engleski

Sintering of Slip Cast Composite Al2O3- ZrO2 Ceramics

Slip casting method can be used for forming monolithic and composite ceramics, in which a stable aqueous suspension of ceramic particles is poured into a plaster mould. Zirconia-toughened alumina composite ceramics possess many attractive properties such as high-temperature mechanical strength, wear resistance, low thermal conductivity and good thermal shock resistance. Compared to monolithic alumina ceramics, composite Al2O3-ZrO2 ceramics have enhanced fracture toughness and flexural strength due to the embedded zirconia grains in the alumina matrix. In this paper, waterbased suspensions with a total of 70 wt. % solid phase content (monolithic Al2O3 and composite Al2O3-ZrO2 ceramic suspensions) were prepared. The solid phase of composite ceramic suspensions consisted of either 1 or 10 dry weight base (dwb) % addition of zirconia (ZrO2) powder, and the rest was alumina powder. The used zirconia (ZrO2) powder was partially stabilized with the 3 mol % yttria (Y2O3). A dispersant (Dolapix CE 64) and a binder (polyvinyl alcohol - PVA) were added for the stabilization of water-based suspensions. The stability of 70 wt. % monolithic (Al2O3) and composite (Al2O3-ZrO2) ceramic suspensions was evaluated by rheological measurements and sedimentation tests. Suspensions were homogenized in a planetary ball mill and green bodies were prepared by slip casting of stable suspensions in a plaster mould. After the sintering, the density of the sintered monolithic and composite ceramic samples was measured and compared.

alumina - zirconia composite ceramics ; slip casting ; stability ; rheology

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