CS201484B1 - Preparation for surface treatment of metallic materials - Google Patents

Description

BACKGROUND OF THE INVENTION The present invention relates to a composition for the surface treatment of metallic materials.

The engineering industry, metallurgical industry, primary and secondary production are increasingly oriented towards the processing of high-quality materials with high demands on surface perfection, removal of scale and impurities arising in the process of processing profiles and individual components. Gradually, a number of methods have been developed for mechanical, physical and chemical removal of oxides and other impurities from the surface of materials, either by applying individual methods or by combining them together.

Of the chemical methods, the acid pickling method is most commonly used. According to the quality of the material and its chemical composition, dilute hydrochloric acid or dilute sulfuric acid, respectively, according to the carbon content of the pretreated material is used. As a rule, acid pickling alone is not sufficient for the final surface treatment of a number of products, and therefore, phosphate, oxalate, etc. are usually followed. This applies in particular to the surface treatment of reinforcing wires, pipes and others. All these surface treatments are. in average fairly lengthy, the exposure time is of the order of hours and in addition, there is a considerable loss of material.

Some of these difficulties are addressed by the introduction of hydride technology, the removal of oxides in selected materials such as high-alloy steels, clad steels and some non-ferrous materials, mainly titanium, nickel and copper. This procedure considerably shortens the surface treatment time to several minutes, while at the same time material losses are up to about 2% lower.

However, this coating does not apply to all materials and, moreover, requires relatively precise adherence to the technological process.

The above-mentioned drawbacks are solved by the preparation for surface treatment of metallic materials according to the invention. The essence of the invention is that. the formulation contains a base solution obtained by dissolving 50 to 200 wt. parts of zinc metal in 180 to 600 wt. % by weight of 85% phosphoric acid, supplemented with 100 to 300 wt. parts of 65% nitric acid and 100 to 300 wt. parts of 85% phosphoric acid, further comprising 0.1 to 1 wt. part by weight of the moderator solution obtained by dissolving 50 to 200% by weight. parts of zinc metal in 180 to 700 wt. parts by weight of phosphoric acid, supplemented with 1 to 10 wt. parts of copper salts, preferably sulfate or copper nitrate, 1 ¹ to 10 wt. parts by weight of nickel carbonate, 1 to 20 wt. parts of magnesium sulfate; and 1 to 10. wt. parts by weight of calcium carbonate; parts of lead oxide and 10 to 100 wt. 100 parts by weight of borax; parts of 65% nitric acid and 100 to 300 wt. parts of 85 /% phosphoric acid. The composition may further contain from 0.01 to 5 wt. parts of ethylenediaminophosphate. In addition, 0.1 to 1 wt. parts of the activator solution obtained by dissolving 100 wt. parts of sodium nitrite in 200-600 wt. parts of the water, to the basic solution or to its mixture with the moderator.

The composition according to the invention consists of three solutions which are mixed prior to application in proportions depending on the surface quality, the contamination and the chemical composition of the material to be treated. The stock solution is obtained by dissolving 50 to 200 parts by weight of zinc metal in 180 to 600 parts by weight. parts of phosphoric acid. The base solution is a saturated solution of zinc acid phosphate, to which several percent of the phosphoric salt of organic diamine may be added. The moderator combines with the basic solution in proportions depending on the quality of the surface contamination. It contains zinc acid phosphate to which several orders of magnitude of calcium, magnesium, nickel or copper salts and tens of percent of the alkali metal salt of boric acid are added. After depletion of the decontamination bath activity due to the presence of reaction products and impurities removed from the metal surface, which is of particular importance in continuous lines, the original decontamination activity can be restored by adding several percent of the activator. This activating solution is essentially a suitable alkali metal nitrite solution.

The preparation according to the invention is suitable for phosphating a wide range of materials and semi-finished products from carbon austenitic and high speed steels, from alloy materials with different carbon and silicon contents and the like. Its application does not pose a risk of over-flow, since the reaction is limited primarily to the removal of the surface layer without significantly attacking the base material. The repair is evenly distributed over the entire surface and the technology is suitable for both continuous and discontinuous processes. An important factor is also the low exposure time, of the order of several minutes, which influences decisively the utilization of the capacity of the production facilities and thus the reduction of investment costs. The use of the preparation according to the invention allows the introduction of surface treatments, where up to now only mechanical cleaning methods have been used with precise preservation of the profile and surface dimensions.

The following examples illustrate the preparation of the solutions of the present invention.

Example 1

Preparation of the stock solution

163 g of zinc are dissolved in 514 g of 85% phosphoric acid, 2 g of copper sulphate, 30 g of ethylenediaminophosphate are added and made up to a 1 liter mixture of 65% nitric acid and 85% phosphoric acid (1: 1). solution.

Example 2 ‘,

Activator preparation

Dissolve 165 g of sodium nitrite in 500 g of water at 60 ° C and make up the solution to 1 liter with water.

Example 3

Moderator preparation

Dissolve 190 g of zinc in 623 g of 85% phosphoric acid, add gradually 6 g of copper nitrate, 1,6 g of nickel carbonate, 3,0 g of magnesium sulphate, 2,6 g of calcium carbonate, 0,43 g of lead oxide, 51 g g borax. The ingredients dissolve after the addition of 65%. nitric acid and 85% phosphoric acid (1: 1 by volume) per liter.

Example 4

Preparation of Zinc Dihydrophosphate Base Solution '

650 g of anhydrous zinc dihydrophosphate are stirred in 200 ml of a mixture of 65% nitric acid and 85% phosphoric acid (1: 1 by volume), 2 g of copper sulphate, 30 g of ethylleriaminophosphate are added and the system is brought to 1 liter.

Claims (3)

What is claimed is: 1. A composition for the treatment of metallic materials comprising a base solution obtained by dissolving 50 to 200 wt. parts of zinc metal in 180 to 600%. % by weight of 85% phosphoric acid, supplemented with 100 to 300 wt. parts of 65% nitric acid and 100 to 300 wt. parts of 85% phosphoric acid, which further. contains 0.1 to 1 wt. panel moderator solution obtained by dissolving ¹ 50 to 200 wt. parts of zinc metal in 180 to 700 wt. % of phosphoric acid, supplemented with 1 to 10 wt. parts by weight of the invention of copper salts, preferably copper sulfate or nitrate, 1 to 10 wt. parts by weight of nickel carbonate, 1 to 20 wt. % magnesium sulphate and 1 to 10 wt. parts by weight of calcium carbonate; parts of lead oxide and 10 to 100 wt. parts of borax and 100 to 300 wt. parts of 65% nitric acid and 100 to 300 wt. parts of 85% phosphoric acid. . 2. The composition of claim 1, further comprising from about 0.01 to about 5 wt. parts of ethylenediamine phosphate. 3. A composition according to claim 1, further comprising from 0.1 to 1 wt. % of the solution of the activator obtained by dissolving 100 wt. parts of sodium nitrite in 200 to 600 wt. parts of water to the basic solution or to its mixture with the modifier.