The cold gas-dynamic spray and characterization of microcrystalline austenitic stainless steel

Abstract

This thesis presents research on the cold gas-dynamic spray process applied to the deposition of stainless steel coatings. Cold spray deposition is a relatively new process utilized to create corrosion protection coatings and to perform additive repair for large steel structures. This thesis aims to study the effectiveness of the low-pressure cold spray process on four, commercially available, austenitic stainless steel powders by characterizing both the powders and the resultant coatings. Particle velocimetry and fluid dynamics simulation were also utilized to study the in-flight characteristics of the powder. Notably, this thesis presents evidence that austenitic stainless steel can be successfully deposited via the low-pressure cold spray process. Substantial variability was observed in the commercially available austenitic stainless powders, particularly in the phase content, the particle size distribution, and the particle shape. These parameters had a large effect on the particle velocity and subsequent deposition characteristics. In fact, the PG-AMP- 10 powder, which possessed the highest ferrite fraction and had irregular particle shapes, achieved much higher velocities and greater deposition efficiency than the phase-pure and spherically-shaped S5001 powder.