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注射成型外文文献和中文翻译

时间:2017-09-30 15:10来源:毕业论文
Micro system and miniaturization technology is regarded as one of the key technologies for the future. Microstructures have become increasingly dominant in every aspect of commercial marketplace, e.g., micro fluidic, biomedical, bioethical,
Micro system and miniaturization technology is regarded as one of the key technologies for the future. Microstructures have become increasingly dominant in every aspect of commercial marketplace, e.g., micro fluidic, biomedical, bioethical, and telecommunications, as the technologies for micro fabrication continue to be developed. Replication methods like embossing and micro plastic injection molding are very suitable for mass production and already provide polymer microstructures for a reasonable price to micro system technology [1, 2]. However, many applications require the production of medium and large volumes of metal or ceramic microstructures with better mechanical, thermal, chemical, and electrical properties [3–6]. Since the end of the last century, one potential process that could meet this requirement, micro powder injection molding, has gained increasing attention.14007
Micro powder injection molding evolved from powder injection molding, a technique combining plastic injection molding technology and powder Metallurgy. Typically, μPIM has the same processing steps as PIM: mixing, injection molding, rebinding, and sintering, as shown in Fig. 1 [7]. Fine metal or ceramic powder is mixed with a binder system to form the feedstock. The granulated feedstock is injection molded into an injection mold cavity with fine details or micro cavities to form the molded part. Eventually the molded part is rebound and sintered.
  For the injection molding step, incomplete filling was one of the key factors hindering the successful production of microstructures [1, 8]. In this research, μPIM was used to produce 316L stainless steel microstructures. The effects of injection molding parameters on the filling of the micro cavities were investigated.
2. EXPERIMENTAL MATERIALS
316L stainless steel feedstock with polyacetal-based binder system was used. The powder has a particle size of D50= 4 μm. As shown in Fig. 2, a round disc of 16mm and thickness 1.5mm with an array of 100 μm × height 200 μm microstructures at the center was injection molded. To replicate the microstructures, a 5mm× 5mm × 0.65mm silicon mold insert with 24 × 24 (576) micro cavities was used. The micro cavities were produced using deep reactive ion etching (DRIE). A scanning electron micrograph of the micro cavity cross-section is shown in Fig. 3. At the entrance of the micro cavity there was a taper of 4 that facilitates the remolding of the microstructures. 源自六`维`论^文-网.加7位QQ3249^114 www.lwfree.cn
3. EXPERIMENTAL PROCEDURE
Before injection molding, thermal and rheological characterizations of feedstock including differential scanning calorimetric (DSC) test, thermo gravimetric analyzer (TGA) test, and capillary remoter test were conducted to determine possible range of melt and mold temperatures. Thus, the initial injection molding parameters could be established. A conventional injection molding machine was used to injection mold the microstructures. This machine had four heating zones (nozzle, zone 1, zone 2, and zone 3). Consequently, the setting of melt temperature profile had four values. In the injection molding experiments, five sets of experiments were conducted by varying one parameter at a time: injection pressure, holding pressure, holding time, mold temperature, and melt temperature. When a parameter was changed from one value to another, the injection machine was allowed to stabilize for 10 minutes before injection molding was conducted. Further, after changing a parameter, the first five parts were not used for evaluation so that representative parts were used for subsequent mass measurements. For each parameter, five molded parts were collected for analysis. The mass variations with different values of the five injection molding parameters were measured using Mettles PB303 weighing equipment. After injection molding, the molded part was remolded at a suitable remolding temperature and rebound catalytically using 100% nitric acid at a temperature of 120℃. Finally, the rebound microstructure part was sintered at the temperature of 1300℃ under vacuum for 60 minutes. 注射成型外文文献和中文翻译:http://www.lwfree.cn/fanyi/20170930/14409.html
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