High-temperature experiments were carried out for the slag systems of“FeO”−SiO_(2)−CaO−Al_(2)O_(3)and“FeO”−SiO_(2)−CaO−MgO at 1200℃and p(O_(2))of 10^(−7)kPa.The equilibrated samples were quenched,and the phase co...High-temperature experiments were carried out for the slag systems of“FeO”−SiO_(2)−CaO−Al_(2)O_(3)and“FeO”−SiO_(2)−CaO−MgO at 1200℃and p(O_(2))of 10^(−7)kPa.The equilibrated samples were quenched,and the phase compositions were measured by electron probe microanalysis(EPMA).A series of pseudo-ternary and pseudo-binary phase diagrams are constructed to demonstrate their applications in copper smelting process and evaluation of the thermodynamic database.Spinel and tridymite are identified to be the major primary phases in the composition range related to the copper smelting slags.It is found that the operating window of the smelting slag is primarily determined by w_(Fe)/w_(SiO_(2))ratio in the slag.Both MgO and Al_(2)O_(3)in the slag reduce the operating window which requires extra fluxing agent to keep the slag to be fully liquid.Complex spinel solid solutions cause inaccurate predictions of the current thermodynamic database.展开更多
Ti_(2)AlC,a MAX phase ceramic,has an attractive self-healing ability to restore performance via the oxidation-induced crack healing mechanism upon healing at high temperatures in air(high oxygen partial pressures).How...Ti_(2)AlC,a MAX phase ceramic,has an attractive self-healing ability to restore performance via the oxidation-induced crack healing mechanism upon healing at high temperatures in air(high oxygen partial pressures).However,such healing ability to repair damages in vacuum or low oxygen partial pressure conditions remains unknown.Here,we report on the self-healing behavior of Ti_(2)AlC at a low oxygen partial pressure of about 1 Pa.The experimental results showed that the strength recovery depends on both healing temperature and time.After healing at 1400℃for 1–4 h,the healed samples exhibited the recovered strengths even exceeding the original strength of 375 MPa.The maximum recovered strength of~422 MPa was achieved in the healed Ti_(2)AlC sample after healing at 1400 for 4 h,about 13%higher than the original strength.Damages were healed by the formed℃TiCx from the decomposition of Ti_(2)AlC.The decomposition-induced crack healing as a new mechanism in the low oxygen partial pressure condition was disclosed for the MAX ceramics.The present study illustrates that key components made of Ti_(2)AlC can prolong their service life and keep their reliability during use at high temperatures in low oxygen partial pressures.展开更多
A high temperature equilibration experiment was carried out to investigate the effect of oxygen partial pres- sure on the phase equilibria and liquidus in CaO-Al2O3- FeOx system with the intermediate oxygen partial pr...A high temperature equilibration experiment was carried out to investigate the effect of oxygen partial pres- sure on the phase equilibria and liquidus in CaO-Al2O3- FeOx system with the intermediate oxygen partial pressures of 10.13 Pa and 1.01 × 10^-3 Pa. The equilibrated phases and their compositions of the quenched samples were analyzed by using SEM/EPMA （Scanning Electron Microscope/Electron Probe Micro Analysis） and XRD （X Ray Diffraction）. The phase equilibrium results include two cases, the two phase coexistence and the three-phase coexistence in the high Al2O3 region with oxygen partial pressure of either 10.13 Pa or 1.01 × 10^-3 Pa. Effects of oxygen partial pressure and temperature on the liquidus along the primary phase fields of CaO · Al2O3 and CaO · 2Al2O3 were nota hle. With the decrease of oxygen partial pressure, the liquid area expands and the liquidus of CaO · Al2O3 and CaO · 2Al2O3 primary fields moves to the Al2O3-FeOx region. On the other hand, the liquid area of CaO Al2O3-FeOx sys tem extends extremely to the high Al2O3 region with the temperature increasing from 1 400 to 1 500℃, especially at lower oxygen partial pressure. The present experiment results are in good agreement with the calculated ones by FactSage.展开更多
