Micro-cantilever testing of diamond - silicon carbide interfaces in silicon carbide bonded diamond materials produced by reactive silicon infiltration

SiC-bonded diamond materials produced by pressureless reactive infiltration of diamond preforms with silicon show high hardness and wear resistance. These properties are due to the relatively high diamond volume content of approximately 50 vol% and the mechanically strong interface between diamond and SiC. To determine the bending strength of individual interfaces between diamond and SiC, micro-cantilevers were prepared by focused ion beam milling at 13 grain boundaries and in-situ bending tests were carried out in a scanning electron microscope. The determined strength of cantilevers showing interface fracture was 10.4 +/- 4.0 GPa. Fracture surfaces were analyzed to verify the fracture behavior and initiation. In addition to fracture at the interface diamond/SiC, fracture occurred inside the SiC grains and at the SiC/silicon interface at comparable strength values. The results prove the high diamond/SiC-interface bonding strength.