Insulating metal-ceramic composite body esp. for liq. metal handling - is diffusion welded together using iron@-chromium@ alloy bond layers

摘要

An insulating metal/ceramic composite body consists of a ceramic layer which is sandwiched between and bonded to inner and outer steel walls. The ceramic layer consists of Al2O3.TiO2 and is bonded to each wall by a metallic bond layer of Fe/5-20% Cr alloy. Prodn. of the above composite body involves (a) coating the inner and outer walls with the Fe/Cr alloy; (b) plasma depositing the ceramic layer onto the Fe/Cr alloy coating on the inner or the outer wall; (c) coating the ceramic layer with the Fe/Cr alloy; and (d) assembling and diffusion welding the coated walls together. The bond layer is pref. a 10-100 microns thick layer of a 13% Cr/87% Fe alloy. The walls are pref. made of a martensitic stainless steel esp.1.4914 steel, and are 0.3-2 mm. thick. The ceramic layer is pref. a 10-300 microns thick Al2O3.TiO2 layer. The bond layers are applied to the walls by plasma coating or by gas phase deposition (PVD or CVD). Diffusion welding may be carried out in a hot isostatic press e.g. at 120 MPa for 30 mins. USE/ADVANTAGE - For fusion reactor blankets, liq. metal pumps and liq. metal generators, esp. operating by the conduction principle. The bond layers promote adherent bonding of the ceramic layer to the walls (esp. of stainless steel), in spite of the large thermal expansion coefft. difference between the materials.