Estudo do efeito da adição de carbeto de titânio nas propriedades microestruturais e mecânicas do metal duro WC-Fe

Abstract

The hard metal is widely used in several areas of industry due to its characteristics such as high wear resistance, high fracture toughness and high hardness. Cobalt is the most used metal as a binding phase for hard metal, but other metals such as iron have been shown to be an alternative replacement, due to the high cost of production and toxicity of cobalt. The present work aimed to study the effect of the addition of 0%, 1.5%, 3.0% and 4.5%, by mass of TiC, to a WC10%Fe composite powder, prepared by grinding at high energy, through properties obtained from sintered powders and compacts. The composite powders were processed in a humid environment, using 99% ethyl alcohol in a high energy planetary mill with a container and carbide balls, under agitation of 400 rpm, with a ball/powder ratio of 5:1 for 10 hours. Subsequently, the ground powders were compacted at 200 MPa, in a uniaxial cylindrical 8 mm stainless steel matrix, and sintered in a resistive oven at 1300 °C, 1400 °C, 1500 °C and 1600 °C for 1 h, under argon atmosphere and a heating rate of 10 °C/min. To evaluate the composition, microstructure and properties, materials characterization techniques were used, such as Vibrating Sample Magnetometer (VSM), Granulometry, Scanning Electron Microscopy (SEM), X-Ray Diffractometry (XRD). In the consolidated samples, microstructural analysis, microhardness measurement and density measurement were performed using the Archimedes method. The results showed that through high energy milling, homogenization and particle size reduction were obtained, favoring the sintering process in hard metal. As well, the addition of TiC to WC10%Fe leads to a greater refinement of the microstructure, leading to a maximum microhardness of 1564 HV, with the addition of 3.0% by mass of TiC, at a sintering temperature of 1600°C.