Study of machinable silicon carbide–boron nitride ceramic composites

Silicon carbide (SiC) particles coated with nano-boron nitride (BN) were synthesized. The SiC/BN ceramic nano-composites and micro-composites were sintered by plasma-activated sintering. For the nano-composites, due to the homogeneous dispersion of the nano-BN crystals around the SiC grains of the matrix, the grain size of nano-composites was smaller than the monolithic SiC and micro-composites. As a result, the bending strength of the nano-composites decreased slowly (for SiC/20% h-BN nano-composite, about 18% decrease), while their hardness decreased sharply and the machinability properties were improved noticeably.