Banca de QUALIFICAÇÃO: CELMO HUDSON REIS DE PAULA

Uma banca de QUALIFICAÇÃO de DOUTORADO foi cadastrada pelo programa.
STUDENT : CELMO HUDSON REIS DE PAULA
DATE: 30/01/2026
TIME: 15:30
LOCAL: Sala PPGCEM
TITLE:

Effect of carbon  on the microstructure and properties of NbC–Fe/FeNi cermets

KEY WORDS:

Cermets, Phase Liquid Sintering, NbC

PAGES: 57
BIG AREA: Engenharias
AREA: Engenharia de Materiais e Metalúrgica
SUMMARY:

The aim of this work was to correlate the total carbon content in the initial NbC-Fe and NbC-FeNi powders with the resulting microstructure, hardness, and fracture toughness of NbC cermets prepared by conventional liquid-phase sintering for 1 h at 1400 °C in vacuum. The microstructure, phase composition, and thermal behavior were analyzed by scanning electron microscopy, X-ray diffraction, thermogravimetric analysis, and differential scanning calorimetry. Additionally, magnetic properties were evaluated using a Physical Properties Measurement System (PPMS) equipped with a Quantum Design Dynacool vibrating sample magnetometer, as a method to confirm the final carbon content and to investigate the variation of magnetic properties as a function of carbon content. Vickers hardness and fracture toughness were measured using the Palmqvist method. The influence of carbon content on sinterability, carbide grain size, morphology, and mechanical and magnetic properties of the cermets was elucidated. A lower carbon content resulted in the agglomeration of NbC grains and a higher mass transfer rate, leading to the formation of coarser NbC grains. With increasing carbon content in the system, carbothermic reduction of surface oxides occurred at lower temperatures, resulting in better sinterability, better binder distribution, and a refined microstructure with superior mechanical properties compared to cermets with lower carbon content.

COMMITTEE MEMBERS:
Presidente - 1350249 - RUBENS MARIBONDO DO NASCIMENTO
Interno - 1674707 - MARCO ANTONIO MORALES TORRES
Interno - 2414250 - MEYSAM MASHHADIKARIMI
Interno - ***.121.804-** - UILAME UMBELINO GOMES - UFRN
Externa à Instituição - ARIADNE DE SOUZA SILVA - UFRN