ESTUDO DA INFLUÊNCIA DA ADIÇÃO DE TiO2 E CuO NA SINTERIZAÇÃO DE ALUMINA
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Tipo de produção
Trabalho de Conclusão de Curso
Data
2020-12
Autores
Guilherme, Bergaro Sagula de Almeida
Orientador
Peralta, Marvin Marco Chambi
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Texto completo (DOI)
Palavras-chave
sinterização,aditivo,alumina,sintering,additive,alumina
Resumo
Neste trabalho, investigou-se o efeito da adição de TiO2 e CuO sobre a sinterização de dois tipos de alumina com diferentes tamanhos médios de partícula: CT3000SG (D50=0,6 micrometros) e CL370 (D50= 2,5 micrometros). Foram preparadas, por colagem de barbotina em molde de gesso, amostras de alumina contendo 3, 5 e 7% em massa de aditivo, formado por uma mistura de TiO2 e CuO em uma proporção de 4:1 em massa, respectivamente. Após secagem, as amostras foram desmoldadas e sinterizadas a 1350°C, com patamar de 1 hora, seguido de resfriamento natural. Antes da etapa de sinterização as amostras foram caracterizadas por dilatometria, com taxa de aquecimento de 10°C/min até 1400°C onde estabeleceu-se um patamar de 10 minutos seguido de resfriamento sem controle. Após a sinterização, a análise macrográfica foi realizada com estereoscópio, tendo a densidade e
porosidade aparente sido determinadas pelo método de Arquimedes. Os resultados dos ensaios de dilatometria mostraram que a temperatura de sinterização da alumina CT3000SG pode ser reduzida de 1550°C para 1300°C pela adição de 3% em massa da mistura de TiO2 e CuO, alcançando 97% da densidade teórica. No caso da CL370, a adição de 5% do aditivo reduziu a temperatura de sinterização para, aproximadamente, 1350°C, obtendo 94% da densidade teórica. A análise macrográfica revelou a presença de macro segregação, crescimento dendrítico e óxido residual em ambas as amostras. A alumina CL370, que apresenta distribuição bimodal, apresentou menor contração durante a sinterização, provavelmente devido a sua menor área superficial específica. Nesta alumina foi observado também maior teor de óxido residual. As amostras com adição de 5 e 7% do aditivo da CT3000SG apresentaram o fenômeno overfiring cujas características são o crescimento anormal de grão e expansão após a contração durante a sinterização. Os resultados indicam que o sistema de aditivos estudado pode levar à redução da temperatura de sinterização da alumina, o que pode trazer benefícios energéticos,
econômicos e técnicos para as indústrias, como por exemplo em aplicações de materiais com gradação de funcionalidade (MGF), quando necessária a redução da temperatura de sinterização da alumina para compatibilidade com os outros componentes.
In this study, the effect of TiO2e CuO addition on sintering behavior of two types of alumina (CT3000SG, D50= 0,6 m; CL370, D50= 2,5 m) was investigated. Alumina samples containing 3, 5 and 7% of wight percentage of additive, formed by a mixture of TiO2and CuO in a ratio of 4:1 by weight, respectively, were prepared by slipcastingin a plaster mold. After drying, the samples were demoldedand sintered at 1350°Cfor one hour, followed by natural cooling. The sintered samples were previously characterized by dilatometry, with a heating rate of 10°C/min to 1400°C, where this temperature was held for 10minutesfollowed by uncontrolled cooling. The macrographic analysis was performed with a stereoscope, beingthe density and apparent porosity determinedby the Archimedes method. The results of the dilatometry tests revealedthat the sintering temperature of the CT3000SGalumina can be reduced from 1550°C to 1300°C byadding 3% by weightof the mixture of TiO2and CuO, reaching 97% of the theoretical density. In the case of CL370, the addition of 5% of the additive reduced the sintering temperature to approximately 1350°C, obtaining 94% of the theoretical density. The macrographic analysis revealed the presence of macro segregation, dendritic growth and residual oxide in both samples. The CL370 alumina, which has a bimodal distribution, showed a fewer contraction during sintering, probably due to its smaller specific surface area, as wellashigher residual oxide content was observed. The CT3000SG samples with 5 and 7%additionhave shownthe overfiring phenomenon whose characteristics are the abnormal growth of grain and expansion after contraction during sintering. The results indicate that the studied additive system couldlead to a reduction in the alumina sintering temperature, which can bring economic and technical benefits to the industries, such as in applications of Functionally Graded Materials (FGM)when it isnecessary to reducealumina sintering temperature for compatibility with other components.
In this study, the effect of TiO2e CuO addition on sintering behavior of two types of alumina (CT3000SG, D50= 0,6 m; CL370, D50= 2,5 m) was investigated. Alumina samples containing 3, 5 and 7% of wight percentage of additive, formed by a mixture of TiO2and CuO in a ratio of 4:1 by weight, respectively, were prepared by slipcastingin a plaster mold. After drying, the samples were demoldedand sintered at 1350°Cfor one hour, followed by natural cooling. The sintered samples were previously characterized by dilatometry, with a heating rate of 10°C/min to 1400°C, where this temperature was held for 10minutesfollowed by uncontrolled cooling. The macrographic analysis was performed with a stereoscope, beingthe density and apparent porosity determinedby the Archimedes method. The results of the dilatometry tests revealedthat the sintering temperature of the CT3000SGalumina can be reduced from 1550°C to 1300°C byadding 3% by weightof the mixture of TiO2and CuO, reaching 97% of the theoretical density. In the case of CL370, the addition of 5% of the additive reduced the sintering temperature to approximately 1350°C, obtaining 94% of the theoretical density. The macrographic analysis revealed the presence of macro segregation, dendritic growth and residual oxide in both samples. The CL370 alumina, which has a bimodal distribution, showed a fewer contraction during sintering, probably due to its smaller specific surface area, as wellashigher residual oxide content was observed. The CT3000SG samples with 5 and 7%additionhave shownthe overfiring phenomenon whose characteristics are the abnormal growth of grain and expansion after contraction during sintering. The results indicate that the studied additive system couldlead to a reduction in the alumina sintering temperature, which can bring economic and technical benefits to the industries, such as in applications of Functionally Graded Materials (FGM)when it isnecessary to reducealumina sintering temperature for compatibility with other components.