Investigation of Phase Composition and Microstructure of the B4C/BN Nanocomposite Powders and the B4C/BN Nanocomposites Sintered Bulks

Abstract

In this research, the B4C/BN nanocomposite powders were fabricated by chemical reaction and heat treatment process, then the B4C/BN nanocomposites bulks were fabricated by hot-pressing process. The B4C/BN nanocomposite powders were fabricated by chemical reaction at 550°C for 15h and heat treatment at 850°C for 6h. The B4C/BN nanocomposites bulks were fabricated by hot-pressing process at 1850°C for 1h under the pressure of 30MPa. In this research, the phase composition and microstructure of the B4C/BN nanocomposite powders produced by chemical reaction and heat treatment process were investigated. The phase composition and microstructure of the B4C/BN nanocomposites produced by hot-pressing process were investigated. The XRD patterns results showed that there existed the B4C phase and amorphous BN phase in the composite powders produced by chemical reaction and heat treatment, and the amorphous BN phase completely transformed into the h-BN phase by hot-pressing process. The XRD patterns results showed that there existed the B4C phase and h-BN phase in the composites sintered bulks. The microstructure of the synthesized B4C/BN composite powders showed that the B4C particles were surrounded with the amorphous BN nano-sized particles, the thickness of amorphous BN coated layer was about 300-500nm. The B4C/BN nanocomposites exhibited the homogenous and compact microstructure, and the nano-sized h-BN particles were homogenously distributed in the B4C matrix. The mean particles size of B4C matrix was about 2-3μm, the length of nano-sized h-BN particles was about 1-2μm and width of nano-sized h-BN particles was about 100-200nm. The B4C/BN nanocomposites bulks exhibited more homogenous and compact microstructure with the increase of h-BN content.