THE CORROSION OF METALS IN CONTACT WITH ESTER OILS AT TEMPERATURES UPTO 200-DEGREES-C

The formation of tarnish layers on copper and steel when contacted by ester fluid formulations (based on an ester fluid) at temperatures up to 200-degrees-C has been studied by a variety of techniques-principal ly impedance spectroscopy and infrared spectroscopy. It has been found that negligible corrosion of the metals occurs if atmospheric oxygen is excluded from the system. In the presence of atmospheric oxygen in most cases the tarnish layers consist of oxides modified by the incorp oration of carboxylate species. The layer thicknesses in some cases ar e less than those which would be formed if the metals were heated dire ctly in air at the same temperature.