Phosphating of metal at home

Since people have learned how to make metal, humanity faces the acute problem of ensuring the protection of the resulting products from corrosion damage. Rust is the main enemy of any metal surface to this day. The long-term improvement of methods and means designed to prevent corrosion has undoubtedly yielded incredible results in the fight against natural chemical processes. Nevertheless, it is impossible to guarantee a 100% non-compliance with corrosion.

Can I process metal at home?

To date, among the available ways to protect iron materials from the effects of destructive factors, phosphating is worth noting. The metal, after carrying out an appropriate chemical reaction, acquires an increased wear resistance, which makes it possible to extend the period of its direct operation considerably.

The best protection of iron from rust and rot is the coating of its surface with a thin, barely noticeable film. At home, the phosphating of the metal seems to be the most difficult task related to the category of impracticable. Really, after all only in industrial shops there is a necessary equipment, required reagents. In fact, if a set of rules and conditions are observed, any person who does not have a professional technical education will be able to achieve the desired result.

Reagents that will be needed for phosphating

An additional advantage of home phosphating is its versatility: a strong protective film is formed on the surfaces of almost any alloys, except for highly alloyed steel. In addition, the surface layer perfectly fits with the base of the iron billet. As materials for metal phosphating, use is made of:

• manganese;
• zinc;
• Iron phosphates.

Advantages of phosphate treatment of iron

Modern technologies of application of phosphoric acid composition allow to cover metal surfaces with a minimum thickness - no more than 5 micrometers. This method of processing iron prevents its destruction and provides protection from external influences, ensuring the continued use of a metal product in any conditions, including:

• At excessive humidity;
• Under the influence of aggressive chemical solvents;
• In contact with engine oils;
• At high electric voltage;
• As a base under a paint and varnish coating.

Phosphating of the metal for painting will provide reliable protection of the material, however, if it enters an acidic or alkaline environment, the product will remain vulnerable. In addition, when painting any iron surface, the paint materials penetrate much deeper into the layers of the protective film, which has a high level of porosity. Improved adhesion of the surface of the alloys is another positive point, allowing one to say yes phosphating before painting the metal.

Technology and methods of industrial phosphating

Before proceeding with the application of the film layer, it is important to understand the composition of the medium in which the iron will be placed. The technology of phosphating metal with subsequent painting with paintwork is not suitable for home use. With the help of the drug "Magef", the solution of which is filled with huge containers in the enterprise, the iron is covered with a very thin, but very durable and practical layer. Fully placed in a phosphating bath, the metal product is heated to the extreme temperatures and boiled for half an hour. After that, the iron is removed, the film is allowed to completely solidify, to harden, at the end of the process the surface is galvanized with abrasive or sandblasting machines.

The use of the above method can be called justified only in the case of processing large-sized structures. Similar services for phosphating metal, provided in industrial metal rolling shops, will cost the customer a decent amount.

How to process metal at home: "cold" galvanic

For the galvanization of medium-sized products, it is more expedient to resort to elementary technology. It's about phosphating the metal with orthophosphoric acid, the preparation of which is available even at home. For a successful reaction, the correct concentration of chemical elements should be adhered to. The following are the components of the solution in the ratio of the amount of the substance (in grams) per 1 liter of water:

• Phosphoric acid - no more than 40;
• Nitric acid zinc - about 200;
• Zinc oxide - 15;
• Sodium sulphate - 8.

The procedure does not take much time - it takes half an hour to prepare the solution and a direct chemical reaction. One of the main requirements, which should be adhered to during iron processing, is the correct concentration of the solution and its temperature (not less than +18 ° C and not more than +25 ° C). This method makes it possible to obtain cold phosphating of the metal at home, but its quality is much inferior to the treatment of the iron product with the "Mazef" preparation - the maximum thickness of the resulting film, as a rule, does not exceed 5 microns.

Electrochemical phosphating of iron parts

Most of the technologies for processing metal products that do not deserve popularity in production are successfully used by amateurs. This is also the electrochemical treatment of iron, implying the surface coating with a reliable film due to the electrolyte reaction and current. The principle of this method is based on the use of phosphoric acid or "Magef".

An electrode is mounted on the iron billet to be phosphated. The design is lowered into the bathroom with the solution prepared in advance, and zinc rods are used as the anode - they must also be supplied with electricity. To qualitatively process the metal does not necessarily have to resort to the use of a high-voltage network, enough 25 V AC or DC electric current.

