To explore the usage of monolayer graphene as an anti-oxidation barrier in simulated primary water of pressurized water reactors（PWRs）,we transferred the monolayer graphene synthesized by low pressure chemical vapor deposition（LPCVD） on Cu foil to Alloy 690 TT.After a 500 h immersion,strong oxidation resistance was obtained from the graphene coated Alloy 690 TT sample,indicating that the transferred monolayer graphene can act as an effective barrier to protect the substrate from oxidation in simulated primary water of PWRs.
Hongliang MingSiyan WangZhiming ZhangJianqiu WangEn-Hou HanWei Ke
Oxidation of Alloy 690 TT samples either manually ground to 400 and 1500 grit, mechanically polished, or electropolished was performed in a solution of 1500 10 6B and 2.3 10 6Li with 2.5 10 6dissolved H2, at 325℃ and 15.6 MPa for 60 days. The oxide films grown on samples with different surface states were analyzed using various techniques. Results show that a triple-layered structure was formed after immersion： an outermost layer with large scattered oxide particles rich in Fe and Ni, an intermediate layer with small compact oxide particles rich in Cr and Fe for the ground surfaces and loose needle-like oxides rich in Ni for the polished surfaces, and an inner layer with continuous Cr-rich oxides. The surface state was found to affect not only the surface morphology, but also the corrosion rate. Grinding accelerated the growth of protective oxide films such that the ground samples showed a lower oxidation rate than the polished ones.Samples of ground Alloy 690 TT showed superior resistance to intergranular attack（IGA）.
In high-temperature and high-pressure water, traditional anticorrosion approaches are not suitable to be used to protect structural materials from oxidation and corrosion. In this study, monolayer graphene was explored as a barrier to protect the materials from degradation. The oxidation and corrosion rate of the monolayer-graphene-coated copper is much lower than that of the bare copper, suggesting that the monolayer graphene can effectively protect the copper from oxidation and corrosion in the simulated primary water of pressurized water reactors.
Hong-Liang MingSi-Yan WangZhi-Ming ZhangJian-Qiu WangEn-Hou HanWei Ke
Multilayer graphene as a potential anti-oxidation barrier to protect nickel foils from oxidation was studied in simulated primary water of pressurized water reactors （PWRs）. The results show that after immersion for 1000 h, the structure of the multilayer graphene remains unchanged and no obvious oxide film formed on the graphene coated nickel foils, indicating multilayer graphene can effectively act as the anti-oxidation barrier to protect the substrate from oxidation and hence can improve the heat transfer efficiency of the substrate in simulated primary water of PWRs.
Hongliang MingJianqiu WangZhiming ZhangSiyan WangEn-Hou HanWei Ke
