Submitted by Automa??o e Estat?stica (sst@bczm.ufrn.br) on 2017-03-14T20:59:53Z No. of bitstreams: 1 GerlaneaSilvaDeOliveira_DISSERT.pdf: 3478391 bytes, checksum: 594895a6c6a847cb2a39bb6ce51e2b62 (MD5) / Approved for entry into archive by Arlan Eloi Leite Silva (eloihistoriador@yahoo.com.br) on 2017-03-15T20:06:06Z (GMT) No. of bitstreams: 1 GerlaneaSilvaDeOliveira_DISSERT.pdf: 3478391 bytes, checksum: 594895a6c6a847cb2a39bb6ce51e2b62 (MD5) / Made available in DSpace on 2017-03-15T20:06:06Z (GMT). No. of bitstreams: 1 GerlaneaSilvaDeOliveira_DISSERT.pdf: 3478391 bytes, checksum: 594895a6c6a847cb2a39bb6ce51e2b62 (MD5) Previous issue date: 2016-07-29 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior (CAPES) / O n?quel tem sido bastante utilizado, em estudos, como substituto do cobalto no metal duro - WC-Co, devido apresentar maior resist?ncia ? corros?o e ? oxida??o, al?m das propriedades mec?nicas e de aspectos econ?micos. Atualmente, carbetos e metais s?o adicionados ao metal duro, para aumentar a sinterabilidade do material, e, consequentemente, as suas propriedades de dureza e tenacidade. Neste trabalho, foram estudados os efeitos da varia??o percentual de Ni e dos par?metros de sinteriza??o (temperaturas de sinteriza??o e isotermas) nas propriedades do sinterizado WC-Ni. Os produtos sinterizados foram obtidos atrav?s das etapas de processamento da metalurgia do p?, no qual p?s de carbeto de tungst?nio ? WC com adi??o de 5 e 15%p. de N?quel ? Ni foram mo?dos em um moinho planet?rio de alta energia durante 8 horas. Em seguida, os p?s particulados foram compactados em uma prensa uniaxial sob carga de 300 Mpa numa matriz cil?ndrica de 5 mm de di?metro. A sinteriza??o dos compactados a verde foi realizada nas temperaturas de 1350 ?C e 1450?C, com isotermas de 30 e 90 minutos, no dilat?metro; e, na temperatura de 1350? C, com isotermas de 30 e 90 minutos, em forno ? v?cuo. Os p?s de partida (WC e Ni) e os mo?dos foram caracterizados por difra??o de raios ? X (DRX), microscopia eletr?nica de varredura (MEV) e espectroscopia de energia dispersiva (EDS); e as amostras sinterizadas foram caracterizadas por MEV, EDS e medidas de microdureza. Os valores de microdureza Vickers foram maiores para as amostras de WC-5%p.Ni sinterizadas a 1450?C, com isotermas de 30 e 90 minutos no dilat?metro (1078,6 HV e 1246,1 HV, respectivemente). No forno a v?cuo, o melhor resultado de microdureza, tamb?m, foi para as amostras WC-5%p.Ni sinterizadas a 1350?C com isoterma de 30 e 90 minutos (849,6 HV e 914,7 HV, respectivemente). As amostras de WC-5%p.Ni sinterizadas no forno a v?cuo a 1350?C com isotermas de 30 e 90 minutos mostraram maiores valores de microdureza comparados aos das amostras WC-5%pNi sinterizadas no dilat?metro a 1350?C com isoterma de 30 e 90 minutos. / Nickel has been widely used as a substitute for cobalt in WC-Co hardmetal studies due to greater corrosion and oxidation resistance as well as mechanical properties and economic aspect. Currently, carbides and metals are added to hard metal in order to increase the sinterability of the material, and consequently their hardness and toughness. In this study, the effects of different amount of Ni and sintering parameters (sintering temperatures and holding time) on properties of sintered WC-Ni were studied. The sintered products were obtained via powder metallurgy processing steps, in which powders of tungsten carbide (WC) with 5 and 15 wt% Nickel (Ni) were milled in a planetary high energy ball milling for 8 hours. Then, the particulate powders were compacted into a cylindrical die with 5 mm in diameter under a uniaxial load of 300 MPa. Sintering of the green samples was carried out at 1350 and 1450?C with holding time of 30 and 90 minutes, in resistance furnace and at 1350? C, with 30 and 90 minutes holding time in vacuum furnace. Starting (WC and Ni) and milled powders were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and Energy Dispersive Spectroscopy (EDS). Sintered samples were also characterized by SEM, EDS and microhardness measurements. Hardness results were higher for WC-5 wt% Ni sintered in the resistance furnace at 1450 ? C with 30 and 90 minutes holding time (1078.6 and 1246.1 Hv respectively). WC-5wt% Ni Samples sintered in vacuum furnace at 1350 ?C with 30 to 90 minutes holding time obtained a higher microhardness compared to ones sintered in the resistance furnace at 1350 ?C with holding time of 30 and 90 minutes.