Effect of Shroud in Plasma Spraying on Chemical Composition and Thickness of Titanium Coatings

Abstract

Titanium and its alloys are wildly used in industries. Shrouded plasma spray can be considered as a useful technology to produce low oxide containing titanium coatings. In this paper, the effect of shroud in plasma spraying on chemical composition and thickness of titanium coatings were investigated. Shrouded plasma-sprayed titanium coatings were deposited onto mild steel substrates. Air plasma-sprayed titanium coatings were also deposited for comparison under the same spraying parameters. Those titanium coatings were then studied in terms of microstructure, oxygen and nitrogen contents and coating’s thickness. The titanium coatings were assessed by scanning electron microscopy and quantitative chemical analysis. The results showed that the shroud played a key role in protecting the particles from oxidation in flight. The shrouded titanium coatings exhibited lower oxygen content and an enhanced microstructure. The reduction in air entrainment with the shroud resulted in better heating of the particles and increases in deposition efficiency and coating thickness.