Wire arc additive manufacturing of a heat-resistant Al-Cu-Ag-Sc alloy:microstructures and high-temperature mechanical properties

With a high energy efficiency,low geometric limitation,and low cracking susceptivity to cracks,wire arc additive manufacturing(WAAM)has become an ideal substitute for casting in the manufacturing of load-bearing high strength aluminum components in aerospace industry.Recently,in scientific researches,the room temperature mechanical performance of additive manufactured high strength aluminum alloys has been continuously broken through,and proves these alloys can achieve comparable or even higher properties than the forged counterpart.Since the aluminum components for aerospace usage experience high-low temperature cycling due to the absence of atmosphere protection,the high temperature performances of additive manufactured high strength aluminum alloys are also important.However,few research focuses on that.A special 2319Ag Sc with 0.4 wt.%Ag and 0.2 wt.%Sc addition designed for high temperature application is deposited successfully via cold metal transfer(CMT)based on WAAM.The microstructures and high temperature tensile properties are investigated.The results show that the as-deposited 2319Ag Sc alloy presents an alternate distribution of columnar grains and equiaxed grains with no significant textures.Main second phases are Al_(2)Cu and Al3Sc,while co-growth of Al_(2)Cu and bulk Al_(3)Sc is found on the grain boundary.During manufacturing,nanoscale Al_(2)Cu can precipitate out from the matrix.Ag and Mg form nano-scaleΩphase on the Al_(2)Cu precipitates.At 260℃,average yield strengths in the horizontal direction and vertical direction are 87 MPa±2 MPa,87 MPa±4 MPa,while average ultimate tensile strengths are 140 MPa±7 MPa,141 MPa±11 MPa,and average elongations are 11.0%±2.5%,13.5%±3.0%.Anisotropy in different directions is weak.

Microstructure and mechanical properties of high-strength low alloy steel by wire and arc additive manufacturing

A high-building multi-directional pipe joint(HBMDPJ)was fabricated by wire and arc additive manufacturing using high-strength low-alloy(HSLA)steel.The microstructure characteristics and transformation were observed and analyzed.The results show that the forming part includes four regions.The solidification zone solidifies as typical columnar crystals from a molten pool.The complete austenitizing zone forms from the solidification zone heated to a temperature greater than 1100℃,and the typical columnar crystals in this zone are difficult to observe.The partial austenitizing zone forms from the completely austenite zone heated between Ac1(austenite transition temperature)and1100℃,which is mainly equiaxed grains.After several thermal cycles,the partial austenitizing zone transforms to the tempering zone,which consistes of fully equiaxed grains.From the solidification zone to the tempering zone,the average grain size decreases from 75 to20μm.The mechanical properties of HBMDPJ satisfies the requirement for the intended application.

Detection and Characterization of Defects in Additive Manufacturing by Polarization-Based Imaging System

Additive manufacturing (AM) technology such as selective laser melting (SLM) often produces a high refection phenomenon that makes defect detection and information extraction challenging. Meanwhile, it is essential to establish a characterization method for defect analysis to provide sufcient information for process diagnosis and optimization. However, there is still a lack of universal standards for the characterization of defects in SLM parts. In this study, a polarization-based imaging system was proposed, and a set of characterization parameters for SLM defects was established. The contrast, defect contour information, and high refection suppression efect of the SLM part defects were analyzed. Comparative analysis was conducted on defect characterization parameters, including geometric and texture parameters. The experimental results demonstrated the efects of the polarization imaging system and verifed the feasibility of the defect feature extraction and characterization method. The research work provides an efective solution for defect detection and helps to establish a universal standard for defect characterization in additive manufacturing.

A Novel High Volume Manufacturing Method for Defect-free and High-yield SiN Micro-sieve Membranes

Micro-sieves have been widely used in medical treatment,quarantine,environment,agriculture,pharmacy and food processing.However,the manufacturing and yield improvement have been difficult due to multiple challenges,such as the sieve unit release defect,cracking,and KOH corrosion.In this paper,we report process details and discuss technical difficulties which are usually the root-causes for process failures,and demonstrate a reliable and high yield production of SiNx micro-sieves processed with our novel method,which is also compatible with high volume manufacturing.

