BN nanosheet reinforced Ni₃Al composite with improved tribological behavior under isooctane-lubricated sliding condition

Tribological behavior under isooctane-lubricated sliding condition of Ni₃Al composite reinforced with hexagonal boron nitride nanosheets (BNNSs), fabricated using selective laser melting (SLM), was investigated in this research to explore its potential applications as components for gasoline direct injection engines. Microstructure observation revealed that the axis of columnar grains of the SLMed Ni₃Al samples paralleled approximately to the deposition direction; BNNSs homogeneously distributed in the SLMed BNNS/Ni₃Al composite, in which a tight and clean BNNS-Ni₃Al interface was formed through mechanical bonding. Benchmarked against Ni₃Al sample, BNNS/Ni₃Al composite exhibited good anti-friction and outstanding wear resistance, its coefficient of friction was anomaly immune to the applied loads and wear resistance was significantly enhanced by up to ∼17 times at a load of 80 N. Synergetic strengthening and toughening mechanisms such as load transfer, crack deflection, BNNS pull-out and BNNS bridging were found to form stronger and tougher tribolayer, which effectively protected the composite from surface damage during sliding test, contributing greatly to the enhanced tribological performance. Therefore, BNNS/Ni₃Al components are expected to be potential candidates in the high-pressure gasoline pumps for gasoline direct injection (GDI) engines.