The requirements of the pickling process, the training purpose of the pickling process

The anti-corrosion of workshop floor and equipment foundation generally adopts resin mortar floor structure, with a total thickness of about 7-10 mm), and the structure is: primer 1-2 + FRP (2 cloth and 3 oil) isolation layer + resin mortar layer (5-7 mm) + surface layer (about 1 mm). Epoxy vinyl resins are now used for anti-corrosion resins for floors and equipment foundations.

However, in the selection of primer, the construction unit is still accustomed to using epoxy resin.

Make a primer material to increase the bonding properties of the resin and the substrate. Epoxy resin generally uses amine curing agent, after curing, there are oily substances floating out of the surface, and then vinyl resin can not be well matched, the cured surface needs to be treated before the subsequent anti-corrosion structure construction, if the treatment is not good, it is easy to delaminate and crack. According to experts, the adhesion between epoxy vinyl resin and concrete foundation is more than 2MPa, so epoxy vinyl resin has sufficient adhesion performance as a primer material, so it is recommended to directly use epoxy vinyl resin as a primer material for priming, and the same epoxy vinyl resin is used for other layers.

Introduction: The pickling solution of the pickling process is generally a mixture of a variety of acids, mainly sulfuric acid, nitric acid and hydrofluoric acid.

These mixed acids are very corrosive and at the same time have strong oxidizing properties.

The high temperature of the corrosive medium puts forward high requirements for the corrosion resistance of anti-corrosion materials. The stainless steel pickling production line process from production to waste water and waste gas system, there is a strong corrosion state in all links, so the quality of anti-corrosion materials is directly related to the normal use of equipment, workshop floor, trench, waste water and waste gas environmental protection system.

The anti-corrosion of workshop floor and equipment foundation generally adopts resin mortar floor structure, with a total thickness of about 7-10 mm), and the structure is: primer 1-2 + FRP (2 cloth and 3 oil) isolation layer + resin mortar layer (5-7 mm) + surface layer (about 1 mm). Epoxy vinyl resin is now used for the anti-corrosion resin of the floor and equipment foundation, but in the selection of primer, the construction unit is still accustomed to using epoxy resin as the primer material to increase the bonding performance of the resin and the base layer.

Epoxy resin generally uses amine curing agent, after curing, there are oily substances floating out of the surface, and then vinyl resin can not be well matched, the cured surface needs to be treated before the subsequent anti-corrosion structure construction, if the treatment is not good, it is easy to delaminate and crack. According to experts, the adhesion between epoxy vinyl resin and concrete foundation is more than 2MPa, so epoxy vinyl resin has sufficient adhesion performance as a primer material, so it is recommended to directly use epoxy vinyl resin as a primer material for priming, and the same epoxy vinyl resin is used for other layers.

1. The use of strong alkali for neutralization due to the long time for the development of the pickling wastewater treatment process, the relevant departments have already paid the necessary attention to the pickling wastewater treatment process, and the pH of the pickling phosphating wastewater is acidic, so the method of neutralization with strong alkali is generally used to reduce the harmfulness of the waste, but it is not possible to completely remove the harmful substances in the wastewater, especially for the removal of phosphorus ions.

2. The use of lime to treat wastewater For pickling and phosphating wastewater, further research on wastewater treatment technology has been carried out, and the use of lime to treat wastewater can not only reduce the acidity of wastewater. At the same time, it can also precipitate calcium phosphate, promote the concentration of phosphorus ions to be controlled to a certain extent, and the lime treatment process can also reduce the concentration of other heavy metal ions, and the treatment process has a certain economy.

3. Biological treatment process With the development of microbial technology, relevant departments have focused on the study of microorganisms that can engulf harmful metal ions and phosphorus ion, although there is a certain technical difficulty, but the cells that can swallow oil have been developed. At present, the relevant research department has developed a biofilm that can filter harmful wastewater from pickling phosphating.

The purpose of this craft training is as follows:1. Master the principle of pickling: The training of pickling process first needs to understand the principle and basic knowledge of pickling.

By learning the principle of pickling, the influence of factors such as the type, concentration, temperature and time of the first washing liquid, we can better grasp the pickling technology and operation methods.

