SU834268A1 - Solution for electrochemical treatment of tin - Google Patents

Description

The invention relates to the electrochemical treatment (ECM) of metals, in particular to polished and soft etching of tin, and can be used for metallographic studies, as well as in preparing the surface of parts with electroplated coating. A known solution is an electrochemical treatment of tin, coaern gium hydroxy potassium. The ECHO is carried out at an anode current density of 15 A / dm, and the product (sample) is the anode 1. However, the ano (treatment in a known solution does not allow to obtain a uniform polishing of flat surfaces of sufficiently large dimensions and a clear height) of the crystal boundaries. The purpose of the invention is to improve the uniformity of processing and clear detection of crystal boundaries. AUC: this goal is achieved by the fact that the solution additionally contains acrylo-nitrile (saturated solution) in the following ratio of components, g / l: Potassium hydroxide 22-25 Acrylonitrile (saturated solution) 9-11. ECO is recommended to be carried out at room temperature and cathode current density 1.2-1.8 A / dm (the tin foil is the cathode, the anode is the carbon rods). The duration of processing depends on the condition of the original surface and the specified depth of etching. . Polishing in this solution occurs because, during the recovery of acrylonitrile in an alkaline medium, a film of organotin film is formed in the tin cathode in the tin cathode, which flows off from the sample, leaving it smooth and showing the surface structure without destroying the base metal. Soft etching of the surface of the Ophazz (and products allows more onko to investigate the residual stresses

at the points of their concentration, which cannot be provided by mechanical treatment or etching under more severe conditions, for example, during anon etching.

The solubility of acrylonitrile in paci thieves of potassium hydroxide is the concentration used (at room temperature) is 9 g / l;

11 g / l is impractical because the concentration of acryl (the nitrile in solution does not change - insoluble acrylonitrile forms a second layer or emulsion.

The solution is stable in operation for 5 days.

The table shows the compositions, modes and results of processing known and pregagaemyh solutions.

Content, g / l in solution

Known

Potassium hydroxide

ZOO Lryrilonitrile

Anode current density, A / OM

Cathode current density, A / dm

Duration, min

Solution temperature, C

1, O 1.01.01.0

0,2350,2350,2450,235

0.0400.0400, O430.04O

0,009О, ОО90, ОО90, ОО9

Roughness after ECM, micron

The proposed

23.5

25 11 10

1.8

1.5

20

25

20

20 .

Thus, the invention allows uniform polishing and soft etching, which can replace the machining of tinned parts, as well as anodic etching of them, which requires the use of a much higher cathode current density, and consequently, high energy costs.

The present invention also makes it possible to remove any predetermined thickness of the surface layer of tin, depending on the time of the process, to fine-tune the tinned parts to exact specified dimensions, excluding damage to the base material of the part in the ECM process.

Table continuation

Claims (1)

Formula of Invention The solution for the electrochemical treatment of tin, containing potassium hydroxide, is different in that, in order to increase the uniformity of processing and to clearly reveal the crystal boundaries, it additionally contains acryl-aditrile (saturated solution) in the following ratio of components, g / l: Potassium hydroxide 22-25 Acrylonitrile (saturated solution) 9-11 Sources of information taken into account in the examination I. Griliches S. Ya. Surface preparation of parts by electroplated pepper, coating., M.-L., Mashgiz, 1961, p. 76,