Electromagnetic powder deposition experiments

The US Department of Defense (DoD) and commercial entities are dependent on chemical plating and coating processes to replace worn or eroded material on damaged parts. Logistics Centers have been forced to consider replacement materials for repair operations due to the tightening of government regulations on the use of toxic and hazardous materials. This paper describes a new process capable of fulfilling many of these requirements. Existing state-of-the-art thermal spray processes (HVOF, D-gun, plasma spray) are limited to powder velocities of about 1 km/s because they rely on the thermodynamic expansion of gases. A new thermal spray process using electromagnetic forces can accelerate powder particles to a final velocity in excess of 2 km/s. At this velocity, powder particles have sufficient kinetic energy to melt their own mass and an equivalent substrate mass on impact. The energetics of the process allow fusion bonding of greater strength than that created by low velocity processes as well as improved coating density. This paper describes the laboratory system designed and constructed to conduct proof of principle experiments. Results of the experiments are presented along with high speed photographs of powder particles confirming system modeling and performance. The paper concludes with a discussion of the future direction of the program.