Banca de DEFESA: MATHEUS DE MEDEIROS TAVARES

Uma banca de DEFESA de DOUTORADO foi cadastrada pelo programa.
STUDENT : MATHEUS DE MEDEIROS TAVARES
DATE: 16/05/2022
TIME: 13:30
LOCAL: Sala Virtual
TITLE:

STUDY OF MICROSTRUCTURE AND PROPERTIES OF THE HARDMETAL WC-(Fe-Nb/NbH-C)

KEY WORDS:

Hardnetals, alternative binders, sintering, hardness, niobium, SPS.

PAGES: 92
BIG AREA: Engenharias
AREA: Engenharia de Materiais e Metalúrgica
SUBÁREA: Metalurgia Física
SUMMARY:

ABSTRACT

The search for alternative binders for hardmetals, also called cemented carbides, has
moved the scientific community. Alternative Fe-based binders have been widely studied
and used in selected applications. An unprecedented addition to this ligand would be the
use of niobium, a metal of high global interest, few explored and abundant in Brazilian
territory. This work aims to investigate the properties of the Fe-Nb/NbH-C system,
using it as an alternative binder to produce WC-(Fe-Nb/NbH-C) cemented carbides. For
this purpose, high energy ring and planetary milling techniques were used, using
controlled atmosphere sintering and spark plasma sintering (SPS) techniques in a
sintering temperature range from 1150ºC to 1450ºC. To evaluate the composition,
microstructure and properties, the ThermoCalc software was used, in addition to the
XRD, MO, SEM, EDS, density, Vickers hardness and fracture toughness techniques.
The preliminary results pointed to planetary mill as the most efficient method for
homogenization and particle size reduction, resulting in samples with better mechanical
properties. Controlled atmosphere sintering for this application proved to be unfeasible,
on the other hand, spark plasma sintering proved to be an efficient method for the
production of densified samples. The sintering temperature of 1250ºC provided the best
microstructure and properties results for all SPS processing conditions. Replacing Nb
for NbH, it was possible to obtain samples with more homogeneous and densified
microstructure by reducing the size of the niobium particles, absence of eta phase, and a
remarkable microstructural gradient formation, as well as hardness values of up to
1620Hv, meaning an increase of approximately 15% in relation to pure niobium
compositions.

BANKING MEMBERS:
Presidente - 345842 - UILAME UMBELINO GOMES
Interno - 1350249 - RUBENS MARIBONDO DO NASCIMENTO
Externo ao Programa - 2414250 - MEYSAM MASHHADIKARIMI
Externo à Instituição - CLODOMIRO ALVES JUNIOR - UFERSA
Externa à Instituição - MARIA JOSÉ SANTOS LIMA
Externo à Instituição - RAFAEL ALEXANDRE RAIMUNDO - UFPB