LOW CTE HIGH STIFFNESS DIAMOND REINFORCED SiC BASED COMPOSITES WITH MACHINEABLE SURFACES FOR MIRRORS STRUCTURES

摘要

Diamond reinforced reaction bonded silicon carbide composites have unique properties such as very high stiffness, low density, low thermal expansion coefficient and high thermal conductivity making them attractive materials for high precision optical and structural components. However, their use in high precision equipments was limited due to significant difficulties in high tolerance machining of these super hard composites. In this present work, machineable diamond reinforced SiC composites were fabricated through forming hybrid monolithic microstructures with diamond free machineable surfaces. This is achieved by coating diamond reinforced SiC green performs with SiC slurries. Coated preforms were then infiltrated with molten silicon. Resulting fully dense monolithic structures have surfaces free of diamond particles thus they can be ground, lapped and polished using conventional technologies.