Kevin Hemker
Johns Hopkins University
The marriage of additive manufacturing with advanced design methodologies is ushering in a new era of digital manufacturing and geometric complexity that holds great promise for the manufacturing of liquid rocket engines that rely on regenerative cooling. Copper liners with integral cooling channels covered by a nickel jacket that provides strength has become an enabling technology for rocketry. This project will introduce “additive grading” of the Cu/Ni interface. At the macroscale, the removal of the discrete, sharp interface and smoothing of material properties will mitigate stress concentrations and promote cohesion across the interface. At the microscale, fundamental scientific questions remain to be addressed before a systematic approach for designing, optimizing, and printing continuously graded interfaces can be realized. This project will integrate selected laser melting (SLM) and directed energy deposition (DED) manufacturing; process and phase modeling; and location-specific measurements to determine the influence of processing, microstructure, and local properties on the optimal length scale for “additively graded” bi-metallic interfaces. The resulting science-based methodology for AM graded interfaces will benefit not only NASA, but commercial space companies interested in additively manufacturing multi-material components, with decreased lead times and increased confidence and creativity.
