Characteristics of Conventional and Cascaded Arc Plasma Spray-Deposited Ceramic Under Standard and High-Throughput Conditions

Cascaded arc plasma torches have now become mainstream in thermal spray industry incorporating both multiple and single cathode configurations. Although there are anecdotal descriptions available for cascaded arc torches in terms of enhanced melting capability and overall process reliability, a critical and direct comparison of material interaction between the two technologies (cascaded arc and conventional torch configurations) through robust scientific methods is not available. In this article, two commercially available APS torches, namely, the conventional torch (F4MB) and the cascaded arc plasma torch (Sinplex Pro), were compared in the same spray cell using the same control equipment by adopting a systematic set of experiments involving voltage measurements, particle behavior, deposit formation dynamics, and infrared-based spray footprint heat flux quantification. The analysis of the data has led to quantitative correlations between torch configurations. The powder loading study indicated the enhanced melting capability of cascaded arc at equivalent parameters along with expanded and more uniform particle temperature over larger feed rates. The combination of higher feed rate and melt efficiency leads to distinction in coating stress evolution and microstructure. The integrated measurements suggest a scaling parameter that can establish process equivalency parameters to guide the transition from conventional to cascade torches.