RU1791468C - Method for protecting dipping solutions against evaporation - Google Patents

Abstract

Usage: in the technology of chemical processing of metals using β-protective layers on the surface of etching solutions, mainly alkaline, in particular in the processes of chemical milling of aluminum parts, chemically. electrochemical degreasing. SUMMARY OF THE INVENTION: a method of protecting etching solutions from evaporation involves applying floats of inert materials to a bath surface of a bath — hydrophobized with silicone fluid expanded clay or shungieit, as well as an anti-evaporator — a mixture of 99.0-99.8 wt.% Liquid paraffin and 0 2-1.0 wt.% Naphthenic acid. 1 tab.

Description

The invention relates to a technology for the chemical treatment of metals using protective layers on the surface of etching solutions, mainly alkaline, and can be used in the chemical milling of aluminum parts, chemical or electrochemical degreasing, and others.

A known method of protecting etching solutions from evaporation comprising applying to the surface of the solutions polyethylene floats and mixtures containing the drug Novosti and skating 1.

The closest solution to the problem in terms of technical essence and the achieved result is a method of protecting etching solutions from evaporation, including applying floats from polymeric materials to the surface of the evaporation of the bath and

anti-evaporator - mixtures of 1.5-2.5 vol.% crude sulphate soap and 98.5-97.5 rb.% technical lignosulphonates 2.

However, the known technical solutions do not provide effective protection of the Environment from harmful fumes of alkaline etching solutions, since the main component of the anti-evaporator, ligosulfonates, have the properties of strong mineral acids and are neutralized by caustic soda, which is part of the protected etching solution, and the product of their interaction is water-soluble, passes into solution and does not perform protective functions. Another component of the anti-evaporator - sulfate soap, in an alkaline environment at an elevated temperature of etching baths up to 70-90 ° C, also goes into a soluble state.

As for floats made of polymer materials, in a highly alkaline environment they are short-lived due to the destruction of their polymer structure.

The purpose of the invention is to increase the efficiency of protection of etching solutions from evaporation.

The goal is achieved in that as floats use expanded clay or schungizite, and a mixture of 99.0-99.8 wt.% Liquid paraffin and 0.2-1.0 wt.% Naphthenic as anti-evaporator acids.

Expanded clay is used standard in accordance with GOST 9759-83 or GOST 9757-83 with a particle size of 10-20 mm. Shungizite is obtained by expanding natural Karelian schungizite schists at a calcination temperature of 1100 ° C, as a result of which a closed-cell porous structure with a porosity of 50-61% is formed in the morning.

Hydrophobization of expanded expanded clay or shungizite granules is carried out by treating them with an organosilicon liquid of the type GKZH-136-41 GOST 1Q834-76 at a residual pressure of 10-15 mm Hg. followed by drying at a temperature of 90-95 ° C to dry, and 145-150 ° C for 15 minutes for polymerization. Under these conditions, the pores are filled and a stable hydrophobic film is formed, which prevents the flooding of granules, which, when etched onto the mirror surface, form a monolayer of floating indent particles.

The anti-vaporizer is prepared by pre-mixing vaseline oil and naphthenic acids in a ratio in wt.%

- vaseline oil and naphthenic acid

- 99.0-99.8 - 0.2-1.0, respectively, and then introduced into the bath in an amount necessary to fill the space between floating inert particles and covering the bath surface with a 1-3 mm thick layer. Inert floating granules of schungizite or expanded clay overlap the mirror surface of the bath by 85-93%, which reduces the amount of introduced anti-evaporator.

Protecting the solution with a surface anti-evaporation film and shungizite or expanded clay granules, firstly, practically eliminates the release of alkali aerosol from the solution, thereby improving sanitary and hygienic working conditions, and secondly, reduces the energy consumption for achieving and maintaining the technological temperature of the solution, since the solution with surface

with an anti-evaporator film and shungizite or expanded clay granules heats up faster and cools more slowly than a solution in an uncoated bathtub due to less evaporation of water from the surface of the bathtub, and thirdly, it insulates it from penetrating carbon dioxide into the alkaline bathtub and accumulating carbonates in it, which increases the life of the solution.

Due to the chemical inertness of petroleum jelly, the organic additive does not violate the protective paint layer applied to the parts for selective etching during chemical milling

aluminum and its alloys, and does not adversely affect pickling quality. The naphthane formed by the interaction of naphthenic acid with alkali, having surface-active properties,

forms a dense, stable foamy layer with liquid paraffin, which increases the anti-evaporation and protective properties of the organic additive.

In addition, the presence of a surface-active component in the surface protective layer promotes the formation of a semi-shiny bright surface during etching that preserves the appearance for a long time of operation, and also provides easy removal of residues of liquid paraffin from the surface of the part during subsequent washing. The remaining trace amounts of liquid paraffin have an inhibitory property and prevent the passivation and oxidation effects on the surface.

A monolayer of floating shungizite or expanded clay granules does not interfere with loading

and unloading parts, easily sliding apart on the surface of the bath.

EXAMPLE: Aluminum etching was carried out in an alkaline etching solution.

at 70 ° С with caustic soda concentration of 150 g / l. On the surface of the evaporation mirror, a layer of an anti-evaporator is first deposited, and then a layer of hydrophobized schungizite

or expanded clay granules. The number of granules is selected so as to cover the surface of the bathtub with a monolayer, and the amount of anti-evaporator is to cover the surface of the bathtub with a layer of 1-3 mm.

The aerosol content above the bath and the amount of accumulating ions in the working solution were determined using standard

techniques.

The experimental results are shown in the table.

As follows from the data obtained, the declared limits of the ratio of the components are optimal ..,

In the absence of a monolayer of floats and naphthenic acid in liquid paraffin (experiment 2), the protection efficiency is insufficient. The protection efficiency is also low in the presence of a monolayer of floats both with vaseline oil and in the presence of small amounts of 0.1 wt.% Naphthenic acid in it (experiment 4). Higher concentrations of naphthenic acid in liquid paraffin (experiments 5-7) provide a high degree of protection against harmful fumes. However, with an increase in the amount of naphthenic acid over 1% (experiments 8 and 9), the protection efficiency does not increase. The limit value is sufficient to achieve the goal.

The technical and economic efficiency of the proposed solution in relation to the prototype is determined by the following factors:

- reduction in social costs due to improved sanitary conditions;

-decrease in energy consumption by 1.1-1.3 times to achieve and maintain the technological temperature of the solution;

- an increase in the life of the solution by 1.2-1.5 times;

- reduced consumption of chemicals;

- improving the quality of the processed surface;

-reducing the cost of ventilation maintenance and equipment operation by eliminating the condensation of alkaline and carbonate aerosols and the accumulation of growths in ventilation systems and on the walls of the working room.

Claims (1)

SUMMARY OF THE INVENTION A method for protecting etching solutions from evaporation, mainly alkaline, comprising applying floats from inert materials to an evaporation surface of a bath and an anti-evaporator from a mixture of organic substances, moreover, in order to increase the efficiency of protection, as floats, hydrophobized with silicone fluid expanded clay or shungizite, and as anti-evaporators, a mixture of 99.0-99.8 may. % vaseline oil and 0.2-1.0 wt.% naphthenic acid,