Abstract
Alumina ceramics were fabricated by spark plasma sintering (SPS) at a temperature range between 1473 K and 1773 K from an ultrafine alumina powder of 120 nm in diameter. Microstructural observation and EDS analyses were carried out for the alumina sintered. When the alumina powder sintered at a temperature range between 1473 K and 1673 K, the grain size of the peripheral parts in the alumina was larger than that of the central part in the alumina. The pore morphology in the peripheral parts of alumina was different from those in the central parts of alumina. The densification behavior of alumina powder during SPS changed according to the position in the alumina powder compact. From above results, the existence of temperature distribution in alumina powder compact during SPS consolidation was suggested. Chemical compositions in the vicinity of the pores on the triple grain boundary in the alumina sintered were different from the stoichiometric composition of alumina, indicating the possibility of reduction of alumina powder during SPS consolidation.
