The metallurgy of zinc-coated steel

Corrosion behaviour of Zn–Al–Mg coated steel sheet in sodium chloride-containing environment

Acidic aqueous coating compositions containing an organic coating-forming material form coatings on metallic surfaces which are immersed therein. The thickness or weight of the coating formed by the coating composition is a function of the time the metallic surface is immersed in the composition. The resulting coatings have adhesion properties thereby providing an adherent base to which other coatings, for example, paint primers and/or final finish paints can be applied.

Process for coating metals

Comparative corrosion behaviour of 55Aluminium-Zinc alloy and Zinc hot-dip coatings deposited on low carbon steel substrates

Corrosion behavior of hard zinc, Zn-5% Al (Galfan), and Zn-55% Al alloy (Zincalume or Galvalume) coated steels was studied using cyclic voltammetry and potential scan/hold technique in the presence of 0.10-0.90 mol L -1 NaCl over a pH range of 2 to 12. Influence of chloride concentration and electrolyte pH on pitting potential values of the above three types of specimens were examined. On the basis of the electrochemical, scanning electron microscopy with energy dispersive X-ray spectroscopy, and chemical equilibria data obtained from hard zinc, a pitting corrosion mechanism involving a series of processes from anion competitive adsorption to penetration to nucleation and growth was proposed.

Pitting Corrosion of Zn and Zn-Al Coated Steels in pH 2 to 12 NaCl Solutions

Ferrous metal article coated with an aluminum zinc alloy

Large steel products such as structural sections, castings, forgings and machined sections are coated with a smooth, adherent, bright metallic coating comprised of 25 to 85% aluminum, silicon in an amount of 0.7% or more by weight of the amount of aluminum and the balance substantially zinc without the occurrence of detrimental exothermic reactions of the coating medium with the base metal.

Aluminum-zinc coated low-alloy ferrous product and method

The influence of the aluminum content of hot-dip aluminum-zinc alloy coatings on their corrosion behavior was studied by means of salt-spray and atmospheric corrosion tests. The objective was to develop an improved aluminum-zinc alloy coating on steel that would be more durable than galvanized coatings and that would be more protective to cut edges and areas of mechanical damage than hot-dip aluminum coatings. The optimum alloy was found to be 55 weight percent aluminum-zinc. This new alloy coating is two to four times as corrosion-resistant as a galvanized coating of similar thickness. Furthermore, for the galvanic protection of cut edges of sheet in some environments, this coating proved to be superior to aluminum coatings.

Atmospheric corrosion behavior of aluminum-zinc alloy-coated steel

Method of forming improved zinc-aluminum coating on ferrous surfaces

ZINC-ALLOY COATED FERROUS PRODUCT RESISTANT TO EMBRITTLEMENT Abstract of the Disclosure This invention is directed to an improved zinc containing metallic coated ferrous product, particularly sheet and strip, which is resistant to intergranular penetration by zinc and embrittlement of the ferrous base. Use of such zinc containing metallic coated ferrous product in elevated-temperature service, such as found with certain appliances and automotive exhaust components, is enhanced by the coated products of this invention. The resistance to embrittlement of the zinc containing metallic coated ferrous base, when subjected to elevated service temperatures, is achieved by the use of a high-phosphorus containing steel base. For a plain carbon steel base, a phosphorus content of at least 0.020% by weight, preferably at least 0.030%, and more preferably at least 0.039% was found sufficient to render such zinc-alloy coated ferrous base resistant to embrittlement by zinc. By use of such high phosphorus ferrous base, for the reception of a zinc containing alloy coating, an improved metallic coated ferrous product has been found which resists intergranular penetration by zinc and embrittlement of the ferrous base. Such coated product has extended service life at temperatures above about 450°F (232°C) and when restored to room temperature possesses a high degree of ductility.

Horton James B

Papers

Ferrous metal article coated with an aluminum zinc alloy

Aluminum-zinc coated low-alloy ferrous product and method

Atmospheric corrosion behavior of aluminum-zinc alloy-coated steel

Method of forming improved zinc-aluminum coating on ferrous surfaces

Zinc-alloy coated ferrous product resistant to embrittlement