Abstract: A process for forming a structure of aluminium components comprises pre-treating aluminium sheet to produce an inorganic non-metallic surface coating thereon, forming the pre-treated sheet to produce components of desired shape and applying adhesive to the components and securing them together by means of the adhesive. Generally, an adhesive-compatible press lubricant is present on the sheet when it is formed. The invention also includes aluminium sheet carrying the inorganic non-metallic surface coating and a press lubricant thereon.

Abstract: A process for forming a structure of aluminium components comprises pre-treating aluminium sheet to produce an inorganic non-metallic surface coating thereon, forming the pre-treated sheet to produce components of desired shape and applying adhesive to the components and securing them together by means of the adhesive. Generally, an adhesive-compatible press lubricant is present on the sheet when it is formed. The invention also includes aluminium sheet carrying the inorganic non-metallic surface coating and a press lubricant thereon.

Abstract: The invention concerns a method of forming a joint between aluminium workpieces. These carry an artifically applied e.g. chromate or anodic oxide coating on their surface. A curable adhesive containing up to 40% by weight of particulate filler having a maximum particle size of 300 microns is provided between the workpieces to be joined. Resistance welding is performed using a welding electrode whose tip has a surface with an average roughness depth of at least 10 microns. This increases electrode life and makes it possible to use lower welding currents than previously recommended.

Abstract: An anodic oxide film is formed on aluminium strip by continuously passing the strip through a phosphoric acid electrolyte at from 25.degree. C. to 80.degree. C., the contact time between the strip and the electrolyte being not more than 15 seconds during which time the strip is anodized at a current density of at least 250 A/m.sup.2. In the resulting film, the pores are enlarged so that the effected surface area is increased. The film forms an excellent substrate for lacquer, paint, or adhesive.

Abstract: The invention provides aluminium articles having porous anodic oxide films colored by means of an optical interference effect. In FIG. 4, the article 10 carries a first anodic oxide film 12 with pores 14 enlarged at their inner ends 20 and containing deposits 22. The products may be made by growing a second anodic oxide film 26 underneath the deposits 22 which are preferably of acid-resistant material. X is at least 26 nm, Y is preferably at least 60 nm, Z is preferably 15 nm to 200 nm, (Y+Z) is preferably 75 nm to 600 nm, and W is preferably at least 15 nm.

Abstract: In a process for the electrocoloring of anodized aluminium in which colors are obtained by interference effects the pores of an anodic oxide film, produced by D.C. anodizing in sulphuric acid, are enlarged by electrolytic treatment in an acid electrolyte having a high dissolving power for aluminium oxide under alternating current conditions.

Abstract: Anodized aluminium having an anodic oxide film of at least 3 microns thickness is colored by electrolytically depositing inorganic pigment from metallic salt solutions, particularly nickel, cobalt, tin and copper salts and mixtures. The pigment deposits are characterized by outer ends of an average size in excess of 260 A lying at a distance of 500 - 3000 A from the aluminium/aluminium oxide interface.In a preferred method of production the anodic oxide coating is formed under conventional anodizing conditions in a sulphuric acid-based electrolyte. The anodized aluminium is then treated in phosphoric acid at a voltage of 8 - 50 volts to enlarge the pores to above 260 A in a region at the base of the pores adjacent the barrier layer. The pigment is then deposited in the pores to the specified depth and interesting new color shades are obtained as a result of optical interference due to the presence of the large size shallow inorganic pigment deposits.