Plasma spraying of enamel onto steel - giving uniform layer using enamels of higher melting points

摘要

Method for preparing an enamelled or vitreous coating on a substrate in which a powder of mean granulometry 40-100 mu and specific surface area 800-3000 cm2/g. is sprayed onto the substrate surface which has been-previously cleaned, is claimed. The powder is sprayed and fused using a plasma flame. The temp. of which inside the reaction tube is 6000-10000 degrees C, and the fusion is effected at such a temp. that the particles reach a viscosity n such that log n is =2.2. Pref. the particles are of difficultly fusible glass and the support substrate is metal and it is preheated to 800-1100 degrees C. Use of a plasma flame instead of the oxyacetylene flame used in the parent patent, allows the range of sprayable enamels to be extended to higher melting points.