Characterization by thermostimulated exoelectronic emission of thin alpha alumina particles obtained through comminution

ABSTRACT The study was concerned with the evolution that occured during alpha alumina comminution (either polycrystalline or monocrystalline, doped or non doped alpha alumina). Comminution of polycrystalline alumina shows that the evolution of the stresses detected throught triboemission is not monotonic as a fonction of the duration of the mechanical treatment. These stresses and those measured through X-ray broadening do not seem to be of the same origin. Triboemission signals transmitted by monocrystalline alumina are different, but the same evolution is observed through comminution. Besides, the evolution of stresses detected through X-ray broadening is different. Doping of monocrystalline alpha alumina (30ppm Cr 3+ ) does not provoke any significant changes when compared to undoped alpha alumina, as regards evolution during the comminution process. On the other hand, the T.S.E.E. signal has pratically disappeared for a 2,000 ppm Cr 3+ content, and the evolutions of the stresses detected through T.E. and X-ray broadening seem to be more complex.