Study on the corrosion inhibition and lubrication behavior of magnesium borate modified with lauryl glycol on cylinder liner materials in methanol engines

In order to solve the problem of acidic corrosion and wear of cylinder liner-piston rings of methanol-fueled marine engines, the present study innovatively synthesized lauryl glycol modified magnesium borate (L-MgB2O4) by plasma-assisted ball milling. The covalent B–O–C bonding mechanism not only achieves nanoscale (200–300 nm) refinement, but also ensures pH-responsive release of borate in acidic environments compared with conventional non-covalent modification methods. Conformational characterization (scanning electron microscopy) confirmed the suppression of agglomeration and improved dispersion, while FTIR analysis verified the covalent grafting of lauryl glycol. Electrochemical tests performed in simulated methanol combustion solution showed that the corrosion inhibition efficiency of L-MgB2O4 was concentration-dependent, reaching 89.3% at 0.07 wt% L-MgB2O4, which was attributed to the synergistic increase in pH and surface passivation. Secondly, the deposition of additives observed on the surface of corroded specimens also had a protective effect on the specimens. Tribological evaluations conducted in accordance with ASTM DG133-05 showed that 0.05 wt% L-MgB2O4 reduced the coefficient of friction by 14% and wear volume by 49% compared to the base oils, which is superior to conventional additives. Three-dimensional profiling shows a concentration of the wear peak distribution, which effectively improves the contact condition. L-MgB2O4 acts as a lubricant additive through physical adsorption (nanoscale refinement) and as a corrosion inhibitor through borate release. It provides a new solution for improving the durability of methanol engine components. This green, solvent-free synthesis meets International Maritime Organization (IMO) emission reduction targets and bridges the gap between corrosion inhibition and lubrication enhancement in alternative fuel systems.为解决甲醇燃料船用发动机缸套-活塞环的酸性腐蚀与磨损难题，本研究通过等离子辅助球磨法创新性合成了十二烷基乙二醇改性硼酸镁（L-MgB₂O₄）。相较于传统非共价改性手段，该共价B-O-C键合机制不仅实现了200~300 nm的纳米级晶粒细化，还可确保硼酸酯在酸性环境中实现pH响应型释放。形貌表征（扫描电子显微镜，scanning electron microscopy）结果证实，该改性剂可抑制团聚并提升分散性；傅里叶变换红外光谱（Fourier Transform Infrared Spectroscopy，FTIR）分析验证了十二烷基乙二醇的共价接枝效果。在模拟甲醇燃烧溶液中开展的电化学测试表明，L-MgB₂O₄的缓蚀效率呈浓度依赖性，当添加量为0.07 wt%时可达89.3%，这一效果源于pH值协同提升与表面钝化的共同作用。其次，在腐蚀试样表面观察到的添加剂沉积层同样可对试样起到防护作用。按照ASTM DG133-05标准开展的摩擦学性能评价结果显示，添加0.05 wt%的L-MgB₂O₄可使基础油的摩擦系数降低14%、磨损体积减少49%，性能优于传统添加剂。三维形貌表征结果显示，磨损峰分布更为集中，有效改善了接触状态。L-MgB₂O₄通过物理吸附（纳米级细化）充当润滑油添加剂，同时通过硼酸酯释放发挥缓蚀剂作用，为提升甲醇发动机部件的耐久性提供了全新解决方案。该绿色无溶剂合成工艺符合国际海事组织（International Maritime Organization，IMO）的减排目标，填补了替代燃料系统中腐蚀抑制与润滑强化之间的技术空白。