NASA has been working on several different ongoing projects for 3D-printed rocket engine components in metals, as we've told you. Now it's reached another first in aerospace 3D printing: a full-scale, 3D-printed rocket engine component made of copper.
Copper is well-known for its heat-conducting abilities in uses from electronics to cookware. But this very reason makes it harder to work with: the copper powders in selective laser melting (SLM) processes like NASA's don't easily melt in the continuous way needed. As a result, very few copper rocket parts have been made with 3D-printing methods.
NASA's copper part is a rocket engine combustion chamber liner that operates at insanely high and low temperatures and pressures. Inside the chamber, propellant burns at 5,000F on the liner's paper-edge thin wall. Outside, hydrogen gas must be kept at temperatures less than 100 degrees above absolute zero to prevent the liner from melting. Between the inner and outer walls of the combustion chamber liner, more than 200 tiny cooling channels circulate the gas.
To fabricate the complex internal geometries of these chambers was a major challenge, said Chris Singer, director of the Engineering Directorate at NASA's Marshall Space Flight Center. Even so, making the part with 3D printing can potentially reduce the time and cost of making rocket engine parts like this one.
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After several test parts were made to characterize the material and create a copper additive manufacturing process, NASA's team used an SLM machine to fuse together 8,255 layers of copper powder to make the chamber liner. That took nearly 11 days. The powder is GRCo-84, an alloy invented by materials scientists at NASA's Glenn Research Center.
The center is developing an extensive database of mechanical properties to help guide future 3D-printed rocket engine designs. The data will be made available in NASA's Materials and Processing Information System (MAPTIS), managed by Marshall, to boost the industrial competitiveness of US manufacturers.
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Ann R. Thryft is senior technical editor, materials & assembly, for Design News. She's been writing about manufacturing- and electronics-related technologies for 25 years, covering manufacturing materials & processes, alternative energy, machine vision, and all kinds of communications.
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