Banca de QUALIFICAÇÃO: PAULO SERGIO PARAGUAI SANTANA

Uma banca de QUALIFICAÇÃO de MESTRADO foi cadastrada pelo programa.
STUDENT : PAULO SERGIO PARAGUAI SANTANA
DATE: 24/06/2025
TIME: 14:00
LOCAL: GOOGLE MEET
TITLE:

Effect of the ammonium paratungstate and copper nitrate powders preparation technique on the densification of W-Cu composites.

KEY WORDS:

W-Cu composites, high-energy milling, powders metallurgy, sintering, densification

PAGES: 54
BIG AREA: Engenharias
AREA: Engenharia de Materiais e Metalúrgica
SUBÁREA: Metalurgia de Transformação
SPECIALTY: Metalurgia de Pó
SUMMARY:

W-Cu composites are materials that combine the high strength of the refractory phases of tungsten (W) with the high thermal and electrical conductivity of copper, which is one of the transition metals. These composites are commonly used to manufacture electrical contact parts, thermal management devices such as heat sinks and spreaders, military applications, etc. However, due to the immiscibility between W and Cu and the high difference in melting points, the densification process of these composites is difficult. This work investigated the effect of the preparation technique of the precursor powders of ammonium paratungstate tetrahydrate (APT) and copper nitrate (NCu) followed by powder metallurgy in order to obtain the W-20%pCu composite. APT powders containing 8.54% NCu were prepared using two different methods: mechanical mixing (MM) and high energy milling (MAE). The powders were reduced in a hydrogen (H2) atmosphere at different temperatures and isotherm times, compacted at 210Mpa and sintered at 1200 °C for 60 minutes of isotherm under an H2 atmosphere. The W-20%pCu powder compacts were characterized by SEM, EDS XRD, thermogravimetric analysis (TG), Vickers microhardness, electrical conductivity and density measurements. The compact produced via MAE obtained a relative density of 97 %, while the compact obtained via MM reached only 55 %. The same sintered compacts obtained microhardness measurements of 452.95 HV and 105.21 HV, respectively, and na electrical condutivity of 16.65 IACS for the sintered compact obtained by MAE and 4.43 IACS for the sintered compact obtained via MM. The sintered compact produced via high-energy milling exhibited better homogenization, higher density values, better mechanical Properties and electrical condutivity.

COMMITTEE MEMBERS:
Presidente - 2613355 - FRANCINE ALVES DA COSTA
Externo ao Programa - 1674707 - MARCO ANTONIO MORALES TORRES - UFRNExterno ao Programa - ***.121.804-** - UILAME UMBELINO GOMES - UFRN
Externo à Instituição - OSCAR OLIMPIO DE ARAÚJO FILHO - UFPE