Investigation of nanofluid minimum quantity lubrication on micro-grinding quality of SiC_f/SiC ceramic matrix composites

SiC_f/SiC composites have gained significant attention as a highly promising material for engine thermal structures, primarily due to their remarkable high-temperature mechanical properties, along with their low density and outstanding resistance to oxidation. In the development background of sustainable and green manufacturing technology, how to realize the low-damage machining of SiC_f/SiC ceramic matrix composites is an urgent problem to be solved. In this study, the effect of dry grinding, flood grinding, minimum quantity lubrication, and nanofluid minimum quantity lubrication (MoS₂ and carbon nanotubes (CNTs)) on the surface quality at different grinding depths was thoroughly investigated. The results showed that the surface quality of grinding was better, and the grinding force was lower under carbon nanotube nanofluid lubrication compared to the other four lubrication methods. Compared with dry grinding, carbon nanotube nanofluid lubrication significantly reduced the grinding temperature by 79.3%, 86.1%, and 83.5% at grinding depths of 0.2 mm, 0.4 mm, and 0.6 mm, respectively. In addition, the stable lubrication film formed by NMQL-CNTs can significantly increase the service life of grinding wheels, improve surface quality, and help obtain a surface morphology with fewer surface defects. Although brittle removal was observed in different lubrication methods, NMQL-CNTs significantly reduced surface damage due to their “filling effect” and excellent friction reduction. This study provides theoretical guidance for the low-damage processing of SiC_f/SiC composites.