| 摘要 |
The invention is a method for monitoring corrosion attack in metal surfaces based on the registration of changed composition in elemental distribution in the corroded areas compared to the non-corroded areas. The changes are registered by means of energy dispersive X-ray fluorescence techniques (EDXRF). The method may be employed under both mobile or stationary conditions. In iron-based alloys changes appear with regard to the concentration of such elements as iron, chromium, molybdenum, nickel etc. in the corroded area compared to adjacent non-corroded areas. Consequently, there is a lower concentration of iron in rusty regions due to two factores. The first factor concerns the fact that rust contains iron oxide with a lower iron content than the iron phase in a defined volume unit of the metal phase, while the other factor relates to the fact that selective release processes from the alloy surface result in a lower concentration of iron in the corroded areas. While the selective release of iron is taking place during the corrosion process, other elements like chromium, molybdenum, nickel etc. are being enriched in the metal surface. These changes are shown by scanning both focused X-rays or gamma-rays across the metal surface. These changed conditions of composition, registered by means of EDXRF-techniques, form the basis for corrosion detection in this invention. The method allows for the non-destructive detection of corrosion attack on an unprotected metal surface or beneath a coating of, for example, paint or varnish. |
