Solution Precursor Plasma Spraying: Are We Missing a Trick by Dismissing It?

Abstract Solution Precursor Plasma Spraying (SPPS), wherein dissolved metal salt precursors are injected into a plasma jet to synthesize diverse functional coatings, offers compelling advantages over conventional thermal spray techniques. These include elimination of powder synthesis, use of aqueous precursor feedstock capable of achieving molecular-level compositional control, and rapid one-step synthesis of coatings with chemistries for which spray-grade powders are readily unavailable, such as high-entropy oxides, perovskites, and related complex oxides. Despite these strengths and an encouraging body of prior research, SPPS research has declined from its modest peak in the mid-2010s. This is attributable primarily to the prohibitively narrow processing windows and low deposition rates imposed by legacy thermal spray hardware. This perspective argues that the advent of high-power axially-fed plasma spray systems fundamentally changes the technological landscape for SPPS. Axial injection delivers symmetric, near-complete thermal energy utilization, broader process windows, and deposition rates of practical interest in early demonstrations, thereby addressing the above limitations at laboratory scale. Emerging axial SPPS results across diverse material systems already demonstrate coating microstructures and performance metrics that rival suspension plasma spray, validating the broader promise of this approach. Although challenges related to precursor handling, feedstock delivery, and economics yet need to be tackled, SPPS with modern axial feed capable plasma torches represents a strategic opportunity that now merits systematic industrially oriented evaluation.