Banca de DEFESA: RENNÁH FRANCISCO FIGUEIREDO GONÇALVES

Uma banca de DEFESA de MESTRADO foi cadastrada pelo programa.
STUDENT : RENNÁH FRANCISCO FIGUEIREDO GONÇALVES
DATE: 13/01/2020
TIME: 08:30
LOCAL: Sala de aulas 2 do DFTE
TITLE:

STUDY OF THE SYNTHESIS COMPOSITE POWDERS AND SYNTERIZATION OF W-NI SYSTEM

KEY WORDS:

powder metallurgy, composite powders, tungsten -nickel, sintering, hardness

PAGES: 87
BIG AREA: Engenharias
AREA: Engenharia de Materiais e Metalúrgica
SUMMARY:

In this work, we studied the use of W-Ni composite powders by high energy milling at different times (2h, 5h and 10h), nickel ammonium paratungstate (APT) precursors (20% p. Ni) and tungsten with nickel (20% p.Ni). Make an ammonium paratungstate (APT) mixed with nickel at a ratio of 20% p.Ni, reducing it with hydrogen gas (H2), at a temperature of 850 °C and with an isotherm time of 60 minutes, compaction and afterwards. sintering of reduced green compacts with heating rate of 10 °C/min. Post and precursors were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The effects of different measurement times (2h, 5h and 10h), compaction loads (500 MPa and 600 MPa) and sintering temperatures (1450 °C and 1550 °C) on the allowed W-Ni properties were investigated. The influence of grinding times on the evolution of hardness and microstructure was analyzed. They were also selected for color densities by the Archimedes method. At the same time, tungsten and nickel metal parts were selected under the same experimental conditions for comparison fins. From the obtained results, it was possible to conclude that the images recorded by SEM of the W-Ni mixtures revealed after the publication of the morphology with display of varied and quite agglomerated sizes and shapes. No case of W-Ni blending from APT-20% p.Ni reduction, the smallest selected post-engravings with good dispersion and phase homogenization. An XRD analysis showed the W and Ni4W phases, and the reduction of ammonium content was confirmed. The compacted dimensions with pressure of 500 MPa and the sintering temperature of 1450 °C presented higher density; and a grinding performed without time 10h allowed the hardening with greater microstructural homogeneity, presenting longer duration value (400.9 HV).

BANKING MEMBERS:
Externa à Instituição - ARIADNE DE SOUZA SILVA - UFRN
Externa à Instituição - MARIA JOSÉ SANTOS LIMA - UFRN
Externo ao Programa - 2414250 - MEYSAM MASHHADIKARIMI
Externa à Instituição - SUYLAN LOURDES DE ARAÚJO DANTAS
Presidente - 345842 - UILAME UMBELINO GOMES