三维打印成型铝硅合金制件的性能及表面处理

目的 研究三维打印成型铝硅合金制件的性能及表面导电氧化处理后的表面质量与形貌。方法 采用激光选区熔化技术打印AlSi10Mg制件,分别测量其成分、密度和抗拉强度,将其性能与铸铝104块体材料进行比较;并对打印成型的AlSi10Mg制件进行表面导电氧化处理,测试分析处理前后的表面粗糙度和表面形貌,对比平面和弧面打印样品的表面质量。结果 三维打印的AlSi10Mg制件密度略小于铸铝104体材料,抗拉强度则较高,达到440 MPa。经过表面导电氧化处理之后,在钝化层中产生裂纹。弧面样品的表面粗糙度较大,为2~5 μm,表面裂纹的宽度和分布都不均匀;平面样品的表面粗糙度较小为1~2 μm,裂纹宽度在800 nm~1 μm,分布均匀,形成尺寸为1~2 μm且均匀分布的岛状结构。结论 三维打印AlSi10Mg制件强度高,可以作为承载力的结构件,并且通过对其进行表面处理,获得了具有潜在应用价值的表面微纳结构。     

高分子基功能复合材料的熔融沉积成型研究进展

3D打印又称增材制造技术,是基于材料、机械控制、计算机软件等多学科交叉的先进制造技术,可得到传统加工不能制备的形状复杂制件。熔融沉积成型(FDM)是目前最通用的3D打印技术之一,具有设备简单、成本低、操作便捷等特点,广泛应用于航空航天、医疗、汽车工业等领域。本文介绍了国内外3D打印技术的整体布局、发展和规划,总结了常见3D打印技术的特点和分类。系统地介绍了FDM加工技术的原理和优势,阐明了 FDM加工对高分子材料的基本要求,介绍了碳基高分子复合材料在FDM加工中的应用。此外,详细综述了国内外基于FDM打印技术制造功能化高分子复合材料及器件的最新研究进展,其中包括FDM打印制造导电高分子复合材料、导热高分子复合材料及生物医用高分子复合材料等,以期为FDM制造高性能多功能高分子复合材料的研究及应用提供借鉴。并对FDM加工面临的挑战及需要解决的关键问题提出了思考并做出展望。      

石墨烯/聚合物基复合材料3D打印成型研究进展

石墨烯因其优异的特性,被广泛用于制备聚合物基复合材料,而3D打印作为一种新兴的成型加工方式,正越来越多地应用到石墨烯/聚合物基复合材料的成型制造当中。本文介绍石墨烯/聚合物基复合材料的溶液混合、熔融混合以及原位聚合三种主要制备方式,重点论述喷墨打印成型、熔融沉积成型、立体光固化成型、选择性激光烧结等目前国内外用于石墨烯/聚合物基复合材料成型的3D打印方式及其各自的优势和劣势,以及3D打印成型的石墨烯/聚合物基复合材料制件在电子、能源、生物医学和航空航天等领域的应用,最后指出可打印性好、石墨烯分散均匀、功能特性优异的石墨烯/聚合物基复合材料的研制将会是未来该方向的研究重点。     

基于FDM的3D打印技术研究现状与发展趋势

熔融沉积制造(FDM)技术是3D打印领域应用最为广泛的类型。为便于相关研究工作的进行,解释了FDM的工作原理,概括了FDM用成型材料的种类和特性以及FDM技术的应用领域,总结了FDM技术在国内外的研究现状及取得成果,分析了FDM技术存在的缺陷并提出相应的改进方法,最后,对FDM打印技术进行了展望。     

结构反应注射成型工艺对聚氨酯复合材料表面性能的影响

采用结构反应注射成型工艺制备的纤维增强聚氨酯复合材料制件(简称SRIM制件)的表面性能差,提高表面性能是SRIM工艺制备高品质产品的关键技术之一。文中研究了SRIM工艺对制件表面性能的影响以及改善方法,即选择适当的无纺织物作为附加表层或在局部保持适当的压力水平。激光共聚焦扫描显微镜的研究结果表明,采用两种不同无纺织物的组合对SRIM制件表面性能的改善效果优于单一无纺织物;保持压力8.0 MPa,同时采用无纺织物B和C,可以明显改善SRIM制件的表面性能,粗糙度为0.30μm,表面观察不到玻璃纤维的痕迹,仅出现细微的桔皮状和极少量的黑色缩痕。     

