New inverse method for identification of constitutive parameters

A new inverse method by coupling iSIGHT and ABAQUS was proposed to determine the constitutive parameters of Al2O3sf/LY12 composite deforming at elevated temperature. It combined the merits of the f＇mite element simulation and optimization technique. The direct model was simulated with finite element code ABAQUS. The inverse problem associated with the identification of the constitutive parameters was expressed as a least square optimization problem. The direct simulation and the parameters optimization were implemented in iSIGHT integrated environment. The aim was to match the output of the direct simulation with the experiment data. The capability of the proposed inverse method was demonstrated through the identification of constitutive parameters of Al2O3sf/LY12 composite. The proposed new inverse method is also applicable to other parameters identification which is hardly determined through experiments or direct analytical method.     

高锰钢的泡沫陶瓷过滤净化

采用泡沫陶瓷过滤片对高锰钢进行过滤处理，对其进行金相分析和测试密度，冲击韧性和耐磨性能，并与未过滤的高锰钢进行对比，实验结果表明，在过滤的高锰钢中，金属夹杂物明显减小，密度提高0．53％，冲击韧性39．5％，耐磨性能提高1．04倍，批量生产结果表明，过滤的高锰钢球磨机衬板的使用寿命提高0．6－0．7倍。     

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.     

定向凝固过程的数值模拟进展

针对定向凝固模拟的研究现状,概述了其中几种用于凝固的模拟方法,如三维枝晶胞膜跟踪法、电磁成形法、相场法等,并着重介绍了相场法。最后,在分析现有相场模型不足的基础上,指出了该领域研究中亟需解决的问题,并对今后的发展方向作了分析。     

无损检测的质量控制技术

以控制无损检测中的误判为例,介绍了质量控制技术在无损检测质量管理工作中的应用.首先利用流程图发现出现误判问题的产生环节,即缺陷的定位或定量错误.然后利用两图一表(因果图、排列图和检查表)分析引起缺陷定量或定位错误的原因.最后制定了防止误判产生的对策表.采用质量控制技术可以实现无损检测质量的持续改进.     

搅拌摩擦加工(FSP)AZ91D镁合金的组织分析

研究了AZ91D镁合金经搅拌摩擦加工后的组织。发现组织中搅拌摩擦区、热机械影响区和热影响区分区不明显。在搅拌摩擦区主要为再结晶形成的细小均匀的等轴晶结构,共晶组织α-Mg β相(Mg17Al12)完全均匀化,仅在晶界处有少量存在。     

Study on sintering process and characteristic of nanosized soft magnetic MnZn ferrite powders

The effect of sintering process (especially the sintering temperature) on the magnetic property and microstructure of sintered sample of nanosized soft magnetic MnZn ferrite powder was investigated. The sintered sample of MnZn ferrite was prepared by both traditional pressing and cool isostatic pressing on MnZn ferrite nanoparticals. The sintering process of which was segmented. Thedensity, microstructure and phase composition of sintered sample were analyzed by Archimedes'law, scanning electron microscopy (SEM) and X-ray diffraction (XRD). The grain growth and densification in sintering process of MnZn ferrite were investigated. The magnetic property was measured by vibrating sample magnetometer (VSM) and Nim2000 magnetic material testing system. The results show that the better sintering temperature is 850 ℃, at which the better magnetic property and microstructure of sintered compact were obtained.     

WD615气缸体铸件材料性能的改善

WD615气缸体铸件曾发生化学成分不稳定、铸件本体组织粗大、铁素体含量偏高、硬度偏低等质量问题，为此，采取了如下措施：1）加强熔炼用材料的质量控制；2）提高冲天炉的熔炼质量；3）改进熔炼工艺（调整C,Si量，采用Cu-Cr-Sn合金化；降低浇注温度）；4）改进孕育工艺；5）采用炉前快速检测技术；6）加强铸件本体质量检测。结果表明，缸体铸件的化学成分、金相组织及力学性能均满足技术要求。     

基于价值链的钢铁企业物料采购策略研究

在价值链中蕴含着很多成本控制机会,价格链分析是制造企业进行成本控制的最有效的途径.文中以价值链的观点分析了某钢铁企业的采购流程,提出了基于价值链的物料采购模型,在此基础上改进了该钢铁企业的管理流程,为钢铁企业节约采购成本提供了指导思想.     

Preparation and properties of nanosize MnZn ferrite from δ-FeOOH

Ferrous ion was transformed into feroxyhyte (δ-FeOOH) by oxidation. Then, manganese sulfate and zinc sulfate in some ratio were added to the feroxyhyte solution. The co-precipitation was boiling reflux conditions sometime under constant stirring. The nanosize MnZn ferrite powder was formed. The mechanism of preparation of the nanosize MnZn ferrite was discussed, and the formation of feroxyhyte which was playing a key role during the process was mentioned. The properties of powder was tested by means of X-ray diffraction, transmission electron microscopy and vibrating sample magnetometer. The results show that the samples of spherical particles about 20 nm, which have characteristics of ferrimagnetism, has larger saturation magnetization, but the remanent magnetization and coercivity are comparatively smaller. The spinel MnZn ferrite nanosize powder was successfully prepared from δ-FeOOH at low temperature, with low-carbon steel and peroxide as main material.