Performance-control-orientated hybrid metal additive manufacturing technologies:state of the art,challenges,and future trends

Metal additive manufacturing(AM)technologies have made significant progress in the basic theoretical field since their invention in the 1970s.However,performance instability during continuous processing,such as thermal history,residual stress accumulation,and columnar grain epitaxial growth,consistently hinders their broad application in standardized industrial production.To overcome these challenges,performance-control-oriented hybrid AM(HAM)technologies have been introduced.These technologies,by leveraging external auxiliary processes,aim to regulate microstructural evolution and mechanical properties during metal AM.This paper provides a systematic and detailed review of performance-control-oriented HAM technology,which is categorized into two main groups:energy field-assisted AM(EFed AM,e.g.ultrasonic,electromagnetic,and heat)technologies and interlayer plastic deformation-assisted AM(IPDed AM,e.g.laser shock peening,rolling,ultrasonic peening,and friction stir process)technologies.This review covers the influence of external energy fields on the melting,flow,and solidification behavior of materials,and the regulatory effects of interlayer plastic deformation on grain refinement,nucleation,and recrystallization.Furthermore,the role of performance-control-oriented HAM technologies in managing residual stress conversion,metallurgical defect closure,mechanical property improvement,and anisotropy regulation is thoroughly reviewed and discussed.The review concludes with an analysis of future development trends in EFed AM and IPDed AM technologies.

A Perspective on Human Exposures to Plastics Additives in Water-Packaging Materials

Plastic and polymer additives (PA) have unique rational advantages for various water and food packaging applications. However, their (bio)chemical natures are recently recognized for their negative human health impacts. The major adverse consequence of these additives in consumer products is in the form of endocrine-disruption related health-downgrades. Such findings still remain underappreciated in most parts globally;part of which could be ascribed to fragmented studies towards better understanding on the occurrence, release and migration, human exposure, epidemiology and risk assessment of PA from packaging materials. In addition there is limited and disconnected dissemination of research findings on PA effects and mitigation measures to society at present. In light of appropriateness of this topic, a trans-disciplinary research agenda is required for addressing exposure routes to PA, human health burden and prevention measures. This perspective article discusses important research questions relating to PA, which try to shed light to a grey scientific area and help increase consumers’ awareness and intervention to such exposures.

Modified Vegetable Oil Based Additives as a Future Polymeric Material—Review

Polymeric materials from renewable resources have attracted a lot of attention in recent years. The development and utilization of vegetable oils for polymeric materials are currently in the spotlight of the polymer and chemical industry, as they are the largest renewable platform due to their universal wide availability, ingrained biodegradability, low cost, and excellent environmental aspects (i.e., low ecotoxicity and low toxicity toward humans). These excellent natural characteristics are now being taken advantage of in research and development, with vegetable oil derived polymers/polymeric materials/composites being used in numerous applications including paints and coatings, adhesives, and nanocomposites. The aim of this review paper is to give a fundamental description of the various vegetable oil applications in polymer materials and its recent developments. Particular emphasis will be placed on study and main application of triglyceride based additive for polymer and to give the reader an insight into the main developments is discussed.

Dechlorination Behavior of Mixed Plastic Waste by Employing Hydrothermal Process and Limestone Additive

The usage of plastic-impregnated waste derived solid fuel in conventional combustor is hindered by many technical factors, especially its organic chlorine content. In this paper, experimental study of hydrothermal treatment on mixed plastic waste using the mixture of polypropylene, polystyrene, polyethylene and polyvinyl chloride （PVC） has been performed to observe the dechlorination effect of hydrothermal treatment on the waste. The system was generally applying saturated steam at around 2.4 MPa in a stirring reactor for about 90 minutes. After undergoing the process, the organic chlorine in treated plastic waste was reduced to 1,700 ppm level while the inorganic chlorine content was increased, suggesting an organic chlorine conversion phenomenon to inorganic chlorine, accompanied with low pH due to dehydrochlorination process. Additional limestone （Ca（OH）2） in subsequent experiment showed that the similar phenomenon was occurred but with higher pH and lower chlorine content in the condensed water, suggesting the production of inorganic salt rather than hydrochloric acid. Laboratory scale experiment was also performed to confirm the dechlorination phenomena especially for PVC, and the result showed that the main parameter which affected the dechlorination phenomena was the amount of water in hydrothermal process rather than limestone addition. It is suggested that a combination ofhydrothermal process and alkali addition would produce a low-chlorine solid product from plastic waste, promoting its usage as alternative solid fuel.

