Study on compressive and shear deformations of an abrasive particle aggregate in chemical mechanical polishing process

本工作的目的是制造一种微压缩测试仪来测量在剪切流动中形成的颗粒骨料的力学性能，并研究几种因素对骨料压缩变形特性的影响。今年，我们开展了以下工作：玻纤探头的制备：采用氢氟酸蚀刻与光学抛光相结合的方法，建立了玻纤探头压缩颗粒聚集体的制备工艺。颗粒骨料压缩变形行为的可视化：建立了激光扫描共聚焦显微镜图像叠加的骨料三维可视化技术。压缩试验：对剪切流动中形成的颗粒聚集体进行压缩试验，验证了本文研制的微压缩试验机的有效性。在压缩试验前，利用激光扫描共聚焦显微镜原位观察装置研究了胶乳颗粒在两平行板间剪切流动中的聚集和破裂行为。结果表明，随着剪切速率的增加，骨料的平均粒径减小，而由于水动力作用于骨料，间隙宽度减小。随着间隙宽度的减小，骨料的粒径分布逐渐变窄。此外，分形维数（即聚集体的结构）几乎与剪切速率和间隙宽度无关，约为1.2，表明聚集体相对致密。

The aims of the present work are to manufacture a micro compression tester to measure the mechanical properties of a particle aggregate formed in a shear flow, and to investigate the effect of several factors on the compressive deformation characteristics of the aggregate. This year, the followings were carried out.1.Manufacture of glass fiber probe : a manufacturing technique of a glass fiber probe to compress a particle aggregate was established by combining hydrofluoric acid etching and optical polishing.2.Visualization of compressive deformation behavior of particle aggregate : a three-dimensional visualization technique of aggregate by superimposing laser scanning confocal microscope images was established.3.Compression test : the compression test of a particle aggregate formed in a shear flow was carried out, and the effectiveness of a micro compression tester developed here was demonstrated.Before the compression test, the aggregation and breakup behaviors of latex particles in shear flow confined between two parallel plates were investigated using an in situ observation apparatus with a laser scanning confocal microscope. As a result, the average size of the aggregates decreases as shear rate increases and the gap width decreases due to the hydrodynamic effect acting on the aggregates. The size distributions of the aggregates become narrow as the gap width decreases. In addition, the fractal dimension, i.e., the structure of the aggregates, was almost independent of shear rate and the gap width, and approximately 1.2, which suggests that the aggregates are relatively compact.