Nanoshit for metal
Hi GT!
I am by nature a terrible choleric. Perhaps this is a common feature of people who are constantly interested in something new or passionate about science. But sometimes I get bored. The next bout of creative blues last week I dispelled in a society of very brave people. These include those who, in spite of the rampant two-currency hysteria and all kinds of crises, are not afraid to develop interesting technologies and even open new productions! Today I will talk about such brave ones who invented and developed the technology of microarc oxidation of non-ferrous metals.
Microarc oxidation (MAO) is a special technology for surface treatment of various metals. The technology is that when a high-density current is passed in a special electrolyte, microplasma discharges begin to appear on the surface of the workpiece. These discharges form on the surface of the part a very high quality oxide-ceramic film - a kind of coating of oxide forms of metal and substances dissolved in the electrolyte. This allows you to betray the details of various amazing shades, and most importantly - the formed ceramic coating has completely unique properties. Hardness, wear resistance increase, light reflecting ones appear, or vice versa - light absorbing properties. Also changes the surface structure, increases adhesion to further coatings or to the banal painting. Parts become resistant to corrosion, and the protective coating has a dielectric strength of up to 2 kV. And this is not an exhaustive list of newly emerged properties. After all, the arcs that process the part form a complex structure on the surface due to the extremely high temperatures and pressures at the “electrode-electrolyte” interface. In the photo you can see how the MDO process is going. Details glow due to microarcs.
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It may seem that the part is very hot during processing. In fact, it remains cold, and the whole process takes place in a layer several microns thick. In the process of MAO, a certain nanostructure is formed layer by layer, which gradually grows up to tens of microns thick, forming the final coating. The processing of parts takes from five minutes to an hour. The time depends on what thickness of the coating we want to get and what type of coating is necessary to form on the part. If it is necessary to apply complex and thick (up to 50 microns) coatings, the process can take several hours. But in most applications this is not required. MAO technology can be subjected to all aluminum alloys, as well as titanium, magnesium and zinc.
Unfortunately, my scanner could not convey the color sensation of the type of parts covered by MDO technology. Still, I cite such a photo. The coating is matte, very warm and looks expensive. The picture shows square aluminum plates for demonstration. By the way, the black coating has a blackness of 94% and can be used in the blackening of optical components, where this level of blackness is sufficient.
Due to the action of microarcs, the structure of the material changes. The surface becomes as if slightly rough and covered with a very dense oxide film. If the task is not to change the color of the coating, for example, it is required to prepare the part for painting, then this is just a wonderful and not expensive technology. Aluminum parts after a few minutes of processing become milky and any paint is applied to them perfectly. It should be remembered that aluminum is not so easy to paint. Many paints on it do not hold up well or are not applied at all, curling up into small balls. After the MAO process, the part can be painted literally in 10 minutes as soon as it dries from water, in which the part is rinsed after the MAO process. With this technology, you can handle the details of the most complex forms. Coverage occurs in all places. If somewhere a coating is not needed, it is necessary to isolate this place, for example, by applying a varnish. The photograph shows micrographs of the metal structure before (upper) and after (lower) MAO processing. As seen on the surface, microcraters are formed. Thus, MAO-coatings are porous ceramics of complex composition, which is formed due to the oxidation of the metal and the inclusion of chemical elements from the electrolyte into the coating composition. This porous structure in turn provides excellent covering properties for further painting of parts. Anodizing is a competing MAO technology, but unlike this technology, MAO has significant advantages. First of all, on the quality of the coating and its adhesion, the absence of complex sample preparation of parts and environmental friendliness.
MAO technology allows the replacement of expensive materials such as bronze, brass and stainless steel with cheaper aluminum alloys coated with an oxide-ceramic coating. In turn, this reduces the weight and cost of the part by reducing the cost of machining. According to MAO technology, it is possible to produce highly efficient heat sinks in radio engineering, effective IR reflectors, excellent and inexpensive enclosures for devices, design materials and much more.
This technology can find an excellent application in mechanical engineering, aerospace, aircraft industry. There is a potential for its use in microelectronics, which has not yet been evaluated. For example, you can create plates on which ultra-bright LEDs are deposited through dielectric layers, and the plate itself is blackened to effectively remove heat from the crystal. The developers have conducted experiments on the coating of complex ribbed heat sinks, the efficiency of which has increased significantly! This allows you to significantly save, because an effective heat sink can be made smaller in weight and size.
Installation is quite simple and differs little from the hydrolysis bath. The most interesting is the processing modes and the composition of the electrolyte. In this case, the electrolyte does not contain heavy metals, chromium ions, strong acids and cyanides.
Of course, the electrolyte is not worth drinking, but the production itself is quite environmentally friendly. Used electrolyte is easily recycled - there are practically no chemicals left in it. All of them are transferred to the ceramic material on the metal surface, and the ceramic itself no longer presents any danger, because this is a sintered structure that has been subjected to the action of micro-arc. At the same time at the initial moment of time the arcs are not visible to the eye. A bright glow occurs gradually and becomes visible when the coating becomes thick enough. Parts to be processed are limited only by the size of the bath. For example, at the moment the company has baths up to 2 meters. The technology also does not require much energy.
And, of course, a small video to see everything with my own eyes.
PS I was pleased to meet and visit this interesting company. I want to somehow support the guys in their project. I do not give a direct link to the company, so as not to get a ban for advertising, but still if you have questions or interest, please write me at asmtomsk@gmail.com and I will pass your questions directly to the experts. Moreover, the company provides not only coating services, but also installations and chemicals for electrolytes.
Have a nice day, everyone!
