A Consideration of Mechanisms for Accelerated Oxidation of Metals Caused by Lead Oxide

Abstract

The purpose of the present study is to make clear the mechanisms of the accelerated oxidation of pure metals by PbO through theoretical consideration of sequential steps in the process and some experiments, such as thermo-analysis of the oxidation of iron and nickel by molten PbO.
The results are summarized as follows.
(1) The rapid oxidation of iron and nickel by PbO caused a significant temperature rise in the reaction system (over 50°C), and strong convection of the melt was observed.
(2) The accelerated oxidation is considered to proceed through the following mechanisms. [(i)] Formation of low melting point eutectic oxide on the metal surface, resulting from the interaction between the metal oxide and solid PbO (T<m.p. of PbO). [(ii)] Temperature rise and convection of molten oxide due to the rapid exothermic oxidation of metal by molten PbO-base oxide accelerate the dissolution of the surface oxide and the diffusion of both oxidizing species and oxidation products, leading to a self-accelerating series of reactions.