GB415732A - Improvements in aluminium coated metal and process of producing the same - Google Patents

Abstract

415,732. Coating with metals; cleaning metals; fluxes. FINK, C. G., 440, Riverside Drive, New York, U.S.A. Feb. 25, 1933, No. 5823. Convention date, Feb. 27, 1932. [Class 82 (ii).] Metals, particularly ferrous metals, to be coated with aluminium or aluminium alloys by dipping are pretreated so that the surface of the metal is highly charged or saturated with hydrogen. The pretreatment, in the case of ferrous metals or nickel, consists in heating the metal in hydrogen at a temperature of about 900‹ C. or above, the metal being thereby deoxidized and charged with hydrogen, the hydrogen being either occluded or present in the form of a hydride. In treating copper, a slightly lower 'temperature may be used. The metal is preferably treated with a solution of boric acid, borax, or other boron compound before the hydrogen treatment. In one method of carrying out the process a wire X, Fig. 1, is cleaned in one or more acid or alkaline baths 10, heated to red heat in an oven 12, passed through a bath 14 containing a concentrated solution of boric acid, passed through a furnace 16 containing hydrogen heated to 1000‹ C., and then passed through the aluminium bath 22 and finally wiped by wipers 45 to remove surplus aluminium. In an alternative form, Fig. 6, the oven 12 is omitted and the hydrogen furnace is not heated, the wire X being brought to the required temperature by the passage of an electric current, the contacts c, c<1> being placed before the boric acid bath and after the hydrogen furnace respectively. The wire is preferably introduced into the molten aluminium in such a manner that it does not pass through an oxide film. As shown in Fig. 3, the wire passes into the bath through an opening 20 below the surface of the molten metal, oxidation being prevented by hydrogen issuing from the furnace 16. The coated wire may be drawn out through a similar opening 26 or through the surface of the bath. In the form shown in Fig. 4, the aluminium pot is provided with a cover 30 having openings 32, 33 for the entrance and exit of the wire. Hydrogen is supplied by pipes 37 to maintain a reducing atmosphere in contact with the aluminium and a guide or roller 35 is provided to ensure the immersion of the wire. Aluminium-coated wire, rods, bars, beams, sheets, and strips, and shaped articles such as hollow-ware, nails, &c. may be produced by the process. The Specification as open to inspection under Sect. 91 describes also the pretreatment of the metal in gas mixtures containing hydrogen, e.g. mixtures of hydrogen with nitrogen, carbon monoxide, or carbon dioxide, such as blast furnace gas or blue gas. This subjectmatter does not appear in the Specification as accepted.