Non-metallic inorganic coatings consisting of inorganic metal compounds include chromate, phosphate, oxide and other coatings. Phosphate coating has a color from light gray to black.

Phosphate films created on the surface of metal products have a number of properties, including:

1. increased corrosion resistance
2. oil absorption
3. adhesion ability
4. anti-friction properties
5. electrical insulating qualities

The process of chemical phosphating can be subjected to steel:

• carbonaceous
• low-alloyed
• medium alloyed
• cast iron
• magnesium
• aluminum alloys
• cadmium
• zinc coatings, etc.

The essence of chemical phosphating of metals and alloys is their processing in acidified solutions of monophosphates or monosubstituted phosphates of iron, zinc, manganese and others.

In the process of chemical phosphating, hydrolysis of monosubstituted metal phosphates occurs, due to which an equilibrium is created between phosphoric acid and one-, two-, three-substituted metal phosphates, and free phosphoric acid, which interacts with the base metal in the process of phosphating, due to which hardly soluble disubstituted and trisubstituted phosphates are created, which make up the main part of phosphate films. The type of cations of the phosphating solution has a great influence on the composition of phosphate films. Iron phosphate, formed as a result of this process, is not oxidized by air oxygen, and therefore phosphate films have high protective properties. The sizes of crystal structures can be different, it all depends on the preparation of the metal surface. Fine-grained films have the highest protective properties. Coarse-crystalline films have the lowest protective properties. The property of phosphate films to increase the adhesion of adhesive, paint and other similar coatings is main reason Phosphating applications for fasteners and springs. The structure of phosphate coatings affects the high adhesion strength of a phosphate film with a paint coating and an increase in protective properties. There is a molecular bond between the metal and the phosphate film. Its oil absorption, porosity and antifriction properties depend on the structure of the phosphate film. Carrying out additional processing improves the quality of the protective properties of the phosphate film. Such treatment is carried out in solutions of chromium compounds, hydrophobization, oiling and coloring.

For oiling phosphated parts, aviation or spindle oil heated to 100-110 C is mainly used. Also used for oiling at room temperature emulsion or solution of oil in organic compounds.

During hydrophobization, a thin water-repellent (hydrophobic) film is formed on the surface of the parts. Oil absorption refers to the degree of absorption of the oil applied to the phosphate film. Approximately twice the phosphate film gives an increase in oil absorption. The following example can characterize how the protective properties of an oiled phosphate film increase: if in a corrosion chamber on a non-phosphorized steel spring (spraying a three percent solution of sodium chloride) corrosion is detected after 0.1 hour, then on a phosphated and oiled spring after 40-48 hours. If the surface of the base metal has phosphate films accumulated by oil or paraffin, then this gives a sharp decrease in the coefficient of friction. When testing non-phosphated steel, pre-ground, at a stress of 0.047 MPa, immediately seizes, while phosphated steel with the same steel, without the use of lubrication, continues to work satisfactorily for 95 minutes. If phosphated steel is lubricated with paraffin, then setting occurs no earlier than after fifty hours. Phosphate films have dielectric properties, which makes it possible to use phosphating to form an electrical insulating coating and use such parts in transformers, generators, etc.
When impregnating phosphate films with bakelite and oil varnishes, the breakdown voltage increases significantly.

For phosphating springs, steel parts of medium and low strength (1400 MPa), the most widely used solution is Mazhef salt. As the initial components for the manufacture of the solution, manganese and iron monophosphate, called Mazhef, is used. The phosphate film formed in the Majef brine can have a thickness of 7 to 50 µm. Phosphate films have high adhesion strength to steel, microporous structure, good electrical insulating properties (breakdown voltage up to 1000 V). The electrical insulating properties and heat resistance of phosphate films are preserved up to approximately 5000 C. If the phosphate film is heated to 350 C, this leads to the loss of crystallized water by the film, which changes its structure and reduces the protective properties by 2-3 times. When high-strength steels are phosphated in the Mazhef solution, corrosion cracking appears in places of elastic tensile stresses (especially for springs). To prevent such manifestations, zinc-phosphate baths are used. In the mass phosphating of small and fasteners, baths with rotating drums installed in them are used, the same ones are used in galvanic processes.

