Abrasive Polishing using Composite Pads with Fixed Vertically Aligned Carbon Nanotubes

Abstract

Surface polishing using fixed-abrasive pads is a common process utilized for planarizing and smoothening the product surfaces. Although the fixed-abrasive pads such as sandpapers are widely used, large geometrical variation and height distribution of the fixed-abrasive limit their use as a precise finishing process for “mirror-like” surfaces with extremely low surface roughness. Also, the abrasives often detach during polishing, which generates unintended scratches. On the other hand, polishing with loosed abrasives are advantages for smooth polishing, but the polishing rate is low and the process generates significant material wastes. In this study, plant sprout was mimicked to fabricate a novel fixed-abrasive pad using vertically aligned carbon nanotubes (VACNTs) to overcome the limitations of the conventional fixed-abrasive pads. We prepare the VACNT thin film via a thermal chemical vapor deposition technique, then impregnated in the surface of a soft polyurethane (PU) pad. Then oxygen plasma was used to selectively etch the PU at the surface for VACNT protrusion. We controlled the procedure to let only few tens of nanometer sized abrasive part of the VACNTs is protruded out from the PU pad surface, while most of the VACNT bodies are embedded inside. VACNTs are advantageous as abrasive due to their excellent mechanical strength, and their high aspect ratio having a diameter of 10-20 nm and a length of few micrometer or more, enables to stably fixed on the soft PU surface during polishing. Using the new fixed VACNT pads, abrasive polishing tests are conducted and their characteristics such as material removal rate and resulting surface roughness are compared with conventional fixed and loosed abrasive polishing.