How to remove the electroplating layer? Chromium plating is a durable electroplating, but it will wear and become ugly and need to be removed. There are many methods besides chromium plating, so be careful with whatever method you use. So how to remove the electroplating layer?

Methods/steps of how to remove electroplating layer

I. Anodizing

Mainly the anodic oxidation of aluminum, using electrochemical principle to form a layer of Al2O3 (alumina) film on the surface of aluminum and aluminum alloy. This oxide film has special characteristics such as protection, decoration, insulation and wear resistance.

Second, electrophoresis.

Used for stainless steel, aluminum alloy, etc. It can make products present various colors, keep metallic luster, enhance surface performance and have good corrosion resistance.

Three. microarc oxidation

The process of applying high voltage in electrolyte solution (usually weak alkaline solution) to form ceramic surface film is the result of the synergistic effect of physical discharge and electrochemical oxidation.

Four. PVD vacuum plating

Physical vapor deposition (PVD) is an industrial manufacturing process, which mainly uses physical processes to deposit thin films.

Verb (abbreviation for verb) electroplating

It is a technology to attach a metal film to the metal surface by electrolysis, so as to achieve anti-corrosion, improve wear resistance, conductivity, reflectivity and improve aesthetics.

Six, powder spraying

Powder coating is sprayed on the surface of the workpiece by powder spraying equipment (electrostatic plastic spraying machine). Under the action of static electricity, powder will be uniformly adsorbed on the surface of the workpiece to form a powder coating. Powder coatings are baked, leveled and cured at high temperature to become final coatings with different effects (different kinds of effects of powder coatings).

How to Remove Electroplated Layer 2 Method 1 3: Special machinery for chromium removal.

Use a grinding sandblasting machine. Abrasive sandblasting machines that use sand blasting and shot blasting can use particulate powder or fine particles to grind materials. Car beauty shops and construction companies are usually equipped with this equipment. Long-term grinding and sandblasting can remove the chrome coating of the object, but after that, some hard-to-reach areas may need to be treated separately.

In order to avoid damage to the underlying metal, it is best to use materials with relatively small particles, such as 400 # sand, when sandblasting the chromium plating layer.

Note that in the process of using the sandblasting machine, the chrome-plated layer will be ground into small pieces and fall off, thus forming dust and deposits in the air. They are poisonous, so we must take appropriate measures to protect our faces and mouths.

Use an ultrasonic cleaner. Ultrasonic cleaning machine is a special kind of equipment, which uses sound waves to clean delicate articles such as jewelry, which are difficult to clean. In some cases, the ultrasonic cleaning machine can even remove the chromium coating. If you loosen the chromium plating layer in other ways, its cleaning effect will be better. Put the chrome-plated articles into the cleaning tank of the ultrasonic cleaning machine and soak them in the cleaning solution. The solution used in ultrasonic cleaning machine is usually ordinary tap water. Then follow the instructions to turn on the cleaning machine.

As mentioned above, replacing water with solvents that can dissolve chromium, such as bleach, can enhance the chromium removal effect of ultrasonic cleaning machine. However, before doing so, please ensure that this solvent will not corrode the cleaning machine or react with it in any other way. For example, as described below, lye will react with aluminum containers.

Please note that although ultrasonic cleaning machines come in various sizes, most of them can only accommodate relatively small items, such as jewelry, hub nuts, tools, decorations and so on.

Method 2: 3: Use chemical solution to remove chromium.

Use hydrochloric acid (hydrochloric acid). Hydrochloric acid is also called hydrochloric acid, which makes it a strong acid and corrosive. Using high concentration hydrochloric acid, the chromium plating layer on metal objects can be removed. A concentration of about 30-40% should be enough. [1] The operation method is as follows:

In a vat for mixing chemical raw materials, such as a corrosion-resistant plastic bucket, hydrochloric acid and water are mixed in a ratio of 1 3 to obtain a 30% acid solution. You can also buy a prefabricated acid solution with the required concentration.

Immerse the chrome-plated object in the solution until the chrome-plated layer falls off.

Wash objects thoroughly with soap and water, and then dry them.

Use sodium hydroxide (alkaline solution) to remove chromium plating on ferrous metal and carbon steel. Sodium hydroxide, commonly known as lye, is a corrosive alkaline chemical. [2] It can dissolve several metal coatings, including chromium, but it will have dangerous chemical reactions with water and aluminum. It will corrode aluminum objects and produce flammable hydrogen. Therefore, it can only be used for articles whose substrates do not contain aluminum. The operation method is as follows:

Mix 250 ml to 350 ml of sodium hydroxide and 4 liters of water in a vat made of neutral raw materials, such as a corrosion-resistant plastic bucket.

Immerse the chrome-plated object in the solution until the chrome-plated layer falls off. This may take a long time, so be sure to check the peeling of chromium plating layer frequently.

Wash objects thoroughly with soap and water, and then dry them.

Carry out reverse electroplating. Chromium is attached to the metal surface by electroplating process. During electroplating, the current will combine chromium and metal at the molecular level. Reversing this process can remove chromium plating layer very effectively. However, this is very dangerous. Because this process requires electricity, and the reaction products also contain several toxic carcinogenic chemicals. For example, hexavalent chromium is an extremely dangerous product. [3] So this method is best used by professionals. The following steps are for reference only.

