Si3N4 ceramic application for large telescope development results

Abstract

Abstract-Thales-Alenia-Space has identified the ceramic Si3N4 as an interesting material for the manufacturing of stiff , stable and lightweight truss structure for future large telescopes. Si3N4 ceramic made by FCT has been selected for its own intrinsic properties ( high specific Young modulus , low CTE, very high intrinsic strength for a ceramics ) and its cost effective beams manufacturing capabilities.In order to qualify beam and beams end fittings for future large and thermo-elastical stable truss structure for space telescope, full development and tests activities have been performed. Manufacturing process has been optimised in order to obtain a very high reliable strength. Beams end fittings made also in Si3N4 and its direct bolting capabilities have been also space qualified by tests.Beside this qualification for current space telescope, developments are continuing thank to CNES R&T to develop high loaded brazed junction between Si3N4 parts, enhanced thermal conductivity and mechanical strength through Si3N4 formulation and manufacturing process tuning.