Low Expansion Metallic Nanolaminate Replicated Mirrors with CTE Matched High Conductivity Graphite Fiber Reinforced Magnesium Mirror Substrate Structu

Magnetron sputtering of "Invar-like" nanolaminates onto a pre-finished/figured mandrel is proposed to produce strong, stiff, damage tolerant, low CTE replicas. The structural substrate will be a high performance discontinuous graphite fiber reinforced Mg AZ31 metal matrix composite manufactured by pressure infiltration casting. MetGraf Mg composites have the following attractive attributes for structural substrates:  CTE precisely matched to the Invar-like nanolaminate replica.  High specific stiffness  High thermal conductivity  High thermal stability  Low manufacturing cost This combination will result in a robust stiff, lightweight (< 8 kg/m2 areal density) meter class mirror. Lawrence Livermore National Laboratory (LLNL) has developed a sputter deposition process, which has been applied to the production of high quality mirror replicas. LLNL will produce ~400 ìm thick Invar-like 250 mm convex and flat nanolaminate replicas for this project with expected expansion coefficients of 2 to 4 ppm/K. MMCC will upgrade its graphite fiber preform to produce highly uniform materials that, after pressure infiltration, results in exact CTE matches to the nanolaminate. MMCC will investigate both resin and solder base approaches to attachment of pre figured and finished nanolaminate to figured MetGraf Mg substructures. 250 mm convex and flat mirrors will be demonstrated.