METHOD OF PRODUCING STEEL PLATE WITH BLACK COATING, DEVICE FOR MAKING STEEL PLATE WITH BLACK COATING AND SYSTEM FOR MAKING STEEL SHEET WITH BLACK COATING Russian patent published in 2019 - IPC C23C2/06 C23C2/26 C23C2/40 C22C18/00 C22C18/04 C22C21/10 

FIELD: metallurgy.

SUBSTANCE: invention relates to production of a steel plate with a black coating. In closed tank steel plate with coating obtained by immersion into melt Zn, containing Al and Mg, is heated in presence of first gas having dew point, which is lower than temperature of steel sheet with coating, and after heating reducing gas pressure in closed reservoir to 70 kPa or less by pumping heated in closed reservoir first atmospheric gas, and after reduction of gas pressure, layer of coating is blackened by introducing water vapour into a closed reservoir. After the coating layer is blackened, the gas pressure in the closed reservoir is reduced to 70 kPa or less by pumping the second atmospheric gas from the closed reservoir and cooling the steel sheet having the blackened coating layer by introducing into the closed reservoir a second gas having a dew point which is lower than the temperature of the steel plate with coating.

EFFECT: invention provides suppression of dew drops formation during heating of coated steel sheet and more uniform blackening of coating layer to produce steel sheet with black coating with more beautiful appearance.

17 cl, 4 dwg