Quo vadis thermal spraying?

This paper is devoted to thermal spraying and presents the state of our cur rent knowledge, as well as the following research or development needs: spr aying heat sources, i.e., flame, high-velocity oxifuel flame (HVOF), detona tion gun (D-Gun), and plasma torches; particle heat and momentum transfer ( measurements and modeling), process on-line control, powder morphologies, a nd injection within the hot jet and reactions with environment; coating for mation, i.e., particle flattening and solidification, splat layering, resid ual stresses, coating microstructure, and properties; and reliability and r eproducibility of coatings.