Densification behaviour and microstructure evolution of γ-Al2O3 nanoceramics during pressureless sintering

摘要: AbstractA high purity γ-Al2O3 sample with an average particle size of 30 nm was sintered in air at temperature 960–1650°C a heating rate 5 K min–1 using dilatometer. The instantaneous density determined by shrinkage compared that measured the Archimedes method room temperature. microstructure evolution during sintering observed scanning electron microscope. shows two stages. first stage, ∼8% linear shrinkage, occurs between 950 and 1150°C. second starts 1150°C extends to higher temperatures. There are peaks respectively 1110 1550°C. stages curve indicate phase transformation has occurred. α-Al2O3 ceramics were prepared grain 1˙32 µm, relative 92˙3%, open porosity 5˙81% closed 1˙89% 1650°C.