is the term used to describe a gas which has been raised
to such a high temperature that it ionises and becomes electrically
When Plasma Spraying, the plasma is created by an electric
arc burning within the nozzle of a plasma gun. The arc gas
is formed into a plasma jet as it emerges from the gun nozzle.
Powder particles are injected into this jet where they melt
and then strike the surface at high velocity to produce a
strongly adherent coating. Almost any material can be sprayed
including metals, ceramics and plastics. The workpiece remains
cool because the plasma is localised at the gun. Applications
for plasma sprayed coatings can be found in all industries
- ranging from scuff resistant coatings on piston rings to
thermal barriers on turbines and abrasion resistant coatings
in the textile and paper industries.