<title>C/SiC high-precision lightweight components for optomechanical applications</title>

Abstract

We contend that carbon fiber reinforced silicon carbide material (C/SiC), developed by IABG, represents the state-of-the-art for ultra-lightweight, high precision optomechanical structures that must operate in adverse environments and over wide ranges of temperature. C/SiC employs conventional NC machining/milling equipment to rapidly fabricate near-net shape parts, providing substantial schedule, cost, and risk savings for high precision components. Unlike powder based SiC ceramics, C/SiC does not experience significant shrinkage during processing, nor does it suffer from incomplete densification. By modifying certain process steps, the thermal and mechanical properties of C/SiC are tunable in certain ranges. This paper focuses on recent advances in C/SiC technology and application of this technology to high precision, lightweight applications such as meter-class optics and optical mounts. We also introduce a design for new, high precision mounts based upon standard optical grade C/SiC (formulation A-3) and a custom formulation of C/SiC (D-4) which was engineered for Schafer Corporation by IABG. The A-3 and D-4 formulations have a near-perfect CTh match with silicon, making them the ideal material to athermally support ultra-lightweight silicon optics that will operate in a cryogenic environment

Si/SiC optical coatings for C/SiC composites via gel-casting and gas silicon infiltration: Effects of carbon black content

“…carbide (C/SiC) composites have been considered in view of their outstanding performance, including the low specific density (2.65g/cm 3 ), low coefficient of thermal expansion (CTE: 2×10 -6 ·K -1 at room temperature and near zero bellow 100 K), high thermal conductivity (~125W/mK), high stiffness (220GPa) and bending strength (160MPa), very high chemical corrosion resistance, etc [1][2][3][4] . However, the short carbon fiber could be oxidized during the optical process, resulting in the roughness of the C/SiC composites (~60nm) cannot meet the demand of high optical performances.…”

<title>Thermo-mechanical performance of precision C/SiC mounts</title>

“…The manufacturing process steps are divided into two major objectives: production of carbon-carbon (C/C) greenbody material and production of near-net shape optomechanical structures. A complete discussion of this manufacturing process can be found in a previous publication of ours 7 . …”