Effects of Coating Materials on the Machinability of a Nickel Base,C-263, Alloy

PVD coated (TiN/TiCN/TiN, TiAIN and TiZrN) and uncoated carbide tools were used to machine a nickel base, C-263, alloy at high-speed conditions. The test results show that the multiple TiN/TiCN/TiN coated inserts gave the best overall performance in terms of tool life when machining at cutting speeds up to 68 m min and at depths of cut of 0.635 mm, 1.25 mm and 2.54 mm. All the tool grades tested gave fairly uniform surface roughness (Ra) values, below the rejection criterion, at lower speed conditions. The TiZrN coated inserts gave the lowest component forces when machining at lower cutting speed conditions while the TiA/N coated inserts gave the lowest component forces when machining at a higher speed of 68 m min^?1 and depth of cut of 1.25 mm. This tool performance can generally be attributed to the difference in their ability to provide effective lubrication at the cutting zone, thermal conductivity of the coating materials as well as the cutting conditions employed. The uncoated carbide tools generally encountered more severe crater wear, chipping/fracture of the cutting edges as well as pronounced notching during machining. This is due to their inability to provide effective lubrication at the cutting zone, thus impeding the gliding motion of the chips along the rake and flank faces respectively, thus accelerating flank wear. Analysis of the worn tool edges revealed adhesion of a compact “fin-shaped” structure of hardened burrs with saw-tooth like edges. This generally alters the initial geometry of the cutting edge, consequently resulting to poor surface finish with prolonged machining.     

Transition Temperatures in Sliding Systems

A pin-on-disk type of apparatus is used to study the effect of operating variables on transition temperatures with dilute solutions of pure fatty acids in pure paraffinic hydrocarbons and with a straight paraffinic mineral oil. It is found that the temperature at which the sudden transition from low to high friction and wear occurs increases with sliding speed, decreases with load, and is otherwise independent of operating variables. Empirically, the reciprocal of the absolute transition temperature varies linearly with the logarithm of the ratio of load to speed. The absence of conventional hydrodynamic lubrication in this system is demonstrated.

It is concluded that these results are inconsistent with the widely accepted concept that boundary lubricants must form a “solid” adsorbed film to be effective. It appears necessary to adopt a modified view of the role of the boundary lubricant, in which rheological and other diverse physical characteristics must be considered, and not simply the state of matter in which it exists. In addition, it appears necessary to consider the interrelated kinetics of boundary film formation and welding between asperities.     

油酸类添加剂的润滑性能研究

本文合成了四种油酸类添加剂,用四球机,摩擦磨损试验机测定了它们的润滑性能,同时对其润滑机理进行了理论探讨。     

微乳型磨削液的研究

本文研制了一种以润滑剂、防锈剂、表面活性剂,低粘度润滑油和自来水等为基本原料组成的透明微乳液,将其作为磨削液使用,能满足轴承加工的润滑性,防锈性和光洁度要求.     

柴油抗磨剂对柴油质量影响研究

针对使用抗磨剂柴油出现的乳化、絮凝等质量问题,借助抗磨剂结构、作用和发展的分析,剖析了酸/酯型抗磨剂原料选择、酯化、后处理等生产工艺对抗磨剂使用性能的影响。表明脂肪酸型抗磨剂仅适用于低酸度柴油,脂肪酸酯型抗磨剂的适应面广,稳定性好;提出控制使用酸型抗磨剂的柴油总不溶物、灰分、10%蒸余物残炭及使用酯型柴油抗磨剂的非烃元素含量、柴油破乳性即可保障柴油质量稳定。     

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章首先介绍了弹性石墨无毒，无味，性能稳定的特点。并介绍了将弹性石墨作为固体润滑剂应用于水基钻井液所进行的系列实验研究，包括弹性石墨对钻井液滤失性及流变性的影响，对钻井液润滑性能的改善等，以及通过对不同加量下的弹性石墨对钻井液性能的改善效果确定其合理加量。研究结果表明，弹性石墨与实验用水基钻井液相容性良好，地流变性影响很小，具有降低钻井液滤失量的作用，并且能明显地改善钻井液润滑性能，是抗温性能优良的钻井液润滑剂；在钻井液中加入0．3％弹性石墨后，在150℃高温条件下老化16h后，可以将钻井液的润滑系数降低30．4％，滤饼粘滞系数降低30．1％。     

