LAUSR

Fine nanoparticles (NPs) exhibit higher sintering activity than large ones and are usually desired for sintering of nanocrystalline (NC) ceramics with fine grains. This paper demonstrates that large alpha-Al2O3 polycrystalline (PC) NPs with a mean particle size of 62 nm show a similar sintering activity as alpha-Al2O3 single-crystal (SC) NPs with a mean particle size of 16 nm.alpha-Al2O3 NC ceramics sintered from the 62 nm alpha-Al2O3 PC NPs and 16 nm alpha-Al2O3 SC NPs by two-step sintering exhibit a similar mean grain size of about 75 nm and a similar relative density of about 99.5%. It may be because the 62 nm alpha-Al2O3 PC NPs and 16 nm alpha-Al2O3 SC NPs have a similar mean grain size of about 19 nm. These results imply that NC ceramics with fine grains may be sintered from large PC NPs with fine grain sizes.