Patent GB-756344-A (GB)
Title: Process of treating surfaces with mixtures sprayed thereon
IPC: C23C22/76
Filed: 1953-05-04
Abstract: A surface treatment for metal workpieces comprises spraying the surface through an annular source of heat with a jet of cleaning or coating mixture under pressure, substances which swell under the application of heat being added to the mixture before it is sprayed, and the substances being heated subsequently to said spraying to cause them to swell.  The method is applicable to pickling metals with acids or lyes, phosphatizing, oxidizing and colouring metal workpieces and coating workpieces with protective metals such as tin, lead, or zinc.  Preferably the heat-swelling substance is flour, which when added with water forms an adhesive paste.  The mixture may also contain soldering fluxes, emulsifiers, colloidal stabilizers, hygroscopic substances, and volatile substances capable of evaporating under the operating conditions.  In one example, a heavy metal work-piece is sprayed with a mixture containing pickling liquor, pickling control agents, oil solvents, finely divided siliceous adsorbing substances (e.g. colloidal clay), phosphoric acid and heat swelling substances, to form on the work piece a layer adapted to adsorb contaminating matter on the surface, the layer then being heated until a heavy-metal phosphate sub-layer has formed as well as portions more easily removable than this sub-layer, and then treated with water to remove the more easily removable portions. The phosphate sub-layer containing some silicerous adsorbing substances may be sintered by heat and the layer so formed covered by applying molten wax.  In another example, an iron workpiece is coated with zinc by spraying with a molten paste containing zinc powder, chemical soldering agents and 10-30 per cent flour, spraying being effected with heated compressed air, the zinc particles being suspended in the molten paste and solidifying on impact with the workpiece.  When the layer so deposited solidifies and cools, the flour breaks up and washes off.  This may be similarly deposited.  Lead may also be deposited provided the workpiece has been given a preliminary coating of zinc.ALSO:A surface treatment for metal workpieces comprises spraying the surface through an annular source of heat with a jet of cleaning or coating mixture under pressure, substances which swell under the application of heat being added to the mixture before it is sprayed, and the substance being heated subsequently to said spraying to cause them to swell.  The method is applicable to pickling metals with acids or lyes, phosphatizing, oxidising and colouring metal workpieces and coating workpieces with protective metal such as tin, lead or zinc.  Preferably the heat-swelling substance is flour, which when added with water forms an adhesive paste.  The mixture may also contain soldering fluxes, emulsifiers, colloidal stabilizers, hygroscopic substance and volatile substances capable of evaporating under the operating conditions.  In one example, a heavy metal workpiece is sprayed with a mixture containing pickling liquor, pickling control agents, finely divided siliceous adsorbing substances (e.g. colloidal clay), phosphoric acid heat-swelling substances, to form on the workpiece a layer adapted to adsorb contaminating matter on the surface, the layer then being heated until a heavy metal phosphate sub-layer has formed as well as portions more easily removable than the sublayer, and then treated with water to remove the more easily removable portions.  The phosphate sub-layer containing some siliceous adsorbing substances may be sintered by heat and the layer so formed covered by applying molten wax.  In another example, an iron work-piece is coated with zinc by spraying with a molten paste containing zinc powder, chemical soldering agents and 10-30 per cent flour, spraying being effected with heated compressed air, the zinc particles being suspended in the molten paste and solidifying on impact with the workpiece.  When the layer so deposited solidifies and cools, the flour breaks up and washes off.  Tin may be similarly deposited. Lead may also be deposited provided the workpiece has been given a preliminary coating of zinc.