Preparation of ultra-fine copper powder and its lead-free conductive thick film

In this paper, non-agglomerated monodispersed ultra-fine copper metallic powders have been synthesized with chemical reduction method. Fine lead-free glass powders were also prepared by solid synthesis process. Thick film paste prepared by above-mentioned copper metallic powders and lead-free glass powders was applied as conductive paste of MLCC. Mixture of glass and zinc oxide give the thick film a high adhesion strength which is attributed to the rough interface from interfacial reaction between glass and chip, and a good densification. Diffusion of metal between copper thick film and nickel thick film is clear. Ni-Cu solid solution appears under high temperature firing.     

Compaction of thick carbon/phenolic fabric composites with autoclave method

Carbon/phenolic composites are used in the nozzle parts of solid rocket motors due to their heat-resisting, ablative, and high strength characteristics, which are required to endure the high temperature and pressure of combustion gas passing through the nozzle. But the thick axi-symmetric structure of the composite nozzle induces high thermal residual stresses due to the large difference of coefficient of thermal expansion (CTE) between the in-plane and the out-of-plane. In this work, in order to reduce the through-thickness CTE and the void content, a compression in the thickness direction was applied to the composite prepreg by a compressive jig during manufacturing of composite to supplement the low autoclave pressure. The through-thickness CTE of the fabric composite was calculated by a compaction model and compared with the measured one by thermo-mechanical analysis. The through-thickness CTE changed drastically with respect to the compaction amount, and the void content of the carbon/phenolic fabric composite laminate showed different characteristics from the ordinary fabric laminates with respect to the autoclave pressure and the jig pressure.     

A viscous titania paste with a single coating-sintering step for 8–24 μm thick,high-haze,high-quality TiO2 films of dye-sensitized solar cells

A viscous TiO₂ paste was prepared by ball-milling commercially available P25 with ethylene glycol and citric acid. The conventional three- or four-fold deposition process was replaced by a single coating-sintering step of TiO₂ compound. That is coating the paste on Fluorine-doped SnO₂ conductive glass, followed by sintering at high temperature. TiO₂ films varying from 8 μm to 24 μm could be fabricated by this single coating-sintering step. The high viscosity of the paste, the esterification between ethylene glycol and citric acid and the subsequently polyester decomposition in the sintering process were the reasons to make high-quality thick film without cracking and delamination. 7.36% photoelectrical-conversion efficiency was achieved by using the photoelectrode with its P25 film thickness of 14.3 μm. Therefore, the paste would have promising applications for industrial production because of its low-price and simple process.     

基于数值模拟的厚板精冲挤压过程分析

针对厚板精密冲裁过程存在的缺陷(塌角与毛刺等),基于Deformed2D分析了10mm厚钢板精密冲裁过程中双齿V形压料板对冲裁质量的影响.采用V形压料板可在一定程度上减小塌角的高度,但不能完全消除.随后采用精冲挤压方法对这一厚板的成形过程进行了分析,结果表明:采用精冲挤压成形工艺后,厚板零件表面塌角得到了完全消除,零件...     

纵波斜射探头检测厚壁高压无缝钢管

在大口径厚壁钢管的超声波检测中,由于受第一临界角的限制,采用接触法纯横波周向检测只能检测壁厚与外径之比〈0．2的管材。通过理论分析,采用入射角为10°的纵波斜射探头,对壁厚与外径之比〉0．2的钢管进行接触法周向检测,并根据折射纵波和折射横波的声压往复透射率（波高）及其在仪器荧光屏上的水平位置加以区分。实践证明,该方法实用可行。     

Three-dimensional vibration, buckling and bending analyses of thick rectangular plates based on discrete singular convolution method

The main objective of this study is to give a numerical solution of three-dimensional analysis of thick rectangular plates. The analysis uses discrete singular convolution (DSC) method. Free vibration, bending and buckling of rectangular plates have been studied in this paper. Regularized Shannon's delta (RSD) kernel is selected as singular convolution to illustrate the present algorithm. In the proposed approach, the derivatives in both the governing equations and the boundary conditions are discretized by the method of DSC. The obtanied results are compared with those of other numerical methods. It is found that the convergence of the DSC approach is very good and the results agree well with those obtained by other researchers.     

厚壁焊缝横向裂纹的超声波判别方法

介绍了采用超声波检测锅炉汽包环缝横向裂纹的方法,分析了缺陷成因。因为厚壁焊缝的横向裂纹危害很大,归纳了鉴别横向裂纹的方法和步骤。通过观察在不同扫查方式下的超声波幅度的变化,可以区分缺陷的性质是否为点状还是密集状,利用不同探头角度变化导致的缺陷回波幅度的变化,可以判断曲线是否为横向裂纹。该方法操作性强,可应用于超声波检测厚壁容器时的横向裂纹缺陷判断。     

厚煤层残采工作面反向安装设备技术实践

一九三〇煤矿是新疆焦煤集团原煤生产骨干矿井之一,该矿井因受F4-2断层影响,二采区36211综采工作面巷道沿中线掘进,36211回风巷与原26211运输巷间最大煤柱达到95 m,经过方案比较,合理设计,在现36211综采工作面回风巷上段三角煤柱设计一残采工作面,为解决残采工作面安装液压支架等设备问题,在36211回风巷设计安装绞车等辅助设施,采用反向安装设备技术,实现了高效、快速、安全安装。     

厚煤层放顶煤大角度扇形收尾施工工艺实践

以左云长春兴煤业公司301综放工作面扇形收尾施工工艺为背景,介绍了在工作面受地质构造或者井田边界影响,工作面两顺槽与盘区大巷斜交布置时,为了多回收煤炭资源,提高经济效益,采取大角度扇形收尾的施工工艺,为厚煤层放顶煤大角度扇形收尾提供了借鉴和理论依据。