Surface chromatization process for different aluminum profiles
Aluminum profile surface is the majority of customers in the choice, the focus of the inspection of the part, but in the production, no matter how careful, will make the surface of a variety of problems, so a variety of aluminum profile surface problems, is a problem that many manufacturers want to solve.
There are many types of industrial aluminum profiles on the market, different kinds of aluminum profiles, there is a big difference in the surface treatment method, the following is to tell you about the surface treatment method of different aluminum profiles:
Frosted profile:
This profile can avoid the light interference formed by the bright aluminum alloy profile in the architectural decoration under certain environment and conditions, and its surface is very delicate and soft. However, the current frosted profiles must overcome the uneven surface sand grain.
Multi-color surface aluminum profile:
the current monotonous color can not meet the architect’s collocation in the decoration, the new stainless steel color, coupled with stained glass can make the decorative effect icing on the cake. However, these profiles must be chemically or mechanically polished and then oxidized for better results.
Powder electrostatic spraying aluminum profiles:
It is characterized by excellent corrosion resistance.
Electrophoretic coating aluminum profile:
The surface luster is soft, and it can resist the erosion of cement and mud acid rain.
Chromium treatment of aluminum alloy is a common pre-treatment method for aluminum products, which forms a passivation film on the surface of the product through chemical reaction to enhance the corrosion resistance of the product and the adhesion of the coating.
At present, the commonly used types of chromium are trivalent chromium chromium and hexavalent chromium chromium.
Due to the serious environmental pollution of chromium film, the residual chromium compounds are harmful to human body. Therefore, the trivalent chromium and hexavalent chromium treatment will be gradually replaced by chromium-free conversion.
Technological process
The general chromation process is as follows:
- Degreasing: Degreasing is the removal of oil from metal surfaces by alkaline degreasing solution. Aluminum alloy alkaline resistance is poor, should not be cleaned with strong alkaline, so should control the concentration of the tank, the general degreasing concentration can be prepared according to the manufacturer’s instructions. In addition, proper heating and continuous stirring will accelerate the chemical reaction and enhance the degreasing effect.
Typical parameters are as follows: bath temperature: 60-65℃ concentration (V/V),
Impregnation time according to instructions: 5-7min Cycle state: ultrasonic oscillation
- Water washing: After degreasing, use tap water to clean the degreasing liquid attached to the surface of the product. The washing tank is usually designed as an automatic overflow form to ensure that the water in the tank is not seriously polluted.
The washing process parameters are as follows:
Tank temperature: normal temperature
Total alkalinity: ≤1.0
Impregnation time: 30-40S
Replenishment status: continuous replenishment
- Light: After degreasing, there will be residual salt corrosion products on the surface of the product, and the purpose of light is to remove these residues. The light-emitting liquid is an acidic liquid, and the concentration of the tank liquid should be controlled, and it should usually be prepared according to the instructions provided by the manufacturer. Process parameters are as follows:
Tank temperature: normal temperature
Concentration (g/L) according to instructions
Impregnation time: 2-3min
Circulation status: Compressed air
- Water washing: two washing processes should be carried out before chromatization, the purpose is to ensure that the residue on the surface of the product is completely removed, the first water can be washed with tap water, and the second water needs to be washed with pure water to prevent the pollution of tap water. The two washing process parameters are as follows:
1) Tap water washing:
Tank temperature: normal temperature
Total acidity: ≤1.0
Impregnation time: 30S
Recharge state: Continuous recharge cycle state: compressed air
2) Wash with pure water;
Tank temperature: normal temperature
Conductivity: ≤100us/cm
Impregnation time: 30S
Replenishment status: continuous replenishment
Circulation status: Compressed air
