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|3D Printed and Additively Manufactured RoboSiC for Space, Cryogenic, Laser and Nuclear Environments|
|Keywords: 3D Printing, Additive Manufacturing, Silicon Carbide|
|Goodman Technologies has been directly responsive to, and focused on, 3D printing and additive manufacturing techniques, and what it takes to manufacture in zero-gravity. During A NASA Phase I SBIR project, using a small multi-printhead machine, we showed that it was possible to formulate and 3D print silicon carbide pastes into shapes appropriate for lightweight mirrors and structures at the production rate of 1.2 square- meter/day. Gradient lattice coupons with feature sizes on order of 0.8mm were printed. The paste was cured to make a thermoset/ceramic greenbody via low temperature heating in an oven. Greenbodies were easily machined to very fine tolerances, ten-thousandths of an inch was demonstrated by the very reputable Coastline Optics in Camarillo, CA. To further elaborate on the summary list of achievements, in Phase I, Team GT demonstrated three different ceramization techniques for 3D printing low areal cost, ultra- lightweight Silicon Carbide (SiC) mirrors and structures, several of which could be employed in microgravity: 1. 3RB-SiC, a very high SiC content reaction bonded silicon carbide made by direct silicon melt- infiltrating of as-printed and cured greenbody material; 2. RoboSiC, use of proprietary and patent pending blend of powders to produce a SiC material with a deterministic microstructure; 3. DirectSiC, a very rapid proprietary ceramization process that converts as-printed or as-cured material preceramic polymer and SiC containing material directly to ceramic. The tremendously successful Phase I project suggests that we will meet or exceed all NASA requirements for the primary mirror of a Far-IR Surveyor such as the Origins Space Telescope (OST) and have a high probability solution for the LUVOIR Surveyor in time for the 2020 Decadal Survey. Results indicate that printing on the ground will achieve an areal density of 7.75 kg/square-meter (~39% of a JWST beryllium segment), a cost to print of $60K/segment, and an optical surface that has nanometer-scale tolerances. Printing in the microgravity environment of space we have the potential to achieve an areal density of 1.0-2.0 kg/square meter (<10% of a JWST beryllium segment), with a cost to print of ~$10K/segment. The areal density is 2-15 times better than the NASA goal of 15 kg/square meter, and the costs are substantially better than the NASA goal of $100K/ square meter. The encapsulated gradient lattice construction provides a uniform CTE throughout the part for dimensional stability, incredible specific stiffness, and the added benefit of cryo-damping. For the extreme wavefront control required by the LUVOIR Surveyor, the regularly spaced lattice construction should also provide deterministic mapping of any optical distortions directly to the regular actuator spacing of a deformable mirror (DM). Some of our processes will also allow for direct embedding of electronics for active structures and segments. Encapsulation of the lattice structures will allow for actively cooling with helium for unprecedented low emissivity and thermal control. The Goodman Technologies briefing presented at 2017 Mirror Technology Days “3D Printed Silicon Carbide Scalable to Meter-Class Segments for Far-Infrared Surveyor: NASA Contract NNX17CM29P” along with sample coupons resulted in extreme interest from both Government and the Contractor communities. The next applications would be for heat sinks and radiation shielding for space electronics.|
|Bill Goodman, President & CEO
Goodman Technologies LLC