Micro-Joints Formation during D-Gun Spraying

Some particular Fe-Al particles in the coating deposited by D-Gun spraying onto the steel substrate are subjected to the detailed analysis. An asymmetrical micro-joint is revealed in each of the analyzed particle. It is concluded that the partially melted particle was solidified directionally from two sides towards the joint axis. The solidification results in the appearance of: amorphous phase sub-layer, oscillatory sub-layer which contains two types lamellae distributed alternately and typically non-equilibrium phase sub-layer. The analogy between diffusion interconnection and micro-joint obtained by means of the D-Gun deposition is discussed. Some Fe-Al particles less than 50 microns in diameter were deposited onto the steel substrate by means of the D-gun spraying. A solidification mechanism of an individual particle is described.