An overview of laser-based multiple metallic material additive manufacturing: from macro- to micro-scales

Additive manufacturing(AM)is an emerging customized three-dimensional(3D)functional product fabrication technology.It provides a higher degree of design freedom,reduces manufacturing steps,cost and production cycles.However,existing metallic component 3D printing techniques are mainly for the manufacture of single material components.With the increasing commercial applications of AM technologies,the need for 3D printing of more than one type of dissimilar materials in a single component increases.Therefore,investigations on multi-material AM(MMAM)emerge over the past decade.Lasers are currently widely used for the AM of metallic components where high temperatures are involved.Here we report the progress and trend in laser-based macro-and micro-scale AM of multiple metallic components.The methods covered in this paper include laser powder bed fusion,laser powder directed energy deposition,and laser-induced forward transfer for MMAM applications.The principles and process/material characteristics are described.Potential applications and challenges are discussed.Finally,future research directions and prospects are proposed.

Microstructure of Zn-Al4 alloy microcastings by micro precision casting based on metal mold

Metal mold micron scale precision casting technology was developed successfully,and three-dimension complicated microgear castings in micron scale were produced.Evolvement regularity of microgear castings were observed by optical microscope and scanning electron microscope.Compared with conventional casting,microcasting is characterized by typical nonequilibrium solidification,for example,its grain size can be refined significantly,eutectic structure is transformed from lamellar morphology to rod eutectic,and the ratio of primary phase is increased.This kind of microstructure can promote mechanical properties of microcasting.

Research on the process of fabricating a multi-layer metal micro-structure based on UV-LIGA overlay technology

In this paper,we report the study of the process of fabricating a multi-layermetal micro-structure using UV-LIGA overlay technology,includingmask fabrication,substrate treatment,and UV-LIGA overlay processes.To solve the process problems in the masking procedure,the swelling problemof the first layer of SU-8 thick photoresist was studied experimentally.The 5μmline-width compensation and closed 20μmand 30μmisolation strips were designed and fabricated around the micro-structure pattern.The pore problemin the Ni micro-electroforming layer was analyzed and the electroforming parameters were improved.The pH value of the electroforming solution should be controlled between 3.8 and 4.4 and the current density should be below 3 A/dm^2.To solve the problems of high inner stress and incomplete development of the micro-cylinder hole array with a diameter of 30μm,the lithography process was optimized.The pre-baking temperature was increased via gradient heating and rose every 5℃ from 65℃ to 85℃ and then remained at 85℃ for 50 min–1 h.In addition,the full contact exposure was used.Finally,a multi-layer metal micro-structure with high precision and good quality of microelectroforming layer was fabricated using UV-LIGA overlay technology.

Micro-yield behaviors of Al_2O_3-SiO_(2(sf))/Al-Si metal matrix composites

Effects of the volume fraction and the size of crystallized alumina silicate short fibers as well as heat treatment processes on micro-yield strength(MYS) of Al2O3-SiO2(sf)/Al-Si metal matrix composite(MMC) that was fabricated by squeezing cast, were investigated by using continuous loading method on an Instron 5569 tester with a special extensometer with an accuracy of 10?7. The results show that MYS of MMC decreases with the increase of volume fraction and length of the alumina silicate short fibers in the metal matrix composite, respectively. MYS of quenched Al2O3-SiO2(sf)/Al-Si MMC is the lowest, MYS of the MMC through peak-aging treatment is higher than that through other heat treatment methods. And before the peak-aging, MYS of MMC aging treated gradually increases with the increase of the aging time. Aging treatment after solution treatment is a preferred way that enhances micro and macro-yield strength of Al2O3-SiO2(sf)/Al-Si MMC.