Chromic acid and sulfuric acid are mixed in water at a ratio of about100:1. For example, 950 grams of chromic acid crystals and 9.5 ml of sulfuric acid solution were added to distilled water to prepare a 4 liter solution. When preparing the solution, electroplating, material testing and chemical treatment must be carried out in an appropriate immersion tank.

Heat the solution. When the decorative chromium plating layer is removed, the temperature of the solution is kept at 35 to 46 degrees Celsius. When hard chromium is removed, the temperature is kept at 49 to 66 degrees Celsius.

The negative charge of DC power supply is introduced into the chromium plating solution through wires.

Connect the positive electrode to the object from which the chromium coating is to be removed and immerse it in the solution. Chromium metal with positive charge on the surface will fall off the surface of the object.

Rinse the items in the drum with tap water, and then rinse again. Professional treatment and disposal of waste.

Method 3: Remove the fake or thin chromium plating layer with household materials.

Remove thin or weak adhesion chromium plating layer with self-made abrasive. You can use simple mechanical action, that is, scrub with abrasive to remove the chromium plating layer. This is the simplest and most suitable method for beginners. Pour baking soda or solid household cleaner into water to make grinding paste. Dip it in a soft cloth and rub it on the chromium until the chromium coating falls off. This method is best used on chromium plating layer or "fake" chromium plating layer with very thin adhesion. Some plastics are coated with fake chromium. Even in this case, you should try to erase it.

When wiping, always check the progress. Scrubbing for too long may scratch the underlying material.

Use oven cleaner. Some types of chromium can be removed with commercial-grade oven cleaners, especially those coated on plastic car models. These powerful degreasing agents are usually packaged in spray cans in the form of foam or liquid. Spray a thick layer of cleaner on the chrome-plated parts, and then wait 10 minutes. Wipe off the chrome coating together with the spray cleaner. [4]

Note that if you wait too long after spraying, the oven cleaning spray may darken the bottom metal, so you should probably spray less at a time and repeat it several times until you get the desired effect.

How to remove and clean the galvanized layer on the metal surface of electroplating layer 3?

How to clean the galvanized layer on the metal surface is environmentally friendly and efficient, and of course laser cleaning is chosen.

Galvanizing refers to the surface treatment technology of plating a layer of zinc on the surface of metal, alloy or other materials to play an aesthetic and antirust role.

The most common method to remove zinc coating is pickling with hydrochloric acid, and zinc dissolves very quickly in hydrochloric acid. In order to save cost, in electroplating plant, the remaining waste acid is used to remove rust from steel. It usually takes only a few tens of seconds to remove the electro-zinc coating with hydrochloric acid, except for hot dip or zinc spraying, because these two kinds of zinc coatings are thicker and the zinc removal time is slightly longer.

Because of the influence of the environment, pickling is no longer suitable for cleaning. At present, the more suitable cleaning method is laser cleaning, which can easily remove the galvanized layer on the metal surface, save time, labor and labor, and truly achieve efficient, environmentally friendly and pollution-free green cleaning.

What are the latest methods for surface cleanliness of metal electroplating?

1, visual and optical methods

The oil stain on the bright metal surface can be observed with the naked eye or with the help of a magnifying glass or an optical microscope. Its disadvantage is that the passive oxide film and extremely thin oil stain on the metal surface will not be detected. For rough and dull metal surfaces, the above methods are powerless, but clean and white cotton, cloth and paper can be used to wipe the surface and then determine whether it is clean.

2. Surface tension method

According to the influence of surface oil pollution on its surface energy, the surface energy is determined by whether the metal is immersed in a series of test solutions with different surface tensions, and the cleanliness of its surface is judged accordingly. If a series of solutions ranging from 80% acetic acid to 20% water (V/V, the same below) to 1% ethanol and 99% water are prepared, the surface tension will increase from 24.5× 10-5N/cm to 66.0× 10-5N/cm.

3. Painting method

Drop the degreasing agent on the metal surface and then evaporate it. If there is no trace, the metal surface of the surface is clean. If there is a ring, it means there is oil pollution.

4. Wetting method

The clean metal plating surface is hydrophilic, so it can be completely wetted by water. When the metal surface contains oil stains, there will be water-stained areas that are not wetted by water. Based on the principle of hydrophilicity, in addition to the simplest and commonly used exhalation method and atomizer spray method, there are the following detection methods. Because the oxide film of metal is also hydrophilic, most of these methods can't detect whether the oxide film on the metal surface has degraded.

5. Talcum powder method

Put the metal sample vertically into water with talcum powder on its surface, and then lift it vertically. You can see that talcum powder will adhere to the clean surface evenly, but there is no talcum powder where there is oil stain.

6, copper replacement method

The ferrous metal is soaked in 63g/l CuSO4 H2O and 17g/LH2SO4, left standing for 10s, taken out, stirred in distilled water for 15s, rinsed with a bottle and dried. On the clean metal surface, pink Cu is produced due to the reaction of Fe+Cu2+→Cu+Fe2+, but pink Cu replacement layer is not seen on the oily surface.

7. Alarm bell method

This method is a special detection method for copper and its alloys. Copper and its alloys will suddenly turn black when soaked in 0.025mol/L sodium polysulfide solution and left standing for a certain period of time, so it is called alarm method. The cleaner the copper surface, the shorter the blackening time.

8. Other methods

In addition to the above methods, some materials also recommend potassium ferricyanide method, fluorescence method, dye method, radioactive tracer method, combustion method and so on. According to their respective application environment and conditions, each has its own advantages and disadvantages.