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1、毕业设计(论文)外文资料翻译系部： 机械工程系 专 业： 机械工程及自动化 姓 名： 学 号： 外文出处： A. Safari and D. J. Waller, Fine Scale PZT Fiber/Polymer Composites” 附 件： 1.外文资料翻译译文；2.外文原文。 指导教师评语：译文准确，条理比较清楚，语句较通畅，基本能符合汉语的习惯。专业用语翻译较为准确，整体翻译质量较好。 签名： 年 月 日附件1：外文资料翻译译文通过注射成型制造压电陶瓷/聚合物复合材料Leslie J. Bowen 和 Kenneth W. French原料系统(有限)公司摩洛哥康考德希尔克雷
2、斯特大道53号, 邮编01742摘要宾夕法尼亚州立大学材料研究室的研究已经证明通过使用压电陶瓷/聚合物复合材料可以改进检漏器(水诊器)潜能。作为美国海军研究局的资助计划的一部分，旨在开发针对这些合成物且具有成本效益制造技术，材料系统正在寻求一种陶瓷制造方法的注射成型。本文简要概览了陶瓷注射成型过程的关键细节，并且记叙了制造压电陶瓷/聚合物复合材料的步骤及方法论。注射成型压电陶瓷的设备和应用程序都是区别于传统的材料的加工。绪论压电陶瓷/聚合物复合材料提供了设计的多功能性和性能优势，在遥感和驱动应用方面都超越单独的陶瓷与聚合物的压电材料。这些合成物已经被开始用于高解析度超声医学以及海军的发展应用。
3、在过去的十三年里，许多复合的配置已经按照一个实验室的规模被构造且评估。其中最成功的组合之一，被指定复合物的纽纳姆号，有一个三维连接陶瓷阶段(压电纤维)内含三维连接有机聚合物的阶段。检漏器的性能系数可使得这个复合物超过那些通过适当选择阶段特征和复合结构的固体材料10000倍。 宾州州立大学复合物的制备是通过在一个跳汰机和封装环氧树脂中手调挤压压电陶瓷棒，之后限制适当的厚度并极化陶瓷。除了这种材料所展示出的性能优势，宾州州立大学的工作所凸显的问题涉及合成物的大规模制造或者甚至以原型为目的。这些是：(1)在通过聚合物封装时大量的压电陶瓷光纤的库存和供给需求。(2)在极化过程中发生率高的介电击穿是起于
4、在一个典型的大型阵列遇到一个或多个有缺陷的纤维的显著概率。在过去的五年里，为了提高制造行业的生存能力并降低材料成本已经多次尝试简化传感器的组装工艺。早期的尝试包括将压电陶瓷的固体块切割至理想的配置和聚合体阶段的空缺回填。这项技术已经被超声医学工业接受并用于制造高频传感器。最近，纤维材料公司已经证明了其用于纤维增强复合材料的编织技术在装配压电材料方面的适应性。另外的一项探索技术涉及复制多孔织物已经有适当的连通性。对于极其精密尺度的复合材料，纤维的直径大约为20至100微米，长宽比大于5以满足装置性能需要的目标。因此，这些困难再加上额外的成型与处理庞大数量且无缺陷的极其精细的纤维的挑战。最近，西门
5、子公司的研究人员表明非常精密尺度的复合材料可以通过一种不定的模具技术来制造。然而，这种方法需要为每一个部分制造一个新的模具。本文介绍一种压电复合加工的新方法，即:陶瓷注射成型。陶瓷注射成型无论对海军的压电陶瓷/聚合物复合材料或是对于极其加工规模的压电复合材料(如那些所需的高频超声医疗及无损评估)都是一种具有成本效益的制造方法。注塑成型过程克服了通过网型预成型陶瓷纤维整列使装配导向陶瓷纤维进入复合材料传感器的困难。除了这个优势，该方法使得比那些以前的设想具有更复杂陶瓷元素几何的复合传感器成为可能，以致产生了为提高声阻抗匹配性的更高的设计柔性以及横向模式的取消。过程描述注塑成型被广泛应用于塑料行业
6、作为一种较低成本、形状复杂的迅速大规模生产。此种方法最适合应用于陶瓷小截面形状，例如线程导向，以及无需烧结至很高密度的大而复杂的形状，如涡轮机的叶片铸造插入。最近，这种方法已被研究用作生产热发动机涡轮部件的技术。如图1所示，注塑成型方法已被用于压电陶瓷的成型。通过将热塑性塑料与陶瓷粉末的混合物有机结合并注入一个冷却模具，复杂的形状就能方便且快速的正常与塑料结合成型。预防例如像金属接触硬化的表面，尽量减少金属从混和与成型器械受到的污染。对于陶瓷，型腔必须无损拆除，迫使高的固体载荷，严格控制型腔移除的过程，以及适当的夹具。一旦型腔移除，随后点火，极化并且环氧树脂的封装过程是和那些常规压电陶瓷/复合
7、材料类似。因此，此方法在替代制造路线上提供了很大优势：复杂，能够同时处理许多纤维的近似网状；快速的生产能力(通常是一部分几秒)；统计过程控制的兼容性；材料的低浪费；有关传感器设计的柔性(允许PZT中元素空间和形状的变化)；以及在中量至大量之间的低成本。一般来说，由于最初加工的高成本，陶瓷注射成型的方法是最适用于复杂形状的构成，需要低成本大批量。 图1 注射成型过程流程 图2 制作合成物的预成型方法 合成物的制造及评价制造1-3压电复合材料的方法如图2a所示，这阐述了使用一个完整的陶瓷胚型到纤维定位作用的压电陶瓷预先成型的概念。在聚合物封装后采用磨削去除陶瓷胚。除了简化许多纤维的处理，这种预先成
8、型的方法允许广泛地选择压电陶瓷元素几何元素范围，以使其性能最优化。工具的设计是取得注塑压电复合材料成功的重要因素。如图2b所示的方法使用了无需导致额外重组成本的嵌入式的并允许局部变化的设计。图2c所示如何配置个别的预加工的成品以形成大批生产在实践中，材料和成型参数必须最优化并成型工具的设计相结合以实现在成型后完整的脱模。关键的参数包括：压电陶瓷/装夹工具之比，压电元件的直径和锥度，压电陶瓷基本轴向厚度，工具表面的磨光，以及成型零件的脱模机构的设计。为了评估这些工艺参数而不承担过多的工艺成本，一种工具的设计根据实验目的采用只有两排的各自19个压电陶瓷要素。每一行的要素都包括三个锥角(0，1和2度
9、)以及两个直径(0.5mm和1mm)。为了容许成型收缩，预加工的工件尺寸维持在50mmX50mm，以尽量减少在制模周期中的冷却部分折断外层纤维的可能性。图3所示的绿色陶瓷瓶坯的制造使用这种工具配置。请注意，所有压电陶瓷在成型后的完整的脱模，包括那些没有纵向尖端不方便的脱模。空气中的缓慢加热已经被发现是一个适合去除有机粘合剂的方法。最后，烧坏的粘合剂被烧结在一个理论值在97-98%的富含氧化铅的气体中。在烧结这些合成物型坯时没有遇到任何控制重量减轻的问题，甚至是那些用于高频超声的高尺寸精度，高表面质量的型坯。 图3 注射成型1-3预成型合成物 图4 电子显微镜扫描PZT表面图4说明了表面为压模和
10、作为烧结的纤维，显示出大约10um宽的存在的浅的折线，这是在注射成型过程中特有的。那个沿其长度方向显现出微小孔型设计的纤维取决于从工具中的脱模过程。图5所示近似网状的成型方式用于制造非常精细尺度的型坯的能力；所示压电元件的尺寸只有30um。由作为这些烧结的表面指出，压电陶瓷的显微结构是密集且均匀的，由直径为2-3um的细碎的等轴晶体构成。 图5 由近似网状的成型的精密尺度的合成物为了示范上述合成物制造的方法，注射成型和烧结的纤维行在用于成型合成物型坯的压电陶瓷被磨光之后，大约总体10%的5H*压电陶瓷合成物以及环氧树脂Spurrs在制造时通过环氧成对封装。图6所示复合材料样品使用刚才复合的压电
11、陶瓷/粘结剂混合物以及再生材料制造。回收复合物和成型的材料似乎是完全可行的，并且结果大大提高材料的利用率。表1比较了使用粉末制造商准备好的那些被报道的用于模压的5H压电陶瓷样品注射成型压电陶瓷样品的压电和介电的性能。当烧结条件最优于压电陶瓷5H的条件，压电和介电的性能都较所有材料有可比性。当压电陶瓷5H的原料物质被考虑到受注射成型设备污染铁的敏感性，这些有关的测量方法对于这种注射成型的压电陶瓷材料可以忽略这类污染。*粉末的提供方是俄亥俄州贝德福德的摩根士丹利公司，105A街区。 表1 压电陶瓷注塑成型的参数 图6 上述方法精制压电陶瓷/树脂合成物的注塑成型总结 陶瓷注射成型已被证明是一种可行的
