kleberrios Posted January 4, 2017 Posted January 4, 2017 In this process the foil don't have Al oxide, https://www.youtube.com/watch?v=ElgvwPMz_rA
August Posted January 5, 2017 Posted January 5, 2017 Um, aluminum reacts with air to create a super thin layer of aluminum oxide on ANY exposed surface. If you milled it in an inert gas, you would notice the increase in temperature when it was exposed to oxygen.
kleberrios Posted January 5, 2017 Author Posted January 5, 2017 Um, aluminum reacts with air to create a super thin layer of aluminum oxide on ANY exposed surface. If you milled it in an inert gas, you would notice the increase in temperature when it was exposed to oxygen.OK, but in this case the temperature was caused because I used a screnn very thin, about 40 mesh then the atrite inside the hammer mill was big, and caused the incrise of temperature do Al. I don'use inert gas in this hammer mill.
August Posted January 7, 2017 Posted January 7, 2017 The mechanical energy is only partially responsible for the increase in temperature. If you milled it in an inert gas, this would become evident. I believe someone had a video of super fine milled aluminium that was milled in an inert gas. When exposed to air, it would react and catch on fire. Aluminum is very reactive and will react quickly with oxygen to form aluminum oxide. Should change title of thread to milling aluminum or milling aluminum with aluminum oxide. 1
MrB Posted January 7, 2017 Posted January 7, 2017 What August is saying is that the end product still contains aluminum oxide, even if the raw materials used don't. Any aluminum surface exposed to oxygen develops a very thin, air tight "skin" of oxide, which protects it.B!
kleberrios Posted January 7, 2017 Author Posted January 7, 2017 Very well observed. Oxide will always exist on the Al, unless it has no contact with the oxygen in the air. In the case of video, I referred to Aluminum Coil, because inside the coil the contact of Al sheet with oxygen is practically zero, but once opened it actually begins to oxidize with air. But the observation was valid. I do not know if you understood. 1
August Posted January 9, 2017 Posted January 9, 2017 Do you think that sheet was made and wrapped up in an oxygen free environment? This is not a slow process like rusting. The second it is exposed it reacts. That's why if you ball mill aluminum into a super fine powder(single micron) in an inert gas, it will react so quickly that it will catch on fire when exposed to air.
August Posted January 9, 2017 Posted January 9, 2017 Even the foil in your kitchen drawer has a thin layer of aluminum oxide on it. I'm saying you started out with foil that has a thin layer of aluminum oxide, then increased surface area and aluminum oxide content. Neither your foil or process is oxide free.
kleberrios Posted January 9, 2017 Author Posted January 9, 2017 In the manufacture of Al sheet they laminate the sheet with a thin layer of lubricating oil avoiding the contact with oxygen, precisely so as not to occur oxidation and to facilitate the lamination, also evoking that the thin sheet sticks to one another. I have a roll of aluminum here with 200 kg, which in the lamination lacked oil, and all the sheets stuck together and became stunned due to oxidation. According to the science books, one of the characteristics of the oxidized Al sheet is a whitish layer On the surface, if the surface is super glossy it is because it is not oxidized or the amount of oxide is negligible. For example: mylar is produced in vacuum, totally without contact with oxygen so as not to affect its reflection. Microscope mirrors are also produced in a vacuum, vaporizing Al on the surface.
kleberrios Posted January 9, 2017 Author Posted January 9, 2017 (edited) Oh, I forgot to say that the oxide I referred to is not the thin oxide but the loose oxide, like a white powder that was 20 percent of the weight in the bale of Al. https://www.youtube.com/watch?v=0duIV17U17o https://www.youtube.com/watch?v=ElgvwPMz_rA Edited January 9, 2017 by kleberrios 1
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