THE EFFECT OF DEBRIS CHEMISTRY ON THE DEBRIS FORMATION AND FRETTING BEHAVIOR OF MILD-STEEL IN CO2 CONTAINING OXYGEN AND WATER-VAPOR

Whilst examining the effect of different CO2-rich atmospheres on the fretting behaviour of mild steel, it was found that the debris was extremely fine, with a particle size of down to 10 nm, and its chemistry was controlled by the composition of the fretting atmosphere. In low oxygen atmospheres the debris was siderite (iron carbonate), but in higher oxygen atmospheres haematite was formed. These two materials were found to behave in very different way in the formation of debris beds in the fretting scar. This difference is largely explained by differences in the mechanical properties of the agglomerated debris, which appear to arise from differences in the adsorption properties of the materials present. The addition of moisture to the fretting atmosphere was not found to affect the fretting behaviour.