First-Principles Molecular Dynamics Study of Silicon-Based Ceramics: Different Tribochemical Reaction Mechanisms during the Running-in Period of Silicon Nitride and Silicon Carbide
First-Principles Molecular Dynamics Study of Silicon-Based Ceramics: Different Tribochemical Reaction Mechanisms during the Running-in Period of Silicon Nitride and Silicon Carbide
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DOI：
10.1021/acs.jpcc.0c04613
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发表时间：
2020-09-17
影响因子：
3.7
通讯作者：
Kubo, Momoji
中科院分区：
文献类型：
--
作者：
Ootani, Yusuke;Xu, Jingxiang;Kubo, Momoji
由于硅基陶瓷在水环境中表现出超低的摩擦力，这些材料在水润滑系统的发展中受到了极大的关注。这种超低摩擦被认为是由磨合过程中复杂的摩擦化学反应形成的摩擦层所产生的。对磨合过程中摩擦化学反应的原子尺度研究对于开发具有超低摩擦和高耐磨性的滑动材料是至关重要的。研究了氮化硅和碳化硅两种硅基陶瓷材料的磨合期。了解氮化硅和碳化硅在磨合过程中的异同，有望为设计具有超低摩擦和高耐磨性的水润滑系统确定原则。我们用第一性原理分子动力学方法对Si3N4和SiC3N4进行了自配对滑动模拟。研究发现，较低的摩擦化学反应能垒和稳定的高配位硅原子中间体有利于氮化硅与碳化硅的摩擦化学反应。这种纳米尺度的机制与以前报道的实验结果很好地吻合，在这些实验中，Si3N4的磨合周期比SiC短。通过对氮化硅和碳化硅摩擦化学反应机理异同的新认识，为设计高性能、高耐磨性的滑动材料奠定了基础。
Because silicon-based ceramics show superlow friction in aqueous environments, these materials have attracted much attention for the development of water lubrication systems. The superlow friction is thought to be derived from a tribolayer that is formed through complicated tribochemical reactions during the running-in period. Atomic-scale insights into the tribochemical reactions during the running-in period are crucial to the development of sliding materials with superlow friction and high wear resistance. This study was focused on the running-in period of two silicon-based ceramics, Si3N4 and SiC. Understanding of the differences and similarities of Si3N4 and SiC during the running-in period is expected to identify principles for the design of water lubrication systems with superlow friction and high wear resistance. We performed self-mated sliding simulations of Si3N4 and SiC using first-principles molecular dynamics. We discovered that a lower tribochemical reaction energy barrier and stable highly coordinated Si-atom intermediates favored the tribochemical reactions of Si3N4 versus SiC. This proposed nanoscale mechanism is in good agreement with previously reported experimental results in which the running-in period has been shorter for Si3N4 than for SiC. Finally, we concluded that this novel understanding of the differences and similarities of the tribochemical reaction mechanisms of Si3N4 and SiC is likely to contribute to the design of sliding materials with high performance and high wear resistance.