I am by nature a terrible choleric. Perhaps this is a common feature of people who are constantly interested in something new or passionate about science. But sometimes I get bored. The next bout of creative blues last week I dispelled in a society of very brave people. These include those who, in spite of the rampant two-currency hysteria and all kinds of crises, are not afraid to develop interesting technologies and even open new productions! Today I will talk about such brave ones who invented and developed the technology of microarc oxidation of non-ferrous metals.About technology
Microarc oxidation (MAO) is a special technology for surface treatment of various metals. The technology is that when a high-density current is passed in a special electrolyte, microplasma discharges begin to appear on the surface of the workpiece. These discharges form on the surface of the part a very high quality oxide-ceramic film - a kind of coating of oxide forms of metal and substances dissolved in the electrolyte. This allows you to betray the details of various amazing shades, and most importantly - the formed ceramic coating has completely unique properties. Hardness, wear resistance increase, light reflecting ones appear, or vice versa - light absorbing properties. Also changes the surface structure, increases adhesion to further coatings or to the banal painting. Parts become resistant to corrosion, and the protective coating has a dielectric strength of up to 2 kV. And this is not an exhaustive list of newly emerged properties. After all, the arcs that process the part form a complex structure on the surface due to the extremely high temperatures and pressures at the “electrode-electrolyte” interface. In the photo you can see how the MDO process is going. Details glow due to microarcs.
')
It may seem that the part is very hot during processing. In fact, it remains cold, and the whole process takes place in a layer several microns thick. In the process of MAO, a certain nanostructure is formed layer by layer, which gradually grows up to tens of microns thick, forming the final coating. The processing of parts takes from five minutes to an hour. The time depends on what thickness of the coating we want to get and what type of coating is necessary to form on the part. If it is necessary to apply complex and thick (up to 50 microns) coatings, the process can take several hours. But in most applications this is not required. MAO technology can be subjected to all aluminum alloys, as well as titanium, magnesium and zinc.
Unfortunately, my scanner could not convey the color sensation of the type of parts covered by MDO technology. Still, I cite such a photo. The coating is matte, very warm and looks expensive. The picture shows square aluminum plates for demonstration. By the way, the black coating has a blackness of 94% and can be used in the blackening of optical components, where this level of blackness is sufficient.
What happens to the material?
Due to the action of microarcs, the structure of the material changes. The surface becomes as if slightly rough and covered with a very dense oxide film. If the task is not to change the color of the coating, for example, it is required to prepare the part for painting, then this is just a wonderful and not expensive technology. Aluminum parts after a few minutes of processing become milky and any paint is applied to them perfectly. It should be remembered that aluminum is not so easy to paint. Many paints on it do not hold up well or are not applied at all, curling up into small balls. After the MAO process, the part can be painted literally in 10 minutes as soon as it dries from water, in which the part is rinsed after the MAO process. With this technology, you can handle the details of the most complex forms. Coverage occurs in all places. If somewhere a coating is not needed, it is necessary to isolate this place, for example, by applying a varnish. The photograph shows micrographs of the metal structure before (upper) and after (lower) MAO processing. As seen on the surface, microcraters are formed. Thus, MAO-coatings are porous ceramics of complex composition, which is formed due to the oxidation of the metal and the inclusion of chemical elements from the electrolyte into the coating composition. This porous structure in turn provides excellent covering properties for further painting of parts. Anodizing is a competing MAO technology, but unlike this technology, MAO has significant advantages. First of all, on the quality of the coating and its adhesion, the absence of complex sample preparation of parts and environmental friendliness.Where can this be applied?
MAO technology allows the replacement of expensive materials such as bronze, brass and stainless steel with cheaper aluminum alloys coated with an oxide-ceramic coating. In turn, this reduces the weight and cost of the part by reducing the cost of machining. According to MAO technology, it is possible to produce highly efficient heat sinks in radio engineering, effective IR reflectors, excellent and inexpensive enclosures for devices, design materials and much more.
This technology can find an excellent application in mechanical engineering, aerospace, aircraft industry. There is a potential for its use in microelectronics, which has not yet been evaluated. For example, you can create plates on which ultra-bright LEDs are deposited through dielectric layers, and the plate itself is blackened to effectively remove heat from the crystal. The developers have conducted experiments on the coating of complex ribbed heat sinks, the efficiency of which has increased significantly! This allows you to significantly save, because an effective heat sink can be made smaller in weight and size.
How does this happen in practice?
Installation is quite simple and differs little from the hydrolysis bath. The most interesting is the processing modes and the composition of the electrolyte. In this case, the electrolyte does not contain heavy metals, chromium ions, strong acids and cyanides.
Of course, the electrolyte is not worth drinking, but the production itself is quite environmentally friendly. Used electrolyte is easily recycled - there are practically no chemicals left in it. All of them are transferred to the ceramic material on the metal surface, and the ceramic itself no longer presents any danger, because this is a sintered structure that has been subjected to the action of micro-arc. At the same time at the initial moment of time the arcs are not visible to the eye. A bright glow occurs gradually and becomes visible when the coating becomes thick enough. Parts to be processed are limited only by the size of the bath. For example, at the moment the company has baths up to 2 meters. The technology also does not require much energy.
And, of course, a small video to see everything with my own eyes.
PS I was pleased to meet and visit this interesting company. I want to somehow support the guys in their project. I do not give a direct link to the company, so as not to get a ban for advertising, but still if you have questions or interest, please write me at asmtomsk@gmail.com and I will pass your questions directly to the experts. Moreover, the company provides not only coating services, but also installations and chemicals for electrolytes.
Have a nice day, everyone!
Source: https://habr.com/ru/post/363637/
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