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

Abstract

A novel WC–Al2O3 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 15wt%) on mechanical properties of WC–Al2O3 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 Al2O3 whiskers, the fracture toughness and flexural strength reached to maximum value of 13.8MPam1/2 and 1335±42MPa respectively, when the concentration of Al2O3 whiskers is 10wt%. Compared to those composites reinforced by 10wt%Al2O3 particle, the values of flexural strength increased by roughly 10wt%. The strengthening mechanisms were attributed to crack deflection, crack bridging and ligamentary bridging between crack surfaces. When the concentration of whiskers goes beyond 10wt%, the agglomerates created low density regions and resulted in lowering of strength.