Model Foundry for Low Cost Rapid Prototyping, Rapid Manufacturing of Metal Matrix Composites Parts

Graphite fiber reinforced Mg alloys show high specific stiffness, CTE less than 2 ppm/K and higher conductivity than competing mirror materials. Mg/Gr was coated with Si and polished to less than 10 angstroms RMS. Most important, the material is cast tonear final figure and is easily machined and rapidly figured to accept the Si Coating. The manufacturing costs of the base material promises to be lower than any competing mirror material. This coupled with its lack of toxicity makes it a prime candidatefor space and airborne mirrors.A program has been designed to optimize the materials and develop thermal seasoning processes to provide for thermal stability during the operational cycle of ABL and deep space applications. Extensive mirror development will be performed on 150 mmhexagonal segments where techniques for joining will be developed and demonstrated, hexagonal segments will be diamond turned to near final figure and Si coated. One hexagonal segment will be polished to aspheric figure; a second will be polished tospherical finish for cryo-testing at NMSFC.Finally, techniques will be developed for manufacturing 500 mm mirrors and joining to demonstrate that a 1.5 m ABL sized primary mirror.