Vol.11 No.2 2018

報告:Additive manufacturing of ceramic components (大司)−84−Synthesiology Vol.11 No.2(2018)the produced materials, wide shape flexibility, and high dimensional accuracy of the obtained products. In addition, material density (or porosity) can be adjusted over a wide range by combining these two approaches. Typical forming procedure of PLM is shown in Fig. 3. It consists of the following: (1) Mixing ceramic powder and polymer binder and putting them in the supply part, (2) Supplying the mixed powder to the forming stage and smoothing them using a squeegee (Fig. 3) or a roller to make a thin layer (typically ~0.1 mm), (3) Melting the binder of the desired part by scanning laser heat and bonding the ceramic powder, (4) Lowering the forming part by the formed layer thickness, (5) Repeating the above process of (2) to (4) for a 3D green body of a desired shape, and (6) Dewaxing and post sintering the obtained green body in a conventional furnace. PLM is a dry forming process itself and does not need a drying process of a wet body which often leads to undesired distortion and deformation of a green body. This, therefore, is advantageous particularly in making large-scaled products. On the other hand, the lack of uidity of powder results in low density of green and sintered bodies, indicating that PLM is suitable for producing porous bodies. For example, a previous study on similar AM approaches for alumina showed that the green and sintered densities are around 30 % and 40 %, respectively.[19] It has been reported that the sintered density was substantially improved to 80 % or more when additional treatments of warm isostatic press and slurry infiltration on the green bodies were done; however, it is essentially important to increase the densities without such treatments in view of industrial application. For this purpose, in the HCMT project, we adjust and optimize the whole process from powder preparation (binder selection, powder mixture, powder fluidity evaluation, etc.) and lamination (powder supply, laser irradiation, etc.) to post-process (dewaxing, Binder jetting(Aka, 3D printing)Liquid binder through a nozzle is selectively deposited to join powder materials.Material jettingDroplets of build material through a nozzle are selectively deposited.Powder bed fusion(Selective lasersintering, PLM)Heat, typically of laser, selectively fuses area of a powder bed.Sheet lamination(Laminated object manufacturing)Sheets of material are bonded and selectively cut by laser.Material extrusion (Fused deposition modeling)Flowable material is selectively dispensed through a nozzle or orice.Vat photo-polymerization (Stereolithography, SLM)Liquid photopolymer in a vat is selectively cured by light, typically of laser.Directed energydepositionFocused heat, typically of laser, selectively fuses materials as being deposited.LaserPowderNozzleFlowable materialNozzleMaterial dropletNozzleLaserPowderPowder supplySheet supplyLaserSheetNozzleBinderPowderPowder supplyLaserPhoto-polymerFormed bodyFormed bodyFormed bodyFormed bodyFormed bodyFormed bodyFormed bodyMethodOutlineTable 1. Classication of additive manufacturing technologies, according to ASTM F2792-12a

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