Novel Ballistic Processing of Thick Films: Structural Evolution and Mechanical Behavior

Ballistic processing (BP) is a new process that promises almost instantaneous processing of thick and thin films, through the acceleration of a carrier through a molten metal stream. The mechanisms by which such films are produced are difficult to study due to the ultrarapid processing speeds involved. In this article, we use the thermal properties of the carrier to reveal the mechanisms of formation of these films. High-speed imaging and extensive postprocessing characterization were used to arrive at a fundamental understanding of the microstructural evolution of thick films in BP. Results show that the thermal characteristics of the carrier material play a role in the morphology, topography, structure, and mechanical behavior of the processed films. An increase in carrier thermal conductivity generally resulted in an increase in film thickness and apparent elastic modulus. Increasing the carrier speed beyond the current limit is forecasted to decrease the thickness and improve the properties.