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问题，本研究通过等离子辅助球磨法创新性合成了月桂二醇改性硼酸镁（L-MgB₂O₄）。相较于传统非共价改性方法，共价B-O-C键合机制不仅实现了200~300纳米级的晶粒细化，还可在酸性环境中实现硼酸根的pH响应型释放。形貌表征（扫描电子显微镜）证实了该改性颗粒的团聚抑制与分散性提升，傅里叶变换红外光谱（FTIR）分析验证了月桂二醇的共价接枝。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，在添加量为0.07wt%时可达89.3%，这一性能归因于pH值协同提升与表面钝化作用。其次，在腐蚀试样表面观察到的添加剂沉积层同样对试样起到了防护作用。依据美国材料与试验协会（ASTM）DG133-05标准开展的摩擦学性能评价结果显示，添加0.05wt%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。三维轮廓分析显示磨损峰分布更为集中，有效改善了接触工况。L-MgB₂O₄可通过物理吸附（纳米级细化）作为润滑油添加剂发挥作用，并通过硼酸根释放实现缓蚀功能，为提升甲醇发动机部件的服役耐久性提供了全新解决方案。该无溶剂绿色合成工艺契合国际海事组织（IMO）的减排目标，填补了替代燃料系统中缓蚀与润滑增强两大需求之间的技术空白。