12、制造压电陶瓷和压电陶瓷/聚合物传感器的方法。注射成型压电陶瓷的电相关特性区别于那些通过传统的准备好的粉末压模，没有证据证明在混合物以及成型设备中产生的金属杂质会产生污染影响。通过陶瓷的注射成型来制造合成物型坯，之后使用型坯来形成大批生产，此种方法已经证明用于网状大量制造压电复合物传感器。致谢 这项工作由海军研究事务所的Stephen E.Newfield先生赞助指导。作者要感谢Hong Pham女士提供的技术援助，以及材料研究实验所的Tomas Shrout博士，宾州州立大学所做的电器测量工作。参考文献1 R. E. Newnham等著，复合压电式传感器，材料工程，第二卷，93-106页，19
13、80年12月出版2 C. Nakaya等著，IEEE超音波专业座谈会，1985年十月16-18日。P6343 S. D. Darrah等著，大面积压电复合材料关于活性物质和构造的ADPA会议，亚历山德里亚，十一月4-8日，1991年，埃德。湾诺尔斯，物理研究所出版，页139-142 。4 A. Safari and D. J. Waller著，精密尺度的烟点陶瓷纤维/聚合物复合材料，在关于活性物质和构造的ADPA会议上提交，亚里山德里亚，危吉利亚，十一月4-8号，1991年。5 U. Bast, D. Cramer and A. Wolff著，一种用来制造1-3连通形压电复合材料的新方法，第七
14、届CIMTEC ， 意大利蒙特卡蒂尼， 6月24至30号， 1990年，Ed.P. Vincenzini, Elsevier，2005-2015页6 G. Bandyopadhyay and K. W. French著，网状的硅的氮化物应用于发动机的制造，对涡轮增压器转自及动力，108，536-539页，1986年出版7 J. Greim等著，烧结注塑涡轮增压转子，第三届关于热动力的陶瓷材料及构造国际研讨，内华达州拉斯维加斯，1365-1375页，Amer. Cer. Soc，1989年附件2：外文原文FABRICATION OF PIEZOELECTRIC CERAMlClPOLYMER C
15、OMPOSITES BY INJECTION MOLDING.Leslie J. Bowen and Kenneth W. French,Materials Systems Inc.53 Hillcrest Road, Concord, MA 01742AbstractResearch at the Materials Research Laboratory, Pennsylvania State University has demonstrated the potential for improving hydrophone performance using piezoelectric
16、ceramic/polymer composites. As part of an ONR-funded initiative to develop cost-effective manufacturing technology for these composites, Materials Systems is pursuing an injection molding ceramic fabrication approach. This paper briefly overviews key features of the ceramic injection molding process
17、, then describes the approach and methodology being used to fabricate PZT ceramic/polymer composites. Properties and applications of injection molded PZT ceramics are compared with conventionally processed material.IntroductionPiezoelectric ceramic/polymer composites offer design versatility and per
18、formance advantages over both single phase ceramic and polymer piezoelectric materials in both sensing and actuating applications. These composites have found use in high resolution medical ultrasound as well as developmental Navy applications. Many composite configurations have been constructed and
19、 evaluated on a laboratory scale over the past thirteen years. One of the most successful combinations, designated 1-3 composite in Newnhams notation l 1, has a one-dimensionally connected ceramic phase (PZT fibers) contained within a three-dimensionally connected organic polymer phase. Hydrophone f
20、igures of merit for this composite can be made over 10,000 times greater than those of solid PZT ceramic by appropriately selecting the phase characteristics and composite structure.The Penn State composites were fabricated l by hand-aligning extruded PZT ceramic rods in a jig and encapsulating in e
21、poxy resin, followed by slicing to the appropriate thickness and poling the ceramic. Asidefrom demonstrating the performance advantages of this material, the Penn State work highlighted thedifficulties involved in fabricating 1-3 composites on a large scale, or even for prototype purposes. These are
22、:1) The requirement to align and support large numbers of PZT fibers during encapsulation by the polymer.2) The high incidence of dielectric breakdown during poling arising from the significant probability of encountering one or more defective fibers in a typical large array. Over the past five year
