The aluminum alloy frame is an aluminum profile with different cross-sectional shapes obtained by hot-melting and extruding aluminum rods. According to the different proportions of various metal components in the aluminum profile, it can be divided into 1024, 2011, 6063, 6061, 6082, 7075 and other alloy grades of aluminum profiles, of which 6 series are the most common.
Aluminum alloys have different requirements, technologies, and materials in various fields. There are special aluminum alloy materials in the solar photovoltaic industry.
The main functions of aluminum alloy frame in photovoltaic modules include the following aspects:
(1) Protect the edge of the glass.
(2) Aluminum alloy combined with silicone edge trimming enhances the sealing performance of the component.
(3) Greatly improve the overall mechanical strength of the component.
(4) It is convenient for the installation and transportation of components.
Therefore, the performance requirements for the aluminum alloy frame include the following aspects:
(1) High hardness; Vickers hardness is greater than 10.
(2) Corrosion resistance (acid rain resistance, salt spray resistance, UV resistance, etc.).
(3) Impact resistance (wind resistance, lightning resistance, etc.).
(4) Twisting performance (installation and use time is more than 20 years).
1. Inspection of aluminum alloy frame
The inspection items of the aluminum alloy frame are as follows
(1) The packaging inspection of the aluminum alloy frame is shown in Figure 1.
(2) The appearance inspection of the aluminum alloy frame is shown in Figure 2.
(3) Surface hardness test.
①Test method: use a Tyrode hardness tester.
②Requirements: The surface hardness is not less than 10HV (kgf/mm²).
(4) Oxide film thickness test.
①Test method: use a film thickness tester, as shown in Figure 3.
②Requirements: The film thickness is 15-25μm.
(5) Bending test.
(a) Place the aluminum alloy sample to be tested on a clean and level work surface.
(b) Use a feeler gauge to measure the size of the gap between the aluminum alloy sample and the work surface from all directions.
②Requirements: The gap is not greater than 1mm (for the cut profiles).
(6) Right angle test.
①Test method: Protractor, as shown in Figure 4.
②Requirements: The angle is not greater than 5′ or 24.
(7) Salt spray corrosion test.
(a) Place the small sample of aluminum alloy to be tested directly in the salt spray test chamber and open the test chamber.
(b) After continuous testing for 1000h, take out the sample of the welding tape to be tested.
②Requirements: There is no corrosion or stain on the surface of the sample to be tested, and the oxide film is intact.
(8) Damp heat aging test.
(a) Put the small sample of aluminum alloy to be tested directly into the damp heat aging box.
(b) Take it out after 1000 hours under the conditions of 85°C and 85% RH, and observe the condition of the sample with the naked eye.
②Requirements: The sample to be tested has no deformation, no cracking, and the oxide film is intact.
2. Storage of aluminum alloy frame
(1) Constant temperature (20℃-30℃); constant humidity (less than 60%).
(2) Avoid direct sunlight or wind.
(3) The storage time shall not exceed one year.
3. Surface oxidation treatment of aluminum alloy frame
1) Surface oxidation treatment process
The surface of the extruded aluminum alloy profile is not strong in corrosion resistance, and must be surface treated by oxidation to increase its corrosion resistance, wear resistance and appearance. Its main process includes the following aspects:
(l) Surface pretreatment: Use chemical or physical methods to clean the surface of the profile to expose the pure substrate, so as to facilitate the acquisition of a complete and dense artificial oxide film. In addition, mirror or matt (matt) surfaces can also be obtained mechanically.
(2) Oxidation: Under certain process conditions, the surface of the pretreated profile is oxidized to form a dense, porous and strong Al2O3 film layer.
(3) Sealing: The pores of the porous oxide film formed after oxidation are closed to enhance the anti-pollution, corrosion resistance and wear resistance of the oxide film. The oxide film is colorless and transparent. Using the strong adsorption of the oxide film before sealing, some metal salts are adsorbed and deposited in the film pores, so that the surface of the aluminum alloy profile can display colors other than the original color (silver white), such as black, yellow, etc. .
2) Oxidation species
(1) Anodizing (electrochemical oxidation).
Anodic oxidation refers to placing aluminum alloy profiles as anodes in the corresponding electrolyte, and conducting electrolysis under specific conditions and the action of an applied current. The simple equipment used is shown in Figure 5. After the aluminum alloy of the anode is oxidized, an aluminum oxide film layer is formed on the surface.
(2) Sandblasting oxidation.
Sandblasting oxidation means that after the aluminum alloy profile is sandblasted, all the oxides on its surface are treated, and after being hit by sandblasting, the surface layer metal is compressed to form a dense arrangement, and the metal crystal changes are small, and the aluminum A firm, dense and hard oxide layer is formed on the surface of the alloy. The aluminum alloy sandblasting oxidation equipment is shown in Figure 6.
(3) Electrophoretic oxidation.
Electrophoretic chlorination refers to the process of plating a thin layer of other metals or alloys on the surface of aluminum alloys using the principle of electrolysis. During electroplating, the plating metal is used as the anode, and the anode is oxidized to form cations that enter the electroplating solution; the aluminum alloy product to be plated is used as the cathode. , the cations of the coating metal are reduced to a metal coating on the surface of the aluminum alloy, as shown in Figure 7.