Effect of heating on the behaviors of hydrogen in C-TiC films with auger electron spectroscopy and secondary ion mass spectroscopy analyses

C-TiC films with a content of 75% TiC were prepared with magnetron sputtering deposition followed by Ar⁺ ion bombardment. Effect of heating on the behaviors of hydrogen in C-TiC films before and after heating was studied with Auger Electron Spectroscopy and Secondary Ion Mass Spectroscopy (SIMS) analyses. SIMS depth profiles of hydrogen after H⁺ ion implantation and thermal treatment show different hydrogen concentrations in C-TiC coatings and stainless steel. SIMS measurements show the existence of TiH, TiH₂, CH₃, CH₄, C₂H₂ bonds in the films after H⁺ ion irradiation and the changes in the Ti LMM, Ti LMV and C KLL Auger line shape reveal that they have a good hydrogen retention ability after heating up to the temperature 393 K. All the results show that C-TiC coatings can be used as a hydrogen retainer or hydrogen permeable barrier on stainless steel to protect it from hydrogen brittleness.     

PCB微钻有限元分析的几个关键问题

随着印制板和封装技术的快速发展,印制板钻孔面临越来越大的挑战。钻孔质量受钻机、钻头、钻削参数和印制板材的影响,文章对微钻有限元分析的几个关键问题进行探讨,以提高微钻设计水平。首先评述了微钻有限元分析的研究现状,然后讨论了微钻三维模型的建模方法,最后对微钻设计中的几个重要参数对微钻性能的影响进行了重点分析。文章的主要创新点包括:(1)提出了通过CAD方法建立微钻三维模型的方法,保证了有限元分析的精度;(2)分析了微钻参数对微钻性能的影响,该结果可以指导实际的微钻设计。     

全位置药芯焊丝自保护焊厚壁钢管焊接试验

为了解决长输管道安装工程中全位置自动化焊接问题,采用自行研制的全位置焊接机器人BIPT3,采用自保护药芯焊丝对管径为4 m壁厚为60 mm的输水钢管进行了打底、填充和盖面焊接.实现了大管径钢管的药芯焊丝自保护焊的全位置自动化焊接.焊接过程稳定,无咬边和驼峰现象,焊接工艺优良,电弧稳定,焊缝外形美观.     

Viscoelastic properties of monodisperse spherical silica suspension

The viscoelastic properties of the suspension of monodisperse spherical silica produced by hydrolysis of tetraethoxysilane in alcohol solvent with ammonia as a catalyst in polyethylene glycol (PEG) were studied. The results show that the SiO2/PEG suspension possesses the reversible shear thinning and shear thickening behaviors. In the shear thinning region, the loss modulus (G″) almost remains unchanged, whereas the storage modulus (G′) decreases. In the shear thickening region, G″ and G′ increase for the formation of the "clusters". The larger G″ over G′ in all the stress studied shows that the system mainly possesses the viscous property, and that the energy dissipated(Ed) is larger than that stored. Ed of this suspension is proportional to the maximum strain (γmax) rising with the exponent of 1.92 under low shear stress; however, in the shear thickening region, Ed is proportional to γmax rising with the exponent of 5.00.     

Influences of nonassociated flow rules on seismic bearing capacity factors of strip footing on soil slope by energy dissipation method

Seismic bearing capacity factors of a strip footing placed on soil slope were determined with both associated and nonassociated flow rules. Quasi-static representation of earthquake effects using a seismic coefficient concept was adopted for seismic bearing capacity calculations. A multi-wedge translational failure mechanism was used to obtain the seismic bearing capacity factors for different seismic coefficients and various inclined angles. Employing the associated flow rule, numerical results were compared with the published solutions. For bearing capacity factors related to cohesion and equivalent surcharge load, the maximum difference approximates 0.1%. However, the difference of bearing capacity factor related to unit weight is larger. With the two flow rules, the seismic bearing capacity factors were presented in the form of design charts for practical use. The results show that seismic bearing capacity factors related to the cohesion, the equivalent surcharge load and the unit weight increase greatly as the dilatancy angle increases, and that the nonassociated flow rule has important influences on the seismic bearing capacity.     

航空阀控式免维护铅酸蓄电池的充电方法研究

简要分析了阀控式免维护铅酸蓄电池的特点,探讨了现行充电方法的优点和缺点,提出了阀控式免维护铅酸蓄电池在没有恒压充电机的情况下,应采用多阶段恒流充电的方法来延长蓄电池的寿命。     

改GE752系列发电机为油田钻井电动机

通过对中海油公司两台美国GE公司5GE-752T5A发电机成功改造为GE公司5GE752AR2A水平钻井电动机,一方面表明系列化电机之间可以相互改造;另一方面为油田钻井维修部门缺少GE752电动机备品提供了一种快速、经济的解决方案.     

横向磁场永磁直线电动机电磁力的分析与计算

直线电动机不需机械转换装置即可实现直线运动,但输出力密度低也限制了其应用场合.针对此不足,文中采用横向磁场结构,提出了一种新型的永磁直线电动机结构形式.在对电动机运行机理进行分析的基础上,从理论上对电动机的定位力特性和"力-位移"特性进行了研究,并应用三维有限元法对其进行了数值计算和分析.计算结果与理论分析结果相符,验证了理论分析的正确性,为横向磁场永磁直线电动机的深入研究奠定了良好的基础.     

神经网络法优化接触器电磁系统

将人工神经网络优化方法引入接触器电磁系统的优化设计中,利用人工神经网络强大的非线性逼近能力和高效率的并行计算功能进行优化.采用改进BP算法前馈神经网络法,建立了接触器反力特性中拐点位置的动态吸力和激磁电流为输入神经元,以电磁系统的尺寸作为输出神经元的前向三层的神经网络,并以CJX1型接触器为样本,通过变步长法训练神经网络.网络训练成熟后,可对接触器的外型尺寸进行优化.采用神经网络法减少了大量的三维电磁场计算,可以得到很高的优化速度,很快得到结果.经优化后的接触器可减小电磁系统的体积.     

蓝宝石衬底上原子级光滑AlN外延层的MOCVD生长

在蓝宝石衬底表面无氮化、低Ⅴ/Ⅲ比的情况下,采用1200℃的衬底温度、5kPa反应室气压,用MOCVD方法在蓝宝石衬底上生长出了表面原子级光滑的AlN外延层.原子力显微镜测试表明其平均粗糙度为0.44nm,X射线衍射(0002)回摆曲线FWHM为166".实验结果和分析表明,极性和气相反应是影响AlN表面形貌的主要原因.以原子级光滑的AlN为模板生长出了高质量的高Al组分的n型AlGaN,证实了AlN模板具有较好的质量.