Effect of ZrO2 Additives on the Nanomechanical Properties of Spark Plasma Sintered 93WC/7-xCo/xZrO2-2mol Y2O3 Powders Prepared by High-Energy Ball Milling

摘要

A high-energy ball milling technique was employed to prepare nanocomposite powders with compositions (wt.%) of 93WC/7-xCo/xZrO2-2mol% Y2O3 powders (x=0, 1, 2, 3, 4, 5, 6, 7 wt%). The nanocomposite powders obtained after 75 h of ball milling possessed excellent morphological characteristics with spherical morphology and an average powder particle size of 150 nm in diameter. The powder of the end-products, which consisted of fine grains with an average grain size of 8 nm in diameter, were then consolidated in vacuum under a uniaxial pressure of 30 MPa at 1250 °C using spark plasma sintering (SPS). The fully dense nanocomposite bulk samples obtained via the SPS process maintain their nanocrystalline structure and have an average size of 55-86 nm in diameter. The indentation fracture toughness (K_(c1)) of the bulk consolidated materials decreased with the increasing mole fractions of ZrO2 and ranged from 8.83 to 15.48 MPa.m ~(1/2). The effet of ZrO2 additives on the nanohardness and elastic modulli of the fabricated bulk nanocomposite system were experimentally investigated and reported in this study.