Influence of Al2O3 whisker concentration on mechanical properties of WC–Al2O3 whisker composite

Abstract A novel WC–Al 2 O 3 whiskers composite was prepared with the addition of VC grain growth inhibitor by hot-pressing sintering. The aim of this investigation was to study the influence of varying whisker concentration (2.5, 5, 10 and 15 wt%) on mechanical properties of WC–Al 2 O 3 whisker composite. Whiskers of hydrothermally synthesized Ammonium Aluminum Carbonate Hydroxide (AACH) were used for composite synthesis. These whiskers transformed in situ into alumina and keep their morphology even after sintering. Results demonstrated that the hardness were decreased slightly with the increasing content of Al 2 O 3 whiskers, the fracture toughness and flexural strength reached to maximum value of 13.8 MPa m 1/2 and 1335±42 MPa respectively, when the concentration of Al 2 O 3 whiskers is 10 wt%. Compared to those composites reinforced by 10 wt%Al 2 O 3 particle, the values of flexural strength increased by roughly 10 wt%. The strengthening mechanisms were attributed to crack deflection, crack bridging and ligamentary bridging between crack surfaces. When the concentration of whiskers goes beyond 10 wt%, the agglomerates created low density regions and resulted in lowering of strength.