Zincroksid S.p.a.

Italsider S.p.a.

Centro Sperimentale Metallurgico S.p.a.

Centaro Sviluppo Materiali S.p.a.

Roberto Bruno

Massimo Memmi

Nazzareno Azzerri

Augusto Musso

Susanna Ramundo

Santa Alota

Paolo Berardi

Valerio Faccenda

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

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

A weathering steel has high toughness and rapidly develops a protective oxide coating and contains C 0.05 - 0.15, Mn 0.5 - 1.5, Cu 0.2 - 0.5,Al 0.2 - 0.5, Si 0.1 - 0.8, Cr 0.5 - 1.5, S up to 0.02, P up to 0.04, Nb up to 0.020, N up to 0.010 Mo up to 0.15, Ti up to 0.1, balance essentially iron, the proportions being as follows:

Weathering steel with high toughness

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

Roberto Bruno