1. Alkaline etching method
This is the most common method. The surface after alkaline etching is bright and delicate. Previously, our country commonly used alkali etching method to eliminate extrusion lines, but this method of aluminum consumption is too high, Japan has adopted the AL (OH) 3 recycling device, get better results and benefits. But in our country due to high investment in equipment and extruder tonnage mismatch and other reasons, failed to promote, I mostly use the European method using corrosion inhibitors. The advantage of this method is to make the aluminum surface more refined, the disadvantage is that waste emissions in the future is difficult to smell to meet environmental requirements.
2, acid corrosion
The prototype of this technology in the fifties and sixties, its principle is the use of fluoride ions in acidic conditions have a more negative electrode potential, the formation of 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. Often acid corrosion are added after a minute Kushi alkali corrosion wastewater is more difficult to deal with (not impossible to deal with). Higher requirements for aluminum composition, the operator to have strict safety protection. Nevertheless, because the acid corrosion after coating matte electrophoresis paint, it is very beautiful, so in Japan, in China and even in the future in Europe and the United States will have a big market.
3, chemical polishing
Chemical polishing of the surface can easily achieve a mirror effect, and because of the consistency of decorative surface and non-decorative surface, so that the aluminum grade, this technology in Europe, especially in Turkey is more widely used. The disadvantages of this technology are: three acid or two acid polishing cost is higher, more pollution, some technical problems are not easy to solve (such as tank fluid insulation, tank fluid aging and other issues) At the same time, the essence of chemical polishing should be called chemical brightening method, because, this method does make the surface of the aluminum bright, but can not be removed from the extrusion pattern, but instead of extrusion pattern is more obvious.
Second, mechanical pretreatment
1, mechanical polishing
Some of our manufacturers have introduced some mechanical polishing machine from Spain. In fact, this technology is the early mechanical sweeping. The extension of mechanical drawing technology. Through mechanical polishing treatment can make aluminum to achieve a mirror effect, if a polishing machine can only throw a maximum of two thousand tons of aluminum a year, so the mirror aluminum production is not large. There are also people polishing holes and then polished, can reach the brightness of electrophoretic coating. But this aluminum is often only 6-7μ film thickness, corrosion resistance is too poor, not worth promoting. Mechanical polishing can make the surface uniform, refine the grain, reduce aluminum consumption, the disadvantage is power consumption, low yield and office can throw decorative surface.
2, mechanical shot blasting and mechanical sandblasting
The earliest such equipment is used in the surface treatment of steel or cast iron. Later, a manufacturer in Fujian, China, from Italy to introduce equipment for aluminum surface treatment, received excellent results. According to the use of raw materials and such technology can be divided into throw stainless steel shot, throw stainless steel shot, throw aluminum shot and quartz sand blasting four categories. This equipment has been localized, such technology can eliminate extrusion marks on the aluminum surface, reduce aluminum consumption, so that the surface to achieve the effect of matte. Recently I noticed that the U.S. KFC fast-food restaurant's door, basically use the shot blasting electrophoresis, it does appear to be a noble identity.
Three, powder coating
It should be said that powder coating because of its color variety, the substrate material requirements are not very strict, etc., more and more popular with many aluminum factory and mass consumers, it also meets the personalized design, according to the user's hobby to choose the color. The development and popularization of heat-break profiles has opened up another important space for powder coated profiles, and the appearance of powder coating has become more varied. The transfer printing method enables us to easily make aluminum into wood grain and marble-like. Nowadays, even the fence spraying method can directly spray out the wood grain effect with a sense of touch. But although the world's powder research is rapidly changing (now also out of the fluorocarbon powder, transparent powder, etc.), but how many of these big powder coating manufacturers will be excellent technology to China to produce, is a matter of concern. Like electrophoretic coating, we produce so many years, the quality has never been able to catch up with Japan.
Four, electrophoretic coating
1, light transparent electrophoresis
This electrophoresis line in China has one hundred and sixty groups, high and low grades, this scenario is more a bit like the early nineties, aluminum in China, the same as the big dry fast, when there is a strict quality control, and there is no oxidation, not sealing holes on the sale. Now more than 80% of the domestic electrophoretic aluminum can not be exported. This is also one of the main reasons why the corresponding national standard is set at a more lenient standard. Electrophoretic aluminum is good, the film is qualified, the first to see where he uses the paint, the second to see what equipment he uses. Now some domestic equipment has been fully qualified, but the paint we should pay attention to, even if it is Japan Coat enterprises, he may not necessarily sell the best paint to China. Therefore, before choosing, we must be careful, ask for advice and do more tests.
2, matte transparent electrophoresis
This product is very rare in Europe and the United States, but in Japan has now accounted for the market. Matte electrophoresis coating has better corrosion resistance and hardness than transparent electrophoresis coating, and at the same time, it avoids light pollution and other hidden problems, and looks more noble and elegant, so it is more and more popular, and at present, only a factory in Guangdong has introduced a production line in China.
3, colored electrophoresis
In order to make up for the monotonous color of electrophoresis and three times of electrolytic coloring into the material rate is not high, Japan developed a colored electrophoresis. At present, there are mainly white, milky white, milky yellow, green system, gray system and soft section color system and so on, especially the latter ones are composite color. Take the gray system as an example, if the base color is silver white, light coffee after electrophoresis; the base color is Gutong color, grey after electrophoresis; when the base color is black, dark blue after electrophoresis, this kind of production line, at present, in our country, only a manufacturer in Fujian introduced a, white electrophoresis is a lot.
4, fluorocarbon electrophoresis
Fluorocarbon coating for electrophoresis which is also considered a Japanese invention, at present in the world, only the new Nippon Light Metal's Funabashi factory has a production line, the electrophoresis for transparent matte electrophoresis, the outdoor service life of the product in the offshore oil platform has been up to 15 years without anomaly. The electrophoresis coating developed by Japan's Nippon Light Metal, the price is equivalent to transparent electrophoresis coating indeed 0 times, but compared to fluorocarbon spraying, or much cheaper, about RMB 18 yuan per square meter, is the curtain wall industry and airports and other landmark buildings of choice, the Hong Kong airport on the use of a lot of this product. Its only drawback is transparent, that is, colorless, not as colorful as fluorocarbon spraying. Whether this technology can be introduced to China, the author is in active contact with the relevant parties in Japan.