Simulation of deformation of layered sheet during micro powder imprinting process

This paper reports simulation of deformation during micro powder imprinting process, which is a newly developed process to form micro patterned surface on ceramic sheets. The process is proposed as a combined process of traditional hot-embossing and powder metallurgy. A compound sheet of powder material and polymer binder is pressed by a mold to be transcribed a micro-pattern on its surface. After pressing, the binder is removed by heating, and the sheet is sintered. Finally dense ceramic sheet with fine pattern can be obtained. This process can be used also for layered sheet of two different materials. By using this layered sheet, we can make a pattern not only on the surface of the upper layer but also along the interface between each layer. Of course, the same pattern with the mold’s shape can be transcribed on the surface, while, there can be found another micro pattern along the interface. These two patterns of the surface and the interface are useful to fabricate ceramic sheet with patterns on its both surfaces. For example, if a compound sheet was used as an upper layer and a pure organic sheet as a lower, the lower organic layer can act as a sacrificed layer. After debinding and sintering, only the upper layer remains, which has micro-patterns on the both sides. The shape of interface between layers can be controlled by changing properties of layers. It could be also influenced by the imprinting conditions, such as temperature and pressure. In order to design the shape of the interface, finite element analysis was employed in the present paper. Mooney-Rivlin’s deformation model was used to express deformation of materials during imprinting. In this paper, we compared the simulated results with experimental data to show effectiveness of the present simulation method

Micrometer-scale Imprinting Process for Ceramic Sheet from Powder Compound Material

AbstractA micro patterning process for thin ceramic sheets is proposed and developed in this paper. Thin sheets with a micro pattern have been expected to improve performance of solid oxide fuel cell. The authors focused on imprinting and powder metallurgy processes, and have developed the combined process, which has been named micro powder imprinting process. In this process, ceramic powder and polymer binder materials are mixed with pure water by milling machine. After drying out the water from the slurry, a thin compound sheet was obtained. Subsequently, the sheet was pressed using a fine patterned mold with heating to transcribe a micro pattern on the sheet. Finally, the imprinted sheet was heated for removing the polymer binder and for sintering. As further improvement of the process, a compound sheet was stacked on a pure polymer sheet during the imprint process to transcribe a micro pattern on the both sides of the sintered sample. The technique is useful for improved solid oxide fuel cell

SCANNING ELECTRON MICROSCOPIC STUDIES ON THE DIRECT BONDING SYSTEM

To study the bonding mechanism and tooth damage in direct bonding of brackets to the tooth surface (Direct Bonding System), a scanning electron microscope was used to observe teeth in vivo. It was found that polishing removed the cuticle, the presence of which affected bonding strength. The creation of many microscopic crevices through acid etching, combined with the application of silane and adhesive, aided in the penetration and firm contact necessary for a strong bond. From the observations, it was concluded that tooth surface damage in the bonding mechanism of DBS was negligible