was prepared by spark plasma sintering technology,so as to prepare TiB reinforced porous pure titanium.The effect of milling speed,sintering temperature,sintering pressure,pore forming agent content,TiB2 content and heat treatment process parameters on the microstructure and mechanical properties of TiB enhanced porous titanium were studied by using an optical microscope(OM),a scanning electron microscope(SEM),an X ray diffraction(XRD)and density,compressive performance tests.And the the growth mechanism and strengthening mechanism of TiB were also explored.The results show that with the increasing of sintering temperature,the density of porous titanium increase,the porosity decreases,the compressive strength and elastic modulus increase.The porosity of porous titanium sintered at 850? and 900? can reache 20%,and the powders are well bonded.The higher the sintering pressure is,the lower porosity and compressive strength and elastic modulus of sintered body are,but the lower sintering pressure particles cannot be well integrated.When the sintered pressure is 5MPa,a good sintered body can be obtained.With the increasing of pore forming agent content,the porosity of materials increases,the compressive strength and elastic modulus decrease.When adding 50%pore forming agents,porous titanium could be obtained.The sintered irregular titanium powder with 30?40 ?m has higher porosity and uniform pore distribution.With the increasing of the amount of TiB2,the porosity of porous titanium increases and the size of the pore size becomes larger at 1150? for 3h,and TiB2 can be completely reacted to form TiB.The morphology and distribution of TiB are closely related to the amount of TiB2.With the increasing of amount of TiB2,the aspect ratio of TiB whiskers decreases.TiB whiskers mainly distribute uniformly on the matrix particles or in the pores.After adding TiB2,the compressive strength of porous titanium increases significantly,but with the increasing of TiB2 content,the compressive strength and elastic modulus of porous titanium first increase and then decrease,when the content of TiB2 was 1%,the porous titanium has the best mechanical properties,and the compressive strength reaches 1454 MPa,the elastic modulus reaches 21 GPa,the porosity of porous titanium is 25%.The TiB on the matrix particles plays a strengthening role by taking on the transfer load,pulling out the bridge and cracking steering,and TiB between the pores increases the strength of the porous titanium by supporting the matrix particles in the pores,thereby increasing the strength of the porous titanium.On the other hand,When TiB2 is added excessively,the aggregation of TiB adversely affects the mechanical properties of the porous titanium.