(國防科技大學(xué) 空天科學(xué)學(xué)院，長(zhǎng)沙 410073)
摘 要: 福島核事故后，核燃料包殼Zr合金的Cr涂層表面改性成為研究熱點(diǎn)，熔鹽電沉積技術(shù)因能有效解決Cr層沉積時(shí)的析氫問題而受到關(guān)注，鑒于Zr合金在熔鹽中易受腐蝕的特點(diǎn)，采用Ni作為過渡層解決Zr合金表面高質(zhì)量Cr涂層的制備難題。為了系統(tǒng)研究Ni表面Cr涂層的熔鹽電沉積工藝，本文在研究Cr涂層生長(zhǎng)過程的基礎(chǔ)上，研究電流密度、溫度及Cr離子濃度對(duì)Cr涂層組織結(jié)構(gòu)的影響，優(yōu)選制備工藝并開展涂層性能測(cè)試。結(jié)果表明：增大電流密度、降低熔鹽溫度或減小Cr離子濃度可以細(xì)化涂層晶粒，提高涂層致密性和連續(xù)性，但同時(shí)易引發(fā)濃差極化，造成涂層質(zhì)量惡化。在優(yōu)選工藝下制得的Cr涂層由〈211〉取向的細(xì)等軸晶構(gòu)成，硬度為(2.47±0.24) GPa，與Ni基體的結(jié)合力約為85 N，表面粗糙度為2.6 μm。
關(guān)鍵字: 熔鹽電沉積；Cr涂層；Ni基體；工藝研究
（Collage of Aerospace Science and Engineering, National University of Defense Technology, Changsha 410073, China）
Abstract:After the Fukushima nuclear accident, the surface modification with Cr coating on nuclear fuel cladding Zr alloys becomes a research hotspot. Molten salt electrodeposition technology has attracted much attention because it can solve the problem of hydrogen evolution during Cr coating deposition effectively. In view of the corrosion characteristics of Zr alloy in molten salt, Ni is used as the transition layer to solve the preparation problem of high-quality Cr coating on the surface of Zr alloy. In order to research the effect of molten salt electrodeposition process of Cr coating on Ni surface systematically, the growth process of Cr coating was studied firstly. On this basis, the effects of current density, temperature and Cr(Ⅱ) ion concentration on the microstructure of Cr coating were characterized. Meanwhile, the preparation parameters of Cr coating were optimized, and the properties ware tested in this paper. The results show that increasing the cathode current density, lowering the molten salt temperature and reducing the Cr(Ⅱ) ion concentration will lead to refine the grain size of the coating, and improve the compactness and continuity within the scope of the study. But at the same time, these changes are easy to induce concentration polarization, causing serious deterioration of the roughness and compactness of the coating. The Cr coating is composed of fine equiaxed crystals with〈211〉orientation under the optimized process conditions, and the hardness is (2.47±0.24) GPa, the binding force is about 85 N and the surface roughness is 2.6 μm.
Key words: molten salt electrodeposition; chromium coating; nickel substrate; process study
