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 optimized in order to obtain a very high reliable strength.
Full scale beams with thin wall have been manufactured and tested in bending and in tension. Full scale beam assembly with integrated junctions have been manufactured and tested up to ultimate loads and have been space qualified.
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.
Dealing with ceramic materials for more than two decades, Thales Alenia Space – France has identified Silicon Nitride Si3N4 as a high potential material for the manufacturing of stiff, stable and lightweight truss structure for future large telescopes. Indeed, for earth observation or astronomic observation, space mission requires more and more telescopes with high spatial resolution, which leads to the use of large primary mirrors, and a long distance between primary and secondary mirrors. Therefore current and future large space telescopes require a huge truss structure to hold and locate precisely the mirrors. Such large structure requires very strong materials with high specific stiffness and a low coefficient of thermal expansion (CTE). Based on the silicon nitride performances and on the know how of FCT Ingenieurkeramik to manufacture complex parts, Thales Alenia Space (TAS) has engaged, in cooperation with FCT, activities to develop and qualify silicon nitride parts for other applications for space projects.
Dealing with ceramic materials for more than two decades, Thales Alenia Space – France has identified Silicon Nitride Si3N4 as a high potential material for the manufacturing of stiff, stable and lightweight truss structure for future large telescopes. Indeed, for earth observation or astronomic observation, space mission requires more and more telescopes with high spatial resolution, which leads to the use of large primary mirrors, and a long distance between primary and secondary mirrors. Therefore current and future large space telescopes require a huge truss structure to hold and locate precisely the mirrors. Such large structure requires very strong materials with high specific stiffness and a low coefficient of thermal expansion (CTE). Based on the silicon nitride performances and on the know how of FCT Ingenieurkeramik to manufacture complex parts, Thales Alenia Space (TAS) has engaged, in cooperation with FCT, activities to develop and qualify silicon nitride parts for other applications for space projects.
Due to their very specific set of material properties, silicon nitride and silicon carbide have gained a lot of interest in the
last 20 years. Moreover, many new approaches in technical equipment and processes were enabled with corresponding
research and production activities.
Also large efforts were made at FCT during the last years, to get able to supply even very large and complex shaped
components made of sintered silicon carbide (SSiC) and of gas pressure sintered silicon nitride (GPSN) ceramics. This
approach has opened new applications and markets for such ceramic materials. On the other side, designers and
engineers are now allowed to think much more complex in designing of ceramic components. In this paper, a new rapid
prototyping routine for very complex components as well as the corresponding materials will be presented. Components
for optical equipment in innovative avionic and space applications, and more conventional technologies are described.
Not only their unique key intrinsic properties, like high Youngs Modulus, very low CTE, very high strength and fracture
toughness for a ceramic but also newly developed and adopted shaping, sintering and machining technologies in both
green and sintered state have let to highly valued products. This enabled FCT to offer Carl Zeiss Optronics using silicon
nitride for a newly designed, very complex housing structure of an avionic pod camera. Due to a very low CTE, high
stiffness and less weight, an improved performance was reached.
Also Thales Alenia Space is engaged since some years in activities to develop and qualify Silicon nitride ceramics for
space projects. Extremely stiff, very lightweight and large truss space structures with a very low CTE, high rigidity and
no outgasing for satellites can now be realized. Deep tests sequence has been performed to qualify truss beams and end
fittings made in the same material.
Also advanced dynamic testing equipment for avionic turbine blades requires new approaches. In cooperation with
TIRA a series of shaker heads were developed which can operate at much higher frequencies and so reduce fatigue
testing time and costs. Last but not least, highly precise and thin walled disc structures with diameters up to 380 mm are
produced for wafer handling and testing equipment.
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