Experimental Study on Magnetorheological Chemical Polishing for Sapphire Substrate

Machining mechanism of magnetorheological chemical polishing is analyzed. Polishing experiments are conducted for sapphire substrate. The results show that magnetorheological chemical polishing sapphire substrate can be processed to sub-nanometer roughness ultra smooth mirror, the material removal rate is affected by the chemical reaction rate and shear action to remove the chemical reaction rate is faster, the stronger the shear removed, material removal rate is higher; higher removal rate is obtained when the magnetorheological chemical fluid which contains colloidal silica and alpha -Al sub(2) O sub(3) abrasive is used as polishing slurry. The material removal rate decreases with the increase in work gap, excitation gap and polishing time, but with the decrease in particle concentrations. Ultra-smooth surface of 0.3 nm in R sub(a) is achieved by using magnetorheological chemical polishing.