Kinetics and Structure Aspects of the Dissolution of Metals in Acids

摘要

The dissolution of metals in acids is a heterogeneous electrochemical reaction, taking place at the interface between a solid and a liquid, described in terms of energy and configuration of the species involved. The energy of activation for two stainless steels in phosphoric acid was determined from their corrosion rates in the temperature range 50-120℃, applying the Arrhenius equation. Energy of activation values for the overall process of anodic metal dissolution and cathodic hydrogen release are in the 10-20 Kcal mol~(-1) range. Metal corrosion is a structure sensitive process; its mechanism and rate are related to the density of surface defects, based on the Boltzman expression. A model for the activated complex is proposed based on considerations of energy and configuration. This work is an integration of a theoretical analysis and an experimental investigation of metal corrosion in acids.