Effects of Low-Modulus Carbon Additives on Physical Properties of ZrC/C Heteromodulus Composites

The article is devoted to the impact of carbon additives on densification and mechanical properties of ZrC/C hetero-modulus composites. In case of addition of small amount of carbon to ZrC residual porosity decreases, whereas higher carbon content leads to more than 3 vol % increase in residual porosity. With the increase of the carbon concentration up to 15 vol %, modulated decrease of elastic modulus and microhardness to 213 and 7.8 GPa, respectively, was observed. Moreover, increase in carbon content in ZrC/C composites enhance toughness of sintered materials. For example, K-IC = 4.3 MPa m(1/2) for ZrC and K-IC = 7 MPa m(1/2) for 3 vol % C. Ultimate strength under diametric compression exponentially decreased from 305 to 55 MPa with the increase of carbon concentration.