Flip Chip Die-to-Wafer Bonding Review:Gaps to High Volume Manufacturing

Flip chip die-to-wafer bonding faces challenges for industry adoption due to a variety of technical gaps or process integration factors that are not fully developed to high volume manufacturing(HVM)maturity.In this paper,flip-chip and wire bonding are compared,then flip-chip bonding techniques are compared to examine advantages for scaling and speed.Specific recent 3-year trends in flip-chip die-to-wafer bonding are reviewed to address the key gaps and challenges to HVM adoption.Finally,some thoughts on the care needed by the packaging technology for successful HVM introduction are reviewed.

Influence of MB-value of Manufactured Sand on the Shrinkage and Cracking of High Strength Concrete

The relation between methylene blue （MB） value of MS and its limestone dust content and clay content was investigated. The effects of MB value ranging from 0.35 to 2.5 on the workability of fresh concrete and crack propagation characteristics at the age of 24 hours, and effects on the mechanical properties, dry shrinkage of the harden concrete were tested. The experimental results show that the MB value is not related with the limestone dust content of MS, but in direct proportion to clay content. With the increase of MB value, the concrete workability decreases, and the flexural strength and 7 d compressive strength reduce markedly, whearas the 28 d compressive strength is not affected. When the MB-value is less than or equal to 1.35, the change of the MB-value has a little influence on early plastic cracking and dry shrinkage property of concrete, but when the MB-value is more than 1.35, the tendency of plastic cracking and dry shrinkage is remarkable.

Laser additive manufacturing of Si/ZrO_(2)tunable crystalline phase 3D nanostructures

The current study is directed to the rapidly developing field of inorganic material 3D object production at nano-/micro scale.The fabrication method includes laser lithography of hybrid organic-inorganic materials with subsequent heat treatment leading to a variety of crystalline phases in 3D structures.In this work,it was examined a series of organometallic polymer precursors with different silicon(Si)and zirconium(Zr)molar ratios,ranging from 9:1 to 5:5,prepared via sol-gel method.All mixtures were examined for perspective to be used in 3D laser manufacturing by fabricating nano-and micro-feature sized structures.Their spatial downscaling and surface morphology were evaluated depending on chemical composition and crystallographic phase.The appearance of a crystalline phase was proven using single-crystal X-ray diffraction analysis,which revealed a lower crystallization temperature for microstructures compared to bulk materials.Fabricated 3D objects retained a complex geometry without any distortion after heat treatment up to 1400℃.Under the proper conditions,a wide variety of crystalline phases as well as zircon(ZrSiO_(4)-a highly stable material)can be observed.In addition,the highest new record of achieved resolution below 60 nm has been reached.The proposed preparation protocol can be used to manufacture micro/nano-devices with high precision and resistance to high temperature and aggressive environment.

Effects of Manufactured-sand on Dry Shrinkage and Crccp of High-strength Concrete

The influences of natural sand, manufactured-sand （MS） and stone-dust （SD） in the manufactured-sand on workability, compressive strength, elastic modulus, drying shrinkage and creep properties of high-strength concrete （HSC） were tested and compared. The results show that the reasonable content （7%-10.5%） of SD in MS will not deteriorate the workability of MS-HSC. It could even improve the workability. Moreover, the compressive strength increases gradually with the increasing SD content,and the MS- HSC with low SD content （smaller than 7%） has the elastic modulus which approaches that of the natural sand HSC, but the elastic modulus reduces when the SD content is high. The influence of the SD content on drying shrinkage performance of MS-HSC is closely related to the hydration age. The shrinkage rate of MS-HSC in the former 7 d age is higher than that of the natural sand HSC, but the difference of the shrinkage rate in the late age is not marked. Meanwhile the shrinkage rate reduces as the fly ash is added; the specific creep and creep coefficient of MS-HSC with 7% SD are close to those of the natural sand HSC.

