Cr2O3 has eminent slag corrosion resistance. So, the magnesite -chrome brick is thought as an important refractory material used in RH refining furnace in the process of steel-making around the world. After chromebear...Cr2O3 has eminent slag corrosion resistance. So, the magnesite -chrome brick is thought as an important refractory material used in RH refining furnace in the process of steel-making around the world. After chromebearing sols being prepared by sol-gel method, single sol （ Cr（ OH）3） and mixed sol （ Mg（ OH）2 - Cr（ OH）3） were impregnated into magnesite - chrome bricks by vacuum impregnation. The corrosion resistance of the impregnated bricks to silicon steel slag was studied by porosimetric analysis and fractal dimension calculation. The results showed that the corrosion resistance of impregnated magnesite -chrome brick was better than that of the unimpregnated brick and the brick impregnated by MgSO4 solution, and the one which has surface-treated by Mg（ OH）2 -Cr（OH）3 sol was the best, mainly because of lower apparent porosity, smaller pores diameter and their smoother inner sarface.展开更多
目前,浏览器已经成为人们接入互联网最主要的入口。HTML5、JavaScript和CSS等Web技术的发展,也极大地增强了Web应用的功能并丰富了用户的交互体验。但是,随着Web应用逻辑日益复杂,人们既要经常完成过程繁琐且需重复执行的任务,也要完成...目前,浏览器已经成为人们接入互联网最主要的入口。HTML5、JavaScript和CSS等Web技术的发展,也极大地增强了Web应用的功能并丰富了用户的交互体验。但是,随着Web应用逻辑日益复杂,人们既要经常完成过程繁琐且需重复执行的任务,也要完成操作复杂且难以记忆的任务。因此,基于目前流行的Chrome浏览器,设计实现了一个动作捕捉与回放工具Scratch(Smart Capture-and-Replay at Chrome),以实现对Web应用操作正确、一致的捕捉与回放,并允许其他用户对已有操作记录进行定制。展开更多
The magnesia composite materials were prepared using fused magnesia, used magnesia chrome bricks, magnesium aluminate spinel, alumina powder and chrome oxide powder as starting materials. In order to improve the perfo...The magnesia composite materials were prepared using fused magnesia, used magnesia chrome bricks, magnesium aluminate spinel, alumina powder and chrome oxide powder as starting materials. In order to improve the performance of magnesia composite material, the influence of chrome oxide concentrate powder on the properties of magnesia composite material was re-searched. The apparent porosity, bulk density, cold crushing streugth, linear expausion and thermal shock resistance of the specimens were determined. The results show that adding chrome oxide concentrate promotes the formation of the composite phases of three kinds of spi-nel, which is beneficial to the thermal shock resistance.The magnesia chrome spbwl can not be .[brined at high temperatures theoreticalby, but can dissolve in the mag-nesia composite material. Comprehensively, the optimal addition of chrome oxide concentrate is 10. 0 mass% for the magnesia composite materials.展开更多
Magnesia-alumina-chrome ramming mixes with same chemical compositions were prepared by using different raw materials such as fused magnesia-chrome synthetic materials and sintered one, wasted bricks and magnesia-alumi...Magnesia-alumina-chrome ramming mixes with same chemical compositions were prepared by using different raw materials such as fused magnesia-chrome synthetic materials and sintered one, wasted bricks and magnesia-alumina spinels. Their physical properties were tested and microstructures were analyzed. The results show that the ramming mixes made of different raw materials bring about different microstructures and properties although the mixes have the same chemical composition, binder content and aggregate size composition.展开更多
A simple and sensitive kinetic spectrophotometric method for the determination of trace amounts of titanium(IV),based upon the catalytic effect of Ti(IV) on the oxidation of acid chrome blue K (ACBK) by hydrogen perox...A simple and sensitive kinetic spectrophotometric method for the determination of trace amounts of titanium(IV),based upon the catalytic effect of Ti(IV) on the oxidation of acid chrome blue K (ACBK) by hydrogen peroxide in 0.002 mol/L sulfuric acid,is described. The reaction rate is monitored spectrophotometrically by measuring the decrease in absorbance of ACBK at 524 nm. The detection limit of the method is 1.01×10?9 