GB1016773A - A process for treating the surface of aluminium or aluminium alloy - Google Patents

Abstract

A process for treating the surface of Al or an Al alloy, e.g. a refrigerator ice tray or a refrigerator evaporator, to reduce the tendency of ice to adhere to it and improve its corrosion resistance and abrasion resistance comprises electrolytically anodizing the surface to form a porous film of aluminium oxide thereon, washing with cold water and immediately thereafter applying an organo hydrogen polysiloxane to the porous surface and heating the surface to a sufficiently high temperature to cause dehydrogenation of the organo hydrogen polysiloxane so that it becomes chemically bonded to the anodized surface of the Al or Al alloy. For anodizing, oxalic or sulphuric acid may be used to produce oxide films, 15, 20 or 25 microns thick. Methyl, ethyl or phenyl hydrogen polysiloxanes may be used, the methyl compound being in solution with benzene, xylene or toluene, the ethyl compound with benzene-butanol and the phenyl compound with benzene. The polysiloxanes may be applied by painting, immersion, or by impregnated cotton wool. The heating may be at 140 DEG C. by steam at 4 atmospheres, by boiling water at 100 DEG C. or by an air drying furnace at 120 DEG C.ALSO:A process for treating the surface of Al or an Al alloy, e.g. a refrigerator ice tray or a refrigerator evaporator, to reduce the tendency of ice to adhere to it and improve its corrosion resistance and abrasion resistance comprises electrolytically anodizing the surface to form a porous film of aluminium oxide thereon, washing with cold water and immediately thereafter applying an organo hydrogen polysiloxane to the porous surface and heating the surface to a sufficiently high temperature to cause dehydrogenation of the organo hydrogen polysiloxane so that it becomes chemically bonded to the anodized surface of the Al or Al alloy. For anodizing, oxalic or sulphuric acid may be used to produce oxide films 15, 20 or 25 microns thick. Methyl, ethyl or phenyl hydrogen polysiloxanes may be used, the methyl compound being in solution with benzene, xylene or toluene, the ethyl compound with benzene-butanol and the phenyl compound with benzene. The polysiloxanes may be applied by painting, immersion, or by impregnated cotton wool. The heating may be at 140 DEG C. by steam at 4 atmospheres, by boiling water at 100 DEG C. or by an air drying furnace at 120 DEG C.