Low Load Wear of Aluminum Alloys

汽车动力传动系统部件磨损率的评估对于材料的选择以及耐用发动机的设计和制造至关重要。在现代汽车中需要纳米（nm）/小时（nm/hr）的磨损速率。传统的测试方法不具备在模拟发动机条件下仅运行几个小时的实验室测试所需的灵敏度。加速试验通常不适用，因为磨损率会随着施加的载荷、滑动速度等发生剧烈变化;这些是所谓的磨损率转变，使得磨损率从一组条件外推到另一组条件基本上是不可能的。在低载荷（< 10牛顿; N）下的测量特别困难，因为实际上磨损率非常低，例如在气缸孔中。随着用于气缸孔的新型轻质材料（如铝硅合金）的开发，必须开发在相关载荷、滑动速度和温度下测量润滑磨损率的方法，并进行仅持续几个小时的试验。早期的方法需要活化待测材料。这项技术是有效的，但产生了需要处理的放射性物质。薄层活化解决了处置问题，但依赖于5至100 MeV范围内的离子的活化。目前的提案汇集了磨损和摩擦，抗磨添加剂如二烷基二硫代磷酸锌（ZDDP）和纳米材料分析的专家，以开发新的方法，该方法基于通过MeV离子注入创建一个已知的元素深度分布，该元素可以被中子活化并通过中子活化分析（NAA）进行分析。这种方法只会产生短寿命的同位素，因此大大减轻了处置问题。该项目将允许评估铝硅合金的纳米/小时磨损率，确定ZDDP抗磨剂在低负荷下的功效（甚至必要性），并研究其他润滑剂包。加拿大通用汽车有限公司（以下简称GM）将把这些信息应用于动力传动系部件的设计。

Evaluation of the wear rate of power train components in automobiles is crucial to the choice of materials, and their design and construction in the production of durable engines. Wear rates of nanometers (nm) per hour (nm/hr) are required in modern automobiles. Conventional testing methods are not capable of the necessary sensitivity for laboratory tests that run for only a few hours under conditions that mimic engine conditions. Accelerated testing is generally not applicable as wear rates can exhibit drastic changes with applied load, sliding velocities etc; these are the so called wear-rate transitions which make extrapolation of wear rates from one set of conditions to another essentially impossible. Measurements at low loads (< 10 Newtons; N) are particularly difficult as the wear rates are very low in practice, for example in a cylinder bore. With the development of new lightweight materials (eg Al-Si alloys) for cylinder bores, it is essential to develop methods of measuring lubricated wear rates at relevant loads, sliding velocities and temperature, in tests that only last a few hours. Earlier methods required activation of the material to be tested. The technique was effective, but produced radioactive material for disposal. Thin layer activation resolves the disposal problem but relies on activation by ions in the 5 to 100 MeV range. The current proposal brings together experts in wear and friction, in antiwear additives such as the zinc dialkyl dithiophospates (ZDDPs), and nanoscale materials analysis to develop new methods based upon the creation, by MeV ion implantation, of a known depth profile of an element that can be neutron activated and analyzed by neutron activation analysis (NAA). The method will only produce short lived isotopes and hence greatly alleviate the disposal problem. The project will permit the evaluation of nm/hr wear rates on Al-Si alloys, determine the efficacy (or even the necessity) of ZDDP antiwear agents at low loads, and investigate other lubricant packages. The information will be applied by General Motors of Canada Ltd. (henceforth GM) to the design of power train components.