ULTRASONIC SEPARATION OF MICRO-SIZED INCLUSIONS IN MOLTEN METAL

The coagulation time and position of micro-sized non-metallic inclusions in molten metal during ultrasonic separation process were investigated, and the motion course of micro-sized non-metallic inclusions in an ultrasonic standing wave field was numerically simulated. The results of theoretical analysis and numerical simulation show that the movement of inclusions depends on the balance between the acoustic radiation force, effective buoyancy force and viscous drag force. It is presented that micro-sized inclusions, agglomerated at antinode-planes may be removed further with horizon tal ultrasound.``

Analysis Microstructure of Weld Metal for HO130+OJ63 High Strength Steel

The microstructure in the weld metals for HQ130 + QJ63 high strength steels,which are welded by Ar-CO_2 gas shielded metal arc welding,was analyzed by means of microscope and scan electron microscope(SEM).The relative content of different microstructure was evaluated with XQF-2000 micro-image analyzer.The effect of acicular ferrite content on the impact toughness was also studied.The test results indicated that the main microstructure in the weld metals of HQ130 + QJ63 high strength steels is acicular ferrite and a few pro-eutectic ferrite on the boundary of original austenite grain.Near the fusion zone there are columnar grains whose direction coefficient(X) is 3.22,but the microstructure in the center of the weld metal is isometric grain,whose direction coefficient X = 1.In order to avoid welding crack and improve welding technology the weld heat input should be strictly controlled in 10-16 kJ/cm.Thus,the main microstructure in the weld metals is fine acicular ferrite and the content of pro-eutectic ferrite is limited.The impact toughness in the weld metals of HQ130+ QJ63 steels can be ensured and can meet the requirements for application in engineering and machinery.

Multifunctional Perovskite Photodetectors: From Molecular-Scale Crystal Structure Design to Micro/Nano-scale Morphology Manipulation

Multifunctional photodetectors boost the development of traditional optical communication technology and emerging artificial intelligence fields, such as robotics and autonomous driving. However, the current implementation of multifunctional detectors is based on the physical combination of optical lenses, gratings, and multiple photodetectors, the large size and its complex structure hinder the miniaturization, lightweight, and integration of devices. In contrast, perovskite materials have achieved remarkable progress in the field of multifunctional photodetectors due to their diverse crystal structures, simple morphology manipulation, and excellent optoelectronic properties. In this review, we first overview the crystal structures and morphology manipulation techniques of perovskite materials and then summarize the working mechanism and performance parameters of multifunctional photodetectors. Furthermore, the fabrication strategies of multifunctional perovskite photodetectors and their advancements are highlighted, including polarized light detection, spectral detection, angle-sensing detection, and selfpowered detection. Finally, the existing problems of multifunctional detectors and the perspectives of their future development are presented.

Metal Nano Layer Coating for Improving the Detection and Recognition of Micro-Poisons Using Reflection Spectroscopic Measurement

Metal nano layer coating for increasing the sensitivity of spectroscopic measurements is proposed and experimentally demonstrated in this paper. The metal nano layer will attract the micro-poisons from any measured aqueous sample increasing the concentration of the micro-poison in the vicinity of the surface and significantly improves the sensitivity of the spectroscopic measurement. The demonstration was carried out using Fourier Transform Infra-Red (FTIR) operating in the MIR 400 cm-1 - 4000 cm-1 and 5 nm Gold layer which was grown on silicon oxide substrate. In the experimental demonstration Malathion organophosphate pesticide was used as micro-poison. The spectroscopic measurement proves that Malathion was attracted to the metal nano layer. Furthermore, the absorption lines of Malathion were detected and recognized. This proof of principle can be applied to any Internal Reflection Elements (IRE) and it can be used to purify any aqueous solutions and atmosphere from micro-poisons which will be attracted to the metal Nano layer.

金属氧化物半导体MEMS气体传感器研究进展

随着物联网的快速发展,各领域对气体监测的需求越来越大,基于先进微机电系统(Micro-electro-mechanical systems, MEMS)技术的金属氧化物半导体(Metal oxide semiconductor, MOS)气体传感器在过去几十年里取得了很大发展。MEMS微热板的多样化设计、MOSs纳米结构的多样化以及机器学习算法的出现为MEMS的传感性能以及智能传感系统的构建提供了很大助力。本文从MEMS气体传感器的分类、制备和应用以及传感器阵列的构建等方面综述了金属氧化物半导体MEMS气体传感器的最新研究进展,并对MEMS基气体传感器的发展前景进行了总结和展望。

