Two-step and conventionally sintered aluminium oxide ceramics which contains waste aluminium oxide powder: a comparison of density and microstructure

Rad prikazuje svojstva i primjenu aluminijeve oksidne keramike, te usporedbu njene gustoće i mikrostrukture primjenjujući dva različita postupka sinteriranja – jednostupanjsko (konvencionalno) i dvostupanjsko. Otpadni prah aluminijeve oksidne keramike nastaje tijekom zelene obrade sirovca i zahtjeva poseban način zbrinjavanja. Dodavanjem otpadnog praha, došlo je do porasta prividne viskoznosti Al2O3 vodene suspenzije. Na temelju provedenih mjerenja stvarne gustoće, izračuna relativne gustoće i analiziranja mikrostrukture, dobiveni su podaci i informacije o efikasnosti postupaka sinteriranja. U radu je primjenom dvostupanjskog sinteriranja postignuta jednoličnija mikrostruktura sitnijeg zrna, te veće vrijednosti stvarne i relativne gustoće u odnosu na konvencionalno sinterirane uzorke. Stoga postupak dvostupanjskog sinteriranja ima prednost u odnosu na konvencionalno sinteriranje.This Master’s thesis describes the properties and applications of aluminum oxide ceramics, and compares its density and microstructure using two different sintering processes: one-step (conventional) and two-step sintering. Waste powder of aluminum oxide ceramics is generated during green processing of the raw material and requires special disposal. Addition of the waste powder resulted in an increase in the apparent viscosity of the Al2O3 aqueous suspension. On the basis of actual density measurements, relative density calculations and microstructure analysis, data and information on the efficiency of sintering processes were obtained. In the thesis, two-step sintering resulted in a more uniform microstructure of finer grains, and higher values of real and relative density compared to conventionally sintered samples. Therefore, the two-step sintering process has an advantage over conventional sintering