GRCop-42 Development and Hot-fire Testing Using Additive Manufacturing Powder Bed Fusion for Channel-cooled Combustion Chambers

Abstract

GRCop-42 is a high conductivity, high-strength dispersion strengthened copper-alloy for use in high heat flux applications such as liquid rocket engine combustion devices. This alloy is part of the family of NASAdeveloped GRCop, copper-chrome-niobium alloys. GRCop alloys were developed for harsh environments specific to regeneratively-cooled combustion chambers and nozzles with good oxidation resistance. Significant development was completed on the GRCop-84 and GRCop-42 alloys in the extruded wrought form demonstrating feasibility for combustion chambers. NASA has recently developed a process for additive manufacturing, specifically Powder Bed Fusion (PBF) or Selective Laser Melting (SLM), of GRCop-42 to establish parameters, characterize the material, and complete testing of components with complex internal features. This evolution of the GRCop-42 was based on the successful predecessor development work using GRCop-84 with the motivation of establishing a new copper-alloy option for use in NASA, government, and industry programs with SLM. A few advantages have been shown with the GRCop-42 that include higher conductivity and faster build speeds over the GRCop-84, and a simplified powder supply chain. Initial property development has shown that it is possible to produce high density builds with strengths equivalent to wrought GRCop-42 and a conductivity greater than GRCop-84. The GRCop-42 has completed process development and initial properties have been established. Several demonstrator combustion chambers have also been fabricated with the SLM GRCop-42 that include integral channels and closeouts. Additional test units have been fabricated and are completing substantial hot-fire testing to demonstrate performance of the material, process, and design.

Design, simulation, and validation of additively manufactured high-temperature combustion chambers for micro gas turbines

“…The use of AM for combustion chambers is not limited to the gas turbine industry. Research is being conducted for its use in rocket engines, for example NASA's AM copper alloy combustion chamber [18], and in combination with artificial intelligence to create combustion chamber designs that were previously unimaginable, such as the cooled rocket engine combustor by Hyperganic [19].…”

Copper-based alloys for structural high-heat-flux applications: a review of development, properties, and performance of Cu-rich Cu–Cr–Nb alloys

“…L-PBF samples that were HIPed demonstrate a similar tensile behaviour compared to as-extruded GRCop-84, though slightly more ductile with a ∼16-33% increase in final elongation [82,86]. In both L-PBF cases, GRCop-42 demonstrated reduced strength but longer elongations compared to GRCop-84 [82].…”

Emerging Functional Metals in Additive Manufacturing

“…NASA's Low Cost Upper Stage Class Propulsion (LCUSP) program developed and validated build parameters for L‐PBF with GRCop alloys in a Concept Laser (a GE Additive Company) AM machine. [ 56 ] The target application for this program is rocket propulsion components such as combustion chamber liners and fuel injector face plates.…”

“…They are targeted for harsh environments, having a high thermal conductivity and strength, compared to conventional copper alloys. [56,57] For use in combustion chambers, they are preferred alloys to other common aerospace copper alloys. GRCop-84 (Cu-8 at% Cr-4 at% Nb) and GRCop-42 (Cu-4 at% Cr-2 at% Nb) received further development for the use in high heat flux applications.…”