Effect of CaO doping on densification of 10NiO-NiFe_2O_4 composite ceramics

The CaO doped 10NiO-NiFe2O4composite ceramics were prepared with the cold isostatic pressing-sinte-ring process,the effects of CaO content and sintering temperature on the phase composition,microstructure and density of 10NiO-NiFe2O4composite ceramics were studied.The results show that the samples are mainly consisted of NiO and NiFe2O4when content of CaO is 0 4%(mass fraction),CaO reacts with the component of 10NiO-NiFe2O4ceramics and forms low melting point phase,and Ca2+dissolves into the ceramic base,which is important to accelerate the sintering densification and reduce sintering temperature.When sintered at 1 200℃,the samples doped with 2% CaO have the maximum relative density(98.75%),which increases about 24% compared with the undoped samples.When the CaO content is 4%,the excessive CaO indwelling between the base ceramic grains re-strains the densification of 10NiO-NiFe2O4composite ceramics.When the sintering temperature rises from 1 200 to 1 400℃,the relative density of the samples doped with 0,0.5% and 1% CaO increase 20%,but the relative densi-ties of the samples doped with 2% and 4% CaO decrease and the grains coarsen obviously.