微注射成型研究进展

微注射成型是一种低成本大规模复制聚合物微制件的有效方法。文中从微结构特征复制性能、工艺参数的分析和优化、模具表面光洁度对聚合物流动行为的影响、过程建模与仿真、微注射成型的熔接痕缺陷以及微塑件的组织形态与力学性能等方面阐述微注射成型的最新研究进展。最后指出开发特殊微注射成型技术、新型微模具加工技术,以及将微注射成型与其他微纳加工技术集成,制作多种材料复杂功能微系统将成为今后的研究方向和发展趋势。     

陶瓷注射成型的关键技术及其研究现状

陶瓷注射成型是一种近净尺寸陶瓷可塑成型方法,是当今国际上发展最快、应用最广的陶瓷零部件精密制造技术.详细阐述了陶瓷注射成型技术的关键因素,重点介绍了粘结剂、注射成型及脱脂等关键工艺及其研究现状,并在此基础上评价和展望了该技术的发展前景.     

基于熔融沉积3D打印聚乳酸基复合材料的研究进展

目的 半结晶性聚乳酸(PLA)因透明性好、力学性能优异、能生物降解等优点,在加工领域表现出适用范围广等特性,因此对PLA基复合材料在3D打印技术中的研究应用及最新进展状况进行总结,以期提供借鉴与参考。方法 以熔融沉积成型(FDM)、PLA基体为主线,在查阅近年中外文献基础上,分别从PLA结构性能、3D打印成型工艺、PLA基复合材料改性等方面进行了探讨,着重分析工艺参数的技术优化,以及复合材料的结构改性最新研究进展。结果 FDM制备PLA基复合材料的研究取得了丰硕的成果,在3D打印行业中表现优异,潜力巨大,商品化程度越来越高。结论 低廉、高效、可定制的3D打印受到国内外科研工作者广泛关注与青睐,随着新技术的不断探索和突破,以及纳米材质和新型聚合物材料等新型材质应用,使3D打印在成型加工技术上占据绝对优势。     

熔融沉积快速成型零件成型方向的多目标优化

为了实现熔融沉积快速成型（FDM）中零件成型精度和成型效率的协同优化,基于零件成型方向对成型精度和成型效率的影响进行分析,以体积误差最小、零件成型方向上高度最低以及所需支撑体积最小为目标,建立了零件成型方向的多目标优化模型。设计了基于非支配排序遗传算法的智能求解算法,通过对模型的优化计算得到零件成型方向的Pareto解集,实现了FDM零件成型方向的智能优化。最后通过实例验证了所建模型的正确性与算法的有效性。     

卡车翼子板的滚塑成型技术

对卡车翼子板滚塑成型原料、工艺条件、制件和模具设计进行了研究.采用热氧老化法确定高密度聚乙烯(HDPE)和线性低密度聚乙烯(LLDPE)的最佳共混配比;通过研究加工热稳定性和制件的抗冲击强度两项指标确定最佳工艺条件;对制品结构及成型模具进行了优化设计,并进行了实验研究.结果表明:LLDPE/HDPE=70:30可作为滚塑成型原料;最佳成型时间15 min,最佳成型温度290℃;制件壁厚为6 mm,近距平行壁距离为3倍壁厚,圆角处内表面半径为6.5 mm,外表面半径为3.2 mm,加强筋采用高度较小的多条平式加强筋;模具为铸铝合金材质.     

