論文中英文翻譯對(duì)照通過注射成型制造壓電陶瓷聚合物復(fù)合材料(已改無錯(cuò)字)
2022-08-24 12:11:27 本頁面
【正文】 gh volumes. In general, because of the high initial tooling cost, the ceramics injection molding process is best applied to plexshaped ponents which require low cost in high volumes. Figure 1 : Injection Molding Process Route. Figure 2: Preform Approach to Composite Fabrication.Composite Fabrication and EvaluationThe approach taken to fabricate 13 piezoelectric posites is shown in Figure 2a, which illustrates a PZT ceramic preform concept in which fiber positioning is achieved using a comolded integral ceramic base. After polymer encapsulation the ceramic base is removed by grinding. Aside from easlng the handling of many fibers, this preform approach allows broad latitude in the selection of piezoelectric ceramic element geometry for posite performance optimization. Tool design is important for successful injection molding of piezoelectric posites. The approach shown in Figure 2b uses shaped tool inserts to allow changes in part design without incurring excessive retooling costs. Figure 2c shows how individual preforms are configured to form larger arraysIn practice, material and molding parameters must be optimized and integrated with injection molding tool design to realize intact preform ejection after molding. Key parameters include: PZT/binder ratio, PZT element diameter and taper, PZT base thickness, tool surface finish, and the molded part ejection mechanism design. In order to evaluate these process parameters without incurring excessive tool cost, a tool design having only two rows of 19 PZT elements each has been adopted for experimental purposes. Each row contains elements having three taper angles (0, 1 and 2 degrees) and two diameters ( and l mm). To acmodate molding shrinkage, the size of the preform is maintained at 5Ox50mm to minimize the possibility of shearing off the outermost fibers during the cooling portion of the molding cycle.Figure 3 shows green ceramic preforms fabricated using this tool configuration. Note that all of the PZT elements ejected intact after molding, including those having no longitudinal tapering to facilitate ejection. Slow heating in air has been found to be a suitable method for organic binder removal. Finally, the burnedout preforms are sintered in a PbOrich atmosphere to 9798% of the theoretical density. No problems have been encountered with controlling the weight loss during sintering of these posite preforms, even for those finescale, highsurface area preforms which are intended for high frequency ultrasound.Figure 4 illustrates the surfaces of asmolded and assintered fibers, showing the presence of shallow fold lines approximately 10pm wide, which are characteristic of the injection molding process. The fibers exhibit minor grooving along their length due to ejection from the tool. Figure 5 shows the capability of near netshape molding for fabricating very fine scale preforms。 PZT element dimensions only 30pm wide have been demonstrated. The assintered surface of these elements indicates that the PZT ceramic microstructure is dense and uniform,n consisting of equiaxed grains 23pm in diameter. Figure 3: Injection Molded 13 Composite Preforms. Figure 4: Scanning Electron Micrographs of Asmolded(Upper) and Assintered (Lower) Surfaces of PZT Fibers Figure 5: Finescale 22 Composite formed by Near Netshape olding (Upper Micrograph). Assintered Surface(Lower Micrograph).In order to de
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