"Magef" - the best composition for priming the metal before painting

The phosphating procedure does not last long - on average, to half an hour. This technique is ideal for the processing of straight-line medium-sized products. For items with a more complex geometric design, another way of phosphating iron should be chosen to avoid uneven distribution of the galvanizing film. Used in production and at home, "Magef" is a high-quality ground composition, having all the certificates and corresponding GOST. Phosphating the metal of the car body is one of the most common causes of the use of the substance. To protect the car from rust, "Magef" is applied even in those places where, as is known, the paint will not last long (for example, on the bottom of the car).

To start the metal processing, dirt, dust, bits of bitumen and thoroughly degrease it from the surface. The working mixture can be prepared independently, but it will save time and will evenly distribute the aerosol form of the release. In this case, some reagents are applied to the processed iron with a brush. But this method of distribution is not suitable in the absence of experience in surface priming - it is extremely important to trace the uniformity of the application of the phosphate composition.

Recommendations for the use of phosphate formulations

When processing small metal parts with "Mage" it becomes possible and a hot way of layering the protective film. An alternative to the acquired composition can be considered a mixture of zinc nitrate and phosphoric acid. During the preparation of the mass, one should not for a moment forget about caution and elementary safety techniques:

• It is advisable to wear special protective goggles.
• To prevent poisoning with vapors released, work outdoors or in a ventilated area.
• At the end of the procedure, you should thoroughly wash your hands so that the chemical particles do not get on the mucous membranes of the eyes and mouth.

Finishing treatment after phosphating of parts

As a rule, the phosphating of metal at home is not the final stage of the treatment of the product. Since the porosity of the galvanic protective film structure can affect its further functionality and performance, the metal surface is passivated. As solutions providing smoothness and evenness of the coating, potassium dichromate or sodium dichromate is used. In the process of finishing metal it is extremely important not to miss the temperature indicators: objects with phosphate films immerse in 80-degree solutions and stand them for at least 20 minutes. After passivation, the products are treated with machine oil, after which a solution of gasoline and silicone fluid is used in a ratio of 1:10.

How to check the quality of the protective film on metal?

An indication that the coating obtained corresponds to the declared characteristics is its finely crystalline structure and the minimum number of pores. The production also takes into account the specific mass of the applied layer: the weight of the film should not exceed three grams per square meter. meter. Normal phosphating (processing of the metal occurs at boiling points) makes it possible to obtain a strong coating, the thickness of which can reach 7 μm, and in the case of a cold type of action, the galvanizing layer leaves a smaller thickness, and therefore has a lower quality.

Some tips on phosphating: what you need to know?

To successfully phosphate the metal outside the production facilities, it is important to pay attention to the following points:

• The easiest way to prepare a phosphating paste, with which you can treat vertical areas, is the following: mix "Majef" or homemade solution of phosphoric acid and zinc nitrate with neutral filler - talc, powder, kaolin. The main thing is to observe the proportion (3 parts of the solution for 2 crumbly substances).
• In the phosphate solutions, degreasing components can be added - this will save the forces in the preparation for the phosphatizing of the metal. To do this, in 1 liter of water, add 45 grams of sodium nitrate and sodium monophosphate, as well as half a tablespoon of detergent. The time of finding the part in the phosphating bath should be doubled.
• To remove rust from the surface of the metal, it is necessary to add complex polyphosphates to phosphoric acid. Increase the effectiveness of the prepared solution will help a special wetting agent - it will clean the surface of iron.
• The phosphating accelerator is a substance added to the surface treatment composition. With it, the whole process takes a minimum of time.

Phosphate treatment of iron structures from any alloy

Considering that simultaneous carrying out of several processes of metal phosphating is a significant advantage not only in industry, but also in everyday life, this branch can become a potential direction for improvement of existing technologies of electroplating. In addition to financial savings, which is evident in home phosphating, this treatment of iron has a number of other advantages. For example, phosphate compounds can protect against destruction not only black, but also colored alloys (copper, cadmium, aluminum, etc.).

To protect metal from rust caused by external factors, climatic conditions, it is processed immediately after purchase. In the case of placing processed iron products in a room with excessive humidity, a bluish coating may form on their surface - it does not carry any danger to the metal itself, but in practice it often acquires a decorative significance.