磨粒刮擦铝膜的亚表层磨损机制纳观探究

Wear Mechanism Analysis in Subsurface for Al Substrate Scraped by Abrasive Particle from Atomic Simulation

磨损常是宏观机械装备出现故障和产生噪音的关键诱因及微/纳机电传动装置的失效主因,伴随摩擦产生的粘着会使磨粒聚合为粘结点而影响机械服役期寿命。然而,碰磨中磨损产生内在机制和粘着诱导主因目前尚未被研究清楚。因此,本工作运用经典分子动力学法,对磨粒与金属Al基底碰磨刮擦中的亚表层磨损机理展开研究,并将温度、磨粒尺寸、刮擦速度分别对刮擦表面形貌与变形特征、切向力贡献度、磨屑数额、温度和应力分布的影响进行对比分析。研究表明:基底被磨粒刮擦时经历三个变形阶段,即刮擦初期弹性变形和刮擦中期弹塑性变形及刮擦稳定期塑性去除。其中,刮擦中期弹塑性变形阶段是诱导粘着产生的主要内因,且粘着犁沟力在整个粘着磨损过程中起主导作用,而磨屑原子对切向力的贡献度较小。另外,与磨粒紧密接触区的温度和应力分布都较其它部分要明显更高,且紧密接触区边缘两侧及被刮擦后表面会因温度升高而促使弹塑性变形阶段原子热运动迁移加剧,从而使小磨屑聚集为新粘结点并分布于被刮擦表面。高温下,基底内、外表面出现大量非晶态,这会诱导被刮擦表面出现加工硬化状态,其外部构型表现出与刮擦速度、磨粒尺寸改变所引起的表面形貌变化有显著差异。本研究结果将为碰磨刮擦时的磨损运动行为和粘结点生成机理这两方面的认识提供原子水平见解,并为宏观机械装备、微/纳机械装置减少摩擦磨损提供重要参考价值,也对超精密表面加工技术的发展起到促进作用。

Wear is a common phenomenon on moving contact surface,whose failure behaviour produced frequently on working environment for macroscopic mechanical equipment,especially for micro/nano electromechanical system.Furthermore,it’s also primary reason that the noise is generated among them.When abrasive particles scraped surface,it would occur occlusion performance around contact region.However,the internal mechanism of adhesive wear and the main cause of adhesion induction are still unclear up to now.Therefore,research on the wear mechanism between abrasive particles and Al substrate using classical molecular dynamics method is of particular importance,and compared the surface topography and deformation characteristics with the scraped substrate affected by external factors(temperature,particle size,scraping velocity).It was found that there were three stages described well during scraping process,namely the elastic deformation at initial scraping stage,the elastic-plastic deformation at middle scraping stage,and the plastic removal at stable scraping stage.Among them,the elastic-plastic defor-mation stages at middle scraping were the main internal cause leading to the adhesion induction,and the adhesion furrow force plays a leading contribution role in the whole scraping process.Moreover,temperature field and static stress distribution on closely contact area shows much more strengthened features than other places,which result in the phenomenons of heat movement migration intensified on local contact region.This research result will plays a practical significant role at atomic level on understanding the internal motion behaviour during scraping process,and deep into the intrinsic mechanism of bond point formation,which will provide a scientific perspective views on development of ultra-precision surface machining.