Fabrication of Diamond/SiC Composites Using HIP from Mixtures of Diamond and Si Powders

Diamond/SiC=75/25-50/50vol% composites have been fabricated utilizing a liquid phase reaction sintering during hot isostatic pressing (HIP) at 1450 degrees C under 196 MPa for 2 h from the mixtures of diamond and Si powders. They were mixed for 30 min in ethanol. After drying, they were compacted uniaxially and isostatically (245 MPa). They were pre-heated at 950 degrees C for 2 h (Process I) or solidified using pulsed electric-current pressure sintering (PECPS) at 1350 or 1450 C for 10 min under 50 MPa in a vacuum (Process II). Both compacts prepared via "Process I" or "II" were densified by Pyrex-glass capsule HIPing (1450 degrees C/2h/196MPa/Ar). The high relative density has been achieved at the composition of diamond/SiC=55/45vo1% using Process II. In order to increase Vickers hardness (H-v), a small amount of B4C particles have been added to diamond/SiC= 55/45vo1% composites using "Process II" at 1350 C and followed by HIP. The H-v values increased from 37.3 to 40.5 GPa at 5vol%B4C addition.