Have questions? [email protected] // 8-912-044-66-44, 8-953-822-86-85

You can order chemical oxidation of steel in accordance with GOST 9.305-84 by phone and e-mail specified in the "CONTACTS" section. To speed up the calculations, please use a special form for on-line order.

An example of the designation of chemical oxidation on steel with oiling: Chem.ox.prm

The coating thickness is not standardized and is usually 2-4 microns.

Coating warranty according to OST5 R.9048-96.Three-step quality control.

Description of coverage. Chemical blackening with oiling - the main coating for giving steel a black color with little or no change in size. At the same time with decorative trim steel is moderately protected from corrosion. In terms of protective ability, chemical oxidation surpasses simple passivation, but is inferior to phosphating, zinc plating and cathodic coatings (nickel, chromium, etc.). Black galvanizing is often used instead of chemical oxidation. No oiling or otherwise finishing oxidation is not applied, because. coating contains a large number of pores where pitting can develop.

Permissible operating temperature: up to +180 о С

Advantages of chemical oxidation of steel with oiling:

A) The Khim.Oks.prm coating is used to protect steel from corrosion under operating conditions. 1. When impregnated with oils or processed in emulsion mixtures, it has sufficiently high anti-corrosion characteristics and acceptable wear resistance compared to pure oxide.

b) In some cases, it can act as a primer for painting or for interoperational preservation of steel products.

V) Chemical blackening creates a highly decorative deep black color.

G) The process practically does not change the dimensions of the parts and does not affect the physical and chemical properties of the metal.

Disadvantages of chemical oxide coating of steel with oiling:

A) Black oxide film Has high porosity and low protective properties in the absence of impregnation with oils or emulsions.

b) Cannot be soldered or welded.

V) Possesses low resistance to wear and friction due to the small thickness of the oxide layer.

We accept orders for blackening as in the Sverdlovsk region (Ekaterinburg, Alapaevsk, Asbest, Berezovsky, Verkhnyaya Pyshma, Verkhoturye, Irbit, Kamensk-Uralsky, Kamyshlov, Krasnoturinsk, Krasnoufimsk, Nizhny Tagil, Novouralsk, Polevskoy, Revda, Rezh, Serov, Severouralsk and others ), and throughout the Urals and Russia (Chelyabinsk, Perm, Ufa, Tyumen, Kazan, Novosibirsk, Moscow and others).

The surfaces of the springs after shot blasting must be protected from atmospheric influences or the action of aggressive media, the surface of the springs is covered with a special layer that protects it from premature destruction.

There are many types protective coatings. The choice of one or another type of coating depends on the operating conditions of the spring.

Anti-corrosion coatings increase the working life of the springs.

The choice of coating must be approached with knowledge of the impact various kinds coatings on elastic elements.

The protective coating must not lead to deterioration mechanical properties springs.

In the process of galvanizing, hydrogenation of metals occurs, which sharply reduces plasticity, long-term strength, which leads to the fragility of products.

Hydrogenation of metals can occur both during their manufacture in the etching process, electroplating, as well as cathodic polarization. The penetration of hydrogen into the metal leads to changes in the parameters of the crystal lattice, electrochemical and mechanical properties.

When using zinc coating, a heating operation is necessarily used to dehydrate.

Main types of coatings

Galvanizing

Electroplating of zinc on the surface of the spring in layers from 6 (Ts6hr.) to 18 (Ts18hr.) microns. The coating has good adhesion and elasticity. Depending on the passivation, it has different shades.

Chemical phosphating (Khim.Phos)

The most common way to protect the anti-corrosion coating. Used for springs when operating in adverse atmospheric conditions. During the coating process, there is no hydrogenation of the metal, it does not require dehydration, there is no risk of spring fragility.

The coating is used before applying enamel or primer or as an independent one - followed by impregnation with chromium peak (Khim.Phos.hr.), oil (Khim.Phos.prm.)

Chemical oxidation

It is an anti-corrosion coating for the protection of springs and hardware in conditions long-term storage also when operating in adverse atmospheric conditions.

The coating is used before applying enamel or primer or as an independent one - followed by impregnation with chromium peak (Chem.Ox.hr.), oil (Chem.Ox.prm.).