激光诱导击穿光谱(LIBS)法微损快速检测党参中Pb

中药材重金属元素快速检测对污染监控及人们健康具有重要意义。激光诱导击穿光谱技术(Laser induced breakdown spectroscopy,LIBS)属于一种快速检测方法,研磨压片等预处理方法相对样品消解已有所简化,但破坏了样品的物理性质,且不能满足中药材大宗品种、大批量检测需求。若进一步简化样品预处理,将更加凸显LIBS快速检测的优势。采用Pb溶液浸泡法获得不同Pb含量的党参切片样品,依次获取Pb LIBS光谱强度,通过排序初步判断Pb含量高低,随机从各含量梯度样品中抽取样品,将其分为三份:38个A样用于ICP-MS检测,建立定标曲线,从而获取B样和C样中Pb真实含量,10个B样作为Pb浓度已知的参考定标样品,用于待测党参样品中Pb微损检测,19个C样用于验证B样微损检测准确性。建立的微损定标曲线线性相关系数R^(2)为0.7764,可用于切片党参LIBS快速检测,对待测党参切片样品检测平均相对误差为3.74%,与电感耦合等离子体质谱(ICP-MS)法对比,相关系数R^(2)为0.7957,验证了LIBS技术微损检测的可行性。制备的党参参考定标样品可多次重复用于待测样定标和仪器标定等。实验对待测党参样品仅进行切片处理,避免了研磨、压片等预处理,更加充分地体现LIBS快速检测的优势,为LIBS技术应用于中药材重金属元素快检等领域提供了一种新方法。

微弧氧化对金属植入物抗菌和抗炎能力的调节效应

背景:微弧氧化技术能够有效地将生物活性元素掺杂到金属表面,提高生物医用金属材料的抗菌性能和抗炎性能,因此该技术已成为生物医用材料的研究热点之一。目的:重点介绍微弧氧化技术及其与其他表面改性技术联合应用制备植入物表面涂层的抗菌性能和抗炎性能。方法:以“微弧氧化,抗炎性能,抗菌性能,金属植入物”为中文检索词检索中国知网和万方数据库,以“micro-arc oxidation、antibacterial properties,anti-inflammatory properties,metal implants”为英文检索词检索PubMed数据库,检索时间范围为1996年1月至2022年12月,根据纳入和排除标准初筛后,最后保留89篇文献进行归纳总结。结果与结论:微弧氧化陶瓷层提高了钛、镁等合金的抗菌性能和抗炎性能,联合其他表面改性技术有效解决了孔隙对合金表面性能的影响,进一步提高了氧化膜的生物学性能,在骨科和牙科等领域有着广泛的应用前景。目前研究多局限于金属涂层,而且大部分研究集中在银、铜等具有良好抗菌性能的金属元素,仅有少数研究提到氧化石墨烯、羟基磷灰石和壳聚糖等非金属涂层,未来可以对无机物涂层和高分子涂层进行广泛研究,也可采取更多种不同生物活性元素的组合来提高抗菌性能。目前微弧氧化技术所制备的植入体涂层炎症研究多局限于免疫系统,且集中在巨噬细胞,而其对于中性粒细胞、血小板等的研究稀缺,未来需联合应用多种先进技术手段探究微弧氧化涂层对其他免疫细胞和炎症细胞的具体影响。

微细金属管制造技术现状与研究进展

微细金属管具有微环境下的微通道封闭、定向导向、稳流导流等功能,被广泛应用于医疗、电工电子、传热、光学等领域。受加工工具小型化、尺寸效应对材料性能和摩擦行为的改变等限制,微细金属管的制备极具挑战性。总结了微细金属管常用制备技术的制备原理、特点、制造能力以及优缺点,包括热挤压成形、冷拔成形、无模拉拔成形以及电铸成形,并对微细金属管制造技术的未来发展趋势与研究重点进行了展望。

