Characterization of plasma sprayed Al2O3 coatings sprayed with two different nozzle diameters

Alumina coatings were deposited onto mild steel substrates by using a plasma spray system. The coatings were sprayed by feeding the alumina powder internally using two nozzles with internal diameters of 7.5 and 8 mm. The influence of nozzle diameter on the microstructure and mechanical properties of as-sprayed alumina coatings was investigated. The results indicated that alumina coatings sprayed with a nozzle diameter 8 mm have higher hardness but lower abrasion wear resistance than alumina coatings sprayed with the 7.5 mm nozzle. The coating porosity increased as the nozzle diameter was increased