g/mL,and the linear range is 0-0.048 mg/L. The influence of acidity,concentration of reactants,reaction time,reaction temperature and for-eign ions is also discussed. The optimum reaction conditions were established and some kinetic parameters determined. The apparent activation energy of the catalytic reaction is 5.32 kJ/mol. The relative standard deviation for the determi-nation of titanium(IV) at the concentration of 0.048 mg/L is calculated to be 1.31% (n = 11). In combination with sol-vent extraction separation,the method has been successfully applied to the determination of trace titanium(IV) in human hair,plant matter,tea and rock samples. The results are in good agreement with the certified values with the relative standard deviations (RSD) of 1.4%-3.5%.展开更多
The feasibility was investigated to substitute chrome-free passivation treatment of electrodeposited zinc in a titanium bath for chromate passivation treatment. The formation mechanism of the chrome-free passivation f...The feasibility was investigated to substitute chrome-free passivation treatment of electrodeposited zinc in a titanium bath for chromate passivation treatment. The formation mechanism of the chrome-free passivation film was further analyzed. The surface mor- phologies and the elemental compositions of the treated samples with varied immersion times were observed by scanning electron mi- croscopy （SEM） and determined by energy dispersion spectrometry （EDS）, respectively. The electrode potential of the sample surface was recorded in the film formation process. The changes of the electrode potential are in accordance with that of SEM and EDS of the sample surface. The results of X-ray photoelectron spectroscopy （XPS） show the chrome-free passivation film composed ofZnO, SiO2, TiO2, Zn4Si207（OH）2, and SrF2. The anode zinc dissolution and the local pH value increase due to the cathode hydrogen ion reduction process result in the formation of the chrome-free passivation film. The macro-images of the chrome-free passivation films formed on electrodeposited zinc show that the color of the film changes from blue to iridescence with the increase of the immersion times.展开更多
Magnesia chrome bricks were prepared with fiLsed MgO- Cr2 O3 synthesized material, fused magnesite and ：hrome ore as main starting materials. Nano-Al2O3 was tdded into refractories （ 2% , 4% and 6% in mass ） ;ubst...Magnesia chrome bricks were prepared with fiLsed MgO- Cr2 O3 synthesized material, fused magnesite and ：hrome ore as main starting materials. Nano-Al2O3 was tdded into refractories （ 2% , 4% and 6% in mass ） ;ubstit,ting for Al203 micropowder. After m＆ing and ;haping, the bricks were fired at 1 550 ℃, 1 600 91℃, t 650 ℃ and 1 750℃, respectively. The microstruc-ure , sintering property, mechanical properties, thermal ;kock resistance and shtg resistance of the specimens with he addition of nano-Al2O3 were investigated. The results indicate that the performance of brick with 4 mass% of nano-Al2O3 is greatly improred afier firing at 1 650 ℃.展开更多
基金supported by the Natural Science Foundation of Hubei Province (2007ABA372)the New Century Excellent Talents in University (NCET-06-0676)
文摘Cr2O3 has eminent slag corrosion resistance. So, the magnesite -chrome brick is thought as an important refractory material used in RH refining furnace in the process of steel-making around the world. After chromebearing sols being prepared by sol-gel method, single sol （ Cr（ OH）3） and mixed sol （ Mg（ OH）2 - Cr（ OH）3） were impregnated into magnesite - chrome bricks by vacuum impregnation. The corrosion resistance of the impregnated bricks to silicon steel slag was studied by porosimetric analysis and fractal dimension calculation. The results showed that the corrosion resistance of impregnated magnesite -chrome brick was better than that of the unimpregnated brick and the brick impregnated by MgSO4 solution, and the one which has surface-treated by Mg（ OH）2 -Cr（OH）3 sol was the best, mainly because of lower apparent porosity, smaller pores diameter and their smoother inner sarface.
