Microestrutura e propriedades mecânicas de vitrocerâmicos do sistema Li2O – CaO – SiO2

• Ano de defesa: 2013
• Autor(a) principal: Santos, Gisele Guimarães dos
• Orientador(a): Zanotto, Edgar Dutra
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal de São Carlos; Câmpus São Carlos
• Programa de Pós-Graduação: Programa de Pós-Graduação em Ciência e Engenharia de Materiais - PPGCEM
• Palavras-chave em Português: Vidro; Vitrocerâmica; Cristalização; Microestrutura; Propriedades mecânicas
• Palavras-chave em Inglês: Glass; Crystallization; Microstructure; Mechanical properties
• Área do conhecimento CNPq: ENGENHARIAS::ENGENHARIA DE MATERIAIS E METALURGICA
• Link de acesso: https://repositorio.ufscar.br/handle/20.500.14289/10241

An interesting characteristic of the Li2O-CaO-SiO2 glass-forming system is the possibility of obtaining certain crystalline phases and morphologies that may lead to tough glass-ceramics. However, very few published works investigated this matter. Glass compositions within the range 30-50% CaSiO3 / 70-50% Li2SiO3 were studied to obtain appropriate microstructures. Heat treatments were conducted using the double treatment technique: nucleation at about the glass transition temperature followed by crystal growth within the temperature range 500 and 700°C. These temperatures were selected according to DSC data. The influence of the size, number and morphology of the crystals on certain mechanical properties of the glass-ceramics, such as hardness and indentation toughness, were estimated by Vickers indentation tests. The samples were also characterized by X-ray diffraction to identify the phases present and by MEV to examine the crystal size, percentage and morphology. The best results were obtained with a composition of 44% mol CaSiO3 using the following thermal treatment conditions: 498°C for 24 hours (nucleation) and 700°C for 2 hours (Crystal growth), that led to a glass-ceramic showing a toughness of 1,9 MPa.m1/2.