Functionalization of the Fine Al2O3 Abrasive by the Polyacrylamide Deposition

Abstract

In order to enhance the dispersion stability of ultra-fine Al₂O₃ powder in aqueous media, the alumina particles were modified with silane coupling agent KH570 at first, and then 2,2'-Azobis(2-amidinopropane) dihydrochloride (AIBA) was anchored onto the modified Al₂O₃ to initiate the graft polymerization of acrylamide monomer (AM), and PAM/Al₂O₃ composite particles were obtained finally. The structure and dispersion property of Al₂O₃ composite particles were characterized by XPS, FTIR, laser particle size analyzer, micro electrophoresis apparatus, SEM and spectrophotometer. The results indicated that the attained composite abrasive when water-soluble azo initiator was added at 40 ℃ showed good dispersion stability in aqueous media with PAM as shell and Al₂O₃ as core. Compared with unmodified Al₂O₃, the reunion phenomenon of grafting polymerization modified Al₂O₃ powder was improved by AM, the D50 of the modified particles reduced. The isoelectric point (IEP) of the grafting modified particles migrated, and the zeta potential of the modified particles reached to the maximum value when the pH was 9. After PAM/Al₂O₃ abrasive polished, the surface roughness of NiP/Al hard disk surface was obviously reduced.