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Comparison of Conventional and Unconventional Sintering of Alumina Ceramics Containing Waste Alumina Powder Obtained by Slip Casting

This paper reports the results of studying the alumina ceramics which contain a considerate amount of waste alumina powder. The study focused on the investigation of the conventional sintering and hybrid microwave sintering of alumina green bodies in which the grain growth and densification were characterized after sintering. Waste alumina powder was obtained by green machining. Alumina green bodies were obtained by the slip casting process. Stable concentrated aqueous alumina suspensions were prepared with the addition of 0.05 wt. % Tiron, 0.1wt. % PVA – poly (vinyl alcohol), 0.2 wt. % magnesium spinel and 20 wt. % of waste alumina powder (expressed on dry weight basis of alumina powders). The used hybrid sintering atmospheric furnace consists of a 2.45 GHz microwave generator with a continuously adjustable power output from 0 to 3 kW and external heating elements. The sintering time for microwave hybrid sintering was significantly shorter than for conventional sintering. After sintering, density, grain size, hardness, fracture toughness and microstructure of the samples were examined, and comparisons were made for the conventional sintering and hybrid microwave sintering methods.

waste alumina ; conventional sintering ; hybrid microwave sintering

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