A new strategy for highly wear-resistant ball using carbon nanotube composites: Study on the impact wear resistance and interfacial bonding mechanism

Traditional low-alloy wear-resistant steel balls have a complex and costly manufacturing process, resulting in poor wear resistance. Fortunately, carbon nanotubes offer a promising solution due to their elastic modulus, lightweight nature and good wear resistance properties. To obtain exceptional impact wear resistance, novel carbon nanotubes/Fe matrix grinding balls were developed, the impact wear resistance was explored, and the carbon nanotube/Fe matrix interfacial bonding mechanism was revealed. The results showed a 30% increase in wear resistance after 2 h of impact-abrasive wear tests, as compared to traditional wear-resistant steel balls (B3). In the composite wear-resistant balls, carbon nanotubes are distributed along the prior austenite grain boundaries and within the grains, hindering the growth of austenite grains and increasing the dislocation density, resulting in fine grain strengthening and dislocation strengthening. At the carbon nanotubes/Fe interface, chemical reactions occurred at the nanotube defects, forming Fe3C, and the presence of Fe3C strengthened the interfacial bonding effect through pinning. During the process of impact-abrasive wear, the carbon nanotubes within the composite grinding ball acted as a bridge and formed a lubricating film, exhibiting exceptional wear resistance.