微纳富磷生物炭对土壤-苏柳系统中Cu和Pb稳定性的影响

土壤重金属污染对生态环境和人类健康造成严重威胁,生物炭作为优秀土壤改良剂,与植物联合发挥作用,是修复受重金属污染的土壤的潜力途径。以动物源生物质骨粉为原料,采用高温裂解联合湿法球磨技术,制备了两种不同粒径(<75μm和<1.0μm)的富磷生物炭(BC和MBC)。通过大棚盆栽试验,考察不同施用剂量(0、0.5%、1.0%和2.0%,w%)的BC和MBC对重金属污染土壤中Cu和Pb的赋存形态及其在苏柳172(Salix jiangsuensis ‘172’)的积累和转运影响。主要结果如下:1)通过对两种粒径的富磷生物炭进行SEM-EDS-mapping、TEM、XRD和FT-IR等分析表征,证明了富磷生物炭为含有大量的羟基磷灰石的富炭固相材料,且球磨后的MBC的比表面积和孔体积较BC可分别提升5.93倍和4.65倍;2)施用BC和MBC均能有效降低土壤Cu和Pb的生物可利用态含量,且同等剂量MBC的效果更优。在添加2%BC和MBC条件下,Cu和Pb的生物可利用态含量较对照显著降低了6.41%、17.31%和8.84%、30.31%(P<0.05);3)添加BC和MBC均显著增加了苏柳172生物量(P<0.05),显著降低了苏柳172根部中Cu和Pb的含量(P<0.05),但对苏柳172积累Cu和Pb无显著影响(P>0.05);4)BC(0-2.0%)对苏柳172的Cu和Pb生物富集和转运能力无显著影响(P>0.05),而MBC(1.0%-2%)显著提升苏柳172对Cu和Pb的生物富集和转运能力(P<0.05),2.0%MBC可使Cu和Pb的TF值分别提升101.06%和25.16%。该文对了解微纳富磷生物炭联合树木修复Cu、Pb复合污染土壤具有重要意义,可为重金属污染土壤的生态修复提供科学依据。

面向磁流体增强的骨架结构微成型设计及回弹特性研究

为提高磁流体密封液膜的刚度和抗压力性能,设计一种应用于磁流体密封的翻边Z型增强骨架,该骨架由软磁金属薄板微成型冲压而成。对软磁金属电工纯铁和无取向硅钢进行单向拉伸试验,得到2种材料的应力应变曲线。利用幂硬化准则对Z型骨架成型回弹特性进行理论分析,确定影响回弹的主要因素为材料参数、厚度、弯曲半径、开孔宽度等。利用有限元软件对成型回弹过程进行仿真,应用因素水平分析,以残余应变和最大回弹量为指标,分析板胚厚度、弯曲半径、开孔宽度对回弹的影响。仿真结果表明:在研究的范围内通过增大板胚厚度、减小弯曲半径、减小翅片宽度能有效降低骨架回弹;当厚度为0.3 mm,弯曲半径0.3 mm,翅片尺寸为2 mm×1 mm时骨架成型回弹量最小,运用硅钢材料比纯铁具有更小的回弹量。研究结果对软磁金属的微成型冲压及磁流体密封复合材料设计提供了参考。

金属波纹管开裂失效分析与防控策略研究

金属波纹管开裂失效是化工流程生产安全重点关注的技术问题。为了提高金属波纹管的安全稳定性,在对金属波纹管开裂失效的主要原因进行综合分析的基础上,以三氯氢硅储罐出料管线金属波纹管开裂失效为例,重点从断口宏观形貌分析、金相组织分析等方面入手,对该金属波纹管开裂失效的行为和原因进行了深入研究,结合现场生产实际运行数据,对金属波纹管开裂失效提出了有意义的防控策略。这有助于及时预防金属波纹管开裂失效事故,对确保设备长周期安全稳定运行具有重要指导意义。

Conventional and micro scale finite element modeling for metal cutting process:A review

The metal cutting process is accompanied by complex stress field,strain field,temperature field.The comprehensive effects of process parameters on chip morphology,cutting force,tool wear and residual stress are complex and inter-connected.Finite element method(FEM)is considered as an effective method to predict process variables and reveal microscopic physical phenomena in the cutting process.Therefore,the finite element(FE)simulation is used to research the conventional and micro scale cutting process,and the differences in the establishment of process variable FE simulation models are distinguished,thereby improving the accuracy of FE simulation.The reliability and effectiveness of FE simulation model largely depend on the accuracy of the simulation method,constitutive model,friction model,damage model in describing mesh element,the dynamic mechanical behavior of materials,the tool-chip-workpiece contact process and the chip formation mechanism.In this paper,the FE models of conventional and micro process variables are comprehensively and up-to-date reviewed for different materials and machining methods.The purpose is to establish a FE model that is more in line with the real cutting conditions,and to provide the possibility for optimizing the cutting process variables.The development direction of FE simulation of metal cutting process is discussed,which provides guidance for future cutting process modeling.

