Algenco Posted February 2, 2011 Share Posted February 2, 2011 I have several buckets of MgAl that I made , when I opened them I was hit with a strong Ammonia odor, any idea why? Link to comment Share on other sites More sharing options...
pillyg Posted February 2, 2011 Share Posted February 2, 2011 (edited) I had this also!!!!I didnt know why or from where. All I can think of is that Mg makes H when mixed with water ( Mg (s) + 2H2O(g) -> Mg(OH)2(aq) + H2(g) )Ammonia is NH3 so the H might of bonded with some nitrogen somewhere (maybe in air) this is all a guess and is probably wrong but thats all i can think of. Edit that is what it is. I put some Mg in a bag with water and later it smelled like ammonia. You must have added water to the Mg sometime Edited February 2, 2011 by pillyg Link to comment Share on other sites More sharing options...
WSM Posted February 2, 2011 Share Posted February 2, 2011 I have several buckets of MgAl that I made , when I opened them I was hit with a strong Ammonia odor, any idea why? Aluminum nitride with atmospheric moisture will generate ammonia and heat. Be careful. If there is any way to exclude air in your process, you can avoid this problem. WSM Link to comment Share on other sites More sharing options...
Algenco Posted February 2, 2011 Author Share Posted February 2, 2011 haven't noticed any heat, just the odor when the bucket is opened,, the odor disapates quickly. Link to comment Share on other sites More sharing options...
pillyg Posted February 2, 2011 Share Posted February 2, 2011 Did you wash it with water or is it humid outside? Link to comment Share on other sites More sharing options...
Algenco Posted February 2, 2011 Author Share Posted February 2, 2011 it's been humid, the MgAl has never been wet. Link to comment Share on other sites More sharing options...
Ralph Posted February 2, 2011 Share Posted February 2, 2011 as some of you may know magnesium is very reactive it will react with even CO2 what some of you may not know is that it will also react with N2 especially when being heated and most nitrides when they come in contact with water release ammonia (just as most carbides release acetylene gas) Link to comment Share on other sites More sharing options...
pillyg Posted February 2, 2011 Share Posted February 2, 2011 So what is happening, is the water making H2 or is it making Aluminum nitride which makes ammonia? Link to comment Share on other sites More sharing options...
Mumbles Posted February 2, 2011 Share Posted February 2, 2011 I actually came in here to ask if anyone who surpresses flare ups with carbon has ever noticed any off gasing of the MgAl. There are three types of carbides, they do not all form acetylene. The carbides of aluminum and magnesium do not for instance. Carbides can exist as C(4-), called methanides, such as Aluminum Carbide (Al4C3), which forms methane by hydrolysis. Beryllium forms a similar structure. Carbides exist as C22-, such as with the common calcium carbide. These analogously are called acetylide. Presumably silver and copper forms this type as well. They form acetylene upon hydrolysis Finally carbides can exist as C3[sup/4-[/sup], these are called sesquicarbides. Magnesium forms this type. I always found it interesting that Beryllium, calcium, and magnesium all form different types. Link to comment Share on other sites More sharing options...
dagabu Posted February 2, 2011 Share Posted February 2, 2011 I actually came in here to ask if anyone who surpresses flare ups with carbon has ever noticed any off gasing of the MgAl. There are three types of carbides, they do not all form acetylene. The carbides of aluminum and magnesium do not for instance. Carbides can exist as C(4-), called methanides, such as Aluminum Carbide (Al4C3), which forms methane by hydrolysis. Beryllium forms a similar structure. Carbides exist as C22-, such as with the common calcium carbide. These analogously are called acetylide. Presumably silver and copper forms this type as well. They form acetylene upon hydrolysis Finally carbides can exist as C3[sup/4-[/sup], these are called sesquicarbides. Magnesium forms this type. I always found it interesting that Beryllium, calcium, and magnesium all form different types. Forgive Mum as most of what you wrote went over my head but I have had off gassing with one type of sawdust but never airfloat charcoal. I dried it and added a container of damprid in the bucket and I didn't get any more off gassing. I also just went out and popped the lid on both my containers of fine MgAl and they have no smell. Link to comment Share on other sites More sharing options...
WSM Posted February 2, 2011 Share Posted February 2, 2011 Aluminum nitride with atmospheric moisture will generate ammonia and heat. Be careful. If there is any way to exclude air in your process, you can avoid this problem. WSM My first attempt to make magnalium from turnings in a small kiln resulted in a small pot of "cinders' that "sizzled" and outgassed ammonia when gotten wet. I figured it was reacted with atmospheric gases, so I looked up magnesium nitride and aluminum nitride in the Merck Index (13th Ed.). I was surprised to learn it wasn't the magnesium but the aluminum nitride that produced the ammonia. I've since learned the best approach to making magnalium is to first melt the aluminum and then add the magnesium. I suspect the purest form of magnalium would be made under an inert gas. A slow feed of argon into the crucible should do to purge the air which is causing problems. WSM Link to comment Share on other sites More sharing options...
petroleum Posted February 2, 2011 Share Posted February 2, 2011 I usualy have this problem with my homemade magnalium 50/50. Melting process of the MgAl I perform under KCl flux. After I mill this product in a ball mill, sieve it and let it stay for about a week in a small bucket without lid. After one week I get the product without any odour (even if I use the water soluble binders, there are no any specific odours in my stars, comets or fountains). Link to comment Share on other sites More sharing options...
Bonny Posted February 2, 2011 Share Posted February 2, 2011 I actually came in here to ask if anyone who surpresses flare ups with carbon has ever noticed any off gasing of the MgAl. I use carbon/charcoal to cover the melt after mixing, but have never added it to suppress flare ups. I get flare ups, but just keep stirring until well mixed, then add the carbon to keep the air off. I've since learned the best approach to making magnalium is to first melt the aluminum and then add the magnesium. WSM I've actaully never heard of any hobbyist making it in a different way... I've smelled the ammonia odor, but some batches of MgAl I've made have been quenched in water once partially cooled. IIRC correctly, my finished and ground material has no smell. Link to comment Share on other sites More sharing options...
FrankRizzo Posted February 3, 2011 Share Posted February 3, 2011 (edited) Forgive Mum as most of what you wrote went over my head but I have had off gassing with one type of sawdust but never airfloat charcoal. I dried it and added a container of damprid in the bucket and I didn't get any more off gassing. I also just went out and popped the lid on both my containers of fine MgAl and they have no smell. Dagabu, because of the way you and I process our magnalium, I would guess that any reaction would happen right away while still exposed to the bulk cooling water. By the time the magnalium granules are separated from the water bucket and dried, any reactive nitrates, hydoxides, or carbides have already reacted and are gone. Guys who process their ingots dry may have residual reactive species that later react with humidity. Edited February 3, 2011 by FrankRizzo Link to comment Share on other sites More sharing options...
dagabu Posted February 3, 2011 Share Posted February 3, 2011 LOL! I think I recall something like that when I was taking the seminar that being the water being of benefit as a "wash". Thanks for the reminder, I think I will process it both ways to see if there is a difference at the end of processing. Link to comment Share on other sites More sharing options...
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