Estudo da Microestrutura e propriedades mecânicas do compósito Al2O3-10%Fe obtido por moagem de alta energia

Abstract

Al2O3 is one of the most widely used ceramic cutting tool materials. Allied to Fe, it becomes a strong candidate to replace conventional materials such as WC-Co, since the alumina ceramic phase, with its high hardness and strength, together with the iron metallic phase, has excellent workability, high ductilities, and high fracture toughness result in a composite with excellent properties. Thus, the present work investigated the effect of High Energy Milling (HEM) on Al2O3 and Fe phase dispersion on microstructural characteristics, density, microhardness, toughness and wear of Al2O3-Fe composites. For this purpose, Al2O3 and Fe powders, in the proportion of 10% by weight of Fe, were ground in the Pulverisatte 7 high energy planetary mill. The powders were milled for 5h, 15h, 30h and 50 hours. The electron micrographs showed the morphology and particle size distribution of the ground powders. X-ray diffraction analyses were performed to detect the present phases and to observe the milling effect on the milled powders. Density calculations were performed by the geometric method (mass/volume) on green and sintered bodies. Besides, to analyze the real viability of using the composite as a cutting tool, three fundamental properties in sintered materials were analyzed: microhardness, fracture toughness and wear. The microhardness Vickers in the sintered bodies ranged from 509 to 1020 HV; In fracture toughness, it was observed that toughness decreased with increasing milling time; And finally, the wear was visualized from the pin-disc method, which showed parameters such as hardness and surface finish are able to cause significant changes in the test behavior.