磁流变抛光中表面彗尾状缺陷的生成与演变行为

Formation and evolution behavior of comet-tail defects in magnetorheological finishing

为了研究磁流变抛光后元件表面"彗尾状缺陷"的生成和演变机理,本文以石英玻璃为样品,分析了磁流变抛光时抛光液中抛光颗粒浓度与水分含量对彗尾状缺陷的影响。研究表明,彗尾状缺陷的生成与元件表面存在的原始缺陷相关,抛光颗粒在缺陷处的堆积是造成原始缺陷转变成彗尾状缺陷的主要原因。随着抛光颗粒浓度的增加,抛光颗粒在原始缺陷处的堆积明显,生成的彗尾状缺陷数量增加;然而随着水分含量的增加,抛光液的流动性增强,抛光颗粒在缺陷处堆积效应减弱,彗尾状缺陷出现的数量降低。在磁流变抛光过程中,原始凹坑缺陷首先演变成彗尾状缺陷,彗尾状缺陷的头部凹坑深度相对于原始缺陷表现出先增加再降低的趋势;而凹坑的边缘角度随抛光的进行单调增加,直到缺陷被完全去除。本文的研究结果为磁流变抛光中抑制元件表面彗尾状缺陷的生成奠定了理论基础,有助于后期研发控制彗尾状缺陷的抛光液和工艺优化方法。

To investigate generation and evolution mechanisms of"comet-tail defects"on surfaces of components after magnetorheological finishing(MRF),a self-developed MRF machine was used to analyze the effects of concentration and moisture content of MR fluid particles on comet-tail defects in MRF,using fused silica glass as a sample.Extant studies show that comet-tail defects are generated following initial defects on component surfaces.Moreover,the accumulation of particles at these initial defects is the main reason for their evolution into comet-tail defects.Increases in the concentration of polishing particles lead to evident accumulation of particles at initial defects,and more comet-tail defects emerge resultantly.However,fluidity is strengthened with increases in the moisture content,thereby resulting in a decreased number of comet-tail defects.With increases in processing times,initial craters evolve into comet-tail defects At this point,the crater depth at the head of the comet-tail initially increases and then decreases when compared to initial defects.Similarly,increases in processing times monotonically increase the crater edge angle until the defects are completely removed.Hence,the results of this study establish a theoretical foundation for restricting the formation of comet-tail defects on surfaces of components in MRF and facilitate subsequent development of MR fluids and process optimization methods to control the generation of comettail defects.