| Abstract:Porous Ni3Al has been applied in industry, but the drawbacks such as low permeability and poor oxidation resistance hinder its wider application. The addition of third component simplifies the preparation process and cuts down the expenses. Meanwhile, the permeability and corrosion resistance of porous Ni3Al are greatly improved, which provides a direction for manufacture and application of porous Ni3AlPhase, microstructure and micro-area composition of porous Ni3Al are analyzed by X-ray diffraction(XRD), scanning electron microscope(SEM) and energy dispersive X-ray detector (EDX). Oxidation kinetics and corrosion kinetics are measured by cyclic oxidation and immersion test, respectively. The Tafel curves are investigated under assistance of electrochemical workstation.With the combination of near-net-shaping powder metallurgy and addition of (NH4)2CO3, Cr and Si, porous samples applied in different environments are prepared. Compared with the porous Ni3Al samples, the phase of porous samples with third component is still Ni3Al. When the amount of (NH4)2CO3is10%(wt.%), the permeability and pore size reach50.8m3·h-1·kPa-1·m2and20.4μim, but the pore size is too large. When the content of Cr is6%(at.%), after cyclic oxidation, the weight increase of porous sample is2.81%, permeability40.74m3·h-1·kPa-1·m-2and pore size9.44μm. With4%(at.%) addition of silicon, the porous samples have both excellent permeability(72.71m3·h-1·kPa-1·m2) and pore size(10.98μ.m). After immersion in6mol/L KOH for50days, the weight increase of porous samples is only0.06%and obvious passivation is tested by electrochemical workstation. Therefore, the addition of third component can improve the comprehensive properties of porous Ni3Al and broaden its application in catalysis, wave-absorption, high temperature and strong alkali separation, etc. |
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