RU2354747C1 - Method of receiving of phosphate coating - Google Patents

Abstract

FIELD: metallurgy.

SUBSTANCE: method includes surface treatment of metal by water solution of phosphating, containing ions of zinc, phosphate, nitrate, chlorates and ions of manganese at following content of components, g/l: Zn²⁺ 2.00-3.15, P₂O₅ 3.80-7.14, NO₃- 1.10-1.95, ClO₃- 0.18-0.51, Mn²⁺ 0.002-0.21. Metal surface treatment by mentioned water solution of phosphating is implemented at the temperature 35-40°C during the time from 2 up to 5 minutes, at that before start of treatment water solution of phosphating is corrected at the temperature 20-25°C by value of free acidity up to 0.4-0.9 points by means of addition NaOH or Na₂CO₃.

EFFECT: phosphate coating with high corrosion stability.

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Description

The invention relates to the protection of metals from corrosion and is intended for pretreatment of the surface of metals for subsequent application of paintwork, in particular by electrophoresis.

A known method of producing a phosphate coating, comprising treating a metal product with an aqueous solution containing zinc, nickel, phosphate, nitrate, chlorate and sulfate ions, and adjusting the solution during production, characterized in that in order to ensure the stability of the protective properties of the phosphate coating, the correction is carried out with a solution, containing, wt.%:

Zn ²⁺ 12-14 P ₂ O ₅ 14.4-18.0 NO ₃ ^- 11.1-13.7 SO ₄ ^2- 3.0-4.0 Ni ²⁺ 0.08-0.1 ClO ₃ ^- 0.1-0.3 water up to 100%

The method of producing a phosphate coating according to claim 1, characterized in that the adjustment is made by adding 4-5 g / dm ^{3 of the} initial concentrate.

Closest to the invention in technical essence and the achieved result is a method for producing a phosphate coating, comprising treating a metal surface with a solution containing zinc, nickel, phosphate, nitrate and chlorate ions, characterized in that to obtain a fine crystalline corrosion-resistant phosphate coating at a phosphating temperature of 30 -45 ° C for a time from 2 to 10 minutes, it additionally contains calcium ions in the following components, g / l:

Zn ²⁺ 1,527-3,225 P ₂ O ₅ 4,347-8,385 NO ₃ ^- 0.822-1.935 Ni ²⁺ 0.023 - 0.086 ClO ₃ ^- 0.587-1.505 Ca ²⁺ 0.06-0.157

The disadvantage of this method is the presence of nickel in the solution, the presence of which, like its compounds, is undesirable from the point of view of hygiene of workplaces and environmental protection from pollution.

The objective of this invention is to provide a method of phosphating metals, with which you can get phosphate films that are not inferior in quality and corrosion resistance to films based on Zn ²⁺ -Ni ²⁺ and at the same time without the disadvantages associated with the presence in the composition of Nickel and its compounds.

The problem is achieved in that the metal surface is treated with an aqueous phosphating solution containing zinc, phosphate, nitrate and chlorate ions, the method differs in that the metal surface is processed at a temperature of 35-40 ° C for a period of 2 to 5 minutes aqueous phosphating solution, additionally containing manganese ions in the following components, g / l:

Zn ²⁺ 2.00-3.15 P ₂ O ₅ 3.80-7.14 NO ₃ ^- 1.10-1.95 ClO ₃ ^- 0.18-0.51 Mn ²⁺ 0.002-0.21

moreover, before treatment, the aqueous phosphate solution is adjusted at a temperature of 20-25 ° C, according to the value of free acidity to 0.4-0.9 "points" by the addition of NaOH or Na ₂ CO ₃ .

The application of the proposed method allows to obtain a phosphate coating, equivalent in quality and corrosion resistance, but more economical and corresponding to environmental requirements, in particular, not containing Nickel.

In accordance with the hygienic standards GN 2.2.5.1313-03 "Maximum permissible concentrations (MPC) of harmful substances in the air of the working zone" of the Ministry of Health of the Russian Federation:

- the MPC value of nickel salt in the form of a hydroaerosol is 0.005 mg / m ³ , hazard class 1 is extremely dangerous, especially the effects on the human body K are carcinogens, A are substances that can cause allergic diseases in an industrial environment.

- the MPC value manganese nitrate hexahydrate 1.5 / 0.5 mg / m ³ , hazard class 2 - highly hazardous, especially the effects on the human body A - substances that can cause allergic diseases in an industrial environment.

In accordance with the hygienic standards GN 2.1.5.1315-03 "Maximum permissible concentrations (MPC) of chemicals in the water of water bodies of drinking, cultural and domestic water use" of the Ministry of Health of the Russian Federation:

- the MPC value of nickel is 0.05 mg / l, hazard class 2.

- MPC value of manganese 0.1 mg / l, hazard class 3.

The proposed method of phosphating can be carried out by spraying.

The tests were carried out on samples of cold-rolled steel sheet 08KP (GOST 16523-97) with a thickness of 08-09 mm and a size of 150 × 70 mm.

The metal surface to be treated before the phosphating operation was degreased, thoroughly washed and treated with an activator based on titanium salts.

