how to heat treat copper wire with dc current?

GopherT

Joined Nov 23, 2012
8,009
Your whole experiment is essentially measuring how well a 45 gauge wire can act as a heat sink. The amount of heat it will take to get a 3 foot long, 45 gauge wire to 500F is negligiable. The total mass of the wire is about 12 milligrams with about 1.3 cm2 of surface area. It will take a few joules of energy to get to that temp (in excess of the rather large energy to overcome heat transfer to still air.

My calculations show your 3 foot wire to have a 10 ohm resistance and assuming the wire heats 50-degrees C per watt of input energy, you need to increase the temp by 237 degrees C, you will need only 5 watts. 5 W = V*V/R = V*V/10. V = sqRT of 50 = 7 volts. Any air movement will greatly impact this calculation and you may need up to 15 volts in what seems to be still air. Maintaining 500F will be a problem with only 12 milligrams of mass. You will likely be under or red-hot as air flows in the room change.
 
Last edited:

bertus

Joined Apr 5, 2008
22,270
Hello,

I looked at the datasheet of the used mosfet and have seen that is capable of a dissipation of only 2.5 Watts mounted on a PCB.

Bertus
 

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dreamer44

Joined Nov 19, 2015
36
Your whole experiment is essentially measuring how well a 45 gauge wire can act as a heat sink. The amount of heat it will take to get a 3 foot long, 45 gauge wire to 500F is negligiable. The total mass of the wire is about 12 milligrams with about 1.3 cm2 of surface area. It will take a few joules of energy to get to that temp (in excess of the rather large energy to overcome heat transfer to still air.

My calculations show your 3 foot wire to have a 10 ohm resistance and assuming the wire heats 50-degrees C per watt of input energy, you need to increase the temp by 237 degrees C, you will need only 5 watts. 5 W = V*V/R = V*V/10. V = sqRT of 50 = 7 volts. Any air movement will greatly impact this calculation and you may need up to 15 volts in what seems to be still air. Maintaining 500F will be a problem with only 12 milligrams of mass. You will likely be under or red-hot as air flows in the room change.
That makes sense, thank you.
 
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