Utilization of Hydrocarbons Obtained by Waste Plastic Pyrolysis： Application for Additive Production （Part Ⅱ）

New route of the utilization of products obtained by waste plastic pyrolysis has been investigated. ct-olefin-succinic-anhydride intermediate based on new experimental additives has been developed and used for achieving the better properties of carbon fibre reinforced polymer composites. Hydrocarbon fractions were produced by the pure thermal pyrolysis of waste polymers in a tube reactor using 550 ℃ in the absence of oxygen. Selected compounds （C30-C50） from pyrolysis products have been used as raw materials in the additive synthesis step. Polymer composite specimens have been investigated among others by universal tensile machine, SEM （scanning electron microscopy） and FTIR （fourier transformed infrared spectroscopy） methods. The tensile strength could be increased by 29.9%, the E-modulus by 24.2% and the Charpy impact strength by 13.3% in the presence of the experimental additive. Fibre-matrix interaction has been studied on SEM micrographs of the fractured face of composites. The results of mechanical testes have been supported by the SEM micrographs and possible shames of the coupling have been proposed.

金属增材制造质量控制及复合制造技术研究现状

相比传统制造工艺,增材制造能够实现复杂结构金属部件的近净成形。然而,增材制造具有冷却速度快、热梯度大、非平衡凝固与往复热循环历史等特点,容易存在孔洞、残余拉应力、各向异性等缺陷,极大限制增材制造的进一步应用。复合增材制造技术是将传统制造方法与增材制造有机结合,充分发挥传统制造工艺在性能调控与尺寸精度等方面的优势,抑制单纯增材制造引起的各类缺陷,获得高质量、无缺陷的增材制造部件。本文首先揭示增材制造工艺缺陷的形成机理,明确工艺参数优化方法在缺陷改善方面的局限性,进而阐明复合增材制造的内涵,综述近年来增材制造与轧制、激光冲击强化、热等静压、热处理等复合制造技术的研究现状与工艺原理,探讨复合增材制造技术对不同缺陷的适用性,并对增材制造未来发展方向进行了展望。

晶体塑性有限元方法在增材制造金属材料力学性能研究中的应用

增材制造作为先进制造技术的代表,已被广泛应用于航空航天等高新技术领域。金属增材制造技术的高能量密度、高热和快速冷却等复杂工艺特点使得成形件的微观结构与传统制造技术所得成形件显著不同,这对金属材料力学性能有着重要影响。晶体塑性有限元方法将晶体塑性理论与有限元方法相结合,能够跨尺度分析增材制造金属材料微观结构与力学性能之间的关系,为优化工艺过程提供支撑。本文综述了近年来晶体塑性有限元方法在金属增材制造中的应用,阐述了代表增材制造金属材料微观结构特征的几何模型的建立方法和有限元应用,提出了相关发展趋势。

