A novel method for producing gradient materials by continuous casting is introduced. By using many-stream-pouring technique, samples with gradient distribution of alloy composition along the cross section have been pr...A novel method for producing gradient materials by continuous casting is introduced. By using many-stream-pouring technique, samples with gradient distribution of alloy composition along the cross section have been prepared. The main difference of this method from the conventional continuous casting is the pouring system equipped with two sets of tundishes for liquid metals of different alloy compositions. Special consideration is given to the promotion and control of the cross-sectional mass transport. The steady heat transfer and mass flow ensure a partial mixing of two metals and yield a continously varying composition distribution. By adjusting the processing parameters, composition profile with different shapes can be achieved. First experiments have been carried out in Al-Si system and Al-Cu system for three series of Al/AlSi, AlSi/Al and AlCu/Al. It is shown that the alloy composition, the microstructure and the mechanical property change smoothly from the centre to the surface of the samples. This simple and practical method is potential for mass prodution of "structural gradient materials" and may offer a new way for alloy design.展开更多
The pipeline transportation of waxy crude oil is a problem both at home and abroad.In this paper,a novel nanohybrid pour-point depressant (PPD) was used to decrease the pour point and viscosity of waxy crude oil.The p...The pipeline transportation of waxy crude oil is a problem both at home and abroad.In this paper,a novel nanohybrid pour-point depressant (PPD) was used to decrease the pour point and viscosity of waxy crude oil.The pour point and apparent viscosity of waxy crude oil was decreased significantly upon addition of the nanohybrid PPD,and the long-term stability of the nanohybrid PPD was superior to that of a conventional ethylene-vinyl acetate copolymer PPD.Polarized optical microscopy and X-ray diffraction were used to study the effect of the nanohybrid PPD on the crystallization of crude oil.Addition of the nanohybrid PPD reduced the amount of wax crystals,prevented their aggregation,and reduced the temperature at which the crude oil started to crystallize.The significant effect of this nanohybrid PPD on the pour point and viscosity depressing of crude oil is of great importance for facilitating the safe,efficient and energy-minimized transportation of waxy crude oil.展开更多
以国内某大型高炉降料面停炉工作为实践背景,对整个降料面停炉过程进行分析总结,通过制订详细的停炉方案,以及停炉前精心准备,停炉过程精细操作,实现了高炉全煤气回收及快速、安全停炉,整个停炉用时6 h 50 min,精准降到目标料线,为缩短...以国内某大型高炉降料面停炉工作为实践背景,对整个降料面停炉过程进行分析总结,通过制订详细的停炉方案,以及停炉前精心准备,停炉过程精细操作,实现了高炉全煤气回收及快速、安全停炉,整个停炉用时6 h 50 min,精准降到目标料线,为缩短检修工期和顺利开炉创造了良好条件。展开更多
文摘A novel method for producing gradient materials by continuous casting is introduced. By using many-stream-pouring technique, samples with gradient distribution of alloy composition along the cross section have been prepared. The main difference of this method from the conventional continuous casting is the pouring system equipped with two sets of tundishes for liquid metals of different alloy compositions. Special consideration is given to the promotion and control of the cross-sectional mass transport. The steady heat transfer and mass flow ensure a partial mixing of two metals and yield a continously varying composition distribution. By adjusting the processing parameters, composition profile with different shapes can be achieved. First experiments have been carried out in Al-Si system and Al-Cu system for three series of Al/AlSi, AlSi/Al and AlCu/Al. It is shown that the alloy composition, the microstructure and the mechanical property change smoothly from the centre to the surface of the samples. This simple and practical method is potential for mass prodution of "structural gradient materials" and may offer a new way for alloy design.
文摘The pipeline transportation of waxy crude oil is a problem both at home and abroad.In this paper,a novel nanohybrid pour-point depressant (PPD) was used to decrease the pour point and viscosity of waxy crude oil.The pour point and apparent viscosity of waxy crude oil was decreased significantly upon addition of the nanohybrid PPD,and the long-term stability of the nanohybrid PPD was superior to that of a conventional ethylene-vinyl acetate copolymer PPD.Polarized optical microscopy and X-ray diffraction were used to study the effect of the nanohybrid PPD on the crystallization of crude oil.Addition of the nanohybrid PPD reduced the amount of wax crystals,prevented their aggregation,and reduced the temperature at which the crude oil started to crystallize.The significant effect of this nanohybrid PPD on the pour point and viscosity depressing of crude oil is of great importance for facilitating the safe,efficient and energy-minimized transportation of waxy crude oil.
