Abstract

Thermal spray is a versatile process that produces high-quality coatings possessing diverse properties such as superhydrophobicity; wear resistance; corrosion resistance; dielectric properties etc. Conventionally; powder feedstock is used in thermal spray; and this process is commercialised in numerous industrial processes. However; liquid feedstock based thermal spray is still in its development phases; due to limited information available on process parameters. Various parameters such as plasma/fuel gas; plasma current; feedrate; feeding angle; type of feedstock (suspension or solution precursor); feedstock concentration; feedstock viscosity; solvent; etc. significantly influence the thermal and kinetic energy exchange between plasma/flame and feedstock material. Suspension plasma spray (SPS) and suspension high velocity oxy-fuel spray (SHVOF); once optimised; can give rise to coatings with multiscale features. An in-depth understanding of the complex interaction between feedstock solution/suspension chemical-physical properties and plasma/flame jet characteristics is essential to understand its specific impact on coating properties and their application. This paper presents comparisons between two different TiO2 coatings; deposited by SPS and S-HVOF; and obtained by varying some of the fundamental spray deposition parameters. The surface morphology and cross-sections of the as-deposited coatings were compared through SEM/EDX. Further; surface wetting properties were analysed through measuring the static and dynamic contact angles.

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