Investigation on impact toughness and wear resistance of nanocomposite Al2O3/WC-Co hammer bit teeth

The material of the hammer bit tooth is cemented carbide YG8, whose impact toughness and wear resistance are insufficient, leading to tooth fracture and wear. In this paper, cemented carbide YG8 teeth and nanocomposite teeth doped with Al2O3 nanoparticles and VC inhibitors were fabricated through a series of processes. Cemented carbide YG8 teeth act as comparison. Two kinds of teeth were analyzed and compared using the scanning electron microscopy (SEM) and the MLD-10 dynamic impact-wear tester. SEM micrographs of samples show that Al2O3/WC-Co nanocomposite grains are finer and more uniform, which can improve impact-wear resistance. Impact-wear tests indicate that nanocomposite teeth had 3 to 5 times higher impact toughness and wear resistance than YG8 teeth. The fracture toughness can be significantly improved by adding the proper amount of Al2O3 nanoparticles. Based on fracture morphology analysis, it is found that the fracture of the YG8 tooth under impact-wear condition is brittle fracture and the fracture of the nanocomposite tooth is ductile fracture.