Approximate Theory of Fluidized Bed Coating.

摘要

The fluidized-bed system for coating metals with plastics has developed from a laboratory curiosity barely thirteen years ago to a routine process in operation today in more than 360 major companies. Applications are increasing in the appliance, chemical processing, electrical, power distribution, and pipeline fields. In the fluidized-bed coating process, a fusible polymeric resin in powder form is applied to the surface of an object that is immersed in a bed or chamber of powder through which a current of gas is passed. The gas serves to levitate the resin powder in such a manner that it resembles a boiling liquid in appearance. The object is heated to a temperature high enough above the melting or softening point of the resin so that, after the object is removed from the heat source, it retains enough heat on its surface to melt the resin powder particles, which then stick fast, melt, and flow together to form a coating.