Synthesis and formation of alumina whiskers from hydrothermal solution
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Al2O3 whiskers with an average length of 5 μm have been synthesized from hydrothermal solution. Al(NO3)3 and urea were mixed and put into a Teflon-lined stainless steel autoclave and then treated at 120 °C to fabricate precursor whiskers NH4Al(OH)2CO3 (AACH). AACH whiskers were heated at 1200 °C in a furnace to obtain Al2O3 whiskers. The time-dependent examinations revealed that the formation process of AACH whiskers involves two sequential processes: a short liquid–solid deposition process in the initial stage and a long Ostwald ripening process. During calcinations, AACH transforms to amorphism then to α-Al2O3. The escape of NH3 and CO2 induced the distortion and toothlike morphology on the surface of the Al2O3 whiskers.
KeywordsTiAl3 Cyanuric Acid Irregular Particle Single Crystal Alumina Alumina Borate
The authors would like to thank the Western Personnel Training Plan of Chinese Academy of Sciences (No. 0810071031) and the Science and Technology Office of Qinghai province for financial support.
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