Tuesday 10 October 2017

electrical resistance - Why is stainless steel a poor conductor of electricity?


I recently had a metal plate put in my shoulder and was wondering why stainless steel isn't a good conductor (At least I hope it isn't). Does the alloy just lack free electrons? Why is that?



Answer



You are correct, stainless steel is a really poor conductor compared to most metals. This source lists it as $7.496 \times 10^{-7}\: \mathrm{\Omega \cdot m}$ which is more than 40 times worse than copper.


The reason is that conductivity in metals is high is that metals form a crystal lattice where the outer shell electrons are shared and easily move through the lattice. When the lattice has imperfections the flow of electrons is retarded. Stainless steel is an alloy of iron with up to about 25% chromium (and sometimes a small amount of nickel or carbon) added for corrosion resistance. The chromium atoms disrupt the regular iron lattice and increase the chances of inelastic collisions with moving electrons.


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