Performance Analysis and Quality Evaluation of Anodic Oxide Film on Aluminum Profiles
As we all know, anodized aluminum alloy film can significantly improve the surface properties of aluminum alloys, especially the surface hardness, corrosion resistance, wear resistance and other important performance related to the service life, so people describe the anodized film as aluminum alloy Functional "surface enhancement processing method.
From the simple small-scale horizontal anodized production line with an annual output of 3,000 tons imported from 20 years ago to the current production of large-scale vertical anodized wires with an annual output of 30,000 tons or more, its rapid development is evident. , integration and improvement, at present, China's aluminum alloy building profiles formed a three series of surface treatment technology, namely, anodizing, anodized electrophoretic coating and organic polymer electrostatic spraying technology, its development direction and level is synchronized with the international development , Equipment level, process characteristics and product quality have reached the international advanced level. As early as the mid-1980s, China's aluminum industry is in its infancy.
In 1986, the China Nonferrous Metals Corporation’s Science and Technology Bureau drafted a document on the performance testing methods and indicators for aluminum profile anodized films according to the opinions of some experts. At that time, it played a role in regulating product quality and promoting the development of production. Good effect. The document proposes the detection of six properties 1) color appearance; (2) oxide film thickness; (3) plugging quality; (4) salt spray corrosion resistance; (5) abrasion resistance and (6) light resistance (Color fastness). Due to the limitations of technology and equipment at the time, only specific requirements were put forward for the first three tests. Corrosion resistance, wear resistance, and light resistance were just a concept, specific performance testing methods and test parameters, As well as the performance acceptance criteria, etc., no provisions have been made. At present, the content of this document may not be perfect enough, but it has been clearly stated that the thickness of anodic oxide film and the quality of the sealing pores are fundamental properties that are essential in the past 20 years. It is the so-called must-measure item that belongs to the performance of the anodic oxidation film.
In the past 20 years, the aluminum industry in China has developed rapidly. The technical requirements for the performance of the corresponding anodized film, acceptance criteria, and inspection methods are relatively clear. The corresponding national standards have been improved and improved, and are basically in line with the standards of advanced industrial countries. Therefore, the current performance testing items and detection methods should have newer and more content, so that they can keep up with the pace of development in China's production, and can more comprehensively and systematically link up with the international advanced technology and international standards.
The China Non-Ferrous Metals Standardization Committee organized and arranged a series of performance testing tests in 2004. The National and South China Nonferrous Metals Quality Supervision and Inspection Center and Jianmei, Nanping, Xingfa, and Minfa have six companies, which are not for the regular production of factories. The specially arranged products took part in this comprehensive test of performance testing and obtained a large number of nearly 20,000 data. The experimental results have been compiled by the National Non-Ferrous Metals Standardization Committee. Although the quality of our products is not uniform across the country. , But overall there has been a great improvement. The test data shows that the above-mentioned factory products are not inferior to the international advanced level. Therefore, we can proudly say that China's aluminum building profile industry is not only a big country, but also a veritable power. Film thickness uniformity and sealing quality The thickness of the anodized film is one of the more important performance indicators. It may be a symbolic data of the service life. The quality of the sealing hole is an important indicator reflecting the corrosion resistance of the oxide film. , Phosphochromic acid weight loss test data changes are in the range of 6% to 15%, or Phosphoric acid corrosion weight loss data within 15%, can be regarded as acceptable measurement error. The forthcoming new standard 8013.1 stipulates that the quality of aluminum alloy building profiles anodized film sealing, nitric acid pre-soaked phosphoric acid test is an arbitration Test, which is the European standard EN12373.6:1999.
The experimental data show that the sample with poorer sealing quality, the greater the “gravity loss†effect of nitric acid pre-soaking, so nitric acid pre-dip is more sensitive to the identification and screening of the sealing quality of the weight loss mark of phosphoric acid and chromatogram. Hole post-treatment can significantly improve the sealing quality and speed up the sealing time. Tests show that if cold post-sealing post-treatment (ie, impregnation with pure water at 60~80°C for 10 min), the aging time can be shortened and the quality of the sealing hole can be quickly reached. Other domestic and foreign tests have also proved that the cold sealing hole post-treatment can significantly improve the plasticity of the cold-sealing anodic oxide film to suit the subsequent mechanical deformation without cracking. Corrosion resistance and weathering resistance The CASS test of the anodic oxide film is resistant to salt spray Conventional test methods for corrosion. Tests have shown that the CASS test of the anodized film and the quality of the plugging quality are not completely comparable, because the quality of the plugging represents the average corrosion rate, while the CASS test reflects the results of localized corrosion, especially for mechanical spraying. Anodized film on the surface of the sand, even if the quality of the sealing hole is acceptable, CASS test can not pass the case, CASS test and alkali of the same sample Comparative ratings, the corrosion level is also lower levels 1-2. Blasted sample morphology may be due to a pit portion of the anodized film is not at full blast, causing increased sensitivity to local corrosion.