EFFECTS OF TIME AND TEMPERATURE ON THE MILD-STEEL CORROSION INHIBITION BY MOLYBDATE AND NITRITE

An investigation has been conducted to find out the effect of soaking time and temperature on the corrosion inhibition of mild steel by sodi um molybdate and sodium nitrite in simulated cooling water (SCW). Incr ease of soaking time increases corrosion rate of the mild steel in SCW . However, when sodium molybdate and sodium nitrite are present corros ion rate decreases or per cent inhibition efficiency (% IE) increases with the soaking time. High concentration of inhibitors or stirring of the solution results in the attainment of the corrosion rate to the c onstant low value at a short soaking period. Molybdate loses its inhib ition capacity comparatively rapidly than nitrite with the rise of tem perature, and none of them alone is effective at the increased tempera ture of SCW. When these two inhibitors are used combinedly effective c orrosion inhibition of mild steel is obtained up to 55 degrees C tempe rature of SCW.