Heating coils heat up so well because they are made of resistance materials - materials that electricity will but doesn't like to travel through. For instance resistance wire made of Nichrome has a resistance factor of 112.2x10^-6 ohm-cm whereas titanium is 43x10^-6. Shape also plays a large aspect in resistance with longer thinner filaments providing more resistance and larger thicker items providing less resistance:
The electrical resistance of a wire is greater for a longer wire and less for a wire of larger cross sectional area. The resistance depend on the material of which it is made and can be expressed as:
R = ρ L / A (1)
where
R = resistance (ohm)
ρ = resistivity coefficient (ohm m)
L = length of wire (m)
A = cross sectional area of wire (m[SUP]2[/SUP])
I have a feeling it would take a dangerous amount of electricity to heat a thick titanium nail. Of course I really have no idea of what I'm talking about.
What if you just vaporized the oil using the electrical arc itself?