Cadmium plating

Electroplating of cadmium on the surface of the spring in layers from 6 (Kd6hr.) to 18 (Kd 18hr.) microns. The coating has good adhesion and elasticity.
It is used in particularly harsh operating conditions of springs, has limited use due to high toxicity when coating products. Depending on the passivation, it has different shades.

Requires dehydration to eliminate the risk of hydrogen saturation.

nickel plating

Applying nickel to the surface of the spring with a layer of 6 to 18 microns. It is applied in especially severe conditions of operation of springs. Due to low adhesion to steel, nickel is deposited on a copper substrate to increase decorative properties at the end, a thin (1 µm) layer of chromium is applied (Chem. H24).

Requires dehydration to eliminate the risk of hydrogen saturation.

Electropolishing

It is an electrochemical process of anodic dissolution of the product surface, placed in a special electrolyte and connected to the positive pole of the current source.

When the current passes through the formed circuit, the treated surface is selectively dissolved - the protrusions of the surface, which are the peaks of roughness, are removed.

Electropolishing levels the surface, i.e. removes large protrusions (waviness) and glosses it, eliminating roughness (up to 0.01 microns).

It is used as a method of extra-clean finishing or finishing of a surface to increase its corrosion resistance and improve its appearance.

Used for heat resistant stainless steels type 12X18H10T, XN77TYUR.

Coatings

composite compositions applied to surfaces in liquid or powder form in uniform thin layers and forming, after drying and hardening, a film that has strong adhesion to the base. The formed film is called a paint coating, the property of which is to protect the surface from external influences (water, corrosion, temperatures, harmful substances), giving it a certain look, color and texture. The required number of layers is indicated in the design documentation. Assigned mainly to large-sized springs.

The word "corrosion" comes from the Latin " corrosio" which means " fret". Corrosion is a physical and chemical process of destruction of materials and products from them, leading to their deterioration operational properties, under influence environment. Many methods and means have been devised to prevent corrosion.

You can learn more about corrosion from the movie:

Types and designation of coatings

There are a fairly large number of coatings applied different ways for fasteners. All coatings can be divided into three types: protective, protective-decorative, decorative.

On the territory of the republics of the former USSR, at the moment, the following symbols for the types of protective and protective and decorative coatings of fasteners -, etc. coatings are shown in the following table:

The name of the coating is placed after the dot at the end of the designation of the fastener element. The number immediately after the designation of the coating indicates the thickness of the applied coating in microns, microns (1 micron = 1/1000 mm). If the coating is multilayer, then the total thickness of all layers of the coating is indicated.

How to define coverage parameters in a fastener symbol

• Bolt М20-6gх80.58. 019 GOST 7798-70 - Coated bolt number 01 thickness 9 µm ;
• Nut M14-6N. 0522 GOST 5927-70 - Coated nut number 05 (chemical oxide impregnated with oil - popularly called "oxidation"; outwardly looks black, glossy or matte) 22 µm ;
• Butter dish 1.2. C6 GOST 19853-74 - coated grease fitting C thickness 6 µm ;
• Washer A.24.01.10kp. Kd6.hr GOST 11371-89 - Coated washer Cd.chr (cadmium, chromated - what is called "cadmium"; looks yellow, with an iridescent sheen) 6 microns ;
• Screw B.M5-6gx25.32. 1315 GOST 1491-80 - plated brass screw number 13 (nickel, simply referred to as "nickel-plated"; looks off-white with a slight sheen) 15 µm ;
• Washer 8.BrAMts9-2. M.N.H.b.32 GOST 6402-70 - bronze washer with multi-layer coating M.N.H.b (plating copper-nickel-chrome, or, more simply, "chrome"; looks like a mirror, with a pronounced shine) total thickness 32 µm .

Introduction date for newly developed products 01.01.87

for products in production - when reviewing technical documentation

This International Standard specifies the designations for metallic and non-metallic inorganic coatings in technical documentation.

1. The designations of the methods of processing the base metal are given in table. 1.

Table 1

2. The designations of the methods for obtaining the coating are given in table. 2.

table 2

* The method of obtaining coatings, painted in the process of anodic oxidation of aluminum and its alloys, magnesium and its alloys, titanium alloys, is designated "Anotsvet".

