Search

In this study, we investigated the feasibility of injection molding (IM) and injection compression molding (ICM) for fabricating 3.5-in. light-guided plates (LGPs). The LGP was 0.4 mm thick with v-grooved microfeatures (10 μm wide and 5 μm deep). A mold was designed to fabricate LGPs by IM and ICM. Micromachining was used to make the mold insert. The Taguchi method and parametric analysis were applied to examine the effects of the process parameters on the molding quality. The following parameters were considered: barrel temperature, mold temperature, packing pressure, and packing time. Mold temperature in this investigation was in the conventional range. Increasing the barrel temperature and mold temperature generally improved the polymer melt fill in the cavities with microdimensions. The experimental results for the replication of microfeatures by IM and ICM are presented and compared. The height of the v-grooved microfeatures replicated by ICM was more accurate than those replicated by IM. Additionally, the flatness of the fabricated LGPs showed that ICM was better than IM for thin-walled molding. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011

This investigation applies metal injection molding (MIM) to fabricate precise microcutters from W-Ni-Fe alloy powder. The hard and brittle W-Ni-Fe alloy is difficult to machine, and MIM must be applied to produce near net-shaped products. MIM involves the injection molding of feedstock by blending metal powder and binders, debinding, and sintering. Liquid-phase sintering is commonly adopted to improve the density and mechanical properties of the sintered parts, but it is inferior in terms of dimensional stability. This study elucidates the dimensional stability of sintered parts made from W-Ni-Fe alloy feedstocks that contain 83 and 93 wt% W. The powder injection molding of microcutters that demand micrometer-scale precision is considered as an example. The Taguchi method is utilized to optimize injection molding and sintering parameters, effectively optimizing the dimensional stability and mechanical properties. Experimental results show that (1) feedstock with 93 wt% W exhibited little and consistent shrinkage (25%–26%); (2) the optimal injection molding parameters determined by the Taguchi method yield an eccentricity of over 18%, and (3) in the sintering process, low heating rate significantly improves dimensional stability. The average hardness of microcutters, sintered at various heating rates, ranges from Vickers hardness 446 to 452.

Polycrystalline Mn-doped, Nb-doped, and pure BiFeO3 (BFO) films were fabricated via chemical solution deposition (CSD) method. Influence of Mn and Nb dopants on electric properties of BFO films were studied. The current density versus electric field (J-E) characteristics indicated that conduction mechanisms of Mn-doped, Nb-doped, and pure BFO films annealed at 500°C were Ohmic conduction, grain boundary limited conduction, and space charge limited conduction, respectively. The effect of Mn and Nb dopants on electric properties of BFO films was interpreted by defect chemistry and chemical reaction in the CSD process. The Nb dopant is effective in improving electrical properties of CSD-derived BFO films, while Mn is harmful in this respect.