Cobalt alloy is an important structural material used as nuclear fuel cladding in water-cooled nuclear power reactors. Corrosion and hydrogen absorption are two important problems encountered in its application, which are related to the life of nuclear fuel components and the safety and reliability of reactor operation. With the further increase of fuel assembly burnup, how to improve the corrosion resistance of cobalt alloy cladding and how to reduce the hydrogen absorption during corrosion are two problems worthy of further study. This work takes Zr-2 (Zr-1.5 Sn-0.2Fe-0.1 Cr-0.05 Ni), Zr-4 (Zr-1.5 Sn-0.2 Fe-0.1 Cr), N36(Zr-1Sn-1Nb-0.3 Fe) and N18 (Zr-1SN-0.35 NB-0.3 FE-0.1 Cr) as the research objects, and uses different heat treatments to prepare samples with different sizes and quantities of the second phase. The corrosion and hydrogen absorption behaviors of these samples in 400°C/10.3MPa superheated steam and 360° C/ 18.6MPa/0.01M LiOH solution were studied. The mechanism of the influence of the second phase on the hydrogen absorption behavior of cobalt alloy was discussed.The composition of the alloy has great influence on the hydrogen absorption behavior during the corrosion of the alloy. After normalized treatment of hydrogen content after corrosion by corrosion weight gain of samples, it can be seen that under the same corrosion weight gain, the hydrogen absorption of Zr-2 alloy is the highest, followed by Zr-4 and N18 alloy, while the hydrogen absorption of N36 alloy is the lowest, which is closely related to the type and composition of the second phase in different alloys. Zr-2 alloy contains Ni, Fe and Cr, and the second phase formed by them with Zr is Zrz(Fe,Ni) and Zr(Fe,Cr). Zr-4 alloy contains Fe and Cr, and the second phase formed by Zr and Zr includes Zr(Fe,Cr) H :N18 alloy is a new alloy with a small amount of Nb added on the basis of Zr-4 alloy, which also contains Zr(Fe, CR) second phase: N36 alloy is also a Nb alloy. Compared with N18 alloy, Nb content is higher but does not contain CR, and the second phase formed is mainly -Nb and Zr-Nb-Fe second phase. As is known to all, Zrz (Fe, Ni) and Zr (Fe, Cr) z itself is a kind of strong hydrogen absorption of intermetallic compounds, that means if you add alloy element and the second phase of Zr forming is a kind of stronger than Zr hydrogen absorbing ability of the material, then it for hydrogen absorption behaviors of cobalt alloy corrosion will have a significant impact, to consider from the Angle of reduce corrosion when the hydrogen absorption, this kind of alloy element to add less as far as possible. These results can provide valuable reference for the selection of alloying elements in the development of new fault alloys.
Tag: Zr-2, Zr-4, Zr
