Abstract
It is an important problem to bring to light the corrosion resistance in aqueous solution at high temperature and high pressure of the materials of nuclear reactor and chemical apparatus.
Therefore, the investigation on corrosion resistance of aluminium sheets with 99.2-99.998% and several aluminium alloys in the aqueous solution at 250°, 150°, 100°C were carried out and following results were confirmed:
1. What differs from the test under the ordinary pressure below 100° is the fact that super pure aluminium is most inferior and 2S is superior in the corrosion resistance.
2. Among the alloys such as 3S, 43S, M63S, reflectal alloys and 2S-1.2%Si, 3S is the most superior and reflectal alloys the most inferior.
3. Addition of Fe or Si to 99.99% aluminium improves corrosion resistancc and Fe is more effective than Si. Addition of both Fe and S is far more effective.
4. Corrosion proceeds clearly along the grain boundary and the reaction product (Al2O3•H2O) of super pure aluminium falls off in layer. Furthermore, the corrosion which, in ordinary condition, occurs usually around the compounds and Si, is not observed.
5. Ni ion is effective as an inhibiter for the corrosion, but the blister corrosion tends to occur on the super pure aluminium. Fe ion delays the corrosion rate at first, but induces the pitting corrosion.
