Michael Nathal, chief of the Advanced Metallic Branch at NASA’s Glenn Research Center, is looking to re-invigorate that facility’s GRCop-84 program, among others. Begun a decade ago, GRCop had reached an advanced stage of development prior to funding cutbacks. GRCop-84 is a new copper-based material for space shuttle main rocket engine combustion chambers.
GRCop is acronymic of “Glenn Research Center copper” and the “84” references its 8% chromium, 4% niobium alloy composition. Although currently in suspension, the project had reached the point where thousands of pounds of material had been manufactured, good life data had been generated, and successful hot firing on stationary rocket engines accomplished.
“It represented an improved resource for space travel,” Nathal said. “Our material properties objectives were two-fold. The first was high thermal conductivity. The combustion chamber is a thin-wall pressure vessel cooled by cryogenic hydrogen fuel flowing around the vessel. Meanwhile, the internal temperatures are around 6000°F. The second was high strength, particularly strength at operating temperatures.”
Ordinarily, the stronger the material, he points out, the lower the thermal conductivity. GRCop-84 added 300°F to the existing baseline, representing a significant upgrade in terms of engine efficiency and power production.
“And, compared to current materials in this application, GRCop appears to offer longer life and heavier lift capability—but the final numbers are hard to quantify until the engine design and testing are complete,” Nathal said.
The Glenn researchers have looked at a few Earth-bound applications, chief among them electrodes for welding automotive bodies and components. GRCop-84’s higher heat capability and longer life play out as longer life on the assembly line, with lower overall manufacturing costs.