Zincroksid S.p.a.

Centro Sperimentale Metallurgico S.p.a.

Centro Sviluppo Materiali S.p.a.

International Lead Zinc Research Organization, Inc.

Italsider S.p.a.

Nuova Italsider S.p.a.

Centaro Sviluppo Materiali S.p.a.

Centro Sviluppo Materiale Spa

Massimo Memmi

Roberto Bruno

Nazzareno Azzerri

Santa Alota

Susanna Ramundo

Augusto Musso

Ferdinando Colaiacovo

Bruno Brevaglieri

Domenico Derchi

Michele Cecchini

Gelasio Giardetti

Paolo Berardi

Vincenzo Ferrari

Stefano Natali

Leonardo Pacelli

A process for non-continuous galvanization of a metal object with a Zn&mdash;Al alloy including the steps of pre-coating the object with a metallic layer of sufficient thickness to protect the object from oxidation and yet sufficiently thin to permit the pre-coating to substantially completely react with or dissolve in the molten Zn&mdash;Al bath, subjecting the precoated object to a surface activation treatment by immersing it in hydrochloric acid and thereafter allowing the surface to dry with a protective coating of a chloride salt, and thereafter immersing the object in the Zn&mdash;Al bath.

Production of a zinc-aluminum alloy coating by immersion into molten metal baths

Zinc-aluminum based alloy containing magnesium and silicon, both present in quantities up to 0.5% by weight, characterized by very good corrosion resistance and suitable for coating steel products, the resulting coatings being extremely durable and highly flexible.

Zinc-aluminium based alloy for coating steel products

The present invention provides a thin continuous organic coating on metals, particularly on continuous metal bodies, so that the product obtained is weldable and resistant to corrosion as well as to the effect of strongly acid and strongly alkaline baths, while being punchable and paintable. The coating according to the invention comprises epoxy resins characterized by ultimate elongation higher than 10%, electrical insulation resistance less than 2000 Ohm/cm.sup.2, able to produce a continuous coating on the metal substrate with micro-roughnesses (Ra) of about 3 .mu.m--Ra being average roughness--and capable of withstanding for thirty minutes liquids with pH between 2 and 12.5.

Organic coating for metals

Electrolytic galvanizing process in which steel strip to be zinc coated is passed continuously through an acid electrolyte solution containing zinc ions and is used as a cathode, while the electrolyte solution is made to flow in the space between the cathode and the anode, in a cell having flat parallel electrodes. The plating current density and the fluid dynamic conditions of the electrolyte are related by the equation

Electrolytic galvanizing processes

In the continuous electrodeposition of chromium metal and chromium oxide on metal surfaces the codeposition of chromium and its oxide, inert and insoluble, is obtained from the same bath and at high current density, by using a number of cycles of impressed cathodic current and defined ranges of electrolyte velocities in the deposition cell. In this manner a product is obtained wherein a specific quantitative relationship between chromium metal and chromium oxide ensures corrosion resistance superior to that obtainable in known products.

Process for continuous electrodeposition of chromium metal and chromium

Improved process for the production of coated steel sheet particularly suitable for the fabrication of car bodies, galvanized and further protected by a layer of metallic chromium and hydrated oxides of chromium. The improvement consists in optimizing process operating conditions, within certain limits, to obtain a protective layer of chromium and hydrated oxides of chromium with absolutely new morphological characteristics which endow the product with corrosion resistance far greater than that of similar products reported in the literature.

Process for the production of galvanized steel sheet protected by

Steel sheet, especially suitable for car-body fabrication, galvanized and further protected by a layer of metallic chromium and hydrated oxides of chromium, electrolytically deposited. The improvement is that the metallic chromium is present in extremely fine particles that exert a very marked covering and protective effect on the underlying zinc. In this way, and with the help of the chromium oxides that further cover and protect the underlying layers, a product is obtained whose corrosion resistance is far superior to that of similar products.

Galvanized steel sheet protected by chromium and chromium oxide layers

Thin metal plate is cleaned and electrolytically pickled in an acid solution. A zinc layer is electrodeposited on one face of the plate, after which a chrome-chromic oxide coating is deposited on both faces of the plate from a sulphuric acid solution containing compounds of trivalent and exhavalent chrome. The plate is then subjected to a drying-oxidating treatment in air. The plate may be steel having a thickness between 0.1 and 2 mm. The plate may be surface treated by phosphating, and then painted. The chrome-chromic oxide coating may have a thickness between 0.05 and 5 .mu.m, and the zinc coating a thickness between 1 and 30 .mu.m.

Process of making long-life thin metal plate for automobile bodies, and

Thin metal plate is cleaned and electrolytically pickled in an acid solution. A zinc layer is electrodeposited on one face of the plate, after which a chrome-chromic oxide coating is deposited on both faces of the plate from a sulphuric acid solution containing compounds of trivalent and hexavalent chrome. The plate is then subjected to a drying-oxidating treatment in air. The plate may be steel having a thickness between 0.1 and 2 mm. The plate may be surface treated by phosphating, and then painted. The chrome-chromic oxide coating may have a thickness between 0.05 and 5 .mu.m, and the zinc coating a thickness between 1 and 30 .mu.m.

Process of making long-life thin metal plate for automobile bodies

The adhesion of paint to steel sheets is improved by pretreating the steel sheets, prior to conventional annealing, surface finishing, oiling, degreasing, phosphating and painting operations, by connecting the steel sheet alternately as cathode and anode in an electrolytic cell containing a bath of 0.5 M-2 M sodium sulphate aqueous solution. The operating temperature is 20.degree.-100.degree. C., the pH is 6-8, the current density is 1 to 50 A/dm.sup.2, and the treatment time is 0.1-30 seconds, preferably 0.5-20 seconds, and most preferably about 5 seconds as cathode followed by about 5 seconds as anode.

Process for improving the adhesion of paint to steel sheets

The present invention relates to a zinc-based alloy for coating steel and products coated therewith. More exactly, the invention relates to a low-alloy zinc suitable for the continuous coating of steel, particularly in the form of sheet and wire, on Sendzimir coating lines and to the products coated with said alloy.

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Rome, Italy

Massimo Memmi