Banca de DEFESA: ELLA RAQUEL DO VALE SOUZA DE LIMA

Uma banca de DEFESA de DOUTORADO foi cadastrada pelo programa.
STUDENT : ELLA RAQUEL DO VALE SOUZA DE LIMA
DATE: 28/02/2024
TIME: 14:00
LOCAL: Auditório do Laboratório de Cimentos da UFRN
TITLE:

Selflubricating Ni-composites sintered using DC plasma

KEY WORDS:

Nickel. Solid lubrication. DC Plasma Sintering. Powder metallurgy.

PAGES: 95
BIG AREA: Engenharias
AREA: Engenharia de Materiais e Metalúrgica
SUBÁREA: Metalurgia de Transformação
SPECIALTY: Metalurgia de Pó
SUMMARY:

The present work aimed to evaluate the respective effects of different solid lubricants dispersed throughout the volume in the nickel matrix, produced via powder metallurgy. Graphite was used as a solid lubricant, which was introduced into the matrix by the conventional route in the simple mixing step, and the lubricant generated In-situ by the dissociation of silicon carbide (SiC) during sintering. In the mixtures, the graphite and SiC content was fixed at 10 vol.%, the conformation of the samples was carried out by uniaxial compaction at a pressure of 600MPa, the sintering took place in a hybrid plasma DC reactor and conventional oven, different sintering temperatures were applied (800 ºC, 900 ºC and 1000 ºC). The study of the microstructure and hardness of these materials was carried out using the analysis of green and sintered densities, XRD, Raman spectroscopy, MO, SEM/FEG-EDS and Vickers microhardness, which showed the influence of different solid lubricants, temperature and sintering medium on the formation of composites, on the continuity of the nickel matrix and on the dissociation kinetics of SiC. The silicon resulting from the dissociation of silicon carbide enriches the nickel matrix, in which the solubility of carbon varies with temperature, however the retained carbon precipitates and remains in the form of graphite. The addition of solid lubricant in the matrix promoted a reduction in the density of the sintered. Increasing the sintering temperature increased densification and reduced porosity. Sintering at 1000 ºC promoted higher hardness values. Graphite deposits increased in SiC containing samples with increasing temperature. Based on this information, the tribological behavior of materials sintered at 1000 ºC was analyzed. Composites containing solid lubricant obtained by the conventional route showed the lowest values of friction coefficient, the wear rate was close to that of the pure nickel matrix. The microstructural and hardness aspects indicate a similarity between plasma sintering processes under abnormal (DC) conditions and in a tubular furnace.

COMMITTEE MEMBERS:
Presidente - 1298936 - ANTONIO EDUARDO MARTINELLI
Interno - 1350249 - RUBENS MARIBONDO DO NASCIMENTO
Interno - 345842 - UILAME UMBELINO GOMES
Externo à Instituição - GUILHERME OLIVEIRA NEVES
Externo à Instituição - CRISTIANO BINDER - UFSC