Decomposition Methods for Manufacturing System Scheduling:A Survey

Manufacturing is the application of labor, tools,machines, chemical and biological processing, to an original raw material by changing its physical and geometrical characteristics, in order to make finished products. Since the first industrial revolution, to accommodate the large-scale production,tremendous changes have happened to manufacturing through the innovations of technology, organization, management, transportation and communication. This work first reviews the highvolume low-mix process by focusing on the quantity production,transfer line and single model assembly line. Then, it reviews the high-volume high-mix process. For such a process type,mixed/multi model assembly line is usually adopted. Hence,two main decisions on them, i.e., balancing and, sequencing are reviewed. Thereafter, it discusses the low-volume high-mix process in detail. Then, technology gap and future work is discussed, and at last, conclusions are given.

Advances in Compact Manufacturing for Shape and Performance Controllability of Large-scale Components-A Review

Research on compact manufacturing technology for shape and performance controllability of metallic components can reanze the simplification and high-reliability of manufacturing process on the premise of satisfying the requirement of macro/micro-structure. It is not only the key paths in improving performance, saving material and energy, and green manufacturing of components used in major equipments, but also the challenging subjects in frontiers of advanced plastic forming. To provide a novel horizon for the manufacturing in the critical components is significant. Focused on the high-performance large-scale components such as bearing rings, flanges, railway wheels, thick-walled pipes, etc, the conventional processes and their developing situations are summarized. The existing problems including multi-pass heating, wasting material and energy, high cost and high-emission are discussed, and the present study unable to meet the manufacturing in high-quality components is also pointed out. Thus, the new techniques related to casting-rolling compound precise forming of rings, compact manufacturing for duplex-metal composite rings, compact manufacturing for railway wheels, and casting-extruding continuous forming of thick-walled pipes are introduced in detail, respectively. The corresponding research contents, such as casting ring blank, hot ring rolling, near solid-state pressure forming, hot extruding, are elaborated. Some findings in through-thickness microstructure evolution and mechanical properties are also presented. The components produced by the new techniques are mainly characterized by fine and homogeneous grains. Moreover, the possible directions for fin＇ther development of those techniques are suggested. Finally, the key scientific problems are first proposed. All of these results and conclusions have reference value and guiding significance for the integrated control of shape and performance in advanced compact manufacturing.

Study of Manufacturing Technology and Properties of AVGCI with Rare Earths

By vermicularizing agent containing RE (REFeSi), austempered vermicular graphite cast iron (AVGCI) with RE can be produced with austempered treatment. The process of austenitization of vermicular graphite cast iron (VGCI) with RE and the transformation of AVGCI with RE with temperature increasing were studied by SEM with heating device. Properties of AVGCI with RE, such as tensile strength, elongation, impact toughness, hardness, thermal fatigue resistance, thermal expansive coefficient and weight increasing by oxidation were measured by electron universal testing machine with heating device. Experimental results indicate that AVGCI with RE possesses good comprehensive properties at room and elevated temperatures.

Revisiting the electrode manufacturing: A look into electrode rheology and active material microenvironment

The microstructures on electrode level are crucial for battery performance, but the ambiguous understanding of both electrode microstructures and their structuring process causes critical challenges in controlling and evaluating the electrode quality during fabrication. In this review, analogous to the cell microenvironment well-known in biology, we introduce the concept of ‘‘active material microenvironment”(ME@AM)that is built by the ion/electron transport structures surrounding the AMs, for better understanding the significance of the electrode microstructures. Further, the scientific significance of electrode processing for electrode quality control is highlighted by its strong links to the structuring and quality control of ME@AM. Meanwhile, the roles of electrode rheology in both electrode structuring and structural characterizations involved in the entire electrode manufacturing process(i.e., slurry preparation, coating/printing/extrusion, drying and calendering) are specifically detailed. The advantages of electrode rheology testing on in-situ characterizations of the electrode qualities/structures are emphasized. This review provides a glimpse of the electrode rheology engaged in electrode manufacturing process and new insights into the understanding and effective regulation of electrode microstructures for future high-performance batteries.

