Preparation And Properties Of Fe-Al Based Intermetallic Compound Porous Material

China,as a major consumer of coal as the main energy source,especially in the thermal power generation and iron and steel industries,will also generate a large amount of high-temperature dust that pollutes the environment during the consumption of coal.Intermetallic compound porous materials have been often used as a filter material in high-temperature dust environment due to their excellent overall performance.In this study,Fe-Al intermetallic compound porous materials were prepared by elemental powder reaction pore formation.However,since Fe and Al were undergone self-propagating high temperature synthesis(SHS)during the sintering process,cracks and deformations occured in porous materials,which affected the performance of the materials.Therefore,the key sintering temperature parameters were selected and the ceramic phase such as Si/TiC was added to improve this situation.Scanning electron microscope(SEM),energy dispersive spectrometer(EDS),and X-ray diffraction(XRD)were used to observe the morphology and phase of the porous material before and after adding Si/TiC,and test related performance of Fe-Al-based porous material.The results are as follows:(1)During the preparation of Fe-Al porous materials,cracks and distortions appeared in the samples.The phases that occured after the sintering process were:Fe,Al,Fe2Al5,and FeAl.Among them,Fe2Al5 was a mesophase that appears during medium-temperature sintering.After sintering at 1000℃,the phase was a single FeAl.The porosity of the porous material generally increases with the increase of the sintering temperature.The increase of the porosity was mainly in the range of 600～650℃.In the pressure range of 100～300MPa,the porosity decreased with the increase of the pressing pressure.The pore-forming mechanism was mainly:interstitial pores formed by powder particles during the pressing stage;Kirkendall pores formed by solid and solid diffusion of Fe and Al below the melting point of Al;in-situ pores left by liquid Al consumed by the reaction;and pores formed by reaction phase change at higher temperature.(2)When the sintering temperature was 650℃,the denseness of the pore framework of the Fe-Al-Si intermetallic compound porous material increased with the increase of the Si content.At this time,the main phases were:Fe,Fe2Al5,Al0.7Fe3Si0.3,FeAl3Si2,Al2FeSi and τ1 phases.At 1000τ,Fe-Al-Si porous materials with different Si contents had no obvious difference in microscopic morphology,and the phase was only FeAl.The porosity of the porous material showed an increasing trend with the increase of the Si ratio during the initial pressing.At 650℃,the porosity increased as the proportion of Si increased.At 1000℃,the porosity of porous materials with different Si contents fluctuated irregularly within a certain range.The Fe-Al-Si porous material prepared at 1000℃ has better high-temperature oxidation resistance,and the high-temperature oxidation resistance increased with the increase in the proportion of Si.In the compression resistance test,the compressive strength of Fe-Al-based porous materials increased with increasing Si content.(3)When sintered at 650℃,the porous framework particles of the Fe-Al-TiC intermetallic compound porous material were made finer,and the main phases were Fe2Al5,Fe,and TiC;and at 1000℃ as the TiC content increased,the density of the porous material decreased,the phases were FeAl and TiC.The high temperature oxidation resistance of Fe-Al-TiC porous materials sintered at 1000℃ was better,and it decreased with the increase of TiC ratio,while its compression resistance increased with the increase of TiC ratio.(4)Through thermal analysis,it was found that the addition of Si and TiC inhibited the self-propagating high temperature synthesis between Fe and Al to a certain extent.Si participated in the reaction during the sintering process,inhibited the formation of mesophase Fe2Al5,and reduced the reaction between Fe and Al;TiC did not participate in the reaction,but reduced the contact area between Fe and Al,and reduced the degree of iron-aluminum reaction,which ensured the integrity of the macroscopic morphology of the porous material.