most terrible disease products, which are made of metal, corrosion appears, which destroys them gradually.How can you overcome this disease?One way to cover the affected area is considered to be a mass that contains a significant amount of zinc: the proportion of its content can reach 95%.The process of creation of the zinc coating on the metal complex is absolutely nothing is not and does not require huge financial costs.
- need to protect against corrosion
- galvanizing Hot-dip galvanizing
- Cold Galvanizing
- Thermodiffusion galvanizing
- Gas-thermal tsynkovanie
- Galvanizing home
The need to protect against corrosion
Any metal needs to create a protective coating against rust, corrosion and other harmful influences that can destroy the product.Due to different techniques of metal processing protect the metal surface and prolong use of the product is a snap.
In world practice of metallic coatings are most commonly
galvanized metal (zinc) - coating the metal surface with zinc, which is due to its fragility and hardness provides a minimum level of protection for any product.The oxide layer on the cover is sturdy enough zinc is more active material than iron, so it significantly inhibits corrosion.
Zinc reacts faster corrosion than it gets to the core of the metal layer, so the item will remain untouched.And until the product is at least a piece of zinc, iron around it does not rust.Even if the zinc coating is damaged or missing in some areas of the protective properties are maintained.
Thus, zinc coatings act as protectors that "smeared" on the surface of the protected parts.Galvanizing metal is generally carried out using a special production equipment in different ways.Besides possible implementation of galvanizing at home.
procedure applying to the product of the metal zinc coating is made by one of the following methods: hot-dip galvanized, cold painting, electroplating, gas-thermal spraying of zinc and thermal diffusion galvanizing.A method for coating a detail taken to choose, depending on the conditions for future use and the desired properties of the tread layer.One item can be used several types of coatings.
Regardless of the choice of the method of galvanizing to get quality results, it is important to choose the right thickness of the zinc coating, which depends on time and temperature treatments.It should also be remembered that the galvanized metal products should not be subjected to any mechanical stress.Hot-dip galvanizing
Zinc coatings that are created through a process of hot dip galvanizing, the volume occupied by galvanizing plants second and durability and quality are today among the best.Although there are problems of ecological safety, which are due to the presence of molten zinc and the use of the chemical methods of surface preparation.
technology of hot dip galvanizing metal consists of two phases: preparation of the surface and directly galvanizing metal.Surface preparation prior to hot-dip galvanized is the sequential execution of such operations: degreasing by galvanizing, etching the metal surface, rinsing and fluxing metal and drying the surface.
After going through all the stages of preparation to dry the product.Application of zinc is accomplished through the use of special equipment for hot-dip galvanizing and dipping dry product prepared in a bath of hot zinc.On the surface of the part is formed alloy Fe-Zn, which protects against corrosion.
disadvantage of this method is that the metal treatment bath, often limited in size and can not provide the opportunity to process the desired structure.Although modern bath easily fit Scaffold mast lighting and power transmission towers.
widespread in recent years received a method of cold galvanizing metal by coloring of metal primer with a high content of zinc powder.The final coating of zinc 89-93%.The method is characterized by high adaptability and ease of implementation.Powdered zinc is applied to the surface as a conventional paint - by roller or brush.You can also use for this purpose sprays, which reduce the time and allow the galvanizing reach the most remote places.
This method is considered to be very effective for designs that can not handle the other way - for example, to fixed pipes, fittings, transmission lines, elements of railways, oil valves, safety fences, furniture accessories and other fixed stationary objects.
procedure is considered to be effective and for repairing surfaces that have been previously galvanized.
Cold galvanizing steel is carried out in a wide temperature limits, and coating is flexible to withstand mechanical deformations and thermal expansion.
Lifetime cold galvanizing may exceed the operation of hot 3-4 times.The disadvantages of methods include low resistance to mechanical damage and need careful control of working conditions due to the use of an organic solvent.
galvanizing procedure to create a particularly smooth and accurate zinc coating of the metal surface.This technique involves the galvanized coating in the commission of electrochemical treatment.It is suitable for conductive and nonconductive materials.The thickness of the plating is typically 20-30 microns.
When Galvanizing metal is deposited coating is precise and uniform size, bright, decorative.Adhesion of the coatings provided by molecular forces, which occur in the interaction of the base metal and zinc molecules.In virtue of such interaction affected by the presence of any of the films (oxide or fat) at the surface of the coated article, which is not completely avoided in mass production.
galvanizing electrolysis technology is as follows: steel structures exposed galvanized and zinc plates immersed in a container with the electrolyte.Plates and article are connected to a current source.Zinc anode during electrolysis dissolves, settling on the surface of the steel parts.