Nanofinishing of FDM-fabricated components using ball end magnetorheological finishing process

Fused deposition modeling (FDM) is among the extensively used and the most economical additive manufacturing processes. Currently, the surface finish obtained for FDM additive manufactured parts are not at par with the current industrial application. To overcome the limitation of high surface roughness of 3D printed parts, a novel finishing technique has been proposed which includes primary and secondary finishing processes. While facing and lapping has been used as primary finishing technique, the secondary finishing involves the use of ball end magnetorheological finishing (BEMRF) process. BEMRF process is an unconventional finishing process which utilizes an advanced approach to impart finish on magnetic as well as non-magnetic materials that may be flat or freeform in shape. This article presents the experimental and analytical study to finish a polylactic acid (PLA) workpiece material manufactured by FDM process and finished using the BEMRF technique. The surface roughness of the FDM component has been reduced from initial surface roughness Ra = 20 µm to final value of Ra = 81 nm by combined primary and secondary finishing processes. The effect of magnetorheological polishing (MRP) fluid’s composition and finishing time is discussed and is followed by optimization of MRP fluid for maximum percentage reduction in surface roughness.     

Effect of chemical treatment on tensile strength and surface roughness of 3D-printed ABS using the FDM process

Fused deposition modelling (FDM) is one of the most commonly used additive manufacturing processes because of its environment-friendly nature and cost-effectiveness. However, it suffers badly from low surface quality due to a larger layer resolution. The surface finish of FDM parts can be enhanced by post chemical treatment using various solvents. The chemical treatment reduces the surface roughness by dissolving the external surfaces of 3D-printed samples. Chemical treatment is an easy, fast and economical technique. In the present investigation, the effect of chemical treatment on surface roughness and tensile strength of acrylonitrile butadiene styrene (ABS) parts made using the FDM process is investigated using two chemicals, namely acetone and 1, 2 dichloroethane. The post chemical treatment dramatically improves the surface finish and dimensional accuracy of ABS specimens. But chemical treatment results in the reduction of the tensile strength. Better tensile strength is obtained while using acetone solvent and a better surface finish is obtained using dichloroethane.     

Investigation on the effect of surface modification of 3D printed parts by nanoclay and dimethyl ketone

Fused deposition modeling (FDM) has emerged as one of the most utilized 3D printing technique. However, the surface properties of the FDM built parts lacks integrity due to layer by layer manufacturing technique. Therefore, post treatment is done on FDM printed parts. In the present research work, an effort has been made to improve the surface properties of the 3D printed parts by surface modification via chemical/nanoparticles. Nanoclay and dimethyl ketone were utilized for the surface modification of acrylonitrile butadiene styrene specimens. Parameters namely nanoclay content, immersion time, heat treatment and layer thickness were investigated to study their effect on surface roughness, surface hardness and dimensions. Also, the effect of nanoclay on UV absorbance of 3D printed parts was observed. Structural and morphological analysis was performed to characterize the surface of the 3D printed specimens after surface modification process. The results show that the surface roughness was reduced by 94.9%, surface hardness was increased by 9.7% while maintaining minimum dimensional deviation of ?0.03 and +0.07?mm. Also, UV absorbance was increased in 350–380?nm range. The results of the present study highlight the capability of the surface modification process for improving the surface properties of FDM parts.     

CNC-assisted selective melting for improved surface finish of FDM parts

A novel CNC-assisted post-finishing tool, namely selective melting (SM) is designed and developed for finishing of fused deposition modelling (FDM) built parts. In this process, unlike the conventional post-finishing processes, materials in the form of chips are removed to reduce peak to valley height. The SM tool adds semi-solidified material to the neighbouring valleys to reduce the peak to valley heights. The present work provides an alternative to overcome the limitations of the poor surface finish of FDM built parts, and issues like location error effect, inner defect, minimisation of scallops and irregular pattern formation during post-finishing operation. In this research, theoretical and semi-empirical models have been developed for the prediction of surface roughness of a part before and after the SM process. The validation results showed that the developed approach played a significant role in improving the surface finish conditions of FDM built parts.     

