Banca de QUALIFICAÇÃO: RENNÁH FRANCISCO FIGUEIREDO GONÇALVES

Uma banca de QUALIFICAÇÃO de MESTRADO foi cadastrada pelo programa.
STUDENT : RENNÁH FRANCISCO FIGUEIREDO GONÇALVES
DATE: 19/11/2019
TIME: 08:30
LOCAL: Departamento de Física
TITLE:

Synthesis of W-Ni composite powders from ammonium paratungstate, sintering and characterization

KEY WORDS:

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

PAGES: 80
BIG AREA: Engenharias
AREA: Engenharia de Materiais e Metalúrgica
SUMMARY:

In this work, we studied the production of W-Ni powders, through high energy grinding at different grinding times (2h, 5h and 10h), followed by the reduction with hydrogen gas (H2) at a temperature of 850 ° C and with reaction time of 60 minutes, the ammonium index (APT) mixed with nickel, in the proportion of 20% p.Ni, after sintering of the post-reduced afterwards. The powders were characterized by X-ray diffraction and scanning electron microscopy - SEM. The effects of different grinding times (2h, 5h and 10h), compaction load (500 MPa and 600 MPa) and sintering temperature (1450 °C and 1550 °C) without behavior of the reduced W-Ni mixtures were investigated. The parts were sintered with heating rate of 10 °C/min. Dilatometric profiles were taxed and estimated by clothing densities by the Archimedes method. The influence of grinding times on the evolution and duration of the microstructure was also analyzed. Tungsten nickel metal particles were also selected under the same conditions for comparison purposes. From the obtained results, it was concluded that: the SEM recorded images of W-Ni mixtures revealed by The Post Morphology with measures of varied sizes, very agglomerated, as well as a good dispersion and homogenization of phases. An analysis of the X-ray diffractogram showed as phases W and Ni4W, and the reduction of the ammonium parameter was confirmed. The compacted dimensions with pressure of 500 MPa and the sintering temperature of 1450 °C presented higher density; and a 10h grinding 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
Presidente - 345842 - UILAME UMBELINO GOMES