FEASIBILITY STUDIES ON GENERATION-, MEASUREMENT- AND APPLICATION-TECHNIQUES OF ULTRA-HIGH TEMPERATURE FIELDS BY ARC-DISCHARGE (PART 4: APPLICATION OF ARC-PLASMA).

The ultra-high-temperature field generated by an arc discharge is not only a heat source with a high density of energy but also a chemically active field. The present state of research and development was surveyed and discussed to utilize the arc-plasma field in the synthesis and processing of highly functional ceramics. Plasma spraying is a useful technique for surface coating and to produce thin films which can amplify the function of ceramics. However, much remains for understanding the changes of physical properties of spraying materials on the spraying process, to establish the evaluation method of the coating layer and to improve its mechanical properties. By controlling the porosity and pore size distribution in a layer, plasma spraying is applied to processing porous materials which are utilized as filters and carriers of catalysts. Since the arc-plasma has a high density of energy, it may also be applied to cutting and machining hard materials such as ceramics. By using plasma chemical reactions, techniques to obtain useful materials by thermally decomposing coal, plastics and hazardous wastes are expected to prevent pollution and conserve natural resources.