Study of indentation induced cracks in MoSi2-reaction bonded SiC ceramics

MoSi2-RBSC composite samples were prepared by infiltration of Si-2 at. % Mo melt into a preform of commercial SiC and petroleum coke powder. The infil trated sample had a density > 92% of the theoretical density (TD) and micro structurally contained SiC, MoSi2, residual Si and unreacted C, The materia l was tested for indentation fracture toughness at room temperature with a Vicker's indenter and K-1C was found to be 4(.)42 MPa rootm which is around 39% higher than the conventional RBSC material. Enhancement in indentation fracture toughness is explained in terms of howing of propagating cracks t hrough MoSi2/SiC interface which is under high thermal stress arising from the thermal expansion mismatch between MoSi2 and SiC.