A new class of dual-functioning solid lubricants providing lubrication and wear protection for contact bodies under extreme loading conditions

在极端负载条件下的接触体由于高摩擦和咬合而易于严重磨损和失效，这与作用在其主体上的高热和机械负载相关联。这种现象具有重大的经济影响，因为从生物医学到航空航天等众多应用中使用的几乎所有关键部件都在加工过程中经历过这种现象，这是大多数制造过程中不可避免的一部分。由于对切削加工的摩擦学方面的知识严重缺乏，导致25-60%的切削能量浪费。据估计，仅在美国，次优加工操作的财政后果每年就超过100亿美元。十多年来，科学家们一直试图减少与加工中的高摩擦相关的刀具磨损和工件损坏的严重程度，但它们仍然是加工难切削材料的严峻挑战。到目前为止，克服严重刀具磨损的常用方法是通过使用超硬刀具或应用超硬和耐磨刀具涂层来硬与硬对抗。这种传统的方法为工业提供了有限的能力来提高工具耐磨性，而不是解决根本原因。已经进行了几种尝试来减少摩擦和机加工引起的应力，例如在不同的润滑剂上采用喷射润滑或增强硬涂层的润滑性。然而，对于加工难切削材料，咬合是如此严重，以至于主要是水基或油基的润滑剂在很大程度上是无效的，因为它们通常不渗透到接触区中以执行润滑功能。此外，在工具-切屑接触区的苛刻的接触压力限制了大多数涂层的适用性。为了从根本上解决这些问题，我首次提出用具有双重界面功能能力的选择性软质和低熔点金属合金涂覆刀具，主要用作有效的原位润滑剂，同时提供高耐磨性。软金属通常用作固体润滑剂，主要用于发动机轴承，但它们的性能受到熔点的限制，并且它们从未用作机械加工中的润滑剂，其中温度和压力的极端条件适用。我独特的涂层方法包括在切割过程中添加一个简单的加工步骤，用于将材料沉积在工具上，这消除了对用于选择性涂层的昂贵工具涂层过程的需要，并且具有当前方法无法实现的优点。短期目标是深入评估新提出的润滑剂和新刀具涂层方法的性能、局限性和能力，并开发用于加工各种难切削材料的新型兼容双功能润滑剂。长期目标是在其他极端条件下发现新的应用机会。

Contact bodies under extreme loading conditions are prone to severe wear and failure as a result of high friction and seizure, which are associated with high thermal and mechanical loads, acting on their bodies. The phenomenon has a significant economic impact since almost all critical parts used in numerous applications, from biomedical to aerospace, experience it during their machining, which is an unavoidable part of most manufacturing processes. Significant lack of knowledge about the tribological aspects of machining results in a 25-60% waste in terms of cutting energy. The fiscal consequences of sub-optimal machining operations are estimated to be more than $10 billion per year for the US industry alone. For more than a decade, scientists have tried to reduce the severity of tool wear and damages to the workpieces linked to high friction in machining, yet they remain serious challenges for machining difficult-to-cut materials. The common approach used so far to overcome severe tool wear is to fight hard with harder by using super hard tooling or applying super hard and wear-resistant tool coatings. This conventional approach has provided the industry with a limited capability to improve the tool wear resistance rather than addressing the root cause. Several attempts have been made to reduce friction and machining-induced stresses such as employing jet lubrication on different lubricants or enhancing the lubricity of hard coatings. However, for machining difficult-to-cut materials, seizure is so severe that lubricants, which are mainly water or oil based, are largely ineffective since they generally do not penetrate into the contact zone to perform a lubricating function. Moreover, the harsh contact pressure at the tool-chip contact zone restricts the applicability of most coatings. To address these problems at their roots, for the first time, I proposed coating the tools with selective soft and low melting point metallic alloys with dual interfacial functional capabilities for acting primarily as effective in-situ lubricants while providing high wear resistance. Soft metals are often used as solid lubricants, mainly in engine bearings, but their performance is limited by their melting point, and they have never been used as lubricants in machining, where extreme conditions of temperature and pressure apply. My unique coating approach involves adding a simple machining step to a cutting process for depositing the material on the tool which eliminates the need for expensive tool coating processes for selective coatings and has advantages not achievable with current methods. The short-term objectives are to evaluate in-depth the behaviour, limitations, and capabilities of the new proposed lubricant and the new tool coating method and to develop new compatible dual-functioning lubricants for the machining of various hard-to-cut materials. The long-term objective is to discover new opportunities for applications under other extreme conditions.