智能制造:概念演化、体系解构与高质量发展

智能制造作为高阶制造业态和新型生产方式,已然成为新一轮工业革命的核心驱动力。当前,我国制造业处于转型升级和提质增效关键期,传统产业亟须通过新旧动能转换焕发新的生机,新兴技术产业和未来产业需要通过富有竞争力的制造模式抢占全球制高点,智能制造高质量发展成为我国制造业嵌入全球价值链高端的关键支撑。智能制造具有以智能工厂为载体、以生产制造关键环节和主要流程的智能化为核心、以工业互联网为关键支撑和以端到端数据流为基础的显著特征。推动智能制造高质量发展,要以关键核心技术攻关为核心,加快智能制造装备、工业软件和智能制造系统解决方案高端化智能化发展,推动智能工厂全面推广落地,打造传统制造业数字化转型样板,推动工业互联网标准体系建设。

HSM strategy study for hardened die and mold steels manufacturing based on the mechanical and thermal load reduction strategy

The paper discussed cutter-work engagement situation hidden behind the mechanical and thermal load effect on cutting edges during high speed hard machining process. The engagement situation was investigated in great detail using experimental and geometrical analytic measures. Experiments were conducted using A1TiN-coated micro-grain carbide end mill cutters to cut hardened die steel. On the basis, a general high speed hard machining strategy, which aimed at eliminating excessive engagement situation during high-speed machining （HSM） hard machining, was proposed. The strategy includes the procedures to identify prone-to-overload areas where excessive engagement situation occurs and then to create a reliable tool path, which has the effect of cutting load reduction to remove the prone-to-overload areas.

应用人工智能优化制造业人力资源结构的对策建议

人工智能相关技术、智能化设备和服务在高技术制造业中的广泛应用,对制造业劳动力素质提出了更高要求。为深入探讨人工智能在高技术制造业中的应用对制造业就业结构的影响,分析保持制造业劳动力资源优势所面临的挑战,开展文献分析和实地调研,认为在智能化时代下,部分就业岗位产生机器替代效应,新技能的岗位需求和用工缺口形成,劳动力市场供给进入负增长常态化阶段,同时多种产业新业态的灵活就业渠道分流了部分高素质劳动力。着眼于人工智能技术发展和应用对制造业(尤其是高技术制造业)及其从业人员的影响,基于对国内3家机构的调研与2018—2020年我国30个省份的面板数据,采用模糊集定性比较分析方法实证分析发现,产业智能化水平、劳动力受教育程度和专利投入规模是影响制造业就业结构变化的3个关键因素。为此,从提高制造业人力资源优势的视角,提出强化统筹规划、推广新兴技术、加快人才培养等多措并举,促进我国制造业就业结构优化,保持制造业人力资源优势的政策建议。

数字化转型、平台化变革与企业创新绩效——基于“技术—组织—创新”范式的分析

在数字经济和实体经济深度融合、全球创新竞争加剧的背景下,加快数字化转型和平台化变革,塑造多元互动和整体进化的创新生态系统,是增强制造业企业自主创新能力的重要途径。在传统技术经济范式中引入数字要素和平台理念,构建“技术—组织—创新”理论框架,分析数字化转型促进组织平台化变革进而提升企业创新绩效的作用机制。在理论分析的基础上,基于2014—2021年中国制造业上市公司的面板数据,实证检验了数字化转型、平台化变革与企业创新绩效之间的关系。研究结果表明:数字化转型对企业创新绩效的提升具有普遍的促进作用,并且对数字化水平更高和股权集中度更高的企业效果更显著;数字化转型促进了企业组织的平台化变革,基于数字平台形成创新生态系统进而增强了企业自主创新能力;数字化对企业平台化的推动作用主要通过专业化分工和企业互联互通实现,这是工业互联网平台发挥作用的两个重要维度。推动制造业企业的数字化转型和平台化变革,充分发挥数字平台的创新基础设施作用,能够提升企业创新绩效,推动制造业高质量发展。

