Grinding steel produces sparks. Grinding aluminium does not. Why?
I found this article about why grinding steel produces sparks but would like to confirm if it is true.
I would also like to know why does it behave so on a molecular level if anyone can explain that.
Best Answer
Some Answers/comments come quite close to the real reason, but stop at commonplace like "must be caused by the oxide layer (of aluminium)" The core reason why is simple: iron is the only metal where the oxide has a melting point lower than the melting point of the metal. This is reason for sparks and why iron/steel is the only metal You can cut with "oxy-fuel cutting". All other metals will develop a solid oxide layer which impedes further burning. Of course there is influence from the "bulkiness" of the steel piece and the oxygen concentration.