In-tube condensation of mixture of R134a and ester oil: empirical correlations

This paper presents a comparative study of the condensation heat transfer coefficients in a smooth tube when operating with pure refrigerant R134a and its mixture with lubricant Castrol “icematic sw”. The lubricant is synthetic polyol ester based oil commonly used in lubricating the compressors. Two concentrations of R134a-oil mixtures of 2% and 5% oil (by mass) were analysed for a range of saturation temperatures of refrigerant R134a between 35 °C and 45 °C. The mass flow rate of the refrigerant and the mixtures was carefully maintained at 1 g/s, with a vapour quality varying between 1.0 and 0. The effects of vapour quality, flow rate, saturation temperature and temperature difference between saturation and tube wall on the heat transfer coefficient are investigated by analysing the experimental data. The experimental results were then compared with predictions from earlier models [Int J Heat Mass Transfer (1979), 185; 6th Int Heat Transfer Congress 3 (1974) 309; Int J Refrig 18 (1995) 524; Trans ASME 120 (1998) 193]. Finally two new empirical models were developed to predict the two-phase condensation heat transfer coefficient for pure refrigerant R134a and a mixture of refrigerant R134a with Castrol “icematic sw”.     

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钻井液润滑剂是一种重要的钻井液化学处理剂，它的作用是改善钻井液润滑性，降低井壁与钻具（或套管）之间的磨擦，降低钻柱旋转扭矩和起下钻阻力，从而减少卡钻事故的发生。文章根据目前使用的白油钻井液润滑剂存在的不足，提出研制一种新型白油钻井液润滑剂。通过正交实验优选了润滑剂配方。经室内实验和现场实验证明该产品润滑性能好，与钻井液配伍性好，无毒性对环境影响小。     

Evaluating the mixing performance of a ribbon blender

This paper investigates the effects of processing and equipment parameters of a ribbon blender (i.e. loading method of lubricant, fill level, blade speed and blade design) on magnesium stearate homogeneity. A core sampling technique is used to obtain at least one hundred samples per sampling event, which are extracted throughout the blender and yield a thorough characterization of the entire bed. The results presented here can be used as a guideline to develop appropriate blending processes and characterization protocols for ribbon blenders.     

Paste extrusion of polytetrafluoroethylene (PTFE): Surface tension and viscosity effects

The effects of the lubricant physical properties on the processing of polytetrafluoroethylene (PTFE) fine powder resins are studied. Lubricants having different surface tension and viscosity were used; the two properties changed independently. These effects were studied by using dies of various contraction angle and reduction ratio for resins having a variety of molecular architecture. It was found that the wettability (surface tension) of the lubricant strongly affects the pressure needed to extrude the PTFE pastes. The viscosity of the lubricant was also found to play a significant role in the process since a lubricant with a low viscosity causes the paste to be extruded at a lower pressure. These effects of the physical properties on the extrusion pressure influence significantly the mechanical properties of the final extrudates. The latter are functions of the degree of fibrillation, which is significantly influenced by the wettability and viscosity of lubricants. Finally, the effects of die geometry on extrusion pressure and mechanical properties of extrudates were also assessed in order to determine the geometrical characteristics and operation conditions for the optimization of the process.     

提高金属摩擦学性能的新型润滑剂研究

从改善润滑性能出发,研制了一种在基础油中添加纳米碳酸钙粒子,用以提高金属摩擦学性能的新型润滑剂。通过X射线光电子能谱法得出:含有纳米碳酸钙粒子的润滑油,在摩擦过程中通过碳酸钙、氧化钙、钙三种物质共同作用提高金属的摩擦学性能。     

压射冲头与压室间的摩擦特性

利用专用模拟装置，研究了载荷、温度及润滑剂等因素对压射冲头与压室间摩擦力的影响，并根据试验结果及摩擦学原理，对实际压射过程的摩擦特性进行了探讨     

钛合金等温锻造进展

等温锻造是一种先进的加工工艺。本文从钛合金高温变形特性、等温锻造参数选择、模具设计、润滑剂摩擦特性等诸方面全面地介绍了这种先进的锻造工艺，它的应用前景及发展方向。     

几种铜带轧制润滑剂的性能评价与研究

对收集到的７种国内外铜带轧制润滑剂进行了基础性能测试，并对其工艺使用性能进行了评价研究，其结果将为有关工厂润滑剂的选用与研制提供一些依据。     

穿孔机导盘润滑技术研究

13Cr钢管在穿孔时的润滑技术和冷却技术与传统轧制工艺有所不同 ,对此问题进行研究 ,使其满足轧制 1 3Cr钢钢管的新工艺要求 ,最终达到轧制高质量 1 3Cr钢钢管的目的     

A study of contact-start-stop wear tracks by TOF SIMS

In magnetic hard disk drive system, an ultra thin layer of lubricant is coated to the thin film media surface to prevent wear. Under the condition of relative motion, the displacement and replenishment of the lubricant at the head and media contact area are the factors that control the friction and wear behavior of the system. In this study, we investigate the sliding wear disk surface prepared by contact-start-stop (CSS) test using TOF SIMS (Time of Flight Secondary Ion Mass Spectrometry). TOF SIMS is a power tool for surface analysis with both high spatial and high mass resolution. Our investigations show that the lubricant thickness variation of the disk media at the contact area can be captured by sharp ion map images of TOF SIMS, and the thickness can be inferred based on the relative ion fragment intensity. In addition, the composition variation of the slider material and the magnetic layer materials can also be monitored. Finally the sliding effect is analyzed.