Architecture-driven enhancement of tribological performance, surface integrity, and hardness in magnesium-carbon fiber hybrid sandwich composites for key aerospace applications

Magnesium-carbon fiber (Mg-CF) sandwich composites are promising lightweight materials for aerospace applications; however, their tribological performance and surface durability under sliding conditions remain insufficiently understood, particularly regarding the influence of fiber architecture. This study addresses this gap by investigating the wear behaviour, surface roughness evolution, and hardness characteristics of Mg-CF sandwich composites with different fiber orientations. The composites were fabricated using filament drum winding, hand lay-up, and compression moulding, incorporating unidirectional ([0°], [45°], [90°]), bidirectional ([0°/90°], [45°/−45°]), and multidirectional ([0°/90°/45°/−45°]) stacking configurations. Tribological performance was evaluated using a pin-on-disc test under dry sliding conditions (20 N load, 300 rpm, and 848 m sliding distance) to determine the specific wear rate and coefficient of friction. Surface roughness and Vickers microhardness were analysed to support tribological performance, while scanning electron microscopy was used to identify dominant wear mechanisms. The results demonstrate that fiber architecture plays a decisive role in wear resistance, with the multidirectional laminate (Mg/CF[0°/90°/45°/−45°] 2 /Mg) exhibiting the lowest specific wear rate (0.86 × 10⁻³ mm³/N·m), corresponding to an improvement of approximately 44% compared to the unidirectional configuration. The reduced wear is supported by a lower coefficient of friction (0.145), minimal surface roughness increment (0.42 μm), and enhanced cross-sectional hardness (47.27 HV), indicating improved load distribution and interfacial stability. SEM observations revealed predominantly abrasive wear with reduced damage in multidirectional configurations. Overall, the study establishes a clear structure-tribology relationship, demonstrating that optimized fiber architectures significantly enhance wear resistance and surface integrity in Mg-CF sandwich composites.