Characterization of Al2O3 colliodal suspensions which contain recycled alumina powder

U radu je ispitana mogućnost korištenja sekundarnog Al2O3 praha kao zamjene za dio primarnog praha sa svrhom recikliranja i uštede. Sekundarni prah nastaje kao otpad tijekom strojne obrade sirovca od aluminijeve oksidne (Al2O3) keramike i obično se dalje ne koristi. Za tehnologiju oblikovanja izabrano je lijevanje suspenzija, kao ekološki i ekonomski prihvatljiva varijanta. Pripravljene su tri skupine 60 %-tnih suspenzija, u kojima je variran međusobni omjer primarnog i sekundarnog praha. Kao disperzant korišten je DOLAPIX CE 64, poli(etilen-glikol) (PEG) kao vezivo te magnezijev klorid heksahidrat (MgCl2×6H2O) kao tvar za sprječavanje abnormalnog rasta zrna. Suspenzije su pripravljene homogenizacijom u planetarnom kugličnom mlinu i tretirane u ultrazvučnoj kupelji. Reološka svojstva (viskoznost, smično naprezanje) određena su na rotacijskom viskozimetru. Utvrđeno je da je zamjenom dijela primarnog Al2O3 praha sekundarnim moguće dobiti stabilne suspenzije. Povećanjem sadržaja sekundarnog praha povećava se viskoznost suspenzijeIn this paper, the use of secondary Al2O3 powder as a partial replacement for primary powder was investigated, in order to recycle and preserve resources. The secondary powder is produced as a result of the green machining of alumina and usually isn’t used any further. Slip casting was used, as an eco-friendly and economically acceptable forming technology. Three groups of suspensions with 60 wt. % of dry powder were prepared. The ratio of primary and secondary powder was varied. DOLAPIX CE 64 was used as a dispersant, polyethylene glycol (PEG) as a binder and magnesium chloride hexahydrate (MgCl2×6H2O) as an abnormal grain growth inhibitor. The suspensions were homogenized in a planetary ball mill and treated in an ultrasonic bath. Rheological properties (viscosity and shear stress) were determined on a rotational viscometer. It was determined that the suspensions prepared by the partial replacement of the primary Al2O3 powder with the secondary one were stable. The increase in the secondary powder content results in the viscosity increase