METHOD OF THERMAL DIFFUSION CHROMIUM PLATING OF STEELS AND IRON-BASED ALLOYS USING CUMULATIVE GRIDS Russian patent published in 2023 - IPC C23C10/38 C23C10/40 C23C10/42 

FIELD: metallurgy.

SUBSTANCE: invention relates to chemical-thermal treatment (CHT) by the method of thermal diffusion saturation and can be used in any mechanical engineering industry for coating products made of steels and iron-based alloys. The method of thermal diffusion chromium plating of iron-based steels and alloys using cumulative grids, in which degreased parts are loaded into a container, filled with a saturating powder mixture, the container is sealed and heated to a temperature of 900-1000°C for 24 hours, according to the invention, ceramic tubes with a diameter of 2 mm are fixed with a nichrome thread along the perimeter of the saturation sides of the surface of the part, a cumulative grid is installed on top of the tubes in the form of a rectangular plate made of nickel or molybdenum sheet, 0.3 mm thick with perforated holes of a conical shape with a diameter 0.2 mm at the top, directed by the base to the surface to be saturated and arranged with a density of 10 pieces/cm²; which, together with the part, is covered with a saturating powder mixture comprising the following components: metal powder based on chromium 32 wt.% with a fraction of not more than 150 microns, granulated ammonium chloride with 4 wt.% with a fraction of 2-3 mm, and as emitters of electrons and O^2- anions, 32 wt.% of serpentine powder with a fraction of not more than 100 microns and 32 wt.% of scheelite powder with a fraction of not more than 100 microns are used.

EFFECT: increased depth of the diffusion layer by creating an additional electron emission flow with the introduction of a mixture of scheelite and serpentine powders into it and controlling this flow by using a cumulative grid.

1 cl, 6 dwg, 4 tbl