Efeito dos parâmetros de retificação no acabamento superficial de cerâmicas aplicadas à biomateriais
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Data
2016-02-05
Autores
Rodrigues, Ana Cláudia [UNESP]
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Editor
Universidade Estadual Paulista (Unesp)
Resumo
As cerâmicas avançadas apresentam uma ampla aplicação, desde componentes para a indústria eletrônica até implantes e próteses. Nas últimas décadas a biocerâmica vem chamando atenção como próteses ósseas e implantes dentários, pois pode ser um material bioinerte, bioativo, apresentar boa biocompatibilidade, além de alta resistência à compressão. Neste trabalho, estudou-se o efeito dos parâmetros de retificação por meio da análise do acabamento superficial em cerâmicas de alumina comercial e de alta alumina preparadas com três granulometrias diferentes. Para a alumina comercial os parâmetros de retificação variados foram profundidades de corte (sendo sete valores) e a velocidade da peça (58 mm/s e 125 mm/s). Os resultados obtidos de medidas de rugosidade da superfície retificada mostraram melhores resultados de rugosidade quando as peças foram submetidas às profundidades de 50 µm e 105 µm e com a velocidade de 125 mm/s, este fato pode estar associado a um menor dano superficial gerado durante o processo retificação. Entretanto, quando a profundidade de corte foi elevada até 350 µm para ambas as velocidades, existiu um aumento substancial da rugosidade, isso pode estar relacionado a defeitos superficiais irreparáveis como trincas e arrancamentos de aglomerados de grão. Para a cerâmica de alta alumina os ensaios foram divididos em duas etapas. Na primeira etapa, os parâmetros de retificação variados foram velocidade da peça (55 mm/s e 250 mm/s) e a profundidade de corte (5 µm e 60 µm). Além dos parâmetros variados, empregaram-se dois tipos de refrigeração convencional e MQL (mínima quantidade de lubrificante). Os resultados obtidos das medidas de rugosidade da superfície retificada e dos dados estatísticos, mostraram que houve uma redução na rugosidade das peças com granulometria media e fina quando se utilizou a refrigeração MQL. As cerâmicas de granulometria fina retificadas com velocidade de 55 mm/s e profundidade de 60 µm apresentaram rugosidade inferior a 0,28 µm usando o sistema de refrigeração MQL. Porém quando retificadas em velocidades maiores utilizando MQL as cerâmicas de granulometria mais fina apresentaram um aumento nos valores de rugosidade. Na segunda etapa foram utilizadas as mesmas velocidades para a mesa, a profundidade de corte além das já utilizadas na primeira parte foi acrescentada mais uma de 110 µm e foi usado apenas o fluido convencional. Foi possível observar que houve um comportamento linear para as três profundidades de corte e que os grãos se comportaram de acordo com sua granulometria, ou seja, o grão grosso apresentou maior rugosidade que o grão mais fino. Independentemente das profundidades de corte ou velocidades da mesa, as cerâmicas fabricadas com grãos de menor granulometria apresentaram sempre a menor rugosidade.
Advanced ceramics have a wide application, from electronics components to implants and prostheses. In the recent decades, bioceramic has been drawing attention as bone prostheses and as in dental implants, because this kind of material is bioinert, bioactive and can show good biocompatibility, as well as high compressive strength. In this present assignment, it was studied the griding parameters effects through the analysis of the superficial finishing in commercial alumina and high alumina ceramics prepared with three different particle size. For commercial alumina, the griding parameters varied between depth of cut (seven different values) and workpiece speed (55 mm/s e 125 mm/s). The results obtained through roughness measures of the grinded surfaces showed better results when the workpieces were submitted to 50 µm and 105 µm depth and 125 mm/s speed, this fact can be associated with a smaller superficial damage generated in the grinding process. However, when the depth of cut was high to 350 µm for both speeds, there was a substantial rise in the roughness, which can be associated to irreparable superficial defects such as cracks and pull-outs of grain agglomerate. For high alumina ceramics the tests were split in two parts: part A and part B. In part A, the variable grinding parameters were workpiece speed (55 mm/s e 250 mm/s) and depth of cut (5 µm e 60 µm). Besides the varied parameters, two types of refrigeration were used, the conventional and the MQL (Minimum Quantity of Lubricant). The results obtained trough roughness measures of the grinding surface as well as from statistics data show that there was a reduction on the roughness of the medium and thin particle size workpieces when the MQL refrigeration was used. The thin particle size ceramics were grinded with 55 mm/s speed and 60 µm depth and showed roughness below 0,28 µm, using the MQL system. For part B, it were used the same speeds for workpiece, depth of cut, and besides that, it was added another one of 110 µm, using the conventional fluid It was observed that there was a linear behavior for the three depths of cut and the grain behave according to their particle size, i.e., the coarse showed a higher surface roughness than the finer grain. Apart of the cut depths and workpiece speeds, the ceramics fabricated with smaller particle size grains always showed the smallest roughness.
Advanced ceramics have a wide application, from electronics components to implants and prostheses. In the recent decades, bioceramic has been drawing attention as bone prostheses and as in dental implants, because this kind of material is bioinert, bioactive and can show good biocompatibility, as well as high compressive strength. In this present assignment, it was studied the griding parameters effects through the analysis of the superficial finishing in commercial alumina and high alumina ceramics prepared with three different particle size. For commercial alumina, the griding parameters varied between depth of cut (seven different values) and workpiece speed (55 mm/s e 125 mm/s). The results obtained through roughness measures of the grinded surfaces showed better results when the workpieces were submitted to 50 µm and 105 µm depth and 125 mm/s speed, this fact can be associated with a smaller superficial damage generated in the grinding process. However, when the depth of cut was high to 350 µm for both speeds, there was a substantial rise in the roughness, which can be associated to irreparable superficial defects such as cracks and pull-outs of grain agglomerate. For high alumina ceramics the tests were split in two parts: part A and part B. In part A, the variable grinding parameters were workpiece speed (55 mm/s e 250 mm/s) and depth of cut (5 µm e 60 µm). Besides the varied parameters, two types of refrigeration were used, the conventional and the MQL (Minimum Quantity of Lubricant). The results obtained trough roughness measures of the grinding surface as well as from statistics data show that there was a reduction on the roughness of the medium and thin particle size workpieces when the MQL refrigeration was used. The thin particle size ceramics were grinded with 55 mm/s speed and 60 µm depth and showed roughness below 0,28 µm, using the MQL system. For part B, it were used the same speeds for workpiece, depth of cut, and besides that, it was added another one of 110 µm, using the conventional fluid It was observed that there was a linear behavior for the three depths of cut and the grain behave according to their particle size, i.e., the coarse showed a higher surface roughness than the finer grain. Apart of the cut depths and workpiece speeds, the ceramics fabricated with smaller particle size grains always showed the smallest roughness.
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Palavras-chave
Alumina, Cerâmica, Retificação, Ceramic, Grinding