塑料添加剂的环境迁移、毒性测试与风险筛查:进展与挑战

塑料和微塑料污染日益严峻,因此引发了对塑料添加剂释放现象的广泛关注,塑料添加剂在固废处置和回收过程中会大量向环境中释放。塑料添加剂种类繁多,功能多样,数量庞大,其复杂性使得其评估工作面临巨大挑战,尤其是目前塑料添加剂的风险评估工作尚未建立起完善的体系。本研究对现有塑料添加剂的释放迁移研究、毒性测试及风险预测方法进行梳理,并基于塑料添加剂在种类、功能、添加量、监管、数据可用性等方面对公开信息的塑料添加剂逐级筛查,最终从1万多种现有塑料添加剂中筛选出106种值得关注的未监管添加剂物质。然后综合以下4项危害性指标,包括基于QSAR模型预测的物质毒性作用方式和危害等级、各化学品机构评估的PBT/PMT性质(持久性、生物累积性、迁移性、毒性)、生态毒性数据可用性、是否纳入化学品未来评估计划(CoRAP,ECHA),使用毒理学优先指数(ToxPi)方法按照等权重计算综合得分并排序,通过层次聚类分析对其进行优先级分类,提出相应风险评估优先序和研究关注的建议。结果表明,这其中很多尚未监管的塑料添加剂物质的潜在生态风险可能被低估。最后,我们提出对微塑料未来的研究挑战应主要聚焦在填补危害数据缺口和技术方法空白,包括其迁移释放机制、环境转化、混合效应及对生态系统的潜在影响等方面。

FDM成型工艺对PEEK/CGF复合材料翘曲变形的影响

为降低连续玻璃纤维增强聚醚醚酮复合材料增材制造样件的翘曲变形,优化增材制造基础工艺参数,通过单因素试验、Plackett-Burman Design试验与Box-Behnken Design试验,研究了打印过程中的热效应,即保温舱温度、层厚、成型平台温度、打印速度等工艺参数对连续玻璃纤维增强聚醚醚酮复合材料样件翘曲变形的影响规律,得出如下结论:研究发现打印工艺对翘曲度的影响程度是不同的,影响程度依次为B(层厚)>C(成型平台温度)>A(保温舱温度)。研究发现打印工艺参数之间是会对翘曲变形产生交互作用的,并且影响程度也较为显著(PB析因试验中大于t值),即B>C>A>AB>BC>D(打印速度)>BD。研究发现喷头温度440℃,成型平台温度100℃,保温舱温度90℃,层厚0.3 mm,道间距为0.5 mm,打印速度2 mm/s时,翘曲度可达到0.23%。

激光增材制造相变诱导型高熵合金的研究进展

高熵合金是以4种及以上元素为主元的合金,热力学上存在高熵效应,动力学上呈现迟滞扩散效应,晶体学上表现为晶格畸变效应,使用时展现出鸡尾酒效应,具有良好的力学性能和耐腐蚀性。相变诱导塑性高熵合金通过在变形过程中发生马氏体相变,延迟了裂纹的产生,同时提高了金属的加工硬化率,解决了塑性-强度难题,具有极大的研究潜力和应用前景。铸造高熵合金存在偏析严重、晶粒粗大等缺陷,成形样品力学性能差。增材制造具有局部熔池快速凝固的特点,成形的高熵合金成分均匀、晶粒细小,力学性能远高于铸件。本文阐述了增材制造成形相变诱导塑性高熵合金的显微组织、力学性能、组织演变、耐蚀性等方面的研究进展,并展望了未来的研究方向。

环氧餐饮废油环保增塑剂的制备

以餐饮废油为原料,制备了不同环氧值的环氧餐饮废油,通过正交实验,探究了影响环氧值的因素。将环氧餐饮废油作为增塑剂,制备天然橡胶混炼胶与硫化胶,并与传统石油基增塑剂(芳烃油、环保芳烃油)的混炼胶和硫化胶进行对比。结果表明,环氧餐饮废油为增塑剂的橡胶制品各项性能均达到了添加传统增塑剂橡胶制品的水平,老化性能优于传统增塑剂的橡胶制品。新型的环氧餐饮废油环保增塑剂兼具经济效益和环保优势,具有广泛的应用前景。

