Effect of AlN-Y2O3 addition on the properties and microstructure of in-situ strengthened SiC-TiB2 composites prepared by hot pressing

SiC-TiB2 composites with 20 vol% TiB2 were fabricated by in situ reaction among TiO2, C and B4C. Samples were densified by hot-pressing at 1900 degrees C with AN and Y2O3 as sintering aids. The effects of the volume fraction of AlN and Y2O3 on the density, flexural strength, hardness and microstructure of the SiC-TiB2 composites were determined. The results showed that SiC-TiB2 composites possess the best comprehensive performance when the content of sintering aids is 10 vol%, at which point the relative density, flexural strength and hardness of the sintered specimens were 99.1%, 641 +/- 45 MPa and 91.8 +/- 0.7 HRA, respectively. The resistivity of the SiC-TiB2 composites decreased with increasing AlN-Y2O3 content and reached a minimum (17.5 +/- 6.7 m Omega cm) at 10 vol% AlN-Y2O3. Pull-out of crystal particles in the sintered body with 10 vol% AlN-Y2O3 was observed from the fracture morphology of the composites. Tightly bonded grains contributed to the excellent combination of properties of SiC-TiB2 composites. (C) 2013 Elsevier Ltd and Techna Group S.r.l. All rights reserved.