正电聚醇钻井液体系在老堡南1井的应用

老堡南1井是冀东油田在近海部署的第一口预探井。该区块油气层埋藏深，地质构造复杂，馆陶组地层底部存在砾岩和玄武岩，易发生坍塌、渗漏，下部奥陶糸地层以灰岩为主，裂缝发育，地层压力乐数低，易发生井漏、井喷等复杂事故。现场正电聚醇钻井痕体系的应用，有效地解决了玄武岩地层的坍塌，该体系配合堵漏材料的使用，顺利完钻，并且电测一次成功。同时该体系具有较强的抑制防塌、润滑防卡能力，体系本身无毒、无荧光，有利于发现和保护油气层，满足了海上环保要求。目前，老堡南1卉已获高产工业油流。正电聚醇钻井液体系的成功应用，开辟了海上预探井的钻井液应用新领域，为冀东油田海上全面开发创造了良好的开端。     

发动机燃料润滑性的研究进展

为适应汽车排放对燃料品质提出的严格要求,研究提高燃料润滑性是当务之急,中报道了测试柴油,汽油润滑性的HFRR和SBOCLE方法,以及组成对燃料润滑性质的影响和规律。     

Lubrication of pharmaceutical powder/wall interfaces and electrostatic effects

The lubrication of powder/wall interfaces was investigated by tracking the evolution of the torque response during wall friction tests. A FT4 rheometer was employed to conduct this study. Two types of surfaces, borosilicate and Delrin, and 3 commercially-available pharmaceutical excipients, xylitol, microcrystalline cellulose and dicalcium phosphate dihydrate, lubricated or not with magnesium stearate, were tested. Two levels of relative humidity (RH), 20% and 60%, at which the powders were stabilized were used. The results showed that wall friction behaviors and, consequently, wall lubrication trends were strongly dependent on the nature of both the surfaces and powders. However, unexpected high data variability was obtained during the wall friction tests with non-lubricated powders sheared with a borosilicate surface at 20% RH. This variability was not observed when magnesium stearate was present in the powder formulations or when the tests were conducted at 60% RH. A particular effort was made to understand the possible causes of this variability. The results with non-lubricated MCC indicate that variability is reduced when the borosilicate surface is ionized at − 20 kV prior to the wall friction tests, while with the same treatment on non-lubricated xylitol did not produce a similar effect. Thus, contrary to the so far prevailing belief in the literature, this preliminary study proves that electrostatic phenomena can, at least partially, explain the reported variability.     

Key properties and blending strategies of hydrotreated vegetable oil as biofuel for diesel engines

Hydrotreating catalysis is becoming a promising alternative to transesterification for the production of biofuels derived from vegetable oils. They have potential advantages with respect to both biodiesel fuels and petroleum-derived diesel fuels in terms of production costs, engine emissions and adaptability to current engine designs, but they have also some limitations which may restrict their capability to replace diesel fuels. Those fuel properties considered the most restrictive ones were measured on different blends of HVO (selected among the variety of names given to these fuels) with a winter ultra low sulfur diesel fuel (in 10, 20, 25, 30, 35, 40, 45, 50, 55, and 75 vol.%) in order to propose some blending strategies to optimize engine performance and emissions, to protect the engine components and to keep the vehicle operability. The results obtained show that the main restrictions are imposed by lubricity and cetane number, and, in case of cold regions, also by cold flow properties. A compromise between lubricity and derived cetane number would lead to a recommendation for low or medium HVO concentrations, and blends with concentrations above 50% would not be recommended. Density and viscosity would not impose direct blending restrictions, although the reductions in density could provide some economic savings and some flexibility to refineries. The loss of heating value per unit volume (and consequently the expected increase in fuel consumption) would be lower than 3% in blends up to 50% in volume. Finally, the sooting tendency of the blends is sharply reduced, indicating lower engine PM emissions and reduced need for regeneration of diesel particulate filters.