1 Scope This standard specifies the definition, classifica- tion, technical requirements, test methods, quality appraisal procedures, packing, marking, transportation, storage, and quality certificate of silicon nitri...1 Scope This standard specifies the definition, classifica- tion, technical requirements, test methods, quality appraisal procedures, packing, marking, transportation, storage, and quality certificate of silicon nitride bonded silicon carbide bricks.展开更多
The specimens were prepared by molding the mixture of silica fume ( w( SiO2 ) =94. 5% ; average particle size : 0. 08 μm ) and silicon nitride ( ≤ 0. 074 mm ) with a mass ratio of 1 : 1, carbon embedded firi...The specimens were prepared by molding the mixture of silica fume ( w( SiO2 ) =94. 5% ; average particle size : 0. 08 μm ) and silicon nitride ( ≤ 0. 074 mm ) with a mass ratio of 1 : 1, carbon embedded firing at 1 300 ℃, 1 450℃, 1 500℃, 1 550 ℃ and 1 600 ℃ for 3 h in air, and then water-cooling, respectively. The microstructure and phase composition of the specimens were analyzed. The results show that: (1) silica fume reacts obviously with Si3N4 forming Si2N2O above 1 550 ℃. The edges and corners of Si3N4 grains become smooth and the Si3 N4 grains distribute in the continuous cementation phase of Si2N2O forming the dense structure of Si2N2o packed Si3N4 ; (2) below 1 500 ℃ , the edges and corners of Si3N4 grains are clear, Si2N2O doesn't form, and only SiO2 crystallizes from silica fume which happens obviously at 1 300 ℃.展开更多
文摘1 Scope This standard specifies the definition, classifica- tion, technical requirements, test methods, quality appraisal procedures, packing, marking, transportation, storage, and quality certificate of silicon nitride bonded silicon carbide bricks.
文摘The specimens were prepared by molding the mixture of silica fume ( w( SiO2 ) =94. 5% ; average particle size : 0. 08 μm ) and silicon nitride ( ≤ 0. 074 mm ) with a mass ratio of 1 : 1, carbon embedded firing at 1 300 ℃, 1 450℃, 1 500℃, 1 550 ℃ and 1 600 ℃ for 3 h in air, and then water-cooling, respectively. The microstructure and phase composition of the specimens were analyzed. The results show that: (1) silica fume reacts obviously with Si3N4 forming Si2N2O above 1 550 ℃. The edges and corners of Si3N4 grains become smooth and the Si3 N4 grains distribute in the continuous cementation phase of Si2N2O forming the dense structure of Si2N2o packed Si3N4 ; (2) below 1 500 ℃ , the edges and corners of Si3N4 grains are clear, Si2N2O doesn't form, and only SiO2 crystallizes from silica fume which happens obviously at 1 300 ℃.