METHOD TO APPLY CHROME COATING ONTO INTERNAL SURFACE OF CYLINDRICAL ITEMS Russian patent published in 2014 - IPC C25D3/04 C25D7/04 C25D19/00 

FIELD: metallurgy.

SUBSTANCE: invention relates to electrolytic metallurgy, particularly, to flow electrolytic chrome plating and can be used in general engineering and other fields of industry. The method involves application of chrome plating under the temperature of chrome-containing electrode of 60-65°C with forced electrolyte feeding into the space between the surfaces of the item being processed and the anode set coaxially to the item, the coating application is performed at reciprocating motion of the anode and rotation of the processed item with the electrolyte flow velocity of 120-200 cm/s at the current density of 60-80 A/dm², the electrolyte contains 80-130 g/l of chromic anhydride and 4-6 g/l of sulphuric acid.

EFFECT: invention is intended to prolong service life of items, namely of cylinders of deep well sucker rod pumps, due to the reduction of porosity and increase of coating's microhardness.

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