This paper reviewed the effect of powder characteristics and additives including metals,rare earth oxides,and ZrO2 on nitridation of Si powder.The decrease of particle size of Si powder increased nitridation.Most of m...This paper reviewed the effect of powder characteristics and additives including metals,rare earth oxides,and ZrO2 on nitridation of Si powder.The decrease of particle size of Si powder increased nitridation.Most of metal additives inhibited nitridation,while some metal additives such as Fe,Cu,Cr,and Ca increased nitrida—tion.Otherwise,the addition of metals might lead to the degradation of physical and mechanical properties of Si3N4.All the rare earth oxides,especially CeO2 and Eu2O3,showed nitridation enhancing effect.In addition,ZrO2 with small particle size showed a stronger enhancing effect.展开更多
ZrO_(2) spherical nanometer powders containing 3.5 mol%Y_(2)O_(3) have been prepared via the coupling route of water/oil(W/O)emulsion with dimethyl oxalate homogenous precipitation.ZrO_(2) powders and their precursor ...ZrO_(2) spherical nanometer powders containing 3.5 mol%Y_(2)O_(3) have been prepared via the coupling route of water/oil(W/O)emulsion with dimethyl oxalate homogenous precipitation.ZrO_(2) powders and their precursor powders have been characterized by XRD,TEM and SEM.According to the XRD result,phase volume fractions of powders were calculated by comparing the peaks’intensities of spectrum.Furthermore,phase crystal lattice constants were obtained using crystal interplanar spacing formula and Bragg equation.With these results,the theoretical density of powders was analyzed.Finally,powders’spherical degree was revealed via the method of comparison between theoretical density and actual density.展开更多
基金financially supported by Guangdong Innovative and Entrepreneurial Research Team Program ( No. 2013G061)the National Natural Science Foundation of China ( No. 51402055)
文摘This paper reviewed the effect of powder characteristics and additives including metals,rare earth oxides,and ZrO2 on nitridation of Si powder.The decrease of particle size of Si powder increased nitridation.Most of metal additives inhibited nitridation,while some metal additives such as Fe,Cu,Cr,and Ca increased nitrida—tion.Otherwise,the addition of metals might lead to the degradation of physical and mechanical properties of Si3N4.All the rare earth oxides,especially CeO2 and Eu2O3,showed nitridation enhancing effect.In addition,ZrO2 with small particle size showed a stronger enhancing effect.
基金The authors acknowledge the support of the National Natural Science Foundation of China(Grant Nos.51004046 and 51075129)the State Key Development Program for Basic Research of China(Project No.2010CB635107)the National Natural Science Foundation of Hubei Province of China(Project No.2010CDB05806).
文摘ZrO_(2) spherical nanometer powders containing 3.5 mol%Y_(2)O_(3) have been prepared via the coupling route of water/oil(W/O)emulsion with dimethyl oxalate homogenous precipitation.ZrO_(2) powders and their precursor powders have been characterized by XRD,TEM and SEM.According to the XRD result,phase volume fractions of powders were calculated by comparing the peaks’intensities of spectrum.Furthermore,phase crystal lattice constants were obtained using crystal interplanar spacing formula and Bragg equation.With these results,the theoretical density of powders was analyzed.Finally,powders’spherical degree was revealed via the method of comparison between theoretical density and actual density.
