Combustion Synthesis of High Density ZrN/ZrSi(2) Composite: Influence of ZrO(2) Addition on the Microstructure and Mechanical Properties

In this study, a high-density ZrN/ZrSi(2) composite reinforced with ZrO(2) as an inert phase was synthesized under vacuum starting with a Zr-Si(4)N(3)-ZrO(2) blend using combustion-synthesis methodology accompanied by compaction. The effects of ZrO(2) additions (10–30 wt%) and compression loads (117–327 MPa) on the microstructure, porosity and hardness of the samples were studied. The process was monitored using XRD, SEM, EDS, porosity, density and hardness measurements. Thermodynamic calculations of the effect of ZrO(2) addition on the combustion reaction were performed including the calculation of the adiabatic temperatures and the estimation of the fractions of the liquid phase. The addition of up to 20 wt% ZrO(2) improved the hardness and reduced the porosity of the samples. Using 20 wt% ZrO(2), the sample porosity was reduced to 1.66 vol%, and the sample hardness was improved to 1165 ± 40.5 HV at 234 MPa.