A SiC/ZrSiO4？SiO2 （SZS） coating was successfully fabricated on the carbon/carbon （C/C） composites by pack cementation, slurry painting and sintering to improve the anti-oxidation property and thermal shock r...A SiC/ZrSiO4？SiO2 （SZS） coating was successfully fabricated on the carbon/carbon （C/C） composites by pack cementation, slurry painting and sintering to improve the anti-oxidation property and thermal shock resistance. The anti-oxidation properties under different oxygen partial pressures （OPP） and thermal shock resistance of the SZS coating were investigated. The results show that the SZS coated sample under low OPP, corresponding to the ambient air, during isothermal oxidation was 0.54% in mass gain after 111 h oxidation at 1500 ° C and less than 0.03% in mass loss after 50 h oxidation in high OPP, corresponding to the air flow rate of 36 L/h. Additionally, the residual compressive strengths （RCS） of the SZS coated samples after oxidation for 50 h in high OPP and 80 h in low OPP remain about 70% and 72.5% of those of original C/C samples, respectively. Moreover, the mass loss of SZS coated samples subjected to the thermal cycle from 1500 ° C in high OPP to boiling water for 30 times was merely 1.61%.展开更多
目的探讨2型糖尿病绝经后女性经皮氧分压水平与骨密度(bone mineral density,BMD)的关系,进一步了解微循环对糖尿病骨密度的影响。方法本横断面研究共纳入162例绝经后2型糖尿病患者。通过双能X射线吸收测定法评估其腰椎、髋部、右侧股...目的探讨2型糖尿病绝经后女性经皮氧分压水平与骨密度(bone mineral density,BMD)的关系,进一步了解微循环对糖尿病骨密度的影响。方法本横断面研究共纳入162例绝经后2型糖尿病患者。通过双能X射线吸收测定法评估其腰椎、髋部、右侧股骨颈、Ward’s三角区、股骨大转子及转子内骨密度。根据T-Score值分为3组:骨质疏松组(T≤-2.5)、骨量减低组(-2.5<T<-1.0)和骨量正常组(T≥-1.0)。Perimed PeriFlux System 5000检测双侧膝下及足背经皮氧分压水平,经皮氧分压是微血管病变的主要检测手段。比较3组间的一般特征,应用Pearson分析骨密度与经皮氧分压之间的关联,多元逐步回归分析骨密度的影响因素。结果骨质疏松组TcPO_(2)、ABI水平低于骨量正常组(40.09 vs.47.89,1.06 vs.1.17,P<0.05)。TcPO_(2)与腰1至腰4、股骨颈、股骨大转子、转子内、总髋及Ward’s三角区BMD呈正相关,r分别为0.259、0.215、0.226、0.217、0.213、0.226。校正年龄、病程、BMI、绝经年限后,TcPO_(2)与腰椎骨密度仍呈正相关。多元逐步回归分析,TcPO_(2)、BMI和年龄是腰椎骨密度的独立影响因素,TcPO_(2)、BMI、Ca和绝经年限是股骨颈的独立影响因素。结论2型糖尿病绝经后女性骨质疏松患者TcPO_(2)、ABI降低,TcPO_(2)下降可能是糖尿病骨密度降低的独立影响因素。展开更多
文摘High-temperature experiments were carried out for the slag systems of“FeO”−SiO_(2)−CaO−Al_(2)O_(3)and“FeO”−SiO_(2)−CaO−MgO at 1200℃and p(O_(2))of 10^(−7)kPa.The equilibrated samples were quenched,and the phase compositions were measured by electron probe microanalysis(EPMA).A series of pseudo-ternary and pseudo-binary phase diagrams are constructed to demonstrate their applications in copper smelting process and evaluation of the thermodynamic database.Spinel and tridymite are identified to be the major primary phases in the composition range related to the copper smelting slags.It is found that the operating window of the smelting slag is primarily determined by w_(Fe)/w_(SiO_(2))ratio in the slag.Both MgO and Al_(2)O_(3)in the slag reduce the operating window which requires extra fluxing agent to keep the slag to be fully liquid.Complex spinel solid solutions cause inaccurate predictions of the current thermodynamic database.
基金supported by the National Natural Science Foundation of China(No.52275171)the PreResearch Program in National 14th Five-Year Plan(No.80923010304).
文摘Ti_(2)AlC,a MAX phase ceramic,has an attractive self-healing ability to restore performance via the oxidation-induced crack healing mechanism upon healing at high temperatures in air(high oxygen partial pressures).However,such healing ability to repair damages in vacuum or low oxygen partial pressure conditions remains unknown.Here,we report on the self-healing behavior of Ti_(2)AlC at a low oxygen partial pressure of about 1 Pa.The experimental results showed that the strength recovery depends on both healing temperature and time.After healing at 1400℃for 1–4 h,the healed samples exhibited the recovered strengths even exceeding the original strength of 375 MPa.The maximum recovered strength of~422 MPa was achieved in the healed Ti_(2)AlC sample after healing at 1400 for 4 h,about 13%higher than the original strength.Damages were healed by the formed℃TiCx from the decomposition of Ti_(2)AlC.The decomposition-induced crack healing as a new mechanism in the low oxygen partial pressure condition was disclosed for the MAX ceramics.The present study illustrates that key components made of Ti_(2)AlC can prolong their service life and keep their reliability during use at high temperatures in low oxygen partial pressures.
