Banca de DEFESA: ISMAR PAULO SIQUEIRA DE ANDRADE

Uma banca de DEFESA de DOUTORADO foi cadastrada pelo programa.
DISCENTE : ISMAR PAULO SIQUEIRA DE ANDRADE
DATA : 26/09/2016
HORA: 08:30
LOCAL: Sala de aulas do PPGCEM
TÍTULO:

DESENVOLVIMENTO DE COMPÓSITOS CERÂMICOS COM DIATOMITA, α-Al₂O₃ E ZrO₂ COM 3%Y₂O₃, PARCIALMENTE ESTABILIZADA(3%Y-TZP)

PALAVRAS-CHAVES:

Diatomite; ceramic composite; mechanical properties; microhardness; toughnes

PÁGINAS: 175
GRANDE ÁREA: Engenharias
ÁREA: Engenharia de Materiais e Metalúrgica
RESUMO:

In Brazil, the largest producers of diatomite are Bahia and Rio Grande do Norte, corresponding respectively to 45% and 35%, and is mainly composed of hydrated silica. This research assessed the scientific and technical feasibility of using comminuted diatomite in a ceramic composite. Diatomite, after comminution for 20 hours in a ball milling, reached D90 equal to 11.40 μm and was aggregated to the ceramic composite with a matrix containing α-Al₂O₃ and ZrO₂ partially stabilized with 3% Y₂O₃, purchased commercially and with granulometry D90 2.86 μm and 7.68 μm respectively. The testing materials were shaped in a uniaxial press with the application of 270 MPA compactness pressure. Two experimental series were developed: D1A and D2A, with respectively 10% and 25% of diatomite and 5% and 10% of ZrO₂ in their formulations and sintered in a conventional manner, with levels ranging from 1350 °C to 1600 °C and most of them with a permanence time of 120 min. Technological tests were performed to characterize the raw materials and those sintered by: granulometry, XRF, XRD, SEM, dilatometry, TG, DSC, μv, Rlq, μapa, μreal, PA, AA,Vickers microhardness, σmx and toughness to K_ICfracture. In several formulations, one found mainly the formation of the following phases: mullite, corundum, sillimanite, tetragonal and monoclinic zirconia. The testing materials of the formulation R6 D1A, thermal cycle with a level of 1600 °C, heating rate of 5 °C/min, permanence time of 120 min, achieved the best overall result of microhardness 1662 HV. The best result for the σmx was in the sample of the formulation R6 D1AZ10, with a value of 115 MPA. The sample R1 D2A achieved the best result of K_IC with 7.0 MPA.m^1/2. From the sintering process used in this research, from the technical and scientific point of view, it is feasible to use particulate diatomite in composites with α-Al₂O₃ and ZrO₂ partially stabilized with 3% Y₂O₃, for applications with requirements for mechanical properties of microhardness up to 1662 HV,σmx with values up to 115 MPA and K_ICup to 7.0 MPA.m^1/2.

MEMBROS DA BANCA:
Presidente - 1300987 - CARLOS ALBERTO PASKOCIMAS
Externo à Instituição - DANIEL ARAÚJO DE MACEDO - UFPB
Interno - 1883170 - MAURÍCIO ROBERTO BOMIO DELMONTE
Externo à Instituição - MAXYMME MENDES DE MELO - IFRN
Externo à Instituição - THARSIA CRISTIANY DE CARVALHO COSTA - IFBA