** The method of obtaining coatings by thermal decomposition of organometallic compounds is designated Mos Tr

table 2

3. The coating material, consisting of metal, is designated by symbols in the form of one or two letters included in the Russian name of the corresponding metal.

The designations of the coating material, consisting of metal, are given in Table. 3.

Table 3

4. Designations for nickel and chromium coatings are given in the mandatory.

5. The coating material, consisting of an alloy, is designated by the symbols of the components that make up the alloy, separating them with a hyphen, and in parentheses indicate the maximum mass fraction of the first or second (in the case of a three-component alloy) components in the alloy, separating them with a semicolon. For example, a copper-zinc alloy coating with a mass fraction of copper 50-60% and zinc 40-50% is designated M-C (60); copper-tin-lead alloy coating with a mass fraction of copper 70-78%, tin 10-18%, lead 4-20% denote M-O-C (78; 18).

In the designation of the coating material with an alloy, if necessary, it is allowed to indicate the minimum and maximum mass fractions of the components, for example, gold-nickel alloy coating with a mass fraction of gold 93.0-95.0%, nickel 5.0-7.0% denote Zl-N ( 93.0-95.0).

In the designation of coating with alloys based on precious metals of watch parts and jewelry, it is allowed to indicate the average mass fraction of the components.

For newly developed alloys, the designation of the components is carried out in order of decreasing their mass fraction.

6. Designations of coatings with alloys are given in Table. 4.

Table 4

Table 4 (Revised edition, Rev. No. 3).

7. In the designation of the coating material obtained by burning in, indicate the grade of the starting material (paste) in accordance with the regulatory and technical documentation.

8. In the designation of the hot solder coating, indicate the brand of solder according to GOST 21930-76, GOST 21931-76.

9. Designations of non-metallic inorganic coatings are given in table. 5.

Table 5

10. If it is necessary to indicate the electrolyte (solution) from which the coating is to be obtained, use the designations given in the mandatory appendices , .

Electrolytes (solutions) not listed in the annexes are designated by their full name, for example, Ts9. ammonium chloride. xp, M15. pyrophosphate.

11. Designations of functional properties of coatings are given in Table. 6.

Table 6

12. Designations of decorative properties of coatings are given in Table. 7.

Table 7

* The color of the coating corresponding to the natural color of the deposited metal (zinc, copper, chromium, gold, etc.) does not serve as a basis for classifying the coating as colored.

The color of the coating is indicated by the full name, with the exception of the black coating - h.

13. Designations of additional processing of a covering are resulted in tab. 8.

Table 8

* If necessary, indicate the color of the chromate film: khaki - khaki, colorless - btsv; iridescent film color - no designation.

14. The designation of additional processing of the coating by impregnation, hydrophobization, application of paintwork may be replaced by the designation of the brand of material used for additional processing.

The brand of material used for additional processing of the coating is designated in accordance with the regulatory and technical documentation for the material.

The designation of a specific paintwork used as an additional treatment is made in accordance with GOST 9.032-74.

15. Production methods, coating material, electrolyte (solution) designation, properties and color of the coating, additional processing not listed in this standard are indicated according to the technical documentation or written down by the full name.

(Revised edition, Rev. No. 2).

16. The order of designation of the coating in the technical documentation:

designation of the method of processing the base metal (if necessary);

designation of the method of obtaining the coating;

designation of the coating material;

minimum coating thickness;

designation of the electrolyte (solution) from which the coating is to be obtained (if necessary);

designation of functional or decorative properties of the coating (if necessary);

designation of additional processing (if necessary).

The designation of the coating does not necessarily contain all of the listed components.

If necessary, in the designation of the coating, it is allowed to indicate the minimum and maximum thicknesses through a hyphen.

It is allowed to indicate in the designation of the coating the method of preparation, material and thickness of the coating, while the remaining components symbol indicated in the technical requirements of the drawing.

(Revised edition, Rev. No. 2).

17. The coating thickness equal to or less than 1 micron is not indicated in the designation, unless there is a technical need (with the exception of precious metals).

