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Wear rates and the TEM characterisation of polycrystalline aluminas

ABSTRACT: Polycrystalline aluminas sintered with differing amounts of calcium oxide and silica in 1:1 molar ratios were made by precipitation, calcination and pressureless sintering. Wet erosive wear rates of the densified pellets were determined and appeared to have a dependence on the amount of additive present. The grain sizes were analysed by SEM. HRTEM revealed the presence of an intergranular glassy phase at two and three grain boundaries. The width of this film, determined by HRTEM, did not appear to change greatly with different levels of additive. EDX and EFTEM showed the segregation of CaO and S1O2 to the glassy intergranular phase.