杉木和米槠人工林细根形态对短期氮和磷添加的可塑性响应

以福建三明地区林龄相似的丛枝菌根树种杉木(Cunninghamia lanceolata)人工林和外生菌根树种米槠(Castanopsis carleisii)人工林为研究对象,采用短期氮添加与根袋法探讨氮和磷添加对不同菌根类型树种细根形态性状的影响。结果表明,杉木细根的直径与组织密度表现出显著正的氮和磷可塑性响应,比根长和比表面积表现出负的氮和磷可塑性响应,而米槠细根的各形态性状均表现出与杉木相反的氮和磷可塑性响应方向;杉木细根形态性状的磷可塑性响应更强,米槠细根形态性状的氮和磷可塑性响应间无显著差异。细根同一形态性状对氮和磷添加的可塑性响应间的方向相同,且具有正相关关系;细根不同形态性状的养分塑性响应间存在着协同与权衡关系。因此,丛枝菌根树种杉木采取了延长细根寿命的资源保守型策略,而外生菌根树种米槠采取快速占有资源的资源获取型策略。此外,杉木和米槠细根对氮和磷添加可能均具有相同的觅食趋向,且杉木细根形态性状对磷添加更敏感。

热辅助超声滚压温度场参数影响激光熔覆涂层表面粗糙度研究

目的降低激光熔覆涂层的表面粗糙度。方法采用激光熔覆技术制备铁基激光熔覆涂层,采用超声温滚压耦合热处理工艺对熔覆层进行熔覆后强化加工,重点研究温度场参数对成形表面粗糙度的影响,通过方差分析(ANOVA)确立参数显著性,同时利用响应曲面法(RSM)构建温度场参数影响铁基涂层表面粗糙度的预测模型,并进行参数优化。结果加热温度和保温时间对成形试样表面粗糙度的影响显著。在实验参数范围内,试样的表面粗糙度与加热温度呈正相关,与保温时间呈负相关。实验结果表明,在相同保温时间下,在加热温度100、250、400℃条件下试样的表面粗糙度Ra分别为0.237、0.158、0.096μm;在相同加热温度下,在保温时间为0.5、1、2 h条件下试样的表面粗糙度Ra分别为0.156、0.164、0.170μm。可见与保温时间相比,加热温度对涂层表面粗糙度的影响更显著。参数优化分析结果表明,在实验参数范围内,在400℃加热温度和0.5 h保温时间条件下,试样具有最小的表面粗糙度Ra(0.089μm)。结论相较于车削及常温滚压工艺,采用超声温滚压耦合热处理工艺可进一步降低激光熔覆涂层的表面粗糙度,在实验参数范围内,加热温度400℃和保温时间0.5 h是最优的温度场参数组合。

基于晶粒形貌的增材制造力学行为数值模拟

为了研究电弧增材制造中材料的各向异性力学行为,本文建立了双椭球热源模拟电弧增材制造过程中的温度场,建立Monte Carlo模型模拟增材层截面微观组织的变化,建立晶体塑性模型表征晶粒形貌对材料力学行为的影响规律,从而修正位错动力学模型,得到基于晶粒形貌特征的电弧增材制造中各向异性的力学行为数值模拟方法。修正后的位错动力学模型可以很好地反映出电弧增材制造工艺特征导致的材料各向异性行为,且与试验结果一致。电弧增材制造构件在增材高度方向上的力学性能显著低于热源移动方向的力学性能,在增材高度方向上和热源移动方向上晶粒尺寸比达到7.5 mm/1.3 mm时,屈服强度比达到787.8 MPa/865.2 MPa。钛合金在600℃以上出现明显的材料软化,这主要是晶粒球化导致的。

Enhancing fatigue performance of AZ31 magnesium alloy components fabricated by cold metal transfer-based wire arc directed energy deposition through LPB