基金Item Sponsored by National Natural Science Foundation of China(50974034,51074039)
文摘A high temperature equilibration experiment was carried out to investigate the effect of oxygen partial pres- sure on the phase equilibria and liquidus in CaO-Al2O3- FeOx system with the intermediate oxygen partial pressures of 10.13 Pa and 1.01 × 10^-3 Pa. The equilibrated phases and their compositions of the quenched samples were analyzed by using SEM/EPMA （Scanning Electron Microscope/Electron Probe Micro Analysis） and XRD （X Ray Diffraction）. The phase equilibrium results include two cases, the two phase coexistence and the three-phase coexistence in the high Al2O3 region with oxygen partial pressure of either 10.13 Pa or 1.01 × 10^-3 Pa. Effects of oxygen partial pressure and temperature on the liquidus along the primary phase fields of CaO · Al2O3 and CaO · 2Al2O3 were nota hle. With the decrease of oxygen partial pressure, the liquid area expands and the liquidus of CaO · Al2O3 and CaO · 2Al2O3 primary fields moves to the Al2O3-FeOx region. On the other hand, the liquid area of CaO Al2O3-FeOx sys tem extends extremely to the high Al2O3 region with the temperature increasing from 1 400 to 1 500℃, especially at lower oxygen partial pressure. The present experiment results are in good agreement with the calculated ones by FactSage.
基金Project supported by the Nonferrous Metal Oriented Advanced Structural Materials and Manufacturing Cooperative Innovation Center,ChinaProject(51205417)supported by the National Natural Science Foundation of China
文摘A SiC/ZrSiO4？SiO2 （SZS） coating was successfully fabricated on the carbon/carbon （C/C） composites by pack cementation, slurry painting and sintering to improve the anti-oxidation property and thermal shock resistance. The anti-oxidation properties under different oxygen partial pressures （OPP） and thermal shock resistance of the SZS coating were investigated. The results show that the SZS coated sample under low OPP, corresponding to the ambient air, during isothermal oxidation was 0.54% in mass gain after 111 h oxidation at 1500 ° C and less than 0.03% in mass loss after 50 h oxidation in high OPP, corresponding to the air flow rate of 36 L/h. Additionally, the residual compressive strengths （RCS） of the SZS coated samples after oxidation for 50 h in high OPP and 80 h in low OPP remain about 70% and 72.5% of those of original C/C samples, respectively. Moreover, the mass loss of SZS coated samples subjected to the thermal cycle from 1500 ° C in high OPP to boiling water for 30 times was merely 1.61%.
文摘目的探讨2型糖尿病绝经后女性经皮氧分压水平与骨密度(bone mineral density,BMD)的关系,进一步了解微循环对糖尿病骨密度的影响。方法本横断面研究共纳入162例绝经后2型糖尿病患者。通过双能X射线吸收测定法评估其腰椎、髋部、右侧股骨颈、Ward’s三角区、股骨大转子及转子内骨密度。根据T-Score值分为3组:骨质疏松组(T≤-2.5)、骨量减低组(-2.5<T<-1.0)和骨量正常组(T≥-1.0)。Perimed PeriFlux System 5000检测双侧膝下及足背经皮氧分压水平,经皮氧分压是微血管病变的主要检测手段。比较3组间的一般特征,应用Pearson分析骨密度与经皮氧分压之间的关联,多元逐步回归分析骨密度的影响因素。结果骨质疏松组TcPO_(2)、ABI水平低于骨量正常组(40.09 vs.47.89,1.06 vs.1.17,P<0.05)。TcPO_(2)与腰1至腰4、股骨颈、股骨大转子、转子内、总髋及Ward’s三角区BMD呈正相关,r分别为0.259、0.215、0.226、0.217、0.213、0.226。校正年龄、病程、BMI、绝经年限后,TcPO_(2)与腰椎骨密度仍呈正相关。多元逐步回归分析,TcPO_(2)、BMI和年龄是腰椎骨密度的独立影响因素,TcPO_(2)、BMI、Ca和绝经年限是股骨颈的独立影响因素。结论2型糖尿病绝经后女性骨质疏松患者TcPO_(2)、ABI降低,TcPO_(2)下降可能是糖尿病骨密度降低的独立影响因素。