强激光加载下铝、锡微喷特性实验研究

基于皮秒激光驱动的高能X射线源具有微焦点、高亮度和高分辨的优良特性,已成为研究金属材料微层裂和微喷射现象的热门诊断方法之一。锡因其熔点较低而成为微喷研究熔化影响的首选材料,铝由于熔点相对较高,不易发生冲击或卸载熔化形成液滴喷射,因此,铝微喷实验研究结果相对较少。基于“星光-III”激光装置的纳秒加载源和皮秒束诊断源,发展了皮秒激光驱动高能X射线背光照相技术,研究了表面含V型几何缺陷的金属锡、铝微喷特性,通过延时控制,获取了两种典型金属微喷射过程的高分辨物理图像,得到了喷射物质的形态分布、平均速度和面密度分布等重要信息。采用SPH方法对实验结果进行了数值模拟分析,揭示了实验中喷射物的形成机理以及高速喷射物质的来源。

微弧氧化处理对医用金属生物活性的影响

背景:在众多金属植入物表面改性技术中,微弧氧化技术因操作方便、成本低且能有效调整表面涂层的微观结构和元素而得到广泛关注。目的:总结微弧氧化技术在不同材料表面制备氧化涂层的理化性能及生物活性的研究进展。方法:应用计算机检索PubMed和Web of Science数据库中有关于微弧氧化技术对医用金属生物活性影响的文献,英文检索词为“MAO、micro-arc oxidation、osseointegration、mechanical property、biological activity、angiogenesis、fibrogenesis”,检索时间范围是2016年1月至2022年12月。根据纳入与排除标准,最终纳入82篇文献进行综述。结果与结论:微弧氧化技术是一种极具潜力的表面改性技术,可以极大提高种植体植入的成功率,也可以广泛应用于其他领域,具体原因如下:①微弧氧化技术在材料表面形成特殊多孔形貌,可以优化其耐磨性、耐腐蚀性等机械性能,降低镁合金的降解速率;②微弧氧化技术可以通过在材料多孔形貌中掺入锶、羟基磷灰石和其他金属或非金属物质,辅助提高其成骨分化、血管生成、纤维生成等生物活性,改善钛和钛合金生物惰性的缺点。

金属尾矿微生物对尾矿环境的适应与调控机制研究进展

当前中国金属尾矿产生量和贮存量大、分布广、监管难度大、综合利用率低,由此而引起的环境污染问题引起了广泛关注。研究金属尾矿微生物对尾矿环境的适应和调控机制对于尾矿的生物修复具有重要的现实意义,是加强重金属污染防控的重要组成部分。综述了金属尾矿微生物群落的物种组成,并从pH、重金属和养分方面阐明其对尾矿环境的适应和调控机制。结果表明,金属尾矿中的优势细菌主要为变形菌门(Proteobacteria)、放线菌门(Actinobacteria)、绿弯菌门(Chloroflexi)、厚壁菌门(Firmicutes)和酸杆菌门(Acidobacteria);优势真菌主要为子囊菌门(Ascomycota)、担子菌门(Basidiomycota)和罗兹菌门(Rozellomycota);奇古菌门(Thaumarchaeota)和广古菌门(Euryarchaeota)是其中的优势古菌。金属尾矿微生物属于K型策略微生物,它们通过阻止质子和重金属离子进入细胞和从细胞内部排出质子和重金属离子的方式来适应尾矿极酸性和高含量重金属环境,并在养分限制下利用有限的资源获取营养。微生物还进化出了主动改变尾矿环境的能力,它们通过中和质子以及转化和沉淀重金属的方式提高尾矿环境pH值和降低重金属的毒性,并通过固碳、固氮作用和溶解无机磷来积累养分。此外,豆科植物等修复植物能通过分泌次级代谢产物,吸引有益微生物参与尾矿环境的改善。对于金属尾矿的微生物修复研究,可以从金属尾矿风化和修复期间微生物群落的动态变化、多组学技术联合筛选尾矿修复菌剂、微生物的水平基因转移机制、金属尾矿中病毒多样性、微生物之间和微生物与植物的相互作用等方面深入研究,充分发掘金属尾矿微生物在促进生态修复方面的潜力,为金属尾矿环境治理提供科学的解决方案。