Abstract: A method of surface pretreatment for aluminium or aluminium alloys before adhesive coating, electroplating or painting comprises a first anodizing step using an acid selected to produce a dense-packed, thick-walled anodic oxide coating followed by an etching step to modify the outer surface of the oxide coating while leaving the inner part unaffected.The anodizing acid may be sulphuric acid or chromic acid and the etch acid may be phosphoric acid, chromic acid or a mixture of sulphuric and chromic acids.

Abstract: A fiber reinforced metal is made by introducing an array of fibers into a die, charging the die with molten metal by vacuum infiltration and then applying pressure by means of an inert gas to improve the penetration of the molten metal into the fiber array. Apparatus for producing a reinforced metal cylinder comprises a cylindrical former (2) onto which a composite fiber (3) of boron, silicon and carbon is wound. The former (2) forms an inner closure member for the die defining a cylindrical die cavity (8) with an outer die body (4). A central cavity (15) within the former (2) is for insertion of a heating element to facilitate the flow of metal through the cavity (8). The die cavity is evacuated via conduit (16) and molten metal is then drawn into the cavity via the passage (7). After charging the die with molten metal the conduit (16) is connected to a source of high pressure nitrogen.