注塑模零件电刷镀纳米镀层的耐磨性能研究

利用电刷镀技术制备了含纳米SiO2和石墨粉的非晶态Ni-P合金复合镀层，并对其摩擦磨损性能进行了研究。研究表明，当纳米粉体在基质镀液中分散良好时，该复合镀层具有较高的显微硬度，较好的耐磨性及减摩性；当分散不良时，镀层的各项性能未见明显改善。模具试验表明，复合镀层有效地降低了干摩擦状态下注塑模推管与摩擦件的表面划伤与金属转移。     

大比例尺数字测图初探

文章论述了大比例尺数字测图的特点、作业方法和基本作业过程 ,提出测绘人员必须充分认识测绘技术发展的大势所趋 ,努力学习和提高自己     

Wear Debris Identification Using Feature Extraction and Neural Network

IntroductionDuringtheoperationofmachinery ,weardebrisareproducedasaresultofcontactbetweenmovingsurfaces.Thecharacteristicsofweardebris (whichincludeshape ,size,concentration ,surface ,color ,etc .) provideimportantinformationabouttheconditionofmachinery ,in particularthestateofwear .However,thecurrenttechniquesforweardebrisanalysisareusuallytime consumingandcostlyduetotherequirementofanalyst sexpertiseto perform particleinspection ,morphologycharacterizationanddatainterpretation .Thus ,manytec…     

Large Eddy Simulation of Particle-Laden Turbulent Flow over a Backward-Facing Step

Particle diffusion in large eddy structures with various Stokes number was analyzed numerically for the two-dimensional gas-particle turbulent flow over a backward-facing step. The continuous phase simulation was analyzed using the large eddy simulation (LES) method while the particle phase was analyzed by the Lagrangian method. The spatial and temporal results were used to analyze the evolution of the large eddy coherent structures and the vortex-particle interactions. The effect of the particle Stokes number on the instantaneous particle concentration distributions was also discussed. The simulations of the single-phase flow reproduced the character of the separation and reattachment flow and the essential features of the coherent structures. Numerous and complex vortex structures appeared at the high Reynolds number. Furthermore, the simulation shows that the Stokes number plays an important role in the particle dispersion and the instantaneous particle distribution. The continuous phase time-averaged results and the particle phase time-averaged results obtained from the LES analysis agree well with previous experimental data.     

Wear Debris Analysis： Fundamental Principle of Wear-Graphy

A new wear-graphy technology was developed, which can simultaneously identify the shape and composition of wear debris, for both metals and non-metals. The fundamental principles of the wear-graphy system and its wear-gram system are discussed here. A method was developed to distribute wear debris on a slide uniformly to reduce overlapping of wear debris while smearing. The composition identification analyzes the wear debris using the scanning electron microscope (SEM) energy spectrum, infrared-thermal imaging and X-ray imaging technology. A wear debris analysis system based on database techniques is demonstrated, and a visible digitized wear-gram is acquired based on the information of wear debris with image collection and processing of the wear debris. The method gives the morphological characteristics of the wear debris, material composition identification of the wear debris, intelligent recognition of the wear debris,and storage and management of wear debris information.     

静态燃烧合成陶瓷涂层技术及其应用研究

磨蚀是一种常见的材料失效形式 ,陶瓷涂层技术是解决磨蚀问题的重要途径之一。介绍了燃烧合成涂层技术的原理及制备陶瓷内衬复合钢管的工艺 ,同时对涂层的结构、组成及性能进行了研究。采用静态燃烧合成表面涂层技术制备了陶瓷内衬复合钢管及弯头 ,其涂层主要由主晶相α Al2 O3 及铁铝尖晶石相、莫来石相组成。反应体系中的添加剂SiO2 可以有效地提高熔体的流动性 ,使陶瓷的凝固、结晶过程得到进一步控制 ,有助于减少孔隙及提高陶瓷涂层的致密度。现场应用试验表明这种涂层具有较好的耐磨蚀性能 ,可大大延长设备的使用寿命。     

大型复杂系统平均寿命评定的Monte Carlo方法

随着现代武器系统和工程系统的大型化与复杂化趋势，大型复杂系统可靠性评定是急待解决的问题，工程中常用可靠性指标有可靠度和平均寿命，平均寿命指标由于直观、物理概念清晰，使用更加方便。基于可靠性框图建模，采用最小路集计算分析，提出了大型复杂系统平均寿命评定的Monte Carlo方法。解决了有限样本条件下，大型复杂系统平均寿命评定问题，对工程中大型复杂系统平均寿命评定具有重要应用价值。     

时序分析中时序约束条件的确立和检验算法

针对同步多相时序电路在满足建立时间约束时却忽视保持时间约束的情况，提出了一个基于锁存器多相时序电路的建立时间约束和保持时间约束的检验算法。该算法考虑了时钟偏斜对建立时间和保持时间的影响。经具体时序电路验证，本文检验算法是可行的。     

Cr3C2-NiCr涂层磨料磨损行为

采用橡胶轮磨损实验机 ,对三种类型粉末制备的 HVOF Cr3 C2 - 2 5 % Ni Cr涂层进行了磨料磨损实验 ,研究了涂层的磨损特性和喷涂工艺条件、粉末制备工艺对涂层磨损速率的影响。在运用扫描电镜对涂层结构和磨损表面观察分析的基础上 ,结合涂层结构和橡胶轮磨料磨损的特征 ,探讨了该涂层的磨料磨损失效行为。     

大变形巷道锚杆力学特性的数值模拟

通过现场观测和实验室试验,对大变形巷道锚杆的力学特性进行了测试,揭示了锚杆与围岩相互作用全过程呈现:初撑、增阻、恒阻、降阻直至失效。论述了锚杆阻力下降和失效是大变形巷道锚杆支护所具有的基本规律。为此,对FLAC3.3中锚杆单元模型进行了修正,使其具备模拟锚杆损伤软化的功能,并将其成功地应用于实际工程中。