Geometrical analysis and pattern recognition using mapping technologies of three-dimensional fracture surfaces in materials

Geometrical analysis of fracture surfaces in materials was made using newly developed computer programs on the three-dimensional images reconstructed by the stereo matching method. The global value of the fractal dimension of the fracture surface was estimated by the box-counting method on a fatigue fracture surface of a Cu-Be alloy and impact fracture surfaces of a SiC and an alumina. The results of the present analysis were well correlated with those of the two-dimensional fractal analysis. The fractal dimension map (FDM) by the box-counting method and the surface roughness map (SRM) proposed in this study can give important information about the local fracture mechanisms, the crack growth direction or the fracture origin in materials. FDM and SRM have interesting characteristics by which one can discriminate the flat regions, the regions of complex geometry or the steeply inclined areas on a given fracture surface. Pattern recognition using mapping technologies of FDM and SRM is also applicable to the extraction of “hidden patterns” on fracture surfaces, which cannot be observed only by microscopes.     

Analysis of the surface roughness and dimensional accuracy capability of fused deposition modelling processes

Building up materials in layers poses significant challenges from the viewpoint of material science, heat transfer and applied mechanics. However, numerous aspects of the use of these technologies have yet to be studied. One of these aspects is the characterization of the surface roughness and dimensional precision obtainable in layered manufacturing processes. In this paper, a study of roughness parameters obtained through the use of these manufacturing processes was made. Prototype parts were manufactured using FDM techniques and an experimental analysis of the resulting roughness average ( R a ) and rms roughness ( R q ) obtained through the use of these manufacturing processes was carried out. Dimensional parameters were also studied in order to determine the capability of the Fused Deposition Modelling process for manufacturing parts.     

核翼比法进行表面粗糙度的标定及测量

介绍了一种表面粗糙度标定及测量的新方法。通过标定一组标准样块的核翼比，可以实现该标定范围内待检样块的粗糙度测量，该方法稳定可靠，试验装置简单，数据处理方便，为表面粗糙度的非接触测量提供了较好的方案。     

球形表面粗糙度测量中两种干涉图像处理方法

讨论了用带有数字图像处理和计算系统的麦克尔逊干涉涉显微镜测量像人工关节这样的球形表面粗糙度的方法，用数字图像处理方法处理等倾干涉和等厚干扰这两种干扰图像，并萃取出反映被测球面微观不平度信息的干涉带的边界线。本文推导了用最小二乘拟合原理计算标准最小二乘圆和圆弧的算法以及用获取的被测表面的微面不平度偏差计算表面粗糙度参数的方法。     

Filter diagonalization method-based mass spectrometry for molecular and macromolecular structure analysis

Molecular and macromolecular structure analysis by high resolution and accurate mass spectrometry (MS) is indispensable for a number of fundamental and applied research areas, including health and energy domains. Comprehensive structure analysis of molecules and macromolecules present in the extremely complex samples and performed under time-constrained experimental conditions demands a substantial increase in the acquisition speed of high resolution MS data. We demonstrate here that signal processing based on the filter diagonalization method (FDM) provides the required resolution for shorter experimental transient signals in ion cyclotron resonance (ICR) MS compared to the Fourier transform (FT) processing. We thus present the development of a FDM-based MS (FDM MS) and demonstrate its implementation in ICR MS. The considered FDM MS applications are in bottom-up and top-down proteomics, metabolomics, and petroleomics.     

A practical stress analysis for predicting fatigue limit of metal with axisymmetric complex surface

In order to predict the fatigue limit of a specimen with an axisymmetric complex surface, a practical method to estimate a stress concentration factor (SCF) of its surface was proposed. The roughness is coarse-grained by removing high frequency components and approximated with a parallel row of a local notch and innumerable average notches. Then, the notches are each approximated with the elliptical holes in the infinite plate, and the SCF is calculated approximately by superposing the elastic solutions of the holes. Moreover, FEM analyses were carried out on the various notch models which consist of the local notch and innumerable average notches to examine the application limit of the present method. Then, the validity of the application limit was examined by using the real roughness and the infinite parallel row of the various notches, and it was shown that the present method was available for the real roughness.