Resistência à flexão e microestrutura de vidro-cerâmicas feldspáticas processadas por injeção em moldes à alta temperatura

• Ano de defesa: 2009
• Autor(a) principal: Costa, José Bernardo Fragoso
• Orientador(a): Silva, Carlos Eduardo Sabrosa Borges da
• Banca de defesa: Monnerat, Antonio Fernando , Fernandes, Cláudio Pinheiro , Andrade Filho, Hugo de , Ogasawara, Tsuneharu , Pinto, Vinícius Bemfica Barreira
• Tipo de documento: Tese
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade do Estado do Rio de Janeiro
• Programa de Pós-Graduação: Programa de Pós-Graduação em Odontologia
• Departamento: Centro Biomédico::Faculdade de Odontologia
• País: BR
• Palavras-chave em Português: Materiais cerâmicos odontológicos; Injeção em moldes; Resistência à flexão; Microestrutura; Cerâmica odontológica; Materiais dentários - Propriedades mecânicas; Resistência de materiais; Microscopia eletrônica de varredura
• Palavras-chave em Inglês: Ceramic dental materials; High-temperature injection molding; Flexural strength; Microstructure
• Área do conhecimento CNPq: CNPQ::CIENCIAS DA SAUDE::ODONTOLOGIA
• Link de acesso: http://www.bdtd.uerj.br/handle/1/13964

While traditional processing routes in the fabrication of ceramic restorations became notorious for their complexity, modern techniques have been priviledging simplicity and automation. High-temperature injection molding is a clear example, and recently has been associated to CAD-CAM technology. Studies demonstrated the use of a low thermal expansion feldspathic glass (Alpha, Vita Zahnfabrik) for injection, although more information is needed in terms of mechanical properties and microstructure of this material after being submitted to injection. The objectives of this study are: produce Alpha glass-ceramic ingots and Alpha with alumina and zirconia particles ingots for injection; evaluate flexural strength of the processed materials and compare it to a compatible product (PM9-Vita Zahnfabrik); study microstructure of the materials and correlate it to their mechanical properties; identify the existing cristalline phases at different processing stages with X-ray diffraction. Injection increased mechanical properties of Alpha glass due to reduction in porosity of the material. Despite the observation of crystal nucleation on both materials during processing, a clear correlation of this phenomenon and mechanical behavior could not be made. No alterations on the pattern of the crystalline phase distribution due to injection were observed on scanning electron microscope images. Flexural strength did not vary significantly between injected Alpha and PM9. The addittion of alumina and zirconia particles resulted in poorer mechanical results due to agglomerate formation during ingot fabrication and the incapacity of its dispersion trough injection. These agglomerates worked as stress concentrators, weakening the material.