BRIGE: Microwear Mechanism of Carbon Film under Extremely High Speed Surface Contact accounting for Phase Transition and Oxidation

项目名称：bridge：考虑相变和氧化的超高速表面接触下碳膜的微磨损机理摘要知识优势：本bridge项目的主要目的是通过考虑材料的热机械稳定性和化学稳定性来研究超高速接触下表面保护碳膜的微磨损机理。将通过(1)粗糙表面滑动接触的解析建模和计算模拟，以及(2)系统的高速接触实验来测量薄膜和衬底材料的磨损、相变和氧化进行综合研究。本研究的独特之处在于：(a)将热、化学薄膜性能的原位变化纳入磨损行为分析；(b)在高速接触实验后定量测量材料的物理和化学降解。在解析建模中，非均匀接触应力和摩擦热流将由改进的粗糙表面接触模型得到。表面凸起的个别闪点温度（即多点热源）将被应用到传热理论中，以计算碳膜和衬底的最终温度。相变改变了碳膜的强度，氧化影响了碳原子在基体上的粘附能。在计算模拟中，这些暂态材料特性将被纳入有限元分析程序，以研究碳膜的原位磨损性能。为了验证和改进所提出的分析/计算研究，将进行系统的实验。更广泛的影响：预计提出的研究将清楚地回答为什么碳膜在极高速接触下即使在轻微的接触负荷下也会经历临界磨损的问题。因此，这项研究的结果将为碳膜提供科学的解决方案，以(a)提高系统的可靠性和准确性，从而(b)减少意外摩擦和磨损造成的能量损失。这些令人兴奋的研究成果将被引入大学生教育和K-12推广计划。这些令人兴奋的研究成果将被带入大学生教育和K-12外展计划。摩擦学和界面工程领域的本科课程将建立，包括课堂授课和动手实验经验，本科生将随时参与实际的研究活动。为K-12年级学生设计一个简化的模型实验，增加他们对固体材料的热机械接触行为的理解。特别是，为了扩大工程和科学领域代表性不足的群体的参与，将在夏令营和实验室体验中为女性和西班牙裔K-12学生提供系统设计的模型。目前有两名女学生参与PI？年代的研究。PI将通过与德克萨斯理工大学西班牙裔学生协会的密切互动，继续努力招收代表性不足的学生。

ECCS-1228059PI: Yeo, Chang-DongInstitution: Texas Tech UniversityTitle: BRIGE: Microwear Mechanism of Carbon Film under Extremely High Speed Surface Contact accounting for Phase Transition and OxidationABSTRACTIntellectual Merit: The main objective of this BRIGE project is to investigate the microwear mechanism of surface protective carbon films under extremely high speed contact by accounting for thermomechanical and chemical stability of materials. An integrated research will be carried out through (1) analytical modeling and computational simulations of rough surface sliding contact, and (2) systematic experiments of high speed contact to measure the wear, phase transition, and oxidation of film and substrate materials. The unique features of the proposed research are to: (a) incorporate the in-situ changes of thermomechanical and chemical film properties into the analysis of wear behaviors, and (b) quantitatively measure the physical and chemical degradation of materials after high speed contact experiments. In analytical modeling, inhomogeneous contact stress and frictional heat flux will be obtained from an improved rough surface contact model. Individual flash temperatures of surface asperities (i.e., multi-points of heat source) will be applied into a theory of heat transfer to calculate the final temperature of carbon film and substrate. The phase transition changes the strength of carbon film, while the oxidation affects the adhesion energy of carbon atoms on substrate. In computational simulations, these transient material properties will be incorporated into finite element analysis code to investigate the in-situ wear performance of carbon film. To verify and improve the proposed analytical/computational researches, systematic experiments will be performed. Broader Impacts: It is expected that the proposed research will clearly answer the question of why carbon films experience critical wear under extremely high-speed contact even with mild contact load. The outcomes of this research will thus deliver scientific solutions for carbon films to (a) improve the reliability and accuracy of a system, and thus (b) reduce energy loss from unexpected friction and wear. The exciting research outcomes will be brought into the education of college students and K-12 outreach program. The exciting research outcomes will be brought into the education of college students and the K-12 outreach program. An undergraduate course in the area of tribology and interface engineering will be created including classroom lectures and hands-on laboratory experience, and undergraduate students will readily participate in actual research activities. A simplified mock-up experiment will be developed for K-12 students, which will increase their understanding on thermomechanical contact behavior in solid materials. In particular, to broaden the participation of underrepresented groups in engineering and science, a systematically designed mock-up will be provided in summer camps and lab experience for female and Hispanic K-12 students. Currently two female students are involved in the PI?s research. The PI will keep efforts on recruitment of the underrepresented students through close interaction with the Hispanic Student Society in Texas Tech University.