Among the advantages of the method can distinguish good decorative aspect.With this procedure galvanizing has one serious drawback: the price of galvanizing is not only the cost of zinc and electrolyte.Electrochemical galvanized accompanied by the formation of hazardous wastes, so need removal of zinc waste water, which is quite costly.
procedure thermal diffusion galvanizing is another kind of galvanizing.Methods TDC known for a long time.It was first used in England in the early 20th century and was named "sherardizatsiya."Subsequently it has been somewhat forgotten, replaced by other methods of galvanizing.However, since the nineties interest in the procedure increased again.SUMMARY
thermodiffusion galvanizing consists in the formation of the zinc coating on the surface of the iron by switching at greater 2600 ° zinc atoms in the vapor phase, which promotes their penetration into the iron substrate.In the process of forming an alloy zheleznotsinkovy complicated phase structure.Technology galvanizing TDC is used if you want to create a zinc layer thickness greater than 15 microns.
emergence of such coverage is possible only at high temperatures and in a closed space muffles or retorts are filled tsinkuemymi parts and powder mixture containing zinc.Metal products, in this case, a similar step as in the hot dip galvanizing process and end loaded into the rotary drum furnace, where the material is coated and zinc.
Methods TDC has a number of advantages over other methods of galvanizing:
- galvanizing process is safe from an environmental position;
- resulting coating is non-porous and has a high adhesion to the substrate through a diffusion layer;
- protective ability of the zinc coating is 5 times greater than that of electroplating;
- coating thickness varies over a wide range;
- cover accurately reproduces the shape of parts of the complex configuration (holes, carving a cavity inner surface of the gap);
- waste disposal process is not required.
However, with this technique TDC has its drawbacks, for example, the zinc coating no decorative properties - coating is without shine, dark gray.Performance - is relatively small, there are harmful aerosols zinc dust often arise such defects zinc coating is uneven in thickness.
When galvanizing zinc metal plated coating is carried out as follows: melted metal powder or wire spraying zinc and the product gas stream occurs.Metalizatsionnye thermal coatings are the ideal solution for the protection of large metal from corrosion, which are not placed in the plating bath or the container with the molten zinc.
molten zinc particles deform when word stress on the metal surface, forming the so-called "scaly" surface.Formed with a porous coating, which needs a sealer coating paints.Such composite coatings have long-term protection in different conditions of use - sea and fresh water, atmospheric conditions.
Prior to galvanizing their own hands the product is necessary to prepare and clean the surface properly.The more you do it better, the smoother and stronger lie zinc.Then the metal piece must be activated for this lower it in sulfuric acid for 2-10 seconds.Then, immediately rinse it, plunging into the water and start the anodization.
galvanizing installations can be made as follows.Pick dishes of inert material - vinyl plastic or glass.If the item is small, you can even take a quart jar.Consider the possibility of fixing the electrode and the article, which is the second electrode on it.The suspension of the electrodes is carried out on the copper wire.
Take as a current source charger 2-6 amps, 6-12 volts.The electrolyte for the galvanizing home theoretically be virtually any salt that is soluble in water, in practice it is easier to prepare the zinc salt.You can take the battery electrolyte (diluted sulfuric acid), place it in zinc.After termination of the reaction will zinc and acid enters salt.If the acid is too concentrated, the crystals in the bottom of any of zinc sulfate, then lightly dilute electrolyte water.
electrolyte Then strain and pour into a bowl to dip galvanizing.Zinc electrode can be made of a piece of zinc, drilling a hole in it and hung on a wire made of copper.The surface area should correspond to the area of the workpiece, the form must be flat and suitable for immersion in the container.By the way, a piece of zinc can be purchased at any point for the metal.
Move minus the product plus the zinc, zinc electrode to "dissolve", and settle on the details of the zinc layer.The most difficult when using the equipment for galvanizing and of the process of galvanizing treatment galvanizing acts: on the product may settle the zinc powder, which is easily removed with a cloth, but can - a solid layer, you need a last option.
The quality of the zinc coating is influenced by such factors:
- current density.This is calculated as the current that is divided by the surface area of the product, and 0.5 - 10 amps per square decimeter.Voltage regulators try to achieve too violent reaction.Covering get weak and uneven, if the items will be with too much activity going bubbles.
- temperature.Pick electrolyte at room temperature.
- density of the electrolyte.This parameter can vary within wide limits - of the value of the solubility of zinc salts to zero.
- geometry of the product.If the item has a complex shape, the coating thickness can be considerable variation, depending on the removal of the product from the zinc electrode.On sharp edges appear growths in the recess cover is weak.
analyzing the above, remember that it is advisable to increase the distance to the electrode, use two zinc anodes, twist detail experiment.Perhaps a galvanizing 2 or 3 layers with intermediate removal process on the sharp edges formed nodules.
Thus, when working with a variety of hardware often have to deal with the damage caused by corrosion.Metal and steel has a solid structure, but it can not save him from this misfortune.Therefore, to protect metal structures and facilities, particularly exposed to corrosion, the ideal option is to appeal to the technology of galvanizing - hot dip galvanizing method, cold painting, plating, gas-thermal spraying of zinc and thermal diffusion galvanizing.