cBN reinforced Y-α-SiAlON composites

Dense alpha-Sialon-cBN composites were produced by FAST/SPS-sintering at 1575-1625 degrees C. The hardness of the materials increases only up to 21 GPa for materials with 10 vol.% cBN. On the other hand the fracture toughness increases up to nearly 8 MPa m(0.5) with 30 vol.% cBN. The reason for the increase in fracture toughness is attributed to crack deflection at cBN grains due to the weak bonding of the grains in the matrix. The weak interfaces are also responsible for the moderate increase in hardness. Detailed investigation of the interface between cBN and the matrix was carried out by TEM. (c) 2013 Elsevier Ltd. All rights reserved.