23、s several attempts have been made to simplify the assembly process for 1-3 transducers with the intention of improving manufacturing viability and lowering the material cost. Early attempts involved dicing solid blocks of PZT ceramic into the desired configuration and back-filling the spaces with a
24、polymer phase. This technique has industry for manufacturing high frequency transducers 2. More recently, Fiber Materials Corp. has demonstrated the applicability of its weaving technology for fiber-reinforced composites to the assembly of piezoelectric composites 31. Another exploratory technique i
25、nvolves replicating porous fabrics having the appropriate connectivity 4. For extremely fine scale composites, fibers having diameters in the order of 25 to 100 pn and aspect ratios in excess of five are required to meet device performance objectives. As a result, these difficulties are compounded b
26、y the additional challenge of forming and handling extremely fine fibers in large quantities without defects. Recently, researchers at Siemens Corp. have shown that very fine scale composites can be produced by a fugitive mold technique. However, this method requires fabricating a new mold for every
27、 part 5. This paper describes a new approach to piezoelectric composite fabrication, viz: Ceramic injection molding. Ceramic injection molding is a costeffective fabrication approach for both Navy piezoelectric ceramic/polymer composites and for the fabrication of ultrafine scale piezoelectric compo
28、sites, such as those required for high frequency medical ultrasound and nondestructive evaluation. The injection molding process overcomes the difficulty of assembling oriented ceramic fibers into composite transducers by net-shape preforming ceramic fiber arrays. Aside from this advantage, the proc
29、ess makes possible the construction of composite transducers having more complex ceramic element geometries than those previously envisioned, leading to greater design flexibility for improved acoustic impedance matching and lateral mode cancellation. Process Description Injection molding is widely
30、used in the plastics industry as a means for rapid mass production of complex shapes at low cost. Its application to ceramics has been most successful for small crosssection shapes, e.g. thread guides, and large, complex shapes which do not require sintering to high density, such as turbine blade ca
31、sting inserts. More recently, the process has been investigated as a production technology for heat-engine turbine components 6,7. The injection molding process used for PZT molding is shown schematically in Figure 1.By injecting a hot thermoplastic mixture of ceramic powder and organic binder into
32、a cooled mold, complex shapes can be formed with the ease and rapidity normally associated with plastics molding. Precautions, such as hard-facing the metal contact surfaces, are important to minimize metallic contamination from the compounding and molding machinery. For ceramics, the binder must be
33、 removed nondestructively, necessitating high solids loading, careful control of the binder removal process, and proper fixturing. Once the binder is removed, the subsequent firing, poling and epoxy encapsulation processes are similar to those used for conventional PZT/polymer composites 1. Thus, th
