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

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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.