Partial Substitution of Chromate by Borate for Cooling Water Inhibition.

Chromate is an effective and versatile inhibitor for industrial cooling water systems. Due to its toxicity, borate is added systematically to substitute chromate from 100 to 1% and tested as inhibitor for a mild steel, using radioactive tracer technique. The amount of chromium in the film thickness of the inhibitor formed on the specimens is found to increase as borate concentration is increased up to 40% and decreases thereafter. The protection is obtained at 303 K at least up to 6 h. By reducing chromate from 100 to 60%, the Cr content in the protective film is found to double in 2–4 h, which shows the synergistic effect of the inhibitor formulation as compared to that of chromate alone.