34、e process offers the following advantages over alternative fabrication routes: Complex, near net-shape capability for handling many fibers simultaneously; rapid throughput (typically seconds per part); compatibility with statistical process control; low material waste; flexibility with respect to tr
35、ansducer design (allows variation in PZT element spacing and shape); and low cost in moderate to high volumes. In general, because of the high initial tooling cost, the ceramics injection molding process is best applied to complex-shaped components which require low cost in high volumes. Figure 1 :
36、Injection Molding Process Route. Figure 2: Preform Approach to Composite Fabrication.Composite Fabrication and EvaluationThe approach taken to fabricate 1-3 piezoelectric composites is shown in Figure 2a, which illustrates a PZT ceramic preform concept in which fiber positioning is achieved using a
37、co-molded 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 composite performance optimization. Tool des
38、ign is important for successful injection molding of piezoelectric composites. 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
39、, 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 mech
40、anism 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 (0.5 a
41、nd l mm). To accommodate 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
42、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 burned-out preforms are sintered in a PbOrich atmosphere to 97-98% of the theo
43、retical density. No problems have been encountered with controlling the weight loss during sintering of these composite preforms, even for those fine-scale, high-surface area preforms which are intended for high frequency ultrasound.Figure 4 illustrates the surfaces of as-molded and as-sintered fibe
44、rs, 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 net-shape molding for fabricating very fine sca
45、le preforms; PZT element dimensions only 30pm wide have been demonstrated. The as-sintered surface of these elements indicates that the PZT ceramic microstructure is dense and uniform,n consisting of equiaxed grains 2-3pm in diameter. Figure 3: Injection Molded 1-3 Composite Preforms. Figure 4: Scan
46、ning Electron Micrographs of As-molded(Upper) and As-sintered (Lower) Surfaces of PZT Fibers Figure 5: Fine-scale 2-2 Composite formed by Near Netshape olding (Upper Micrograph). As-sintered Surface(Lower Micrograph).In order to demonstrate the lay-up approach for composite fabrication, composites o
47、f approximately 10 volume percent PZT-5H fibers and Spurrs epoxy resin were fabricated by epoxy encapsulating laid-up pairs of injection molded and sintered fiber rows followed by grinding away the PZT ceramic stock used to mold the composite preform. Figure 6 shows composite samples made from fresh
48、ly-compounded PZT/binder mixture and from reused material. Recycling of the compounded and molded material appears to be entirely feasible and results in greatly enhanced material utilization. Table 1 compares the piezoelectric and dielectric properties of injection molded PZT ceramic specimens with those reported for pressed PZT-5H sam
