RU2595194C1 - Method of applying protective coating on parts made from aluminium alloys - Google Patents

Abstract

FIELD: electroplating.

SUBSTANCE: invention relates to electroplating, particularly to electrolytic method of coating, specifically, to anodic treatment of aluminium and its alloys. Method of applying protective coating on sheet from 0.4 mm, large from 1,000 mm part made from aluminium alloy involves chemical degreasing, etching, clarification, anodising in a solution of sulphuric acid with concentration of 180 g/l, filling anode film, washing after each operation, wherein anodising of part is performed by arranging part between two rectangular frames with welded thereto suspension, placed on anode rod, with further lowering frames with part into bath with anodising electrolyte, holding at temperature 15-23 °C for 40 minutes and monitoring of anode-oxide coating by drop method.

EFFECT: technical result is high corrosion resistance of large-size from 1,000 mm thin-sheet parts with thickness of 0,4 mm from aluminium alloys due to fixation and rigid contact, which reduces amount of rejects and higher efficiency.

1 cl, 1 dwg

Description

The invention relates to the field of chemistry and metallurgy, in particular to an electrolytic coating method, namely, anodizing of aluminum.

The prior art method for anodizing aluminum plates and a device for its implementation (SU 1115503 A1, published April 20, 2012), consisting of a bath with an electrolyte circulation system, a cathode, a current source and a plate holder equipped with a rotation drive. The disadvantages of this technical solution is the impossibility of coating large-sized thin-sheet parts.

The task to which the invention is directed is to increase the corrosion resistance of large-sized (from 1000 m) thin-sheet parts (with a thickness of 0.4 mm or more) from aluminum alloys, which is achieved by ensuring fixation and hard contact, which reduces the number of scrap and therefore, to increase productivity.

This problem is solved due to the fact that the claimed method of applying a protective coating to thin-sheeted from 0.4 mm large-sized from 1000 mm aluminum alloy part includes chemical degreasing, etching, clarification, anodizing in a solution of sulfuric acid with a concentration of 180 g / l, anode filling films and rinsing after each operation, while anodizing the part is carried out by placing the part between two rectangular frames, with a suspension welded to them, which is placed on the anode rod, and then lowered using frames with a part in a bath with anodizing electrolyte, holding it at a temperature of 15-23 ° C for 40 minutes and controlling the anode-oxide coating by the drop method. The invention is illustrated by drawings, which depict:

In the figure 1:

1 - a rectangular frame made of aluminum alloy;

2 - suspension.

Description of the device.

The device consists of 2 rectangular frames, which are welded by continuous welding from a sheet of aluminum alloy with a thickness of 10-12 mm, a width of 150 mm. 2 pendants from a sheet of aluminum alloy 40 mm wide, 10-12 mm thick, which at the free end should be bent under a diameter of 60 mm, are welded to one frame. On one frame around the perimeter there are 16 holes with a diameter of M10 bolt. On another frame around the entire perimeter, 16 threaded holes with a diameter of M10 bolt are located in response to the first frame.

The device may have different sizes depending on the dimensions of the parts.

The device works as follows: the parts are placed between two frames that are connected together by bolts. Strong fastening is necessary so that the parts do not twist (since the parts are thin-sheeted) and do not fall off, and in order to ensure a constant and reliable electrical contact. Next, the frames with the part are hung with suspensions on the middle of the anode rod of the bathtub, i.e. are connected to the positive pole of the current source, and cathodes attached to the negative pole are lead plates located inside the plating bath at the edges. After preliminary processing (degreasing, etching, clarification, washing after each operation), the part is placed between the frames, and then the frames with the part are placed in the middle of the anodizing electrolyte bath and kept at a temperature of 15-23 ° C for 40 minutes, while as The electrolyte uses a solution with sulfuric acid concentration of 180 g / l. Sulfuric acid under the influence of a passing electric current begins to decompose: hydrogen is formed at the cathode, and negatively charged oxygen and sulfur ions (cations) are attracted to the anode - the part. The electric charge of the circuit causes positively charged aluminum ions (anions) to move toward the cathode. At the same time, on the surface of the anode, aluminum anions combine with oxygen cations, forming aluminum oxide - an anode film appears.

This invention provides a uniform distribution of current over the surface of the part, which helps to obtain a more uniform coating thickness with good mechanical and protective-decorative properties.

Claims (1)

The method of applying a protective coating to thin sheet from 0.4 mm large from 1000 mm aluminum alloy part, including chemical degreasing, etching, bleaching, anodizing in a solution of sulfuric acid with a concentration of 180 g / l, filling the anode film and washing after each operation, different the fact that anodizing is carried out by placing the part between two rectangular frames, with a suspension welded to them, which is placed on the anode rod, followed by lowering the frames with the part into the bath with electrolyte ano doping and exposure at a temperature of 15-23 ° C for 40 min and the control of the anode-oxide coating by the drop method.

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