The occurrence of γ phase, a high\|pressure polymorph of olivine （α phase）, in the shock veins of Si\| xiangkou chondrite was due to a greater cooling rate （>10 000℃·s -1 ） in the veins. Because γ phas...The occurrence of γ phase, a high\|pressure polymorph of olivine （α phase）, in the shock veins of Si\| xiangkou chondrite was due to a greater cooling rate （>10 000℃·s -1 ） in the veins. Because γ phase partially reverted to β phase and no back\|transformation from β phase to α phase took place, the shock veins of Peace River chondrite with a cooling rate of 1 000\2 000℃·s -1 contain a great amount of β phase. In the shock veins of Mbale chondrite with a cooling rate of <500℃·s -1 , the majority of γ phase reverted to α phase. The heat dissipation in shock veins took place after a stage of shock compression of chondrite parent body, and the parent body was broken into fragmental pieces. Cooling rate in the shock veins constrained the back\|transformations of （Mg,Fe）\-2SiO\-4 high\|pressure polymorphs.展开更多
Because of the effect of silicon on the formation of oxide scale, red scale is the main surface defect of hot rolled Fe-Si plate, making the scale difficult for descaling compared with carbon steel. Thermogravimetric ...Because of the effect of silicon on the formation of oxide scale, red scale is the main surface defect of hot rolled Fe-Si plate, making the scale difficult for descaling compared with carbon steel. Thermogravimetric analyzer （TGA） is used to simulate isothermal oxidation process of Fe-1.5Si alloy for 60 min under air condition, and the temperature range is from 700 to 1 200 ℃. Electron probe microanalysis （EPMA） is used to observe cross-sectional scale morphology and analyze elemental distribution of the scale. Relational graph of temperature, scale thickness and scale structure is obtained. It is found that scale structure （outer Fe oxide layer＋inner FeO/Fe2SiO4 layer＋internal Si oxide precipitates） is almost unchanged with temperature except at 1000 and 1 200 ℃. At 1000 ℃ internal Si ox- ide precipitates cannot be found at the subsurface of the alloy, and at 1200 ℃ FeO/Fe2SiO4 not only forms a layer as usual but also penetrates into the outer Fe oxide layer deeply.展开更多
Because of the effect of silicon on the formation of oxide scale, black strip defect is common on the surface of compact strip production （CSP） hot-rolled silicon steel, which leads to difficulty in pickling process...Because of the effect of silicon on the formation of oxide scale, black strip defect is common on the surface of compact strip production （CSP） hot-rolled silicon steel, which leads to difficulty in pickling process compared with plain carbon steels. Although high-temperature oxidation of Fe-Si alloy has been discussed a lot, few studies have explained the mechanism of black strip defect generated on the surface of hot-rolled silicon steel and proposed means to prevent it effectively. Thermogravimetric analyzer （TGA） is used to simulate oxidation of Fe-2.2Si alloy for 30 min under air condition, and temperature range is from 1000 to 1150 ℃. Effect of rolling deformation on scale morphology is also discussed. Electron probe microanalysis （EPMA） is used to analyze cross-sectional morphology and elemental distribution of the oxide scale. Schematic diagram of formation of black strip defect is obtained, which helps to provide theoretic basis for proposing of solutions for the Problem. It is proposed that lowering furnace tem-perature and shortening time to stay at high teniperature condition after rolling will be helpful tO relieve the black strip problem.展开更多
文摘The occurrence of γ phase, a high\|pressure polymorph of olivine （α phase）, in the shock veins of Si\| xiangkou chondrite was due to a greater cooling rate （>10 000℃·s -1 ） in the veins. Because γ phase partially reverted to β phase and no back\|transformation from β phase to α phase took place, the shock veins of Peace River chondrite with a cooling rate of 1 000\2 000℃·s -1 contain a great amount of β phase. In the shock veins of Mbale chondrite with a cooling rate of <500℃·s -1 , the majority of γ phase reverted to α phase. The heat dissipation in shock veins took place after a stage of shock compression of chondrite parent body, and the parent body was broken into fragmental pieces. Cooling rate in the shock veins constrained the back\|transformations of （Mg,Fe）\-2SiO\-4 high\|pressure polymorphs.
基金Sponsored by National High Technology Research and Development Program of China(2011BAE13B04)National Natural Science Foundation of China(51204047)
文摘Because of the effect of silicon on the formation of oxide scale, red scale is the main surface defect of hot rolled Fe-Si plate, making the scale difficult for descaling compared with carbon steel. Thermogravimetric analyzer （TGA） is used to simulate isothermal oxidation process of Fe-1.5Si alloy for 60 min under air condition, and the temperature range is from 700 to 1 200 ℃. Electron probe microanalysis （EPMA） is used to observe cross-sectional scale morphology and analyze elemental distribution of the scale. Relational graph of temperature, scale thickness and scale structure is obtained. It is found that scale structure （outer Fe oxide layer＋inner FeO/Fe2SiO4 layer＋internal Si oxide precipitates） is almost unchanged with temperature except at 1000 and 1 200 ℃. At 1000 ℃ internal Si ox- ide precipitates cannot be found at the subsurface of the alloy, and at 1200 ℃ FeO/Fe2SiO4 not only forms a layer as usual but also penetrates into the outer Fe oxide layer deeply.
基金Item Sponsored by National High-Tech Research and Development Program(863Program)of China(2011BAE13B04)Fundamental Research Funds for Central Universities of China(N100307006)
文摘Because of the effect of silicon on the formation of oxide scale, black strip defect is common on the surface of compact strip production （CSP） hot-rolled silicon steel, which leads to difficulty in pickling process compared with plain carbon steels. Although high-temperature oxidation of Fe-Si alloy has been discussed a lot, few studies have explained the mechanism of black strip defect generated on the surface of hot-rolled silicon steel and proposed means to prevent it effectively. Thermogravimetric analyzer （TGA） is used to simulate oxidation of Fe-2.2Si alloy for 30 min under air condition, and temperature range is from 1000 to 1150 ℃. Effect of rolling deformation on scale morphology is also discussed. Electron probe microanalysis （EPMA） is used to analyze cross-sectional morphology and elemental distribution of the oxide scale. Schematic diagram of formation of black strip defect is obtained, which helps to provide theoretic basis for proposing of solutions for the Problem. It is proposed that lowering furnace tem-perature and shortening time to stay at high teniperature condition after rolling will be helpful tO relieve the black strip problem.
