Microestrutura e propriedades mecânicas de vitrocerâmicos do sistema Li2O – CaO – SiO2
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 / 7...
| Autor: | |
|---|---|
| Tipo de recurso: | tesis de maestría |
| Estado: | Versión publicada |
| Fecha de publicación: | 2013 |
| País: | Brasil |
| Institución: | Universidade Federal de São Carlos (UFSCAR) |
| Repositorio: | Repositório Institucional da UFSCAR |
| Idioma: | portugués |
| OAI Identifier: | oai:repositorio.ufscar.br:20.500.14289/10241 |
| Acceso en línea: | https://repositorio.ufscar.br/handle/20.500.14289/10241 |
| Access Level: | acceso abierto |
| Palabra clave: | Vidro Vitrocerâmica Cristalização Microestrutura Propriedades mecânicas Glass Crystallization Microstructure Mechanical properties ENGENHARIAS::ENGENHARIA DE MATERIAIS E METALURGICA |
| Sumario: | 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. |
|---|