Highly Efficient Grinding of Ceramic Parts by Electrolytic In-Process Dressing (ELID) Grinding

In the manfacture of structural ceramic components, it has been well documented that the grinding costs can be as high as 90% of the total cost. Grinding costs of ceramics can be reduced by maximizing the material removal rates (MRR). A novel grinding technology that incorporates in-process dressing of metal bonded superabrasive wheels, known as Electrolytic In-Process Dressing (ELID) has been developed (1) which can significantly increase the MRR. This technique uses a metal bonded grinding wheel that is electrolytically dressed, during the grinding process, for continuous protrudent abrasive from superabrasi ve wheels. The principle of ELID grinding technology will be discussed in this paper as will its application for rough grinding. The effects of various parameters such as wheel bond type and type of power supply on the ELID grinding mechanism will also be addressed in this paper.     

ELID精密磨削钢结硬质合金及其AFM表面形貌分析

对钢结硬质合金（GT35）进行在线电解修整（ELID）精密磨削,对钢结硬质合金难磨机理以及ELID磨削钢结硬质合金的磨削机理进行了分析,并通过原子力显微镜（AFM）对镜面钢结硬质合金表面不同区域进行了微观表面形貌的分析,研究结果表明,采用ELID磨削技术实现对钢结构硬质合质合金零件的精密磨削加工,钢结硬质合金磨削表面粗糙度可达nm级,Ra≤20nm。     

Ductile Regime Mirror Finish Grinding of Ceramics with Electrolytic In-process Dressing (ELED) Grinding

Advanced structural ceramics, such as silicon nitride based materials, are of interest owing to their unique physical and mechanical properties. However the cost of grinding these ceramics, which is an integral part of their fabrication, is very high. Moreover, grinding can result in surface and sub-surface damage in the material and these defects can significantly reduce the strength and reliability of the finished components. Grinding damage is sensitive to grinding parameters. Two types of silicon nitride based ceramic materials were ground with Electrolytic In-Process Dressing (ELID) using different grit sized metal bonded diamond grinding wheels. With the application of ELID technology, mirror surface finish was realized with a #4000 mesh size wheel (average grain size = 4μm). Differences in ground surface topography caused by wheel grain size were analyzed using scanning electron microscopy (SEM) and atomic force microscopy (AFM). The SEM and AFM studies reveal that material was predominantly removed in the ductile mode when ELID grinding was performed with a #4000 grit size wheel or finer.     

多孔再生纤维素/聚乳酸复合材料的制备与性能

通过简易、绿色环保的方法,将纤维素用NaOH/尿素体系进行溶解、再生、冷冻干燥获得再生纤维素(RC)多孔材料,再浸渍聚乳酸(PLA)获得多孔RC/PLA复合材料。该复合材料具有与多孔RC材料相同的开孔结构,超轻,高孔隙率等特性。随PLA的引入,多孔复合材料的三维纤维网络结构向密实片层结构转变,缺陷结构逐渐完善,其压缩强度大幅度提高。RC/PLA的压缩强度和模量相比于RC分别提高了369.8%和633.6%。     

聚乳酸复合纳米纤维创面敷料的制备及性能

采用静电纺丝技术制备了聚乳酸(PLLA)纳米纤维毡、壳聚糖/PLLA纳米纤维毡和明胶/PLLA纳米纤维毡。利用扫描电镜(SEM)、图像分析软件等手段研究了纳米纤维微观形貌,并研究各种创面敷料的吸水性、保水性和水蒸汽通透性等性能。结果表明,壳聚糖/PLLA、明胶/PLLA复合纳米纤维毡的吸水性和保水性有显著提高,水蒸汽通透性略有下降,是理想的创面敷料材料。     

梯度结构Al_2O_3-(W,Ti)C-TiN-Mo-Ni纳米金属陶瓷刀具材料的设计及制备

基于对高速硬切削时刀具应力和温度分布,以及刀具内部疲劳裂纹扩展仿真分析,提出一个组分含量分布和微观结构具有梯度特征的设计模型。通过韧性相的添加和梯度结构的引入,实现疲劳裂纹扩展速率的减缓,从而提高刀具寿命。采用二阶段热压烧结工艺制备出具有梯度结构的Al_2O_3-(W,Ti)C-TiN-Mo-Ni纳米复合刀具材料,并对其微观结构和力学性能进行研究。结果表明:所制备的梯度结构金属陶瓷材料表层硬度、内层的断裂韧度和抗弯强度分别达到19.258GPa,10.015MPa·m~(1/2)和1017.475MPa,满足高速硬切削刀具的性能要求。材料的断口出现韧窝和黏结相撕裂形成的断裂棱,有利于断裂韧度和抗弯强度的增强,从而提高刀具抗疲劳裂纹扩展能力。     

