glocksmith wrote:A bit off topic, and not about steel, but since you guys know a lot about metal I thought I'd ask about some powered metals I brought back from my grandfather's basement. I was curious if there were any safety issues with exposing them to fresh air for the first time in decades. He had some of those tin lid Mason jars with things like powdered Nickel, aluminum etc. I was browsing Youtube yesterday and somehow came across a guy talking about making "dark aluminum" and he mentioned something about it spontaneously igniting. That reminded me of the jars I had downstairs. They haven't been opened for decades AFAIK and I was wondering if it would be safe to remove the lid. The nickel is the consistency of flour and pitch black - would the shock of a blast of fresh oxygen cause any problems?
Probably safe to open the jars of anything except alkali metals (Lithium, Sodium, Potassium, etc...).
What gets dangerous is when you apply heat or an aggressive source of oxidation to a powdered metal. Then the large surface area of all that metallic powder reacts very rapidly and can get interesting quickly. Consider that Thermite uses metallic powder.
One route of providing heat is friction. Thus, some of the things suggested in those videos, like ball milling in a tumbler, are inherently risky. Cooling it off intermittently by opening the drum (and thus exposing it to fresh oxygen) might even be more hazardous.
In short, making powder metallurgy supplies is best left to the experts with the right equipment and expertise. If you're not a professional fireworks manufacturer or powder metallurgist I would highly advise against it. Frankly, even with my knowledge of metallurgy, including a fair bit of aluminum work and some powder metallurgy work, I would not attempt what you have seen on the videos. I tend to like my house and skin unburnt.
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