REVETEMENT ANTI-CORROSION, NOTAMMENT POUR ARTICLES EN METAUX FERREUX

摘要

1345128 Coated metal substrates CHROMALLOY AMERICAN CORP 14 April 1972 [17 May 1971] 17328/72 Heading B2E [Also in Division C7] A ferrous metal substrate such as a steel compressor blade or vane shroud is protected against corrosion by means of an adherent protective duplex coating comprising a sacrificial thermally aluminised surface containing iron aluminide and a cured non-metallic barrier layer obtained from sodium silicate, potassium silicate, lithium silicate or ethyl silicate. A number of coats of the silicate may be applied by dipping and/or spraying with a solution containing also an anionic phosphate surfactant, the coats being cured in an infra-red furnace at 150-430‹C. A conversion coating which reacts with the silicate coat may also be sprayed on. The conversion coating may comprise phosphates and chromates, especially of Al, Mg, Be, Zn, Ba, Sr or Ce, Ba(OH) 2 or Ce 2 (CO 3 ) 3 . A further coating of silicate solution may then be sprayed over the conversion coating. The ferrous surface is initially aluminised by embedding the substrate in aluminium powder containing also some Al 2 O 3 and AlCl 3 , and heating.