Preparation And Characterization Of Ti-Ti₅Si₃ Composite Gradient Porous Material

Ti₅Si₃ has many excellent properties such as high melting point,high hardness,low density,corrosion resistance,et al.It has certain theoretical significance and practical application value to carry out research on high-efficiency sound absorption,heat transfer and filtration industries under high temperature corrosion environment.This project takes the preparation of new filter materials as the research background.Using Ti powder and high-purity quartz tubes as raw materials,the Ti-Ti₅Si₃ composite gradient porous material was first prepared by an in-situ reactive sintering process in confined spaces,which proved the feasibility of this fabrication technology.The pore structure of porous material was analyzed by SEM,and it was found that the substrate of Ti-Ti₅Si₃composite gradient porous material had a pore size of 10⁵0μm;the membrane pore size was0.1⁰.3μm,the thickness was 1³μm,and presents openpores throughout the membrane.X-ray diffraction and EDS analysis were carried out on the porous membrane layer,and the main phase composition of the porous membrane formed by in-situ reaction was determined to be Ti₅Si₃ phase,and the secondary phases were TiSi phase and TiO₂ phase.By analyzing the experimental data of pore performance,it was found that the maximum bubble point pore size of Ti-Ti₅Si₃ composite gradient porous material as the original Ti powder size decreased,the sintering temperature increased and the holding time extended,and the maximum bubble point pore size can be as small as 7.3μm;relative to porous titanium,the relative permeability coefficient decreases,the minimum is 35.83 m³/h·kPa·m²,and the reduction rate is 45.84%;the relative permeability coefficient also decreases,the minimum is9.29 m³/h·kPa·m²,and the reduction rate is 62.6%.The thermal expansion test proves that the linear expansion coefficient of porous titanium metal sample is much greater than that of quartz tube.Therefore,in the in-situ reaction sintering process,the inner wall of the quartz tube produces a sintering compressive stress on the porous titanium green body.This stress is benefit for the formation of porous membrane during in-situ reactive process on the surface of the porous green body.Since Ti₅Si₃ phase has the most stable chemical energy among Ti-Si intermetallic compounds,if the in-situ reaction proceeds sufficiently,the composition of porous membrane obtained finally should be Ti₅Si₃phase.