Heat content and structure of particles in plasma spraying with a current-conducting wire

Abstract

The heat content of plasma flow and particles for the following materials is determined: for aluminium 112.05 kJ, for copper 64.45 kJ, for BrKMts3-1 bronze 59.43 kJ, for metal-sprayed wires Np65G, PP-100Kh15M2G2R and Sv07Kh20N9G7T 64.45, 79.32 and 39.6 kJ, respectively. The high values of the heat content of the plasma flows with aluminium and the flux-cored wire are evidently associated with the occurrence of the exothermic reactions of aluminium and graphite in the composition of the flux-cored wire. Experimental results show that the main part of sprayed coatings produced from the investigated materials consists of more than 80% of the fractions with dimensions 0.4–0.1 mm, whereas the fine dispersion fractions with sizes of 0.1 mm and less are characterized by poor cohesion bonding and impaired strength properties of the coating. The removal of the individual layers by a rapidly rotating steel brush increases the strength of the coatings by 25–30%.

Keywords:

• Plasma jet calorimeter heat balance
• enthalpy
• particle size
• particle composition
• exothermic reaction