Effect of carbon fiber on the tribo-mechanical properties of boron carbide: Comparison with carbon nanotube reinforcement

Composites with boron carbide (B4C) as the matrix and short carbon fiber (C-f) as reinforcement in 2, 5 and 10 vol % were fabricated by hot pressing route. Microstructural analysis by scanning electron microscopy reveled that C-f got aligned perpendicular to the hot press direction. Agglomeration of C-f was observed at 10 vol% C-f. The addition of C-f improved the flexural strength of B4C-C-f composite and was superior to that of B4C-CNT composite. On other hand, the hardness and fracture toughness of B4C-C-f composite were inferior to that of B4C-CNT composite. The tribological studies revealed that B4C-CNT had superior wear resistance. Both B4C-C-f and B4C-CNT had lower coefficient of friction than monolithic B4C. The possible reasons for deviation of properties due to change in length scale of carbon reinforcement has been analyzed.