长三角地区数字经济对高端装备制造业高质量发展的影响研究——基于有调节的中介效应分析

借助数字经济实现高端装备制造业高质量发展是中国式现代化建设的重要议题。本文基于长三角地区面板数据,利用有调节的中介效应模型检验了数字经济对高端装备制造业高质量发展的影响。结果发现:数字经济可以显著促进高端装备制造业高质量发展,稳健性检验后仍然成立;数字经济通过技术创新正向促进高端装备制造业高质量发展,且技术创新发挥部分中介效应;政府支持对技术创新的中介效应发挥正向调节作用;进一步异质性检验发现,数字经济对不同地区、不同细分行业高质量发展的影响存在显著差异。最后,从三个方面提出相关建议:构建全方位的区域协调发展机制,提升融合效能;聚焦重点领域,推动核心技术突破创新;聚焦制度创新,释放政策红利。

Optimization of Extrusion Process Parameters of Recycled High-Density Polyethylene-Thermoplastic Starch Composite for Fused Filament Fabrication

High-density poly-ethylene (HDPE) is a nonbiodegradable recyclable plastic which is widely utilized in single use packaging applications. Consequently, it constitutes a significant amount of plastic waste found in landfills. From literature, it has been shown that parts produced using composites of HDPE with carbohydrate-based polymers, such as thermoplastic starch (TPS), experience mechanical degradation through hydrolytic degradation process. The possible utilization of recycled-HDPE (rHDPE) and TPS composite in nonconventional manufacturing processes such as Fused filament fabrication (FFF) has however not been explored. This study explores the potential application of rHDPE and TPS composites in FFF and optimizes the extrusion process parameters used in rHDPE-TPS filament production process. Taguchi method was utilized to analyze the extrusion process. The extrusion process parameters studied were the spooling speed, extrusion speed and the extrusion temperatures. The response variable studied was the filament diameter. In this research, the maximum TPS content achieved during filament production was 40 wt%. This filament was however challenging to use in FFF printers due to frequent nozzle clogging. Printing was therefore done with filaments that contained 0 - 30 wt% TPS. The experimental results showed that the most significant parameter in extrusion process was the spooling speed, followed by extrusion speed. Extrusion temperature had the least significant influence on the filament diameter. It was observed that increase in TPS content resulted in reduced warping and increased rate of hydrolytic degradation. Mechanical properties of printed parts were investigated and the results showed that increasing TPS content resulted in reduction in tensile strength, reduction in compression strength and increase in stiffness. The findings of this research provide valuable insights to plastic recycling industries and researchers regarding the utilization of recycled HDPE and TPS composites as substitute materials in FFF.

体育用品制造企业数字化建设对其高质量发展的影响及作用机制——基于沪深A股和新三板的体育用品制造企业的实证研究

运用文本挖掘法分析沪深A股体育用品制造企业和新三板体育用品制造企业在2010—2021年的企业年报,基于样本企业在2010—2021年的非均衡面板数据评估企业数字化建设水平,在此基础上分析样本企业通过数字化建设对自身高质量发展的影响及作用机制。经研究表明:1)样本企业通过数字化建设能有效促进自身高质量发展,该结论在经过稳健性检验和内生性检验后依然成立;2)样本企业人力资本结构调整和组织集权强化在通过数字化建设促进企业自身高质量发展时存在中介效应;3)样本企业数字化建设显著增加了研发投入,但是研发投入增加在数字化建设促进企业自身高质量发展时存在遮掩效应;4)数字化建设能减少融资约束,但是融资约束减少对样本企业高质量发展的推动效应在短期内难以显现;5)大型样本企业、劳动密集型样本企业和资本密集型样本企业通过数字化建设能有效促进企业自身高质量发展,但是中小型样本企业在以数字化建设促进自身高质量发展时存在阻力。由此得出相关启示。