The influence of substrate temperature and spraying distance on the properties of plasma sprayed tungsten and steel coatings deposited in a shrouding chamber

This work is focused on the effects of substrate temperature on the properties of plasma sprayed tungsten and steel coatings. A range of substrate temperatures was achieved by varying the preheating temperature, pauses between torch passes, spraying distance and intensity of cooling. To suppress oxidation, the substrates were placed in a special shrouding chamber flushed with argon-hydrogen mixture. The coatings were characterized for their structure, porosity, hardness, thermal conductivity and oxygen content. A marked improvement of these properties with substrate temperature was observed and correlated to the spraying parameters.