Functionalization of the Fine Al2O3 Abrasive by the Polyacrylamide Deposition
Keywords:Al2O3 ultrafine powder, azo initiator, dispersion, surface modification, composite abrasive
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.
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