Cold Metal Transfer-Based Wire Arc Directed Energy Deposition(CMT-WA-DED)presents a promising avenue for the rapid fabrication of components crucial to automotive,shipbuilding,and aerospace industries.However,the susceptibility to fatigue of CMT-WA-DED-produced AZ31 Mg alloy components has impeded their widespread adoption for critical load-bearing applications.In this study,a comprehensive investigation into the fatigue behaviour of WA-DED-fabricated AZ31 Mg alloy has been carried out and compared to commercially available wrought AZ31 alloy.Our findings indicate that the as-deposited parts exhibit a lower fatigue life than wrought Mg alloy,primarily due to poor surface finish,tensile residual stress,porosity,and coarse grain microstructure inherent in the WA-DED process.Low Plasticity Burnishing(LPB)treatment is applied to mitigate these issues,which induce significant plastic deformation on the surface.This treatment resulted in a remarkable improvement of fatigue life by 42%,accompanied by a reduction in surface roughness,grain refinement and enhancement of compressive residual stress levels.Furthermore,during cyclic deformation,WA-DED specimens exhibited higher plasticity and dislocation density compared to both wrought and WA-DED+LPB specimens.A higher fraction of Low Angle Grain Boundaries(LAGBs)in WA-DED specimens contributed to multiple crack initiation sites and convoluted crack paths,ultimately leading to premature failure.In contrast,wrought and WA-DED+LPB specimens displayed a higher percentage of High Angle Grain Boundaries(HAGBs),which hindered dislocation movement and resulted in fewer crack initiation sites and less complex crack paths,thereby extending fatigue life.These findings underscore the effectiveness of LPB as a post-processing technique to enhance the fatigue performance of WA-DED-fabricated AZ31 Mg alloy components.Our study highlights the importance of LPB surface treatment on AZ31 Mg components produced by CMT-WA-DED to remove surface defects,enabling their widespread use in load-bearing applications.

食品包装塑料添加剂的暴露评估研究进展

随着塑料食品包装材料的广泛使用,食品包装塑料衍生的食品安全问题日益成为学术界关注的焦点。食品包装塑料在与食品接触过程中可释放出多种塑料添加剂(food packaging plastic additives,FPPAs)而产生食品安全隐患,部分FPPAs已被证实具有内分泌干扰性、致突变性和致癌性等毒性效应,也使其潜在健康风险备受关注。本文对FPPAs的检测方法及其在食品及人体生物样本中的检出情况进行综述,在详细阐述FPPAs的识别和筛选分析方法及其局限性的基础上,结合在食品和人体生物样本中可检出的多种FPPAs,阐述采用拟靶向和非靶向分析策略建立FPPAs分析方法的必要性。

增材铜合金拉伸力学行为的卷积神经网络预测

深度学习因其在处理复杂数据和解决复杂问题方面的显著优势而备受关注,已应用于材料性能预测领域。本文提出了一种结合卷积神经网络模型与晶体塑性有限元方法的预测框架,在晶体塑性模型中考虑了增材铜合金(CuCrZr)固溶强化、位错强化以及晶界强化的贡献,实现了基于增材铜合金的晶体学织构极图、微结构图和晶粒尺寸预测单轴拉伸力学行为的目标。首先,基于实验结果对晶体塑性模型参数进行校正,验证了模型的准确性及预测能力。随后,使用参数校正后的晶体塑性模型对增材铜合金不同的代表体积元进行了一系列的有限元模拟,并利用这些模拟结果对卷积神经网络模型进行了训练、验证与测试。研究结果表明,该卷积神经网络模型在保证预测精度的同时,显著减少了计算时间,展示了其在增材铜合金力学性能预测方面的应用前景。

环保钙/锌PVC热稳定剂的发展现状及应用

热稳定剂是聚氯乙烯(PVC)加工过程中重要的塑料助剂,可以抑制聚氯乙烯在高温下发生热降解,改善PVC热稳定性能。PVC是全球五大通用塑料之一,国内外对PVC的需求量逐渐增大,热稳定剂的消耗量随之增长,因此,低毒、无污染且高效环保的钙/锌热稳定剂成为研究热点。介绍了近年来国内外聚氯乙烯热稳定剂的发展现状,由于铅、镉盐类热稳定剂有毒,已被欧盟禁用,有机锡类热稳定剂价格昂贵,而环保钙/锌热稳定剂市场需求急剧增加。综述了钙/锌热稳定剂的研究现状,分析了环保热稳定剂对PVC的作用机理,提出了钙/锌热稳定剂市场应用前景和未来的发展重点及方向。

金属增材制造晶体塑性有限胞元自洽聚类分析方法

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