Faraday corrosion rate calculator

Enter corrosion current density i_corr in amperes per square centimetre, metal molar mass in grams per mole, density in grams per cubic centimetre, and the number of electrons transferred when the metal oxidizes; the tool returns the penetration rate in centimetres per second, millimetres per year, and mils per year (mpy), plus equivalent weight EW equals M over n and a full substitution trail. Zero density is rejected with invalid_input because Faraday’s law divides by ρ.

What Faraday’s law says about corrosion penetration

When density is zero the formula is undefined—there is no physical metal volume to convert mass loss into thickness—so the API returns a clear invalid_input error instead of Infinity or a silent NaN.

How to call the API and what comes back

Current density must be non-negative; molar mass and the Faraday constant must be strictly positive; density and electrons must be non-zero. Send a JSON body with four required finite numbers: current_density (aliases i_corr, i, j_corr, current, icorr) in A/cm², molar_mass (aliases M, atomic_weight, atomic_mass, molarMass, mw) in g/mol, density (aliases rho, density_g_cm3, metal_density) in g/cm³, and electrons (aliases n, n_e, z, valence, n_electrons, electrons_transferred). Optionally pass faraday (aliases F, faraday_constant) in C/mol; when omitted the solver uses nine six four eight five point three three two one. Absolute values must stay within the published limit of one trillion so intermediate products remain finite in IEEE double precision on the Worker and in the browser. On success the response echoes rounded inputs, sets equivalent_weight and EW to M over n, rate_cm_per_s to the base Faraday result, rate_mm_per_year and penetration_rate_mm_year to the same millimetre-per-year value, rate_mpy and penetration_rate_mpy to mils per year, formula to the string CR equals i times M over n times F times ρ, rearrange to the EW form, equation to a compact substitution line, message to a short English summary, and steps to an ordered array of given-data and conversion lines. Failed validation—missing fields, non-finite numbers, values outside absolute limits, negative current density, non-positive molar mass or F, zero density, or zero electrons—returns invalid_input and is never charged. Pricing is a flat $0.002 per successful request with unit item and zero marginal unit price.

Practical tips, units, and related searches

Convert microamperes carefully: one microampere per square centimetre equals one times ten to the minus six amperes per square centimetre, so enter one e minus six rather than one when your polarization fit reported one µA/cm². Typical iron or mild-steel checks use M about fifty-five point eight four five g/mol, n equals two for Fe to Fe two plus, and ρ about seven point eight seven g/cm³; at one µA/cm² the penetration rate is on the order of zero point zero one millimetres per year, matching the handbook constant form three point two seven e minus three times i_µA times EW over ρ. Keep n consistent with the dominant anodic reaction: copper often uses n equals two, aluminium n equals three, and mixed oxides may need a weighted equivalent weight from ASTM G102 practice rather than a single integer n. Prefer positive densities that match the alloy you are modelling—using pure-iron density for a highly alloyed stainless can bias the millimetre-per-year figure even when i_corr is correct. This landing targets people searching for a Faraday corrosion rate calculator, corrosion penetration rate from current density, or mpy from i_corr online; it is not a Tafel-fit polarization analyser, not a remaining-life FEA model, and not a galvanic-couple simulator. Prefer this capability when you already have i_corr, M, ρ, and n and only need the Faraday thickness rate; if your source is a potentiodynamic scan, extract i_corr first. Failed tasks that return invalid_input do not consume prepaid balance, which keeps exploratory scripts cheap when learners deliberately set density to zero. Round-trip checks are easy: recompute i times M over n times F times ρ by hand and confirm it equals rate_cm_per_s within twelve-decimal rounding, then confirm mm/year equals that value times ten times thirty-one million five hundred fifty-seven thousand six hundred.