Selective electrochemical stripping of chromium nitride coatings from tool steels using a neutral phosphate-molybdate electrolyte

Stripping hard coatings is critical for tool remanufacturing, however conventional acidic or alkaline methods often compromise substrate integrity. This study reports a highly selective electrochemical stripping process for chromium nitride coatings using a near-neutral phosphate-molybdate-tungstate electrolyte. Exploiting the anodic inhibition of molybdate and tungstate ions, the electrolyte facilitates coating dissolution while forming a stable passive film on the steel substrate. Chronoamperometry at a controlled potential demonstrated complete coating removal with precise end-point detection, avoiding substrate over-etching. Surface analysis confirmed that the original surface integrity, including roughness and hardness, of both alloy and high-speed tool steels was preserved. This neutral-pH process provides a safer, damage-free alternative to traditional methods, enhancing the re-coatability and lifecycle management of high-value industrial tools.