Influence of Yb2O3 addition on microstructure and corrosion resistance of 10Cu/(10NiO-NiFe2O4) cermets

10Cu/(10NiO-NiFe2O4) cermets doped with Yb2O3 were prepared by conventional powder metallurgy technique. The effects of Yb2O3 content and sintering temperature on the relative density, phase composition, microstructure of the sintered cermets and the corrosion resistance to Na3AlF6-Al2O3 melts were investigated by sintered density test, XRD analysis and SEM. YbFeO3 phase, which distributes in the ceramics grain boundary as particles or film, is produced by the reaction between Yb2O3 and ceramics. The addition of Yb2O3 accelerates the sintering process of ceramics matrix, eliminates pores in the boundary and results in coarsened crystalline grain. The relative density of the cermets with about 1% (mass fraction) Yb2O3 sintered at 1275 °C increases to above 95%. Addition of about 1.0% Yb2O3 can inhibit obviously the corrosion of NiFe2O4 grain boundary and Cu phase in Na3AlF6-Al2O3 melts.