METHOD FOR APPLYING THERMODIFFUSION ZINC COATING ONTO STEEL PIPES AND STEEL PIPE WITH SAID COATING Russian patent published in 2022 - IPC C23C10/36 

FIELD: coatings.

SUBSTANCE: invention relates to thermochemical treatment of metal items and can be used for applying zinc-based thermodiffusion coatings onto oilfield tubular goods, couplings, fasteners and other articles. Method for applying a thermodiffusion zinc coating onto steel pipes includes loading the pipes with a saturating mixture into a container, sealing the container, filling the cavity of the container with a non-oxidising gas, and heating. One or multiple tertiary amines are added to the saturating mixture as a flux, and a filler containing one or multiple components selected from a group including silica, wollastonite, carbon black, aluminium oxide, and copper alloys is used as an activating substance. Said saturating mixture contains components at the following ratio, % wt.: flux 0.1 to 1.0, filler 25 to 45, two-component zinc powder the rest. After the container is sealed, it is evacuated, and after the cavity of the container is filled with the non-oxidising gas, heating and holding are performed at a temperature of 300 to 425 °C, followed by cooling the container and removing the pipes. The steel pipe comprises a hollow body with thermodiffusion zinc coating created by the above method.

EFFECT: shorter duration of holding the steel pipes in the temperature range of thermodiffusion zinc-plating while producing coatings of a given thickness with better values of corrosion resistance, homogeneity and density of the coating on the entire surface of the pipes; lower power consumption and higher productivity with the ensured high strength of the pipes.

12 cl, 1 dwg, 1 tbl, 8 ex