The characterisation of passive oxide films on heterogeneous microstructures is needed to assess local degradation (corrosion, cracking) in aggressive environments. The Volta potential is a surface-sensitive parameter which can be used to assess the surface nobility and hence passive films. In this work, it is shown that the Volta potential, measured on super duplex stainless steel by scanning Kelvin probe force microscopy, correlates with the electrochemical properties of the passive film, measured by electrochemical impedance spectroscopy and potentiodynamic polarisation. Natural oxidation by ageing in ambient air as well as artificial oxidation by immersion in concentrated nitric acid improved the nobility, both reflected by increased Volta potentials and electrochemical parameters. Passivation was associated with vanishing of the inherent Volta potential difference between the ferrite and austenite, thereby reducing the galvanic coupling and hence improving the corrosion resistance of the material. Hydrogen-passive film interactions, triggered by cathodic polarisation, however, largely increased the Volta potential difference between the phases, resulting in loss of electrochemical nobility, with the ferrite being more affected than the austenite. A correlative approach of using the Volta potential in conjunction with electrochemical data has been introduced to characterise the nobility of passive films in global and local scale.

需要在异质微结构上表征钝化氧化膜，以评估侵蚀性环境中的局部降解（腐蚀，破裂）。伏特电势是一种表面敏感参数，可用于评估表面贵金属，从而评估钝化膜。在这项工作中，表明通过扫描开尔文探针力显微镜在超级双相不锈钢上测量的伏特电位与通过电化学阻抗谱法和电位动力学极化法测量的无源膜的电化学性质相关。通过在环境空气中老化而自然氧化，以及通过浸入浓硝酸中进行人工氧化，可以提高贵金属性，这都可以通过增加的伏特电势和电化学参数来体现。钝化与铁素体和奥氏体之间固有的伏特电位差消失有关，从而减少了电耦合，从而提高了材料的耐腐蚀性。然而，由阴极极化触发的氢钝化膜相互作用极大地增加了相之间的伏特电位差，导致电化学贵族性的损失，其中铁素体比奥氏体受到的影响更大。引入了将Volta电位与电化学数据结合使用的相关方法，以表征钝化膜在全球和局部范围内的贵金属特性。然而，由阴极极化引起的激发大大增加了相之间的伏特电势差，导致电化学贵族性的损失，其中铁素体比奥氏体受到的影响更大。引入了将Volta电位与电化学数据结合使用的相关方法，以表征钝化膜在全球和局部范围内的贵金属特性。然而，由阴极极化引起的激发大大增加了相之间的伏特电势差，导致电化学贵族性的损失，其中铁素体比奥氏体受到的影响更大。引入了将Volta电位与电化学数据结合使用的相关方法，以表征钝化膜在全球和局部范围内的贵金属特性。