基金教育部人文社会科学重点研究基地重大项目(编号:12JJD880013)“教学伦理学研究”加拿大Social Sciences and Humanities Research Council(SSHRC)政府资助项目+2 种基金天津市2013年度哲学社会科学规划课题(编号:TJJX13-010)“中小学信息化课程资源的校际共享机制研究”国家教师科研“十二五”全国重点课题(编号:KT0801958A-XXX)“`课程改进-教学跟进`式学校发展研究”北京市教育科学“十二五”规划重点课题(编号:ABA14010)“信息化条件下北京市中小学学生学习方式变革实验研究”阶段性研究成果
文摘目前,浏览器已经成为人们接入互联网最主要的入口。HTML5、JavaScript和CSS等Web技术的发展,也极大地增强了Web应用的功能并丰富了用户的交互体验。但是,随着Web应用逻辑日益复杂,人们既要经常完成过程繁琐且需重复执行的任务,也要完成操作复杂且难以记忆的任务。因此,基于目前流行的Chrome浏览器,设计实现了一个动作捕捉与回放工具Scratch(Smart Capture-and-Replay at Chrome),以实现对Web应用操作正确、一致的捕捉与回放,并允许其他用户对已有操作记录进行定制。
基金supported by the Industrial Special Resource Protecting Office of Liaoning Province
文摘The magnesia composite materials were prepared using fused magnesia, used magnesia chrome bricks, magnesium aluminate spinel, alumina powder and chrome oxide powder as starting materials. In order to improve the performance of magnesia composite material, the influence of chrome oxide concentrate powder on the properties of magnesia composite material was re-searched. The apparent porosity, bulk density, cold crushing streugth, linear expausion and thermal shock resistance of the specimens were determined. The results show that adding chrome oxide concentrate promotes the formation of the composite phases of three kinds of spi-nel, which is beneficial to the thermal shock resistance.The magnesia chrome spbwl can not be .[brined at high temperatures theoreticalby, but can dissolve in the mag-nesia composite material. Comprehensively, the optimal addition of chrome oxide concentrate is 10. 0 mass% for the magnesia composite materials.
文摘Magnesia-alumina-chrome ramming mixes with same chemical compositions were prepared by using different raw materials such as fused magnesia-chrome synthetic materials and sintered one, wasted bricks and magnesia-alumina spinels. Their physical properties were tested and microstructures were analyzed. The results show that the ramming mixes made of different raw materials bring about different microstructures and properties although the mixes have the same chemical composition, binder content and aggregate size composition.
基金Project 0520002 supported by the Natural Science Foundation of Jiangxi Province
文摘A simple and sensitive kinetic spectrophotometric method for the determination of trace amounts of titanium(IV),based upon the catalytic effect of Ti(IV) on the oxidation of acid chrome blue K (ACBK) by hydrogen peroxide in 0.002 mol/L sulfuric acid,is described. The reaction rate is monitored spectrophotometrically by measuring the decrease in absorbance of ACBK at 524 nm. The detection limit of the method is 1.01×10?9 g/mL,and the linear range is 0-0.048 mg/L. The influence of acidity,concentration of reactants,reaction time,reaction temperature and for-eign ions is also discussed. The optimum reaction conditions were established and some kinetic parameters determined. The apparent activation energy of the catalytic reaction is 5.32 kJ/mol. The relative standard deviation for the determi-nation of titanium(IV) at the concentration of 0.048 mg/L is calculated to be 1.31% (n = 11). In combination with sol-vent extraction separation,the method has been successfully applied to the determination of trace titanium(IV) in human hair,plant matter,tea and rock samples. The results are in good agreement with the certified values with the relative standard deviations (RSD) of 1.4%-3.5%.
文摘The feasibility was investigated to substitute chrome-free passivation treatment of electrodeposited zinc in a titanium bath for chromate passivation treatment. The formation mechanism of the chrome-free passivation film was further analyzed. The surface mor- phologies and the elemental compositions of the treated samples with varied immersion times were observed by scanning electron mi- croscopy （SEM） and determined by energy dispersion spectrometry （EDS）, respectively. The electrode potential of the sample surface was recorded in the film formation process. The changes of the electrode potential are in accordance with that of SEM and EDS of the sample surface. The results of X-ray photoelectron spectroscopy （XPS） show the chrome-free passivation film composed ofZnO, SiO2, TiO2, Zn4Si207（OH）2, and SrF2. The anode zinc dissolution and the local pH value increase due to the cathode hydrogen ion reduction process result in the formation of the chrome-free passivation film. The macro-images of the chrome-free passivation films formed on electrodeposited zinc show that the color of the film changes from blue to iridescence with the increase of the immersion times.
文摘Magnesia chrome bricks were prepared with fiLsed MgO- Cr2 O3 synthesized material, fused magnesite and ：hrome ore as main starting materials. Nano-Al2O3 was tdded into refractories （ 2% , 4% and 6% in mass ） ;ubstit,ting for Al203 micropowder. After m＆ing and ;haping, the bricks were fired at 1 550 ℃, 1 600 91℃, t 650 ℃ and 1 750℃, respectively. The microstruc-ure , sintering property, mechanical properties, thermal ;kock resistance and shtg resistance of the specimens with he addition of nano-Al2O3 were investigated. The results indicate that the performance of brick with 4 mass% of nano-Al2O3 is greatly improred afier firing at 1 650 ℃.
