Corrosion behavior of marine engine cylinder liner materials in simulated environment of ammonia fuel combustion products

• An autoclave with real-time corrosion monitoring is used to investigate the corrosion. • At low NH 3 concentrations, NH 3 inhibits the corrosion of gray cast iron by adsorption. • At 3.2 vol.% NH 3 , iron ammonia complexation promotes the corrosion of gray cast iron. Ammonia, as a zero-carbon fuel, aids the shipping industry in reaching carbon neutrality but may accelerate corrosion of cylinder liner materials. A high-temperature, high-pressure autoclave with real-time corrosion rate monitoring was employed to investigate the corrosion behavior of gray cast iron, a typical cylinder liner material, under exposure to ammonia combustion products. Corrosion products and surface morphologies were characterized through scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and scanning Kelvin probe microscopy (SKPM). Results demonstrate a complex corrosion response to varying ammonia concentrations. At low ammonia concentration, corrosion rate initially decreased, attributed to the formation of a protective passivation layer consisting of Fe 2 O 3 , Fe 3 O 4 , and FeOOH. However, as ammonia concentration increased, stability of the passivation layer diminished, leading to increased corrosion rate. In the absence of ammonia, corrosion primarily produced loose, non-protective layers of α -Fe 2 O 3 and FeOOH. Once ammonia concentration exceeded 0.8 mol/L, the formation of Fe(NH 3 ) n 2+ complexes disrupted the passivation layer, accelerating localized corrosion of cast iron matrix.