《材料开发与应用》第22卷(2007)总目次

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《材料开发与应用》第21卷(2006)总目次

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《材料开发与应用》第20卷(2005)总目次

★第1期★Bi-Pb-Sn-Cd易熔合金的设计与性能研究……………………………………………………王吉会,杨亚群,李群英,等(1)AZ91D镁合金的触变成形及其磨损性能的研究……………………………………………陈体军,李元东,马颖,等(4)Nb、Ti微合金元素对连铸10MnNiCr钢埋弧焊接头组织与韧性的影响…………………刘刚,姚润钢,孔红雨,等(9)低钨白口铸铁共晶碳化物团球化研究……………………………………………………………………………符定梅(13)WC基高锰钢结硬质合金的异常碎裂机理研究………………………………………………吴瑞祥,陈成,张春…     

材料智能处理与制造(IPMM)与金属半固态成形技术

介绍了材料智能处理与制造(IPMM)的概念,结合半固态成形技术特点,分析了材料智能处理在金属半固态成形技术中的应用结合点,从材料成形的模拟仿真预测、工艺过程的智能控制、智能传感器的研究和控制方法等方面提出了金属半固态成形技术智能处理的研究方向.     

Fabrication and characterization of chemical sensors made from nanostructured films of poly(o-ethoxyaniline) prepared with different doping acids

Chemical sensors made from nanostructured films of poly(o-ethoxyaniline) POEA and poly(sodium 4-styrene sulfonate) PSS are produced and used to detect and distinguish 4 chemicals in solution at 20 mM, including sucrose, NaCl, HCl, and caffeine. These substances are used in order to mimic the 4 basic tastes recognized by humans, namely sweet, salty, sour, and bitter, respectively. The sensors are produced by the deposition of POEA/PSS films at the top of interdigitated microelectrodes via the layer-by-layer technique, using POEA solutions containing different dopant acids. Besides the different characteristics of the POEA/PSS films investigated by UV-Vis and Raman spectroscopies, and by atomic force microscopy, it is observed that their electrical response to the different chemicals in liquid media is very fast, in the order of seconds, systematical, reproducible, and extremely dependent on the type of acid used for film fabrication. The responses of the as-prepared sensors are reproducible and repetitive after many cycles of operation. Furthermore, the use of an “electronic tongue” composed by an array of these sensors and principal component analysis as pattern recognition tool allows one to reasonably distinguish test solutions according to their chemical composition.     

Fabrication and characterization of zirconium carbide (ZrC) nanofibers with thermal storage property

Zirconium carbide (ZrC) nanofibers were fabricated by the electrospinning method and subsequent heat-treatment. The solution for electrospinning was prepared by dissolving zirconium acetyl acetonate and cellulose acetate in glacial acetic acid and 2,4-pentanedione as common solvents. The effects of the solution properties used for electrospinning, including the concentrations of the starting materials, the C/Zr ratio of the solutions, and soaking conditions, were investigated. The electrospinning process parameters and heat-treatment conditions were also investigated. The electrospun precursors and the heat-treated nanofibers were characterized by scanning electron microscopy, X-ray diffraction, elemental analysis, and Fourier transform infrared spectroscopy. ZrC nanofibers with a thermal emissivity above 90% have a great potential for thermal storage barrier membrane.     

