Process and special apparatus for electrogalvenizing inner and outer walls of steel pipe

Abstract

A process for electroplating the inner and outer surfaces of steel tube with Zn is disclosed. It is characterized by that its electroplating liquid has the merits of both alkaline zincate and cyanide used for plating zinc. Its apparatus is characterized by that an auxiliary anode is additionally used inside the steel tube to be plated, that is, its hanger plays the roles of both cathode and anodes. Its advantages are high anticorrosion power of its plated layer and enough thickness of internal plated layer.

Description

Technical field [0001] The invention belongs to an electroplating process and equipment, in particular to an electroplating process for the inner and outer walls of a rotating pipe and a special electroplating tank structure. Background technique [0002] Existing electroplating processes include potassium chloride galvanizing: poor oil resistance, general deep plating ability, brittle coating and general corrosion resistance; ordinary alkaline zincate galvanizing: strong oil resistance, and fine coating grains Poor ability; ordinary cyanide zinc plating (containing micro, low, medium, and high cyanide): although the ability of deep plating and refining the grain of the coating is good, the allowable current density range is narrow. Existing electroplating equipment and including electroplating tank, anode and cathode are not suitable for plating long tubular products. It is necessary to galvanize long tubular products. CN1319685A discloses a kind of auxiliary anode spraying...

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Problems solved by technology

[0002] The existing electroplating processes include potassium chloride galvanizing: poor oil resistance, general deep plating ability, brittle coating and general corrosion resistance; ordinary alkaline zincate galvanizing: strong oil resistance, and fine coating grains Poor ability; ordinary cyanide zinc plating (containing micro, low, medium, and high cyanide): although the ability to deep-dip and refine the grain of the coating is good, the allowable current density range is narrow

Existing electroplating equipment and including electroplating tank, anode and cathode are not suitable for plating long tubular products. It is necessary to galvanize long tubular products. The hollow steel pipe with the liquid spray hole is used as the auxiliary anode, and the hollow steel pipe is equipped with an insulating layer matching the cathode on the inner wall of the steel pipe to be plated. The flow of the plating solution in the steel pipe is difficult, but it is not suitable for the galvanizing problem of the inner wall of the small-diameter steel pipe

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