Investigation of Microstructure Characterization and Machinability of the B<sub>4</sub>C/BN Nanocomposites Bulks Fabricated by Chemical Reaction Process and Hot-Pressing Process

Abstract

The B4C/BN nanocomposites were fabricated by hot-pressing process in this research. The B4C/BN nanocomposite powders were fabricated by chemical reaction and heat treatment process. The B4C/BN nanocomposites sintered bulks were fabricated by hot-pressing process at 1850oC for 1h under the pressure of 30MPa. In this research, the phase composition, microstructure, mechanical property and machinability of the B4C/BN nanocomposites fabricated by hot-pressing process were investigated. The XRD patterns results showed that there existed the B4C phase and h-BN phase in hot-pressed B4C/BN composites. The microstructure of the B4C/BN nanocomposites was investigated by SEM and TEM. The SEM micrographs showed that the B4C/BN nanocomposites bulks exhibited the homogenous and compact microstructure, and the h-BN particles were homogenously distributed in the B4C matrix. The TEM micrographs showed that there existed the weak interface between the B4C matrix grains and h-BN particles, as well as the microcracks within the laminate structured h-BN particles. The mechanical property of the B4C/BN nanocomposites decreased gradually with the increase of h-BN content. The B4C/BN nanocomposites exhibited the high mechanical property. The machinability of B4C/BN nanocomposites increased gradually with the increase of h-BN content, the drilling rates of the B4C/BN nanocomposites increased gradually with the increase of h-BN content.