As a degreasing preparation, the detergent preparation Foscon 205 TU 2149-067-10964029-97, amendment 1, was used.

concentration, g / l 5-12 temperature, ° С 55-65 processing time, min 2-5

Rinsing with tap water

temperature, ° С 20-35 processing time, min 1-2

The activation of the metal surface was carried out by the phosphatization activator Foscon 471 TU 2149-095-10964029-98, amend. 1

concentration, g / l 0.5-1.5 temperature, ° С 20-40 processing time, min 1-2

Phosphating a metal surface

temperature, ° С 35-40 processing time, min 2-5 free acidity, "points" 0.4-0.9

Rinsing with tap water

temperature, ° С 20-35 processing time, min 1-2

To increase the corrosion resistance, it is desirable to carry out passivation in a CrO ₃ solution by immersion

concentration, g / l 0.25 temperature, ° С 40 processing time, min 2 solution pH 4.2

Drying

temperature, ° С 110 processing time, min 10

Determination of the mass of phosphate coating per unit surface area.

The mass of phosphate coating (m), g / m ² , is determined by the gravimetric method and calculated by the formula

,

,

where m ₁ is the mass of the sample after removal of the coating, g;

m ₂ is the mass of the coated sample, g;

S is the coating area of the sample, m ² .

The appearance of the phosphate coating is determined visually.

The control of the protective properties of phosphate coatings is carried out only in combination with a paint coating in accordance with GOST 9.401.

The essence of the invention is illustrated by the following examples:

Example 1

Samples were prepared and phosphated according to the above scheme with a phosphating solution of the following composition, g / l:

Zn ²⁺ 2.00 P ₂ O ₅ 3.80 NO ₃ ^- 1.10 Clo ₃ 0.18 Mn ²⁺ 0.002

The phosphating solution was adjusted at 20 ° C. by adding NaOH to a free acidity of 0.4 points.

The phosphating temperature is 35 ° C, the phosphating time is 2 minutes, the mass of the phosphate coating is 1.5 g / m ² .

The appearance of the phosphate coating is crystalline, light gray.

The corrosion resistance of the phosphate coating is 427 hours.

Example 2

Samples were prepared and phosphated according to the above scheme with a phosphating solution of the following composition, g / l:

Zn ²⁺ 3.15 P ₂ O ₅ 7.14 NO ₃ ^- 1.95 ClO ₃ ^- 0.75 Mn ²⁺ 0.15

The phosphate solution was adjusted at 25 ° C. by the addition of NaOH to a free acidity value of 0.9 “points”.

The phosphating temperature is 40 ° C, the phosphating time is 5 minutes, the mass of the phosphate coating is 5.0 g / m ² .

The appearance of the phosphate coating is crystalline, light gray.

The corrosion resistance of the phosphate coating is 450 hours.

Example 3

Samples were prepared and phosphated according to the above scheme with a phosphating solution of the following composition, g / l:

Zn ²⁺ 2.46 P ₂ O ₅ 5.47 NO ₃ ^- 1,53 ClO ₃ ^- 0.45 Mn ²⁺ 0.10

The phosphate solution was adjusted at 22.5 ° C. by the addition of Na ₂ CO ₃ to a free acidity value of 0.65 “points”.

The phosphating temperature is 35 ° C, the phosphating time is 3.5 minutes, the mass of the phosphate coating is 3.0 g / m ² .

The appearance of the phosphate coating is crystalline, light gray.

The corrosion resistance of the phosphate coating is 435 hours.

Prototype Example

Phosphating was carried out with a phosphating solution of the following composition, g / l:

Zn ²⁺ 2,376 P ₂ O ₅ 6.366 NO ₃ ^- 1.378 Ni ²⁺ 0.054 ClO ₃ ^- 1.046 Ca ²⁺ 0.108

The phosphating temperature is 35 ° C, the phosphating time is 5 minutes, the mass of the phosphate coating is 3.0 g / m ² . The appearance of the phosphate coating is crystalline, light gray.

The corrosion resistance of the phosphate coating is 435 hours.

Thus, the application of the proposed method for producing a phosphate coating provides the following technical and economic advantages:

1. Improving the hygiene of the workplace;

2. Environmental protection from pollution;

3. Reducing the cost of phosphate concentrate;

4. High corrosion resistance of the phosphate coating in combination with paintwork.

This invention is successfully used in the phosphating of cabs and bodies of cars and trucks with obtaining fine crystalline corrosion-resistant phosphate coating before painting with anodic electrodeposition.

Literature

1. RF patent 2070617 "Method for producing a phosphate coating."

2. RF patent 2240378 "Method for producing a phosphate coating" (prototype).

Claims (1)

A method for producing a phosphate coating, comprising treating a metal surface with an aqueous phosphating solution containing zinc, phosphate, nitrate and chlorate ions, characterized in that the metal surface is treated at a temperature of 35-40 ° C. for 2 to 5 minutes with an aqueous phosphating solution, additionally containing manganese ions in the following components, g / l:
Zn ²⁺ 2.00-3.15 P ₂ O ₅ 3.80-7.14 NO ₃ ^- 1.10-1.95 ClO ₃ ^- 0.18-0.51 Mn ²⁺ 0.002-0.21
moreover, before treatment, the aqueous phosphate solution is adjusted at a temperature of 20-25 ° C according to the value of free acidity to 0.4-0.9 points by the addition of NaOH or Na ₂ CO ₃ .