Effect of LZSA Glass-Ceramic Addition on Pressureless Sintered Alumina. Part II: Mechanical Behavior

• Published in: Materials research (São Carlos, São Paulo, Brazil) Vol. 21; no. 1; p. 1
• Main Authors: Montedo, Oscar Rubem Klegues, Milak, Pâmela Cabreira, Faller, Cristian Arnaldo, Peterson, Michael, Noni Junior, Agenor De
• Format: Journal Article
• Language: English
• Published: Sao Carlos Universidade Federal do Sao Carlos, Departamento de Engenharia de Materiais 01-01-2018; ABM, ABC, ABPol; Associação Brasileira de Metalurgia e Materiais (ABM); Associação Brasileira de Cerâmica (ABC); Associação Brasileira de Polímeros (ABPol)
• Subjects: Alumina; Aluminum oxide; Bulk density; Bulk modulus; composites; Composition; Crack propagation; Crystal structure; Crystallinity; ENGINEERING, CHEMICAL; Flexing; Flexural strength; Fracture mechanics; Fracture toughness; Glass ceramics; Lithium oxides; LZSA glass-ceramic; MATERIALS SCIENCE, MULTIDISCIPLINARY; mechanical behavior; Mechanical properties; METALLURGY & METALLURGICAL ENGINEERING; Modulus of elasticity; Porosity; Silicon dioxide; Sintering (powder metallurgy); Structural analysis; Zirconium dioxide; composites; LZSA glass-ceramic; Alumina; mechanical behavior
• ISSN: 1516-1439; 1980-5373; 1980-5373
• DOI: 10.1590/1980-5373-mr-2017-0012

This work aims to evaluate the influence of a Li2O-ZrO2-SiO2-Al2O3 (LZSA) glass-ceramic on the mechanical behavior of alumina. Composites were prepared from alumina with three different particle sizes and 7 to 21 vol% of an LZSA glass-ceramic composition (11.6Li2O-16.8ZrO2-68.2SiO2-3.4Al2O3,). Specimens were obtained by uniaxial pressing. The optimum sintering temperature and holding time were found to be different for each composite. Structural characterization (bulk density and crystalline phases); mechanical characterization (flexure strength, elastic modulus, fracture toughness, and fracture energy); and microstructural analyses were carried out. Fine-grained alumina-based composite containing 21 vol% of glass-ceramic (1470 ºC and 3 h holding time, 2.0% porosity) showed a fracture toughness of 4.93 MPa·m0.5, an elastic modulus of 210 GPa, a fracture energy of 57 J·m-2, and a flexural strength of 170 MPa, in very good agreement with values reported by the literature. An increase of 37-177% in the fracture energy due to 21 vol% LZSA addition in the alumina was achieved for the range of grain size obtained in this work. Even though the final composition included a glassy component, the observed mechanical properties confirmed the effectiveness of the crystalline phases that were formed from LZSA glass-ceramic in reducing the propagation of cracks. The results showed that the addition of the LZSA glass-ceramic improved the mechanical properties of alumina.