Study on Development of Composite PAM/PI Gel Abrasive Tools and Finishing Performance on the Sapphire Substrates

Abstract

A sol-gel method was proposed to prepare the abrasive tool to solve the problem of abrasive agglomeration in the traditional hot-pressing abrasive tool. In this paper, the effect of AM acrylamide (AM) monomer concentration on the polyacrylamide (PAM) gel performance and the effect of abrasive mass fraction on viscosity were investigated. Experiments about the effect of polyimide (PI) resin mass fraction on the mechanical properties, surface morphologies and friction wear performance of the abrasive tool were conducted. The polishing experiments were conducted to compare the machining effect of the gel abrasive tool, hot-pressing abrasive tool and the polyurethane polishing pad. Results show that the PAM gel has the best uniformity when the concentration of AM monomer reaches 7 wt%, when the mass fraction of PI resin in the abrasive tool reaches 12 wt%, the mechanical properties is the best. When the mass fraction of PI resin is 8 wt%, the gel abrasive tool has the most stable friction coefficient. The average surface roughness reaches 2.706 nm, and the flatness reaches 0.631 μm when the sapphire was processed by the gel abrasive tool. After Chemical mechanical polishing (CMP), a scratch-free surface was obtained and the average surface roughness reached 0.724 nm.