Obtaining silicon-carbide-based ceramics from ash and slag wastes

The possibility of obtaining solid silicon-carbide-based ceramics from ash and slag wastes (ASWs) is demonstrated. The technological process contains three stages: (i) nonvacuum processing of the initial ASWs in dc arc discharge carbon plasma under normal atmospheric condition, (ii) cleaning of the obtained powdered material from unbound carbon by annealing in atmospheric furnace, and (iii) final spark plasma sintering of the powder. Analytical data indicate that the obtained product is a silicon-carbide-based ceramics with a density of 3.05 g/cm$^3$ and a hardness of up to 19.9 GPa.