New Materials

Abstract

The combination of rigidity, light weight, and thorough stabilization of the skins which is achieved by the use of a honeycomb core in sandwich structural components has made it a popular material, and its use is likely to increase. In the case of metal honey‐comb the main limitations are imposed by the difficulty of achieving a good bond between core and skin. To this end an adaptation of the now familiar Redux process has been announced by Aero Research Ltd., of Duxford, Cambridge, who first introduced the original process in 1942. The new variant involves the same materials as the normal process, but the powder is supplied in film form, in rolls, with a protective covering. In application the film is first consolidated on to the pickled skin sheet by heat and vacuum pressure. No priming of the metal surfaces is needed. Pressure can be applied by a rubber blanket, aluminium foil being used to separate it from the film, to prevent adhesion to the rubber. This operation is carried out at 145 deg. C. for ten minutes. The foil is then stripped off, and liquid Redux 120 applied by brush to the film and the honeycomb core. The liquid is dried for 30–60 minutes at 80 deg. C, and the component assembled. The whole is then cured at 145 deg. C. under vacuum pressure. Curing times vary with the proportions of the component, but are of the order of one hour.