Friction and plasticity of amorphous metal coatings

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The research objective of this grant is to elucidate the fundamental mechanisms of friction and plasticity in amorphous metal coatings. Certain MEMS/NEMS devices operated in dynamic mode have long been haunted by tribological issues. The scale-down of devices leads to large increases in surface force, including friction. In miniaturized gears manufactured by electrodeposited nanocrystalline metal, wear becomes an important issue. Environmental issues associated with electrodeposition of hard Cr coatings also call for commensurate replacement that can be fabricated by environment benign process. High-strength, amorphous metal coating is an appealing candidate for these purposes as it has high hardness, low surface roughness, and compatible elastic modulus and thermal expansion coefficient in comparison to metal substrates. However its friction behavior is poorly understood. Plasticity in amorphous coatings is an equally important subject, as it directly impacts tribological properties of these coatings. Several hypotheses will be tested, including amorphous metal coatings may have much lower friction coefficient than their crystalline counterparts, layer interface may induce unique friction and wear properties in amorphous multilayers. To examine these hypotheses, the PI will combine nanofabrication of amorphous films with advanced friction and nanomechanical testing techniques.If successful, the project may significantly improve the reliability and functionality of NEMS/MEMS components, magnetic data storage devices and wear resistant coatings. The concept and knowledge derived from this project will be of great scientific interest to metallic glass, coatings, nanomechanics, NEMS/MEMS, and the tribology community. Additionally this project will offer research training to graduate and undergraduate students at Texas A & M University (TAMU). Special effort will be made to recruit female and other minority students through the "Pathway to Ph.D program" funded by TAMU. The project will also enhance the materials science and nanoengineering curricula by incorporating the relevant results into classes when introducing advanced nanomaterials and benefit the relatively new Materials Science and Engineering graduate program. The PI will disseminate results to a much broader audience by involving high school teachers in the research project through NSF-RET program and through participation in international conferences. Collaborations with national laboratories will offer graduate students summer research experiences.