Assessment of Microstructure, Porosity and Hardness of Plasma Sprayed Nanostructured YSZ-alumina Composite Coatings on 316L Stainless Steel
J. Environ. Nanotechnol., Volume 15, No 2 (June 2026) pp. 452-462
Abstract
AISI 316L stainless steel is extensively used in various engineering applications owing to its ability to resist corrosion and mechanical stability; however, the material suffers from limited tribological behaviour in view of its limited hardness and poor wear resistance. Though atmospheric plasma-sprayed (APS) YSZ–Al2O3 coatings have the promise to improve the surface characteristics, there is little information available on synergistic impacts of plasma power (PP) and stand-off distance (SOD) for the nanostructured 70 wt.% 8 mol.% yttria-stabilised zirconia (8YSZ)–30 wt.% Al2O3 coatings on AISI 316L stainless steel. This study systematically investigates the deposition of nanostructured 70YSZ-30Al2O3 composite coatings onto AISI 316L substrates through APS by varying the PP level at 20,25 and 30 kW and SOD at 100 and 120 mm. Coating microstructure, porosity, surface roughness (Ra) and microhardness were evaluated using optical microscopy and standard testing procedures. The findings revealed that PP and SOD influences more on the coating’s microstructure and mechanical properties. It was observed that the coating deposited using 30kW PP and 100 mm SOD exhibited a lower porosity level and higher microhardness value as compared to the other conditions. The porosity level, microhardness and Ra of the coating under 30kW PP and 100mm SOD yielded 5.63%, 914H V0.3 and 6.09 μm, respectively. The enhancement in hardness and reduction in porosity level and Ra is due to enhanced particle melting and reduced unmelted particles, resulting in denser splat formation at higher PP and moderate SOD. The results showed that the micro-mechanical properties of the 70YSZ–30Al2O3 coatings can be successfully controlled by adjusting the PP and SOD, which provides a new perspective for the development of wear-resistant surfaces for 316L SS components for industrial applications.
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Reference
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