Invention Grant
US08637154B2 Ceramic beads with smooth surfaces and process for producing the same 有权
具有光滑表面的陶瓷珠及其制造方法

Ceramic beads with smooth surfaces and process for producing the same
Abstract:
A subject for the invention is to provide a process for ceramic bead production in which ceramic beads with smooth surfaces are obtained by a simpler method without using a complicated process involving, for example, a DC plasma/radio-frequency plasma combination or a two-stage radio-frequency plasma. Another subject is to provide such ceramic beads. The invention relates to a technique in which a preheated raw ceramic material is introduced into a laminar-flow thermal plasma obtained using a high-voltage type direct-current (DC) plasma gun and is cooled and solidified and the resultant ceramic beads are collected. It is preferred that the raw ceramic material should be preheated by passing the raw material through a refractory tube which runs through a furnace, while sending the raw ceramic material with a carrier gas, and that the preheated raw-material powder should be introduced into and treated with the thermal plasma under such conditions that the resultant ceramic beads are discharged from the thermal plasma at a discharge angle of 60° or larger with the thermal plasma. Thus, satisfactory ceramic beads which have smooth surfaces and have few crack defects and few internal void defects are obtained.
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