{Cleaning agent for aluminum} Pretreatment method

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{Cleaning agent for aluminum} Pretreatment method
1. chemical pretreatment
1. Alkali etching method
This is the most common method. The surface after alkali etching is bright and delicate. In the past, China has commonly used alkali etching method to eliminate extrusion lines, but this method of aluminum consumption is too high, Japan used AL(OH)3 recovery device, to get better results and benefits. However, in our country due to high investment in equipment and extrusion machine tonnage mismatch and other reasons, can not be promoted, I mostly use the European method to use corrosion inhibitors. The advantage of this method is to make the aluminum surface more refined, the disadvantage is that the waste discharge will smell bad in the future to meet the environmental requirements.
2. Acid corrosion
The prototype of this technology has been in the 1950 s and 1960 s. The principle is to use fluoride ions to have a relatively negative electrode potential under acidic conditions to form pitting corrosion on the aluminum surface. This technology was first introduced from Japan by a manufacturer in Guangdong (this technology is used by a small number of aluminum groups in Japan). This technology is characterized by low aluminum consumption, uniform surface, the disadvantage is that the surface is not bright. It is often difficult to treat (not impossible to treat) the waste water of alkali corrosion after acid corrosion. The composition of aluminum is required to be high, and the operator must have strict safety protection. Nevertheless, because of acid corrosion after the application of extinction electrophoretic paint, it is indeed very beautiful.
3. Chemical polishing
The chemically polished surface can easily achieve a mirror effect, and because of the consistency of the decorative surface and the non-decorative surface, the aluminum grade is improved. This technology is widely used in Europe, especially in Turkey. The disadvantages of this technology are: three acid or two acid polishing cost is high, pollution is large, some technical problems are not easy to solve (such as bath heat preservation, bath aging, etc.) at the same time, the essence of chemical polishing should be called chemical brightening method, because this method can really make the surface of aluminum bright, but can not remove the extrusion lines, but make the extrusion lines more obvious.
2. mechanical pretreatment
1. Mechanical polishing
Some manufacturers in China have introduced some mechanical polishing machines from Spain. In fact, this technology is an early mechanical sweep. Extension of mechanical wire drawing technology. If aluminum can achieve mirror effect through mechanical polishing, a polishing machine can only throw about 2,000 tons of aluminum a year at most, so the output of mirror aluminum is not large. There are also people who polish the holes and then polish them to achieve the brightness of electrophoretic coating. However, this kind of aluminum often has a film thickness of only 6-7μ, and its corrosion resistance is too poor to be popularized. Mechanical polishing can make the surface uniform, refine the lines and reduce aluminum consumption. The disadvantages are electricity consumption, low output and ability to polish the decorative surface.
2. Mechanical shot blasting and mechanical sand blasting
The earliest such equipment used in steel plate or cast iron surface treatment. Later, a manufacturer in Fujian, China imported equipment from Italy for aluminum surface treatment, and received excellent results. According to the raw materials used, such technologies can be divided into four categories: stainless steel shot, stainless steel shot, aluminum shot and quartz sand. This equipment has been localized, such technology can eliminate the aluminum surface extrusion indentation, reduce aluminum consumption, so that the surface to achieve the effect of matte. Recently, the author noticed that the doors of KFC fast food restaurants in the United States basically use shot blasting electrophoresis, which is indeed noble.

3. powder spraying
Powder spraying because of its diverse colors, the material requirements of the substrate is not very strict and other reasons, more and more welcomed by many aluminum factories and mass consumers, it also meets the personalized design, according to the user's preference to choose the color. The development and popularization of thermal insulation profiles has opened up an important space for powder spraying profiles, and the appearance of powder spraying is more diverse. The transfer printing method allows us to easily make aluminum into wood grain and marble samples. The current grille spraying method can even directly spray the wood grain effect with a feel. However, despite the rapid development of powder research in the world (now there are also fluorine carbon powder, transparent powder, etc.), how many of these large powder spraying factories will bring excellent technology to China for production.