Efeito dos parâmetros de retificação no acabamento superficial de cerâmicas avançadas

Abstract

RESUMOAs cerâmicas avançadas apresentam uma ampla aplicação, desde componentes para a indústria eletrônica até implantes e próteses. Nas últimas décadas a biocerâmica vem chamando atenção em aplicações como próte-ses ósseas e implantes dentários, pois apresentacaracterísticas de material bioinerte, bioativo, com boa biocompatibilidade, além de alta resistência à compressão. Neste trabalho, estudou-se o efeito dos parâmetros de retificação em cerâmicas de alta alumina preparadas com três granulometrias diferentes, através da análise do acabamento superficial destas cerâmicas. Durante o processo de retificação, os parâmetros variados foram: velocidade da peça (55 mm/s e 250 mm/s) e profundidade de corte (5 µm e 60 µm). Além destes parâmetros, empregaram-se dois tipos de lubri-refrigeração: convencional e MQL (Mínima Quantidade de Lubrificante). Os resultados obtidos através de medidas de rugosidade da superfície retificadae análises estatísticas mostram que houve uma redução na rugosidade das peças com granulometria media e fina quando se utilizou a lubrirefrigeração MQL. As cerâmicas de granulometria fina retificadas com velocidade da peça de 55 mm/s e profundidade de corte de 60 µm apresentaram rugosidade inferior a 0,28 µm usando o sistema de lubrirefrigeração MQL. Porém quando retificadas em velocidades maiores utilizando MQL as cerâmicas de granulometria mais fina apresentaram um aumento nos valores de rugosidade.Palavras-chave: cerâmica, alumina, retificação. ABSTRACTThe advanced ceramics shows a wide application, from components for the electronic industry to implants and prostheses. In the last decades the bioceramic has been drawing attention in applications such as bone prostheses and dental implants because it presents bioinert and bioactive material characteristics, with good biocompatibility, and high compressive strength. We studied the effect of grinding parameters for ceramics with high alumina, prepared with three different particle sizes by examining the surface finish of these ceramics. During the grinding process, the parameters were: table speed (55 mm / s 250 mm / s) and the depth of cut (5 µm and 60 µm). Apart from these parameters, two cooling types were used: conventional cooling and MQL (Minimum Quantity Lubricant). The results obtained through the roughness of the grinded surface and statistical analyzes showed a reduction in the roughness of the parts with small and medium grain size when using MQL cooling. The ceramics with small grain size grinded with a table speed of 55 mm/s and depth of cut of 60 µm showed roughness of less than 0.28 µm using the MQL cooling system. However, when grinded at higher speeds using MQL the ceramics with smaller grain size showed an increase in surface roughness values.

Evaluation of the self-healing capacity of ceramics produced with alumina and silicon carbide

“…The self-healing property also allows these materials to be used to protect or reduce oxidation or corrosion, as a self-healing protective coating, or even to improve mechanical properties [5][6][7]. The self-healing process would be a great advance in the use of ceramic materials, since it is known that the mechanical properties of these materials limit their use in some applications because they are subject to catastrophic fractures in a fragile way, with little energy absorption [8]. Therefore, studies have been carried out to create a ceramic material with the capacity of self-healing, and so providing a longer useful life and, consequently, an increase in the applicability of advanced ceramics [2,8].…”

“…The self-healing process would be a great advance in the use of ceramic materials, since it is known that the mechanical properties of these materials limit their use in some applications because they are subject to catastrophic fractures in a fragile way, with little energy absorption [8]. Therefore, studies have been carried out to create a ceramic material with the capacity of self-healing, and so providing a longer useful life and, consequently, an increase in the applicability of advanced ceramics [2,8]. This technology can also become economically viable, since the self-healing process would reduce the replacement and exchange of parts with some superficial defect, influencing its functionality.…”