Study Of Rust Preventive Characteristics Of Rust Preventive Oil From Polarization Curve Measurement

Abstract

Fe-Cu-C sintered steels are widely used as powder materials, because of its small volumetric shrinkage. However, Cu, which acts as cathode enhance formation of rust Fe2O3·xH2O during fabrication. To prevent formation of Fe2O3·xH2O rust preventive oils are widely used. High viscosity of those rust preventive oils decrease workability. While, low viscosity degrade rust preventive performance. Therefore, it is necessary to develop new rust preventive oils with contradictory properties of low viscosity and superior rust prevention. In this study, we developed technique to quantitatively evaluate rust prevention ability by measuring polarization curve through thin corrosive solution on Fe-Cu-C sintered steels coated with rust preventive oils. The electrochemical measurements were carried out in corrosive solution of 0.35 mass % NaCl. Using a double capillary was added dropwise to the specimen. From the experimental, it is possible to evaluate the corrosion rate quantitatively in the surface of specimen, which was coated with rust preventive oil through thin corrosive solution. From the measurement results, Corrosion rate is reduced by coating the rust preventive oil. Especially, corrosion rate of the specimen coated with oil that showed best performance indicated 10000 times better than that of without oil ones. Zn addition negative correlation between corrosion rate and period of potential oscillation.

Keywords

• sintered steel
• polarization curve
• rust preventive oil