This study focusses on optimising High-Velocity Oxy-Fuel (HVOF) spraying parameters to enhance NiCrFeSiAlBC coatings on AISI 316L stainless steel. The effects of nozzle geometry and spray distance on microstructural, mechanical, and tribological properties are systematically evaluated. Coatings produced using 4-inch and 8-inch (100 and 200 mm) nozzles are characterised via scanning electron microscopy (SEM), X-ray diffraction (XRD), and image-based porosity analysis. Vickers microhardness testing (3 N load) and ball-on-flat wear tests (10 N, 5000 cycles, alumina counter-body) assess mechanical performance. Results show that the 4-inch (100 mm) nozzle significantly improves coating integrity, hardness, and wear resistance. Additionally, spray distances of 330, 350, and 370 mm are investigated, with 350 mm providing the best balance of coating quality and adhesion due to enhanced thermal transfer and particle flattening. These findings underscore the importance of optimising nozzle design and spray distance to improve the performance and durability of HVOF coatings in demanding industrial environments.
Harabi et al. (Fri,) studied this question.