原子力显微镜在有机缓蚀剂研究中的应用

有机缓蚀剂具有低毒性和高性价比等优点，在低浓度的注射剂量下可以实现优良的缓蚀效果，被广泛应用于石油化工（碳钢）、电子工业（铜）、车辆船舶和航空航天工业（铝），保护合金材料免受腐蚀危害。现有的电化学测试技术已经在有机缓蚀剂领域得以广泛应用，这种传统的研究方法可以提供有关界面电化学反应的平均动力学信息，但是无法直接解析缓蚀剂的吸附及作用机制。随着金属腐蚀与缓蚀剂研究的微观化和系统化发展，电化学分析手段逐渐与其他分析技术（如扫描电镜、X射线光电子能谱、拉曼光谱等）紧密结合，开展了对缓蚀剂作用机制的深入研究。在这些分析技术中，原子力显微镜（AFM）由于空间分辨率成像能力高，受工作环境和样品性质的局限较少，在有机缓蚀剂于金属/溶液界面的直观研究中起到了重要作用。本文结合近年来原子力显微镜在有机缓蚀剂领域的研究进展，简述了原子力显微镜的工作原理和几种操作模式，详述了AFM的接触模式在有机缓蚀剂研究中的普遍应用和其局限性，总结了AFM的敲击模式在表面活性剂吸附研究中的重要作用和研究现状并延伸到有机缓蚀剂的吸附研究，综述了AFM几个衍生功能（包括纳米刮擦、力-距离曲线、摩擦力和电化学原子力显微镜）在有...

Application of Atomic Force Microscopy in Organic Corrosion Inhibitor Research

Organic corrosion inhibitors have advantages such as low toxicity and cost-effectiveness. They demonstrate excellent corrosion inhibition efficiency at low injection doses and are used extensively to protect alloy materials from corrosion in petrochemical (carbon steel), electronic (copper), automotive, maritime and aerospace industries (aluminum). The study on the mechanism of organic corrosion inhibitors helps improve and optimize the design of inhibitors and the adjustment of their molecular structure or formulation can enhance their anti-corrosion performance. The existing electrochemical testing techniques have been widely applied in the field of organic corrosion inhibitors. While these methods can only offer information about the average kinetic of interfacial electrochemical reactions, they do not directly decipher the adsorption mechanisms of corrosion inhibitors. With the microscopic and systematic development in the study of metal corrosion and corrosion inhibitors, electrochemical analysis methods are progressively integrated with other analytical techniques (such as scanning electron microscopy, X-ray photoelectron spectroscopy, Raman spectroscopy, etc.), enabling an in-depth analysis of the mechanisms behind corrosion inhibitor action. Among these analytical techniques, Atomic Force Microscopy (AFM) has played a significant role in the direct study of organic corrosion inhibitors at the metal/solution interface due to its high spatial resolution imaging capabilities and fewer limitations concerning working environments and sample properties. In the field of organic corrosion inhibitor research for metals and alloys, the most widely used AFM technique is the morphology characterization and the analysis of surface roughness in contact mode, and the aim is to assess the corrosion inhibition effectiveness of organic corrosion inhibitors by evaluating the corrosion level of the materials. This technique provides high-resolution and intuitive microscale corrosion morphology, coupled with electrochemical and surface composition analysis, which is highly beneficial for studying corrosion efficiency and mechanisms. Additionally, this operation mode is simple, leading to the majority of AFM work in corrosion inhibitor research being conducted with this technique. However, the limitation of AFM contact mode lies in its inability to deeply investigate the adsorption behavior of corrosion inhibitor films. Due to the lateral force inherent in AFM contact mode, there is a possibility for surface damage during the study of soft materials like organic corrosion inhibitor films. To address this, the tapping mode of AFM is introduced. Initially utilized for studying the adsorption and desorption of surface-active agent substances on hydrophilic or hydrophobic inert surfaces, this tapping mode has gradually extended to the study of organic corrosion inhibitors in recent years. Particularly, the phase imaging technique in this mode directly acquires the adsorption structure of corrosion inhibitor molecules, thus significantly facilitating in-situ studies of organic corrosion inhibitor films. However, its limitation lies in the restricted scanning and frequency modulation speed in corrosion inhibitor solutions, making it challenging to monitor the adsorption kinetics and dynamic adsorption-desorption processes. Currently, some developing technologies, such as peak force tapping mode, aim to enhance the existing tapping mode for better suitability in studying soft materials. Apart from the fundamental contact and tapping modes, AFM has been combined with other analytical techniques, developing multifunctional analysis methods for organic corrosion inhibitor research. For instance, Electrochemical Atomic Force Microscopy (EC-AFM) not only records local corrosion morphology, but also applies voltage on surface for polarization modification or synchronizes electrochemical tests to gather corrosion electrochemical process information. Additionally, AFM force-distance curve functionality and lateral force microscopy enable simultaneous acquisition of surface microstructure and mechanical properties of organic adsorption films, significantly aiding in evaluating inhibitor effects and studying corrosion mechanisms. These comprehensive analysis techniques can be widely applied in corrosion inhibition on materials like gold or stainless steel, while their use on carbon steel is limited due to the rapid corrosion rate of carbon steel surfaces, surpassing the scanning rate of AFM probes, making these finer mechanical measurements or surface electrochemical modifications challenging. In the future, AFM will evolve towards multifunctionality, high sensitivity, high speed, and efficiency. Its application in the field of organic corrosion inhibitor research will further integrate with other advanced surface micro-area analysis technologies, interpreting the structure of organic corrosion inhibitors/metal interfaces and corrosion mechanisms from various perspectives such as surface chemistry, electrochemistry, mechanics, physics, and materials science. The continuous improvement of AFM technique will facilitate deeper studies of in-situ dynamic corrosion processes and drive research in the field of organic corrosion inhibitors.