THE EFFECT OF ADDITIONS OF HCL ON THE CORROSION BEHAVIOR OF 304-STAINLESS-STEEL IN CONCENTRATED H3PO4 AT DIFFERENT TEMPERATURES

Anodic polarisation experiments were conducted on AISI 304 SS in 14 M H3PO4 containing 0-30000 ppm of HCl a 298, 308 and 318 K. Anodic parameters i(c), i(p), E(pp), E(p), E(b) were determined from anodic polarisation curves. The protection potential (Epr) was determined form cyclic anodic polarisation curves at concentration at which pitting had been detected earlier. It was found that both critical current density, i(c) and passive current density, i(p) increased with the successive addition of HCl in larger quantity and temperature. Breakdown potential (E(b)), pitting potential (E(pit)) and protection potential (E(pr)) at any given concentration of HCl tend to attain more active values with increase in temperature.