1993 Volume 42 Issue 1 Pages 37-47
This paper explains bases of molecular orbital (MO) theories and reviews of applications of the MO theories to new developments of materials and inhibitions of corrosions of iron, steel and aluminum. Shapes and symmetries of atomic orbitals (AOs) and MOs are explained. Schrödinger equation is introduced understandably and physical meaning of each term of the equation is described. Application of the MO theories (Xα method) has been very succeeded to developments of super heat-stable Ti alloys. The applications are based on the bond order (B0) between a mother metallic atom and alloy atoms and are based on the energy level of d-AO of the alloy atom (Md). Electron densities (Q) of the C and N atoms in p-substituted anilines have been calculated by CNDO/2 method and the good correlations between Q and corrosion rate (K) and between Q and corrosion current (icorr) of a steel are obtained. Carboxylic acids inhibit the corrosion of Al and the O-H bound energy (ΔH) has theoretically been obtained by 6-31G calculations. The strong acid has small ΔH value and the acid dissolves easily in an equeous solution and the acid shows large corrosion inhibition effect.
