Estudo da preparação e sinterização do composto de W-Cu a partir de pós iniciais de W e CuO

• Autor(a) principal: Lopes, Felipe César da Silva
• Data de Publicação: 2018
• Tipo de documento: Trabalho de conclusão de curso
• Idioma: por
• Título da fonte: Repositório Institucional da UFRN
• Texto Completo: https://repositorio.ufrn.br/handle/123456789/43093
• topic: Tungstênio; Óxido de Cobre; Moagem de alta energia; Sinterização

In this work, the steps of preparation and sintering of the W-Cu compound from W and CuO powders were studied. For this purpose, high energy milling (HEM) was used to produce composite powders with refined and homogeneous phases. After milling in a high energy planetary mill, two distinct conditions of compacts of powders were prepared for the sintering in a resistive furnace with hydrogen atmosphere. In the first condition, powders of W-25% p.CuO powders ground for 5, 10, 20 and 30 hours were sintered in a resistive oven at 1030ºC for 60 minutes under H2 atmosphere. In this case, the compact cylindrical W-25% p.CuO powders were obtained under a pressure of 1280 kgf / cm² in a uniaxial matrix, and the reduction of the copper oxide occurred during sintering. In the second condition, samples of W-25% p.CuO powders, milled for 5 and 30 hours, were reduced in a resistive oven at a temperature of 800 ° C for 60 minutes under H2 atmosphere. Then the W21.45% p.Cu ground and reduced powders were compacted at a pressure of 1280 kgf / cm² in a uniaxial cylindrical matrix, and sintered at temperatures of 1050 ° C and 1100 ° C, for 60 minutes under H2 atmosphere. A heating rate of 10 ° C / min. was used both for the reduction of the ground powders and for the sintering of the compacts of powders. The initial, ground and reduced powders were characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD). The sintered powders compacts were also characterized by MEV and XRD. Density measurements were performed on green and sintered compacts. The results show that there was no amorphization of the phases even after 30 hours of milling. However, a greater dispersion of the CuO phase in the W phase is observed, as well as a large deformation of the tungsten particles. The sintered compacts, of ground and reduced powders, reached higher density and densification. This result is more interesting, being of greater value, for the sintering carried out in liquid phase at 1100 ºC.