Why mixture of aluminium and iron(3) oxide is used for repairing cracks in railway tracks??
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HEY FOLK..
The mixture of aluminium and iron(3) is used for repairing cracks bcoz in exothermic welding, aluminium dust reduces the oxide of another metal, most commonly iron oxide(copper oxide can also be used), because aluminium is highly reactive. The reaction can be
Fe2O3 + 2 A l ----> 2F e + Al2O3
This is a strongly exothermic (heat-generating) reaction which occurs via reduction and oxidation produces a white color substance of molten iron and a sla.g of refractory aluminium oxide. The molten iron is the actual welding material; the aluminium oxide is much less dense than the liquid iron and so floats to the top of the reaction, so the set-up for welding must take into account that the actual molten metal is at the bottom of the crucible and covered by floating sla.g. This results in tough setting. so we commonly used this mixture
Now a thought can strike ur mind that many other metals are there which r more hard and strong than iron.... ?
Possibly the answer can be that iron is easy to store , easy to handle and most important it is CHEAP...!
THANK YOU..
HOPE IT HELPS...!
The mixture of aluminium and iron(3) is used for repairing cracks bcoz in exothermic welding, aluminium dust reduces the oxide of another metal, most commonly iron oxide(copper oxide can also be used), because aluminium is highly reactive. The reaction can be
Fe2O3 + 2 A l ----> 2F e + Al2O3
This is a strongly exothermic (heat-generating) reaction which occurs via reduction and oxidation produces a white color substance of molten iron and a sla.g of refractory aluminium oxide. The molten iron is the actual welding material; the aluminium oxide is much less dense than the liquid iron and so floats to the top of the reaction, so the set-up for welding must take into account that the actual molten metal is at the bottom of the crucible and covered by floating sla.g. This results in tough setting. so we commonly used this mixture
Now a thought can strike ur mind that many other metals are there which r more hard and strong than iron.... ?
Possibly the answer can be that iron is easy to store , easy to handle and most important it is CHEAP...!
THANK YOU..
HOPE IT HELPS...!
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