<title>Influence of polishing fluid on ultrasmoothness polishing of Al-Mg alloy plate</title>

In the ultra smoothness polishing of a kind of Al-Mg alloy plate with alumina and colloidal silica abrasives, the influence of the hydrogen exponent of polishing fluids on the removal rate and the smoothness are examined and discussed by polishing in four hydrogen exponent of fluids of pH equals 2.3 (acid), pH equals 7.3 (neutral), pH equals 9.7 (middle alkaline) and pH equals 11.7 (strong alkaline). In case of polishing with alumina abrasives, the acid fluid has better influence on the removal rate and the surface smoothness than the neutral and the alkaline fluid. The removal rate and the smoothness for alumina-polishing in the neutral fluid are extremely small and worse than those before polishing. The best micro-area smoothness obtained by alumina-polishing in the acid fluid is about 13 nm (P-V). In case of polishing with colloidal silica abrasives, the alkaline fluid has better influence on the removal rate but the hydrogen exponent of fluid has little influence on the smoothness. The best micro-area smoothness is about 5 nm (P-V) for silica-polishing but that excluding pits of about 5 nm in depth becomes below 2 nm. In the silica-polishing of pure aluminum plate, the pit is not formed on the polished surface.