Cladding by Plasma Transferred Arc Process: Influence of the Process Parameter on Plasma Behaviour and Molten Bath

Coatings, a few-millimeter thick, are widely used to protect new mechanical parts against abrasion and erosion or rebuild worn parts. The plasma transferred arc process is a commonly used process to deposit such coatings. It makes it possible to bring about a metal bath inside which melted powders are introduced to form an alloyed coating between the feedstock material and substrate material with metallurgical adhesion. This process consists to establish an electrical arc between the cathode and the workpiece. . The arc melts the part surface and the powder injected inside the plasma column. The latter is protected from the surrounding air with an inert gas shrouding around the working area. The main parameters of the process are the arc current intensity, plasma and shrouding gas flow rates, distance between the cathode tip and piece, velocity of plasma torch displacement; they all have a notable effect on the produced coating. This study investigates the plasma behaviour and properties of the clad by using a design of experiments. The properties of the coating are the dilution level, porosity, efficiency of material deposition, heat flux transferred to a water-cooled calorimeter, and hardness in the clad and fringes to estimate the thermally affected area.