Spark plasma sintering of boron carbide ceramics using different sample Geometries and Dimensions

B₄C ceramics were fabricated by spark plasma sintering technique at 1700°C 1800°C for 5 min under applied pressure of 50 MPa under vacuum atmosphere. Two different grades of B₄C powder from H.C. Starck Company namely HP grade and HS grade were used in all related experiments. Effect of sample geometry and dimensions as well as sample thickness on sintering parameters were analyzed. Samples having 5 mm thickness and 50 mm diameter, 8 mm thickness in circular geometries and 50×50 square cross-section, 8 mm thickness were fabricated. Using the powder, which provided the densest sample, yttrium oxide (Y₂O₃) was added, mixed and sintered. Optimization of SPS method production parameters for pure B ₄C samples and B₄C samples with 5 wt% yttrium oxide additive were accomplished. The effect of geometry on density, Vickers hardness, fracture toughness, and microstructure were examined. The hardness and fracture toughness values of the samples were evaluated by the Vickers indentation technique.