CORROSION AND ELECTROCHEMICAL CHARACTERISTICS OF STAINLESS-STEELS IN THE COOKING MEDIA OF PULP-AND-PAPER INDUSTRY

The electrochemical and chemical instability of sulfurous acid (C-SO2 = 0.47, 0.78 and 1.66 M; T = 293 +/- 2 K), bisulfite cooking solution (NaHSO3 + SO2, C-SO2(tot) = 0.6 M, C-SO2(cb) = CHSO3- = 0.4 M; PH 4.8, T = 353 K), and acidic sulfite liquor (Na-base) are investigated duri ng the storage and production of pulp. The causes of the instability o f the cooking media are shown to be connected to the equilibrium poten tial values E-eq that belong to the potential range of low cathodic an d anodic polarization of 08X17H15M3T and 10X17H13M2T steels. Potential limits of instability range for bisulfite cooking solution similar to 0.4 V wide at i less than or equal to 0.1 A/m(2) and those for acidic sulfite liquor 0.7 V wide are determined on Pt electrode.