A new synthetic method for the fabrication of SiC/BN nanocomposites was devised to attain strong machinable ceramics. SiC/BN nanocomposites that contained 10, 20, and 30 vol% hexagonal BN (h-BN) were successfully fabricated by sintering SiC-BN nanocomposite powders by carbothermal reduction and nitridation of borosilicate glass powders. Homogeneous mixtures of silica (SiO2), boric acid (H3BO3), and carbon powder were heated in a nitrogen atmosphere to synthesize SiC-BN nanocomposite powders. Borosilicate glass was obtained by reacting SiO2 and B 2O3 above 800°C, and SiC and turbostratic BN (t-BN) were obtained by reacting borosilicate glass with carbon powder and nitrogen gas at 1500°C. Carbothermal reduction followed by nitridation yielded SiC-BN nanocomposite powder composed of nanosized SiC and t-BN. By hot-pressing nanocomposite SiC-BN powders containing 7 wt% Al2O3 and 2 wt% Y2O3, machinable SiC/BN nanocomposites were obtained without a significant decrease in their fracture strength.
ASJC Scopus subject areas
- Materials Science(all)
- Mechanics of Materials
- Mechanical Engineering
- Electrical and Electronic Engineering