2. Learn pickling operation skills: Pickling process training also needs to learn pickling operation skills and safety precautions. How to correctly select the pickling solution, adjust the pickling temperature and concentration, control the pickling time, etc., all need to be carefully studied and practiced.

3. Improve the quality of pickling: Another purpose of the training of the ignition process is to improve the quality of pickling. With the right handling techniques and quality control methods, you can ensure that the pickling results are optimum and that the damage to the material during the pickling process is reduced.

1) hydrochloric acid is volatile, the initial preparation should not be too thin, if less than 1:1, it will soon lose its effectiveness, although by prolonging the pickling time, it can still be used, but the pickling is not easy to be thorough; If the concentration is too large, the smell is too large during operation, and it is inconvenient to operate. Generally, the ratio of water to hydrochloric acid is 1:

2. It is more appropriate.

2) The hydrochloric acid tank should be equipped with a lid and an exhaust device to reduce the volatilization of hydrochloric acid and improve the operating conditions.

3) If there are fine washing parts in the pickling parts, in order to prevent them from over-corrosion, it is advisable to add 2-3g l of urotropine (corrosion inhibitor), but the hidden hall should not add too much, because it is not economical in the first place, and it will also affect the speed of rust removal.

4) Hydrochloric acid is not suitable for heating, although the speed of rust removal can be accelerated when the temperature is high, the salt cavity acid will accelerate volatilization, and urotropine will also accelerate the decomposition of the stove, the utilization rate of the material will be reduced, and if the pickling time is not properly controlled, the workpiece may also be corroded.

5) It is forbidden to pickle copper workpieces in the hydrochloric acid pickling solution, such as the pickling parts should be tied with iron wire, not copper wire, and the hook should not be in direct contact with the acid, otherwise the copper layer will be replaced on the surface of the steel parts due to the presence of copper in the pickling solution, which will affect the bonding strength of the coating and the matrix.

6) Adding 1-2g lop emulsifier or, sodium lauryl sulfate to hydrochloric acid is conducive to improving the rust removal speed and rust removal effect.

1.It is suitable for pickling of wire rods and semi-finished products.

Taking wire rod as an example, several commonly used pickling processes are described. As for the semi-finished products that have undergone heat treatment, they generally go directly to pickling without peeling the shell and removing the rust. The rest of the operation sequence is the same as for wires.

1) The pickling process is mainly based on shelling and lime paste.

Wire rod - shelling and rust removal - pickling - washing with water - high-pressure water washing - grease lime paste - drying.

This process has been widely used in the past, and is suitable for the drawing of blanks and semi-finished products of ordinary carbon steel wire, structural steel wire, steel core aluminum stranded steel wire, general spring steel wire. The disadvantage is that there is a lot of dust, and there is a tendency to be replaced by other pickling processes.

2) The pickling process based on shelling and rusting - the process flow is.

Wire rod - shelling and rust removal - pickling - water washing - high-pressure water washing - rusting - thinning lime water - drying.

This kind of wire drawing dust is less, and it is one of the most used at present. It is suitable for the drawing of blanks and semi-finished products of ordinary carbon steel wire, structural steel wire, rope making steel wire, steel core aluminum stranded steel wire, general spring steel wire, etc. Some units also save the rusting process and directly stain the ash after washing.

3) Pickling process based on shelling and phosphating

Degreasing, watering, pickling, passivation, water neutralization, pure water, drying 1, must be degreased and rusted before processing.

2. The water is to clean the degreaser, ordinary tap water (tap water 1 3 minutes) 3, pickling passivation liquid, the original solution is soaked at room temperature for 5-10 minutes, depending on the situation of the workpiece 4, the water is to rinse the passivation liquid remaining on the surface of the workpiece (flowing tap water for 1 3 minutes) 5, because the passivation liquid is acidic water is difficult to clean thoroughly, we use 5% flake alkali (sodium carbonate or sodium hydroxide) to neutralize (5 minutes).

6. The passivation liquid remaining on the surface of the workpiece is rinsed clean (running tap water for 1 3 minutes) 7. Because ordinary tap water contains impurities, impurities and water marks can be removed with pure water (1 3 minutes).

8. Dry or dry in an oven below 180°C (time depends on the size of the workpiece and the result).