METHOD OF FORMING PROTECTIVE COATING Russian patent published in 2016 - IPC C23C10/36 

FIELD: metal processing.

SUBSTANCE: invention relates to anticorrosive treatment, in particular, to thermodiffusion zinc coating of articles from ferromagnetic materials, and can be used in any machine building industry branch and in other industries, where protection of metal items from corrosion and ageing is required. Method of forming protective coating on articles from ferromagnetic materials by thermodiffusion zinc coating in electric heating installation, made in form of inductor, includes loading into retort items and saturating powder zinc containing mixture, arrangement of retort inside inductor and heating of products in contact with saturating zinc containing mixture until formation of protective coating of required thickness, as well as unloading and cooling down of galvanized items. Said retort with items and saturating powder zinc containing mixture is placed in high-resistance inductor, and items heating is performed in two steps to preset temperature value for each of them, measured near inductor spiral turns. At first stage heating is performed to temperature of 280-300 °C, and at second stage is to temperature of 520-650 °C with model pulse control impact on feed current of inductor with pulse duty ratio of 1.5-5.0 at total duration of pulse and pause from 2 to 3 minutes.

EFFECT: provides for formation in structure of galvanized metal item of fine-grained uniform thickness, as well as in phase and chemical composition intermetallic layer with required thickness, serving as high-quality protective coating, having required strength and corrosion resistance under conditions of aggressive media.

1 cl, 5 dwg, 1 ex