By Sean Mann | Updated Mar 24, 2022
Electroplating coats a conductive substrate with a thin metal layer by driving ions from an electrolyte through an electric field. Common practice in automotive manufacturing plates steel with copper, nickel, and chromium to protect against corrosion and weathering.
Examine the half‑reaction to determine how many electrons are needed to deposit one mole of the target metal. For example, depositing copper (Cu²⁺ → Cu) requires two electrons per atom, i.e. two moles of electrons per mole of copper.
The charge needed is given by the Faraday equation:
Q = n(e) · F
where Q is the charge in coulombs, n(e) is the number of moles of electrons, and F is the Faraday constant (96 485 C mol⁻¹). Using the copper example:
Q = 2 mol × 96 485 C mol⁻¹ = 192 970 C
The duration required to deposit one mole of metal at a constant current I follows:
t = Q / I
With a 25‑amp supply:
t = 192 970 C / 25 A ≈ 7 718 s ≈ 2.14 h
You can reverse the equations to find how much metal will be plated for a given current and time.
