The ceramic injection molding technique was used in the gas-pressure sintering of ultra-fine Si3N4 powder. The feedstock＇s flowability, debinding rate, defect evolution, and microstructural evolution during productio...The ceramic injection molding technique was used in the gas-pressure sintering of ultra-fine Si3N4 powder. The feedstock＇s flowability, debinding rate, defect evolution, and microstructural evolution during production were explored. The results show that the solid volume loading of less than 50vol% and the surfactant mass fraction of 6wt% result in a perfect flowability of feedstock; this feedstock is suitable for injection molding. When the debinding time is 8 h at 40°C, approximately 50% of the wax can be solvent debinded. Defects detected during the preparation are traced to improper injection parameters, mold design, debinding parameters, residual stress, or inhomogeneous composition distribution in the green body. The bulk density, Vickers hardness, and fracture toughness of the gas-pressure-sintered Si3N4 ceramic reach 3.2 g/cm^3, 16.5 GPa, and 7.2 MPa·m^1/2, respectively.展开更多
Transparent conductive indium tin oxide （ITO） nanoparticles were synthesized by a novel sol-gel method. Granulated indium and tin were dissolved in HNO3 and partially complexed with citric acid. A sol-gel process wa...Transparent conductive indium tin oxide （ITO） nanoparticles were synthesized by a novel sol-gel method. Granulated indium and tin were dissolved in HNO3 and partially complexed with citric acid. A sol-gel process was induced when tertiary butyl alcohol was added dropwise to the above solution. ITO nanopartides with an average crystallite size of 18.5 nm and surface area of 32.6 m^2 ]g were obtained after the gel was heat-treated at 700 ℃, The ITO nanoparticles showed good sinterability, the starting sintering temperature decreased sharply to 900 ℃, and the 1400 ℃ sintered pellet had a density of 98.1% of theoretical density （TD）.展开更多
基金financially supported by the National Nature Science Foundation of China (Nos. 51102024 and 21276028)
文摘The ceramic injection molding technique was used in the gas-pressure sintering of ultra-fine Si3N4 powder. The feedstock＇s flowability, debinding rate, defect evolution, and microstructural evolution during production were explored. The results show that the solid volume loading of less than 50vol% and the surfactant mass fraction of 6wt% result in a perfect flowability of feedstock; this feedstock is suitable for injection molding. When the debinding time is 8 h at 40°C, approximately 50% of the wax can be solvent debinded. Defects detected during the preparation are traced to improper injection parameters, mold design, debinding parameters, residual stress, or inhomogeneous composition distribution in the green body. The bulk density, Vickers hardness, and fracture toughness of the gas-pressure-sintered Si3N4 ceramic reach 3.2 g/cm^3, 16.5 GPa, and 7.2 MPa·m^1/2, respectively.
基金supported by grants from Ph.D. Programs Foundation of Ministry of Education of China (200802511022)National Natural Science Foundation of China (50902049)
文摘Transparent conductive indium tin oxide （ITO） nanoparticles were synthesized by a novel sol-gel method. Granulated indium and tin were dissolved in HNO3 and partially complexed with citric acid. A sol-gel process was induced when tertiary butyl alcohol was added dropwise to the above solution. ITO nanopartides with an average crystallite size of 18.5 nm and surface area of 32.6 m^2 ]g were obtained after the gel was heat-treated at 700 ℃, The ITO nanoparticles showed good sinterability, the starting sintering temperature decreased sharply to 900 ℃, and the 1400 ℃ sintered pellet had a density of 98.1% of theoretical density （TD）.
