食品的防霉腐包装设计

食品的卫生与营养是食品包装技术要解决的问题.从食品霉腐的因素、食品包装的要求和食品的防霉腐包装设计3个方面出发,阐述了食品防霉腐包装设计的方法,希能为包装设计者提供参考.     

软接触结晶器电磁连铸技术研究现状

 从磁场分布和结晶器设计、磁场对铸坯表面质量改善的机理、电磁场作用下结晶器内弯月面的行为、磁场施加方式的演变等几个方面，综合论述了软接触结晶器电磁连铸技术的发展现状，并指出了该技术未来发展过程中值得注意的几个方面。     

热处理对Cu50Zr42Al8块状非晶力学性能的影响

采用铜模吸铸法成功制备了Cu50Zr42Al8块状非晶,用纳米压痕法研究了铸态和低于玻璃化转变温度(Tg)退火后试样的力学性能,等温退火后试样的塑性增加而硬度和弹性减小。     

宽板坯连铸结晶器内卷渣现象试验研究

结合宽板坯连铸结晶器的4种断面尺寸,采用1:1水模型进行试验,研究了浸入式水口吹气量、水口浸入深度、水口吐出孔数、水口底部形状、拉速和结晶器断面宽度等工艺参数对结晶器内流体流动行为的影响情况,观察到结晶器内水口周围有旋涡卷渣和液面扰动卷渣,断面1/4区域是液面扰动卷渣,窄面区域有"类旋涡"卷渣和剪切卷渣.结果表明,结晶器内的卷渣与各种工艺参数是相关的,对工艺参数进行优化,就可减少卷渣的发生.     

小方坯连铸结晶器电磁搅拌的数值模拟

借助有限元分析软件ANSYS,对150mm×150mm小方坯连铸结晶器电磁搅拌在电流为150A,频率变化情况下的钢液内部磁感应强度和电磁力进行了数值分析,并分析了结晶器厚度对钢液内部磁场的影响以及不同时刻钢液内部电磁力的分布。模拟结果表明,在结晶器电磁搅拌时,同一个断面上,4个角部的磁感应强度最大;随着频率的增加,钢液内部磁感应强度降低,钢液边部电磁力在4~5Hz时最大;钢液内部的电磁力在1个周期的不同时刻,形成了同一个方向的力偶,在这个力偶的作用下,完成了对钢液的搅拌;结晶器厚度对钢液内部磁场影响很大,厚度增加,钢液内部磁感应强度降低。     

板坯连铸机浸入式水口结构优化的水模研究

通过水力模型实验,研究了水口结构对南钢板坯连铸机结晶器内钢水流动特性的影响.研究结果表明:使用现有水口结晶器内液面波动大且存在明显裸露并有严重的卷渣现象,适当增加浸入式水口出口面积,在不改变水口其它结构参数和插入深度条件下,能够获得液面波动小,保护渣覆盖良好且没有卷渣的钢水流动特性,不仅能够实现提高拉速的要求,还能提高铸坯质量.     

Finite Element Analysis of 3D Electromagnetic Field in Bloom Continuous Casting Mold

Threedimensional finite element model of electromagnetic stirrer was built to predict magnetic field in a bloom continuous casting mold for steel during operation. The effects of current intensity, current frequency, and mold copper plate thickness on the magnetic field distribution in the mold were investigated. The results show that the magnetic induction intensity increases linearly with the increase in current intensity and decreases with the increase in current frequency. Increasing current intensity and frequency is available in increasing the electromagnetic force. The Joule heat decreases gradually from surface to center of bloom, and a maximum Joule heat can be found on corner of bloom. The prediction of magnetic induction intensity is in good agreement with the measured values.     

Numerical Simulation of Heat Transfer and Deformation of Initial Shell in Soft Contact Continuous Casting Mold Under High Frequency Electromagnetic Field

  Heat transfer and deformation of initial solidification shell in soft contact continuous casting mold under high frequency electromagnetic field were analyzed using numerical simulation method; the relative electromagnetic parameters were obtained from the previous studies. Owing to the induction heating of a high frequency electromagnetic field (20 kHz), the thickness of initial solidification shell decreases, and the temperature of strand surface and slit copper mold increases when compared with the case without the electromagnetic filed. The viscosity of flux decreases because of the induction heating of the high frequency electromagnetic field, and the dimension of the flux channel increases with electromagnetic pressure; thus, the deformation behavior of initial solidification shell was different before and after the action of high frequency electromagnetic field. Furthermore, the abatement mechanism of oscillation marks under high frequency electromagnetic field was explained.     

Enhanced field emission from nano-graphite coated carbon nanotubes

An effective method by low energy carbonhydrogen ion treatment to enhance field emission of the carbon nanotubes (CNTs) is demonstrated. Comparing with control, field emission (FE) currents of the CNTs by carbonhydrogen ion irradiation increased, and the turn-on field and the threshold field decreased significantly. The structure characteristic revealed by transmission electron microscopy demonstrates that CNTs are coated by nano-graphite particles after being treated with low energy carbonhydrogen ion and that there are large quantities of defects and grain boundaries in the coated layer. It is considered that the coating layer can decrease the effective surface work function of CNTs and correspondingly increase field emission. In addition, the defects, the grain boundaries and the C-H dipoles forming in the process of the low energy ions irradiation can effectively enhance the field emission.     

高能重离子辐照制备碳氮化合物材料研究

室温下,先用100-120 keV的N离子注入类金刚石薄膜和石墨中,注入剂量5×1017至5×1018 cm-2,再用高能Xe、U、C60离子分别辐照注氮后的样品,然后用显微FTIR和Raman、XRD/XPS等手段进行分析表征,研究了实验样品中由辐照引起的新化学键和新相的产生.实验结果显示,高能重离子辐照可在所有样品中产生大量的CN键,高N浓度和大密度能量沉积导致sp3/sp2键比率的增加以及形成α-和β-C3N4必需的N-sp3C键的量的增加.C60离子辐照在注氮石墨样品中引起了ta-C、N=sp2C和N-sp3C键的形成;而高能离子辐照在注氮类金刚石薄膜样品中产生了α-和β-C3N4晶态夹杂物,其尺寸在1.4-3.6 nm之间.