CORROSION INHIBITION IN HIGHLY AGGRESSIVE SOLUTIONS

摘要

The application of inhibitors to very highly aggressive media for protection of steels raises many issues relating to the mechanisms of inhibition and its effects on the protected steel surface. Such environments are employed in areas such as oil-well acidizing where high concentrations of hydrochloric acid together with high temperatures conspire to cause very rapid corrosion of steels. The issue of the role of the inhibitor is clearly as important as it is vexed, with many papers being published on the subject over many years. That inhibitors must be adsorbed to become inhibitive is clear, since in the absence of adsorption, no mechanism of inhibition can be yiably derived. This must in fact be the first step in any mechanism of inhibition of corrosion, and the fact has been recognized long ago. For example, already in 1956 Ride (1) published a paper concerning the role of adsorption of nitrogen-containing organic molecules on the corrosion inhibition of steel in sulphuric acid, and Ride was not the first. The question of whether this is the mechanism of inhibition or not is actually rarely raised. The question of what causes inhibition in highly aggressive solutions is really quite important, since it allows in principle the design of new inhibitors, of improved characteristics.