Microstructure, mechanical properties and sintering model of B ₄C nozzle with micro holes by powder injection molding

Powder injection molding was adopted to prepare B ₄C matrix composites with the additions of silicon carbide and zirconia. The B ₄C nozzles with micro holes were well replicated from the mold, then successfully debound and sintered. The sintering characteristics, microstructures and mechanical properties of the B ₄C matrix composites materials were investigated. The results show that the additions of SiC and ZrO ₂ and increase of sintering temperature are in favor of the densification of the B ₄C matrix composites materials. In addition, the X-ray analysis shows that the sintered composites are composed of B ₄C, SiC and ZrB ₂ phases. The morphologies of ZrB ₂ and SiC phases change from nearly equiaxed to plate-like grains with increasing the sintering temperature. The fracture strength and hardness value of composites sintered at 2240°C reach to 305.9MPa and 3201HV, respectively. The sintering model between the linear shrinkage and relative density was also established, predicting the sintering density and revising the measured density by the Archimedes and other methods. The calculated and measured results correspond well with each other.