Use of graded coatings is a well-known strategy for creating materials with continuously changing physical properties. The stiffness (modulus of elasticity) and density of flyer plates used in light gas gun testing directly influences the shape of the shock wave produced by the flyer plate. Many strategies exist for creating flyer plates that produce variable shock profiles, including stacked foils and powder compaction. We have investigated graded thermal spray coatings as an alternative method for creating flyer plates that produce variable shock profiles. An initial proof of concept demonstration has been completed by air plasma spraying a graded coating of Cu & Al onto a copper substrate. This composite flyer plate was tested in a light gas gun to demonstrate that a non-linear shock profile can be created. The plasma spray strategies used to create a group of similar graded density impactors are discussed. Initial light gas gun testing shows that graded density impactors can be created using thermal spray coatings.

The effect of torch hardware, operating parameters, and powder type on substrate surface heat flux was quantitatively investigated using calorimeters. The Sulzer-Metco 6P oxyacetylene torch with two nozzles and two air caps and the Alamo PG-550 torch were studied using designed experiments to show the effects of total combustible gas flow, oxy-fuel ratio, air flow, and standoff distance on surface heat flux. Air caps which directed cooling air toward the flame produced lower heat flux than air caps providing gun cooling. For the 6P torch, nozzle geometry did not have a significant effect on heat flux. With low air flow rates, both torches exhibited similar heat fluxes. At high air flows, the surface heat flux of the PG-550 was larger than that of the 6P.

The effect of hardware on operating parameters and the resultant coating are qualitatively known; however, the quantitative effects have not been well defined. This study quantitatively characterizes particle temperature and velocity for the Sulzer-Metco 6P oxy-acetylene torch with 3 different nozzles and 3 air caps and also, the Alamo PG-550 then relates those data to particle diagnostics, deposition efficiency and coating microstructure. Both torches were evaluated using statistically designed experiments where the process inputs of oxy-fuel ratio, total combustible gas flow, and standoff distance were varied. Both torches can access similar regions of particle temperature - particle velocity space. Increasing total combustible gas flow increased particle velocity with little effect on particle temperature. Increasing oxy-fuel ratio decreased particle temperature with little effect on particle velocity. Higher particle velocity and particle temperature conditions yielded denser, less porous coatings. Flame cooling air caps increase the particle speed while decreasing particle temperature. Nozzles which inject powder directly into the flame jets significantly increase particle temperature as compared to nozzles which do not. Deposition efficiency is shown to not only be affected by particle temperature and particle velocity where hotter and faster usually increase efficiency, but is also dependent on the distribution of particles within the plume.