TiB2和SiCW对Al2O3陶瓷材料高温摩擦磨损特性的影响

研究了Ａｌ２Ｏ３、Ａｌ２ｏ３／ＴｉＢ２和Ａｌ２Ｏ３／ＴｉＢ２／ＳｉＣＷ三处陶瓷材料在不同条件下的擦靡损特性。结果表明：三种陶瓷材料与硬质合金摩擦副的摩擦系数随温度温度的增加有不同的变化规律，摩擦表面的Ｘ射线衍射分析表明，摩擦系数的变化与陶瓷物膜的和结构有关，在高温下Ａｌ２Ｏ３／ＴｉＢ２陶瓷材料摩擦表面形成了具有优良的高温润性的ＴｉＯ２氧化膜，因而ＴｉＢ２的加入明显改善了Ａｌ２Ｏ３陶瓷材料 摩擦磨损     

机器人离散滑模变结构—PI控制器

本文采用离散滑模变结构控制方法，针对机器人提出了一种滑模变结构——ＰＩ控制方案，给出了该控制方案滑模存在条件及控制器设计方案。该控制器将离散滑模变结构控制和ＰＩ控制两者的优点有机地结合起来，理论分析和仿真结果表明该控制器能使机器人在各种复杂非线性动力学情况下具有良好的性能指标。这种控制器输出切换小，可以投入应用。     

Knowledge-based diagnosis of drill conditions

One major bottleneck in the automation of the drilling process by robots in the aerospace industry is drill condition monitoring. This paper describes a system approach to solve this problem through the advancement of new machine design, sensor instrumentation, metal-cutting research, and intelligent software development. All drill failures can be detected and distinguished: chisel edge wear, flank wear, crater wear, margin wear, corner wear, breakage, asymmetry, lip height difference, and chipping at lips. However, in the real manufacturing environment, different workpiece materials, drill size, drill geometry, drill material, cutting speed, feed rate, etc. will change the criteria for judging the drill condition. The knowledge base used for diagnosing the drill failures requires a huge data bank and prior exhaustive testing. A self-learning scheme is therefore introduced to the machine in order to acquire the threshold history needed for automatic diagnosis by using the same new tool under the same drilling conditions.     

Superplastic behaviour of Ti-48at.%Al two-phase titanium aluminide compacts made from mechanically alloyed powder

An HIP compact of MA-processed powder having a nominal composition of Ti-48at.% Al was produced. The compact consisted of a large amount of TiAl(λ) and a small amount of Ti₃Al (₂), in a completely ultra-fine equiaxed grain structure. This two-phase compact showed typical superplastic deformation behaviour. A maximum elongation of 550% was obtained. A strain exponent, n = 2, and grain size exponent, p = 2, were determined from the results of a strain-rate-change test and a creep test at constant initial stress using samples having various grain sizes, respectively. The activation energy for creep, Q_c at constant stress was calculated to be 350 kJ/mole. It is concluded that the superplastic deformation mechanism of the material under study is grain boundary sliding controlled by lattice diffusion in the TiAl phase.     

n-Al2O3/Ni复合镀层的组织与滑动磨损性能研究

用电刷镀技术制得了镍基n-Al2O3复合镀层，并对镀层的滑动磨损性能进行了试验研究。纳米复合镀层的表面形貌比较细腻，镀层中纳米粒子分布均匀，与基质金属结合紧密。镀层显微硬度达到HV700，比快速镍镀层提高约40％。滑动磨损试验结果表明，随着纳米粒子含量的增大，镀层的耐磨性提高，摩擦系数也呈增大趋势；但当镀层中n-Al2O3粒子的超过2.56%(质量分数）时，镀层的耐磨性显著下降。纳米复合镀层的磨损机制以疲劳磨损为主，而快速镍底层以粘着磨损为主。     

石灰竖窑工作衬砖蚀损机理的探讨

阐述了石灰竖窑的预热带、煅烧带和冷却带工作衬砖蚀损机理，并讨论了如何根据耐火砖性能和石灰竖窑不同区域的蚀损机理，选择耐火材料。     

Experience with Applying Formal Methods to Protocol Specification and System Architecture

In the last three years or so we at Enterprise Platforms Group at Intel Corporation have been applying formal methods to various problems that arose during the process of defining platform architectures for Intel's processor families. In this paper we give an overview of some of the problems we have worked on, the results we have obtained, and the lessons we have learned. The last topic is addressed mainly from the perspective of platform architects.     

Wear resistance of plasma coatings for a constant work of friction

We analyze the wear resistance of plasma coatings for a constant work of friction. The dependences of the wear resistance of the coatings are obtained for a broad range of loading conditions. It is shown that the minimum sensitivity to loading conditions is exhibited by the molybdenum coatings. It is also established that the wear resistance of the coatings decreases as the amplitude of displacements increases and the cyclic frequency of the tests decreases due to the intensification of fatigue processes on the surfaces. The comparative characteristics of coatings are presented. __________ Translated from Problemy Prochnosti, No. 5, pp. 94–100, September–October, 2007.     

Influence of load and speed on wear characteristics of grey cast iron in dry sliding — selection for minimum wear

The wear of grey cast iron in dry sliding conditions has been studied with the aims of (1) finding the influence of working conditions on the wear rate, and (2) determining the region of speed and load where low wear is accomplished. Grey cast iron with flake and nodular graphite was submitted to investigation using a pin-on-disc machine. The results indicate that the flake graphite cast iron is more suitable for applications at speeds greater than 4 m s⁻¹ and lower loads, while nodular cast iron has greater wear resistance at lower speeds in the range of loads investigated - from 50 N cm⁻² to 200 N cm⁻²