Spark plasma sintering of boron nitride-aluminum nitride composites

Aluminum Nitride/hexagonal boron nitride (h-BN) composites were prepared by the method of spark plasma sintering, varying the amount of h-BN from 0 to 30wt%. Physical properties of h-BN/AIN with different content of h-BN were investigated, such as mechanical properties and microstructure. The results show that the composites have been complete densificated when sintered at 1650 degrees C for just 4 min under the pressure of 25 MPa with 4Wt%Y2O3 and 2wt%CaF2 as additives, and the Young's modulus and bending strength of this material have reached as high as 184.6 GPa and 394.8 MPa respectively. Furthermore, the machinability of h-BN/AIN has been greatly improved due to the addition of h-BN. The hardness of the composites is only 4.98 GPa when the content of h-BN is 15wt%.