Efeito da moagem de alta energia sobre a densificação e microestrutura do sistema Al2O3-Co de matriz metálica

Abstract

Ceramic materials, such as alumina (Al2O3) and cobalt (Co), present characteristics like high hardness and the high melting point for application as cutting tools. However, its application is limited because of its low toughness and low mechanical strength. Thus, in order to increase the toughness and maintaining the high mechanical properties, some metals such as cobalt (Co) have been used. In this work, the effect of the high energy milling and different amount of Co on densification, microstructure and mechanical properties of the Al2O3-Co compound were studied. The particulate powders (Al2O3 and Co), with 5 and 20 wt% of cobalt, were milled in a planetary milling for 50 hours, and powder mixture samples were collected at the intervals of 2, 10, 15, 20, 30, 40 and 50 hours. The milled powders were characterized by X-ray diffraction (XRD), particulometric analyzes, scanning electron microscopy (SEM); And compacted in a cylindrical matrix under a uniaxial pressure of 100 MPa. Subsequently, green compacts were sintered in a resistance furnace at 1200 to 1500 °C with holding time of 60 minutes under an argon atmosphere with a heating rate of 10 °C/min. The sintered samples were characterized by XRD, SEM and EDS. Density was measured using the geometric method (mass/volume), and the best values were obtained for the samples sintered at 1500 °C with relative density of 78% compared with sample sintering at 1350 and 1300 °C which presented relative densities of 68% and 62% respectively.