Carrier Gas: The gas used to carry powdered material from the powder feeder or hopper to the thermal spray gun
Usually nitrogen or argon gas that carries powder into the thermal spray process. Casehardening See Carburising
an inert gas used to carry some other substance into a process For example a carrier gas would be bubbled through a bubbler to carry vapor into a process. The carrier gas is inert to the extent that it does not take part in the process reaction.