《Development and Application of Materials》Vol.1 7(2002) Contents

Ｎｏ .1 ＤｒｙＳｌｉｄｉｎｇＷｅａｒａｎｄＦｒｉｃｔｉｏｎＢｅｈａｖｉｏｒｓｏｆＰｌａｓｍａ ｓｐｒａｙｅｄＮｉｃｋｅｌ ｂａｓｅｄＭｏＳ2 ＣｅｒｍｅｔｓＣｏａｔｉｎｇＣｈｅｎＡｉｚｈｉ　ＺｈａｎｇＹｏｎｇｚｈｅｎ　ＸｉａｏＨｏｎｇｂｉｎ ,ｅｔａｌ(1)………………………………………………………………………………………………ＥｆｆｅｃｔｓｏｆＨｅａｔＴｒｅａｔｍｅｎｔｏｎＭｉｃｒｏｓｔｒｕｃｔｕｒｅａｎｄＰｒｏｐｅｒｔｙｏｆＤ70 7ＣｅｍｅｎｔｅｄＣａｒｂｉｄｅＳｕｒｆａｃｉｎｇＬａｙｅｒＰｅｎｇＪｉ…     

Fabrication of 3-D gelatin-patterned glass substrates with layer-by-layer and lift-off (LbL-LO) technology

The assembly of multilayer films of gelatin onto glass substrates using layer-by-layer and lift-off (LbL-LO) technology to modify the surface topography and chemistry properties of in vitro cell culture scaffolds is described. The ability to generate such nanoscale systems containing cell-adhesive materials on optically transparent substrates with microscale lateral dimensions, nanoscale vertical dimensions, molecular vertical precision, and flexibility in material selection has important implications for tissue engineering, drug discovery, and basic research in cell biology. Toward this goal, a systematic study on the electrostatic adsorption properties of fluorescein 5-isothiocyanate-gelatin B (FITC-gelatin) was completed. In addition, the integration of protein nanoassembly with microlithographic feature definition was used to pattern three-dimensional FITC-gelatin nanofilms on planar glass substrates. The experimental results indicate that FITC-gelatin is negatively charged at pH 9 and can be alternately assembled with a positively charged polyion, poly(diallyldimethylammonium chloride) (PDDA), to form multilayer films on solid templates with thickness of 5-10 nm per bilayer. Furthermore, images of protein/polymer nanocomposites indicate that LbL-LO is an efficient way to realize the designed substrates. These findings will benefit future research on cell culture and tissue engineering that require methods of generating protein patterns to fabricate novel in vitro cell culture systems.     

Method of determining the control functions for wave processes in regions with mobile boundaries (Cylindrical symmetry)

Exact analytical solutions of the wave equation in regions with mobile boundaries for the general case of cylindrical symmetry are obtained using an original method previously developed for solving inverse problems with allowance for the interaction of nonlinear arguments. The obtained solutions are universal and valid for both inverse and direct problems. A method of eliminating logarithmic singularities, known to exist in the case of cylindrical symmetry, is proposed for the quantitative determination of the control functions of wave processes in regions with mobile boundaries.     

聚乙烯二氧噻吩热分解性能对其作阴极片式钽电解电容器自愈性能的影响

以化学原位聚合制备的导电聚合物聚乙烯二氧噻吩(3,4-polyethylene dioxythio phene,简称PEDT)薄膜在固体钽电解电容器上的应用为背景,采用TG研究了化学聚合中单体/氧化剂配比对PEDT热分解温度的影响,并以此为基础,分析了材料热性能对PEDT作阴极的固体钽电解电容器自愈特性的影响.实验结果表明,随着单体/氧化剂配比的增大,材料的热分解温度有较大变化.而以PEDT作阴极的固体钽电解电容器的自愈速度则随材料热分解温度的增大有所下降.     

高内相乳液法制备P(St-DVB)多孔吸油材料及其在油水分离中的应用

利用超疏水多孔材料的选择吸油性可以很好地处理突发性溢油事故和肆意排放的含油废水.本实验通过高内相乳液法制备了一种可压缩的聚苯乙烯多孔材料,通过SEM、IR对该材料结构进行了表征,并测试了其油-水分离性能.结果显示,在传统小分子乳化剂Span 80的基础上加入牡蛎壳粉(OSP)可以有效阻止液滴的合并,能显著提升乳液的稳定性.在75℃下通过偶氮二异丁腈(AIBN)引发自由基聚合制得了具有多孔结构的海绵材料,材料的密度、孔径和孔隙率可通过水量调节,当水的体积比达到98.22％时,材料呈现出可压缩性.通过接触角测量仪测试了材料的水接触角(WCA)为147.8°,油接触角接近0°,表明材料具有超疏水性和超亲油性.材料对不同油品的饱和吸油倍率在46.7～101.9 g/g,且在30 s内可达到吸油饱和;吸油后的材料可通过离心或挤压实现二次利用,该材料有望在油水分离领域得到广泛应用.