Sobre o comportamento em abrasão de cerâmicos e metais duros e sua correlação com a dureza e a tenacidade à fratura

• Ano de defesa: 2023
• Autor(a) principal: Magnol, Renan Valter
• Tipo de documento: Tese
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal do Espírito Santo; BR; Doutorado em Engenharia Mecânica; Centro Tecnológico; UFES; Programa de Pós-Graduação em Engenharia Mecânica
• Palavras-chave em Português: Cerâmicos de engenharia; metal duro; desgaste abrasivo; ensaio roda de borracha horizontal a seco; ensaio de riscamento; múltiplas indentações; tenacidade à fratura via indentação; Engenharia Mecânica
• Link de acesso: http://repositorio.ufes.br/handle/10/12645

Abrasive wear is responsible for large global economic and energy losses, whereas a group of materials, with high toughness and hardness, known as hard metals, is commonly used in situations where this type of wear is dominant. However, these materials are expensive and their susceptibility to corrosion is widely reported in the literature, moreover, in this work, it was shown that these materials are not only subject to degradation due to corrosion, but also that an active liquid with the surface (corrosive) can facilitate brittle fracture. Ceramic materials, which have already shown relative success in abrasive applications, are more cheap, have high hardness and corrosion resistance, despite lower fracture toughness, when compared to hard metals. Thus, in order to carry out a systematic study of these materials when undergoing abrasive wear, ceramic materials and hard metal samples with different percentages of cobalt were characterized in relation to density, hardness, microstructure and fracture toughness via indentation and also tribologically, through mono and multi-event abrasive tests, with test results being correlated with hardness, toughness and the classic Evans and Wilshaw quantity (H1/2 KC 3/4) used to predict the behavior of ceramic materials under this type of wear. As a result, ceramic materials performed better in mild situations, the opposite occurred with hard metals which, considering their greater susceptibility to corrosion and cost, replacing these materials with ceramics in these situations may be viable. The Vickers indenter scratch tests and the dry sand/rubber wheel tests showed reasonable correlations with the fracture toughness via indentation and with the quantity H1/2 KC 3/4. As for hardness, it did not show any correlation with the volume of material removed in any of the tests studied. High data dispersion was observed, therefore, behavior predictions for materials with similar mechanical properties become difficult to make.