Effect of oxygen precipitates in solar grade silicon on minority carrier lifetime and efficiency of solar cells

The effect of oxygen precipitates on minority carrier lifetime and performance of solar cell was studied by means of Fourier Transform Infrared Spectroscopy (FTIR), quasi-steady state photoconductance (QSSPCD), optical microscope, spectrumresponse and solar cell efficiency test. The minority carrier lifetime and performance of solar cell reduced depend on oxygen precipitates. A few of oxygen precipitates have formed after single-step annealing; and they do not impact the efficiency dramatically. Pre-annealing at 650 ℃ for 4 h enhances the oxygen precipitation when it is subjected to middle temperature annealing. The solar cells performance decayed sharply. Especially annealing at 950 ℃ for 3 h, the V os and I sc of cells decrease 12% and 25% respectively. Few oxygen precipitates have formed in silicon after high temperature annealing at about 1050 ℃ whether pre-annealing is used or not, and the performance of cells is notbe affected.     

冷却介质对ZG30CrMn2Si2NiMo组织和力学性能的影响

研究了不同冷却介质对ZG30CrMn2Si2NiMo铸钢力学性能及组织的影响.试验结果表明,奥氏体化后空冷ZG30CrMn2Si2NiMo组织为板条贝氏体型铁素体和残余奥氏体组织,奥氏体化后淬火ZG30CrMn2Si2NiMo组织为板条马氏体、贝氏体型铁素体和残余奥氏体组织.ZG30CrMn2Si2NiMo获得板条马氏体、贝氏体型铁素体和残余奥氏体组织时,具有良好的力学性能.     

CSP技术连铸薄板坯气瓶钢中夹杂物研究

系统研究了珠钢电炉炼钢－钢包炉－CSP薄板坯连铸工艺生产气瓶钢的薄板坯中夹杂物在厚度方向分布规律以及夹杂物的种类，这些分析结果为进一步提高薄板坯的洁净度提供理论依据。     

TiO_2直接电解还原过程的研究

采用SEM、EDS、XRD等方法对TiO2直接电化学还原产物进行分析,指出TiO2电极的还原是从外向内由高价到低价再到金属逐步进行的。对还原过程中电流、还原气相产物的分析结果表明:还原过程电流效率低,并且电流效率随电解时间延续而降低,阳极产物CO、CO2与阴极中间产物Ca发生副反应以及副反应产物炭黑造成电流短路是电流效率低的主要原因。提高电流效率的途径有两条:一是增大阴、阳极间距,减小副反应的发生;二是使电解池表面熔盐不断导出,或采取某一隔离措施,使副反应产生的炭黑在阴、阳极之间不造成电流短路。     

Performances of electrically heated microgroove vaporizers

An electrically heated microgroove vaporizer was proposed. The vaporizer mainly comprised an outer tube, an inner tube and an electrical heater cartridge. Microgrooves were fabricated on the external surface of the inner tube by micro-cutting method, which formed the flow passage for fluid between the external surface of the inner tube and the internal surface of the outer tube. Experiments related to the temperature rise response of water and the thermal conversion efficiency of vaporizer were done to estimate the influences of microgroove＇s direction, feed flow rate and input voltage on the performances of the vaporizer. The results indicate that the microgroove＇s direction dominates the vaporizer performance at a lower input voltage. The longitudinal microgroove vaporizer exhibits the best performances for the temperature rise response of water and thermal conversion efficiency of vaporizer. For a moderate input voltage, the microgroove＇s direction and the feed flow rate of water together govern the vaporizer performances. The input voltage becomes the key influencing factor when the vaporizer works at a high input voltage, resulting in the similar performances of longitudinal, oblique and latitudinal microgroove vaporizers.     

Y型纳米碳管的结构表征与光学性能研究

对Y型纳米碳管的形貌和超微观结构进行了SEM、HRTEM和XRD分析，并着重测试了其光学性能。结果表明，碳管内包裹Fe纳米微粒，管径分布在50～60nm之间；纳米碳管呈Y型是由于管内催化剂的粒度不均，使之在生长过程中产生分支；首次报道了产物的发光性能，认为其在红光范围内存在荧光效应。     

回转窑窑壁非稳态传热模型及窑皮厚度优化

烟气、料床、窑壁是回转窑传热过程的三要素,在确定这三要素之间传热量的基础上,建立了回转窑窑壁非稳态传热数学模型。对中铝河南分公司2号窑窑壁的非稳态传热过程进行了数值计算。结果表明:窑体旋转一周,烧成带窑壁内表面温度将在1 232~1 334℃变化,这易导致窑壁热疲劳破坏;窑皮越厚,窑壁的径向温度梯度越小,热应力越低;将烧成带窑皮厚度控制在252 mm,可使烧成带窑壁外表面温度维持在200℃。     

Calculation of cooling rate of amorphous aluminum alloy melt-spun ribbons

Based on the heat transfer theory and liquid solidification theory, the heat transfer during the rapid solidification process of amorphous ribbons prepared by melt spinning was approximately modeled by one-dimensional heat conduction equation. Besides, integration with the temperature gradient, the relationship between the ribbon thickness and solidification time was derived according to the boundary conditions of ribbon-copper wheel. A simply theoretical model was obtained to calculate the cooling rates of aluminum amorphous ribbons. According to the above theoretical model, the critical cooling rate of aluminum amorphous ribbons by melt spinning is above 10^6 K/s, which proves that the aluminum based alloys belong to the marginal glass forming ability of alloys. The calculated results are in good agreement with other estimated values reported previously.     

测定金属凝固温度场的实验教学

介绍材料成型与控制专业材料成形原理中测定金属凝固温度场实验的教学案例。从建立Fe-C状态图的实验方法讲起，较为清晰地说明各种成分金属液的冷却曲线对了解合金性质，了解合金动态凝固行为的作用，并进一步引伸到近代利用所测定的金属凝固温度场的数据对相应温度场所开展的数学模拟和计算机仿真的结果进行评估，从而为用遗传算法、人工神经网络依据试验设计所取得的凝固温度数据，进行高精度建模、优化和预测服务。