Friction and plasticity of amorphous metal coatings

这项资助的研究目的是阐明非晶态金属涂层中摩擦和塑性的基本机制。某些在动态模式下运行的MEMS/NEMS设备长期以来一直受到摩擦学问题的困扰。设备的缩小导致表面力的大幅增加，包括摩擦力。在电沉积纳米晶金属制造的小型化齿轮中，磨损成为一个重要的问题。与电沉积硬铬涂层相关的环境问题也要求通过环境友好的工艺来制造相应的替代。高强度、非晶态金属涂层具有较高的硬度、较低的表面粗糙度、与金属基材相比具有相容的弹性模量和热膨胀系数，因此是一种很有吸引力的涂层。然而，人们对其摩擦行为知之甚少。非晶态涂层的可塑性也是一个同样重要的课题，因为它直接影响这些涂层的摩擦学性能。将检验几个假设，包括非晶态金属涂层可能具有比晶态涂层低得多的摩擦系数，层界面可能在非晶态多层膜中诱导出独特的摩擦磨损性能。为了验证这些假设，PI将把非晶膜的纳米制造与先进的摩擦和纳米机械测试技术相结合。如果该项目成功，该项目可能会显著提高NEMS/MEMS组件、磁数据存储设备和耐磨涂层的可靠性和功能。该项目产生的概念和知识将对金属玻璃、涂层、纳米机械、NEMS/MEMS和摩擦学领域产生巨大的科学兴趣。此外，该项目将为德克萨斯农工大学(TAMU)的研究生和本科生提供研究培训。将特别努力招收女性和其他少数族裔学生，通过TAMU资助的“博士之路”项目。该项目还将加强材料科学和纳米工程课程，在介绍先进纳米材料时将相关成果纳入课堂，并使相对较新的材料科学和工程研究生课程受益。PI将通过NSF-RET计划和参加国际会议，让高中教师参与研究项目，从而将成果传播给更广泛的受众。与国家实验室的合作将为研究生提供暑期研究体验。

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.