Preparation And Characterization Of Fe Doped Ti-Si Intermetallic Compound Porous Membrane

With the development of process industry technology,the operating conditions of filtration and separation are becoming more complex,resulting in higher requirements for filtration elements.Ti-Si intermetallic compounds have been widely used in the areas of high-temperature structural materials,heat-proof materials,coating materials,electronic devices and other fields,because of their high melting point,high hardness and excellent high-temperature mechanical properties.Therefore,it is necessary to carry out the preparation and characterization of Ti-Si intermetallic compound porous membrane materials.In this work,the Fe doped Ti-SiO₂ and Fe doped Ti-Si systems were used for the preparation of new porous membrane,respectively.And the Fe doped Ti-Si porous membrane were prepared by pressure-sintering analogue to the technique of in-situ reaction sintering in confined space.The effects of Fe doping,sintering temperature and sintering pressure on the microstructure,phase composition and pore properties of porous membrane were systematically investigated,and the preliminary analysis of the forming mechanism of Ti-Si metal compound porous membranes of the two systems was carried out.The results show that for the Fe-doped Ti-SiO₂ system,the particle size on the surface of the porous membrane layer is 1～3μm,and the thickness of the porous membrane layer is 3～7μm;the main phase of the prepared porous membrane layer is Ti₅Si₃,and a small amount of new phases Fe Ti and FeO are generated.With the increase of Fe doping amount,sintering temperature and sintering pressure,the Ti₅Si₃ generated on the membrane surface and the content of new phases increased,and the size of the generated Ti₅Si₃ particles become larger gradually.The density of the membrane also increased,resulting in the relative air permeability coefficient and the maximum bubbling pore size of the porous membrane decreased.For the Fe-doped Ti-Si system,a little new phases Ti Fe Si and Ti Fe Si₂ are generated in the prepared porous membrane except the main phase Ti₅Si₃.Meanwhile,the Ti₅Si₃ content on the surface of the porous membrane decreases gradually with the increase of the Fe doping amount,while the new phases Ti Fe Si and Ti Fe Si₂ increase gradually.Increasing the sintering temperature can promote the contents of both Ti₅Si₃and new phases.In addition,with the increase of Fe doping and sintering temperature,the size of Ti₅Si₃ particles generated on the porous membrane becomes larger and the density of the membrane increases gradually,leading to decreases of the relative air permeability coefficient and the maximum bubbling pore size of the porous membrane.Focusing on the pore forming mechanism of the Ti-Si porous membrane prepared by the Fe-doped Ti-SiO₂ system,it was found that with increasing the sintering temperature,O diffused rapidly into the Fe-doped Ti matrix after the decomposition of SiO₂ due to the faster diffusion ofO in Ti than that of SiO₂ decomposition.As the reaction process proceeds,the solubility ofO in the Fe doped Ti matrix exceeds its limitation,and then Fe,Ti andO form FeO,Fe Ti and Ti-O by solid state diffusion reaction.As sintering progresses,Ti-Si intermetallic compound porous membrane was finally obtained at the target sintering temperature.