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

Fabrication and mechanical characterization of biocompatible oxide ceramic parts by injection molding

In this study, we proposed a new fabrication method of artificial bone materials using Ceramic Injection Molding (CIM) and verified the mechanical properties of the fabricated compacts. Since ceramic parts can be machined in the green parts from CIM, it is possible to manufacture custom-made artificial bones that match the defective parts. The porosity of sintered compacts affected cell growth. Thus, powder loading, binder composition, and content were changed for controlling the porosity of sintered compacts. As a result, it was confirmed that porosity and mechanical properties were controlled. Bending strength slightly decreased with increasing porosity, however, it is enough for artificial bone

Improvement in thermal conductivity and mechanical properties for polyamide-6 composite including carbon fiber and alumina particle

In this study, we will report the efficiency of hybrid filler for the mechanical properties and the thermal conductivity of Polyamide-6 (PA6) composite. One of the ways to improve the thermal conductivity of the composite is to add fillers to the matrix, but the excessive filler causes the composite to form aggregation and void. They make the mechanical properties and thermal conductivity decline. As the solution to this problem, to use of hybrid filler is expected to realize the lower filler content of composite with keeping the properties. However, the most efficient ratio of hybrid filler is unclear. In this study, PA6 and filler were composited using a twin-shaft melt-mixing machine. A manual injection molding machine was then used to produce test specimens for thermal conductivity measurement and tensile test specimens. Thermal conductivity was measured based on the laser flash method. The structure of the composite was also investigated by fracture surface observation after tensile testing. It is revealed that two types of fillers were composited with PA6 to obtain higher thermal conductivity than that of a single filler with the same filler content. This is because the different shapes of the two fillers made the thermally conductive path

Hierarchical patterning by multi-step micro-imprinting with layered materials

The objective of the work reported in this paper is to create multi-scale and hierarchical surface structures using a simple imprinting process. The hierarchical structures can be fabricated with only simple patterned molds by proposed multi-step imprinting process, instead of using a high cost hierarchical-patterned mold. In the proposed process, the starting material is a layered sheet material. The layered sheet is pressed by a mold with a finer pattern, and subsequently pressed by a mold with a rougher pattern. A pure polymer sheet is employed as the upper layer, which will be removed during heating processes as a sacrificed layer, while the lower layer is a compound material of polymer and ceramic powder. After heating process, ceramic compact is sintered and formed a full-dense patterned sheet. By the proposed multi-step imprinting process with a layered material, ceramic sheets with micro hierarchical pattern can be fabricated with low cost. In the present work, poly(vinyl alcohol) (PVA) was prepared as the upper layer, and a compound material of alumina powder and PVA as a lower layer. Molds with finer and rougher patterns were also prepared for multi-step imprinting. As a result, a hierarchical structure on a thin ceramic sheet could be fabricated