Low Load Wear of Aluminum Alloys

评估汽车动力传动系统部件的磨损率对耐用发动机的材料选择、设计和制造至关重要。现代汽车要求每小时的磨损率达到纳米（nm/hr）。对于在模拟发动机条件下仅运行几个小时的实验室测试，传统的测试方法无法达到必要的灵敏度。加速测试通常不适用，因为磨损率会随着施加的载荷、滑动速度等发生剧烈变化；这些就是所谓的磨损率转换，它使得从一组条件到另一组条件的磨损率的外推基本上是不可能的。在低载荷（< 10牛顿；N）下的测量尤其困难，因为在实践中，例如在气缸内，磨损率非常低。随着新型轻质材料（如铝硅合金）的发展，在相关载荷、滑动速度和温度下，在仅持续几个小时的测试中，开发测量润滑磨损率的方法至关重要。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（ZDDPs））和纳米级材料分析方面的专家，以开发基于MeV离子注入创建的已知深度分布的新方法，该元素可以被中子激活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，因此大大缓解了处置问题。该项目将评估Al-Si合金的纳米/小时磨损率，确定ZDDP抗磨剂在低负荷下的有效性（甚至必要性），并研究其他润滑剂包。这些信息将由加拿大通用汽车有限公司（以下简称通用）应用于动力总成部件的设计。

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.