18. Coatings used as technological coatings (for example, zinc in the zincate treatment of aluminum and its alloys, nickel on corrosion-resistant steel, copper on copper alloys, copper on steel from cyanide electrolyte before acid copper plating) may not be indicated in the designation.

19. If the coating is subjected to several types of additional processing, they are indicated in the technological sequence.

20. Recording of the designation of the coating is carried out in a line. All components of the designation are separated from each other by dots, with the exception of the coating material and thickness, as well as the designation of additional processing with a paint and varnish coating, which is separated from the designation of a metallic or non-metallic inorganic coating by a shot line.

The designation of the method of preparation and the coating material should be written with a capital letter, the other components - with lowercase letters.

Examples of recording the designation of coatings are given in.

(Changed edition, Rev. No. 1, 2, 3).

21. The procedure for designating coatings according to international standards is given in.

21. Introduced additionally (Changed edition, Amendment No. 3).

ANNEX 1

Mandatory

DESIGNATIONS FOR NICKEL AND CHROME PLATES

* If necessary, the technical requirements of the drawing indicate the symbol of the chemical element or the formula of the chemical compound used as the precipitated substance.

Note . It is allowed to use abbreviations and indicate the total thickness of the coating.

(Revised edition, Rev. No. 2).

APPENDIX 2

Mandatory

DESIGNATIONS OF ELECTROLYTES FOR OBTAINING COATINGS

APPENDIX 3

Mandatory

DESIGNATIONS OF SOLUTIONS FOR OBTAINING COATINGS

(Revised edition, Rev. No. 1).

APPENDIX 4

Mandatory

EXAMPLES OF RECORDING DESIGNATIONS OF COATINGS

APPENDIX 5

Reference

DESIGNATION OF COATINGS ACCORDING TO INTERNATIONAL STANDARDS

1. The material of the base metal and coating is designated by the chemical symbol of the element.

The base metal material, consisting of an alloy, is designated by the chemical symbol of the element with the maximum mass fraction. The main non-metallic material is designated NM, plastic - PL.

The coating material, consisting of an alloy, is designated by the chemical symbols of the components included in the alloy, separating them with a hyphen. The maximum mass fraction of the first component is indicated after the chemical symbol of the first component before the hyphen.

2. The designation of methods for obtaining a coating is given in table. 9.

Table 9

3. Designations of additional processing of a covering are resulted in tab. 10.

Table 10

* The color of the chromate film is indicated by:

A - colorless with a bluish tint; B - colorless with an iridescent tint; C - yellow, rainbow; D - olive (khaki).

Coatings A and B belong to the 1st class of chromate coatings, coatings C and D , which have a higher corrosion resistance, belong to the 2nd class.

4. The designation of the types of nickel and chromium coatings are given in Table. eleven.

Table 11

5. The designation is written on a line in the following order:

the chemical symbol of the base metal or the designation of the non-metal, followed by a slash;

a coating method in which the chemical symbol of the sublayer metal is indicated;

chemical symbol of the coating metal (if necessary, in parentheses indicate the purity of the metal as a percentage);

a figure expressing the minimum thickness of the coating on working surface in microns;

coating type designation (if necessary);

designation of additional processing and class (if necessary).

Examples of designations are given in Table. 12.

Table 12

Annex 5 Added additionally (Amendment No. 3).

INFORMATION DATA

1. DEVELOPED AND INTRODUCED by the Academy of the Lithuanian SSR

DEVELOPERS

E.B. Davidavichus, cand. chem. sciences; G.V. Kozlova, cand. tech. sciences (topic leaders); E.B. Romashkene, cand. chem. sciences; T.I. Berezhnyak; A.I. Volkov, cand. tech. sciences; T.A. Karmanova

2. APPROVED AND INTRODUCED BY Decree of the USSR State Committee for Standards No. 164 dated January 24, 1985

3. The term of the first check is 1992; inspection frequency - 5 years

4. Instead of GOST 9.037-77; GOST 21484-76

5. REFERENCE REGULATIONS AND TECHNICAL DOCUMENTS

6. REPUBLICATION with Amendments No. 1, 2, approved in October 1985, February 1987 (IUS 1-86, 5-87)