Silicon carbide (SiC) is a new type candidate material for large-scale lightweight space mirror. Its low thermal distortion,
high stiffness, fine optical quality and dimensional stability, make SiC an ideal material for large space born telescope.
Since ten years Changchun institute optics, fine mechanics and physics (CIOMP) has developed reaction bonded SiC
(RB-SiC) technology for space application, and can fabricate RB-SiC mirror with scale less than 1.0 meter for telescope.
The green body is prepared with gel-casting method which is an attractive new ceramic forming process for making
high-quality, complex-shaped ceramic parts. And then unmolding, drying, binder burning out, reacting bonded, the
RB-SiC can be obtained.
But with the development of space-born or ground telescope, the scale of primary mirror has exceeded 1.0 meter. So
CIOMP has developed an assembly technique which called novel reaction-formed joint technology for larger RB-SiC
mirror blank. The steps include joining of green bodies with mixture comprised of SiC particles and phenolic resin etc,
firing, machining and sintering.
Joining the Φ1.2 meter RB-SiC mirror blank by the novel reaction-formed joint technology. And testing the welding
layer's performance, the results show that the thickness of 54-77μm, the microstructure and thermal property can be
comparable to the substrate and the mechanical property are excellent in bending strength of 307MPa.