In situ tribology and microtribology of coatings for aerospace and MEMS applications

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Everyday, developed nations utilize sophisticated machines for transportation, manufacturing and many other applications. Almost all of these require lubrication to prevent wear and failure of the system. An estimate made in 1990 found that a nation could save on the order of a billion dollars annually through increased attention to tribological principles (i.e. reduction of friction and wear). These concepts become increasingly important as the world enters an era of energy consciousness. One strategy for aiding in aerospace and automotive systems is the use of solid coatings that provide mechanical protection from wear and lubrication by the inclusion of low friction materials. A highly effective, next generation class of coatings are nanocomposites consisting of a matrix of the relevant hard, protective and lubricating phases in nano-scale dimensions. The implementation of these coatings requires accurate data of their performance prior to their use in aerospace systems, where even one failure can be catastrophic. Another industrial area that requires increased attention to tribology is the manufacture of micro-electromechanical systems (MEMS). There is a strong desire in the MEMS industry to create reliable, complex devices with moving and contacting parts. Many aerospace coatings are also candidates for lubrication at the microscale. Successful utilization of tribological principles would lead to a next generation of innovative MEMS devices for a host of applications. This work will focus on two techniques to study next generation coatings for aerospace and MEMS applications. Using an in situ tribometer, in-service performance and changes of aerospace coatings will be examined. Direct observation of wear mechanisms will aid in the design and surface engineering necessary to optimize aerospace coating performance. For MEMS applications, coatings will be studied by nanoindenation for mechanical properties and microscale friction and wear properties. In summary, the tribology of coating materials will be studied over a range of length scales for advanced aerospace and MEMS applications.