Best practices for making high integrity lightweight metal castings-molten metal composition and cleanliness control

To make high integrity lightweight metal castings,best practices are required in various stages of casting and heat treatment processes,including liquid metal composition and quality control,casting and gating/riser system design,and process optimization.This paper presents best practices for liquid metal processing and quality assurance of molten metal in both melting and mold filling.Best practices for other aspects of lightweight metal casting will be published separately.

A Lightweight, Adhesive, Dual-Functionalized Over-Coating Interphase Toward Ultra-Stable High-Current Density Lithium Metal Anodes

Coherent manipulation of the lithium plating pattern is at the heart of the safe operation of metallic anodes in the battery technologies. In this article,a lightweight (~0.3 mg cm^(-2)), dual-functionalized carbon spheres are anchored onto the Cu foil as the interfacial protective layer via the chelation process of the catechol groups in the polydopamine precursor and the copper foil. The dual-functionalized carbon spheres exhibit the intriguing complementary features:Lithiophilic nitrogen dopants favor the Li+ion absorption and mitigate the nucleation barrier, while the micro/mesopore reservoir spatially homogenizes the ion flux distribution, confining the metallic propagation without dendrite-like protrusions. The metallic anode exhibits an ultra-stable plating/stripping process for 1 400 hr with the average Coulombic efficiency of ~99%. A full-cell prototype is constructed by pairing the N-doped carbon spheres on the bare Cu (NCS-Cu) electrode with the high-mass-loading LiVPO4F (12.5 mg cm^(-2)) cathode that can deliver a high energy density of 421.2 Wh kg^(-1) with the highest power density of 2106 W kg^(-1) to promise the anode use for high-power/energy-dense metallic batteries.

航空航天先进结构材料技术现状及发展趋势

先进材料技术是航空航天高新装备的发展先导,是支撑现代工业的关键基础技术,渗透到国防建设、国民经济和社会生活等方方面面,已成为世界各国争相发展的技术高地和国防重点。本文梳理分析航空航天先进结构材料近年来的技术现状及发展趋势,在高性能高分子材料及其复合材料、高温与特种金属结构材料、轻质高强金属及其复合材料、先进结构陶瓷及其复合材料四方面进行重点阐释,明确我国航空航天结构材料的研发与生产仍面临着跟踪研仿多、自主创新少、技术封锁严重、技术瓶颈亟待突破等困境。同时,本文对航空航天结构材料未来研究和发展提出展望,点明建立“产-学-研-用”完整技术体系的重要性。

非金属材料在汽车轻量化中的应用浅析

在碳达峰碳中和的背景下,汽车轻量化具有极其重要的意义。文章从汽车轻量化的技术路线着手,对非金属材料在汽车轻量化中的主要应用方向进行了梳理,主要包括:以塑代钢、以塑代塑、薄壁化、微发泡。对每个技术方向例举相关使用案例并进行了粗略分析,给出了现有技术汽车轻量化方向以及未来汽车轻量化趋势,最后对非金属在汽车轻量化的方向进行了总结。

基于不同焊材的超高强钢与BS700高强钢焊接接头裂纹的试验研究

采用熔化极活性气体保护焊对抗拉强度大于1600 MPa的超高强钢与抗拉强度大于760 MPa的BS700高强钢进行焊接时,组合接头焊缝易出现焊接裂纹,为解决该问题,使用直径1.0 mm的ER70-G焊材或ER307Mo焊材,在打底焊接电流160~180 A、电压21~24 V,盖面焊接电流190~210 A、电压23~26 V条件下开展了焊接对比试验。工艺性和焊接性试验结果表明,使用ER307Mo焊材焊接的试样弯曲性能明显优于使用ER70-G焊材焊接的试样;使用ER70-G焊材焊接的试样焊缝存在未贯穿的微裂纹,焊缝断面裂纹率达到35.29%;使用ER307Mo焊材焊接的试样焊缝断面未发现裂纹。ER307Mo焊材更适合超高强钢与BS700高强钢的焊接。试验解决了超高强钢与BS700高强钢组合接头的开裂问题,为抗拉强度相差较大的异种高强钢的焊接提供了解决方案。

Identification of the Intrinsic Dielectric Properties of Metal Single Atoms for Electromagnetic Wave Absorption

Atomically dispersed metals on N-doped carbon supports(M-N_(xCs)) have great potential applications in various fields.However,a precise understanding of the definitive relationship between the configuration of metal single atoms and the dielectric loss properties of M-N_(xCs) at the atomic-level is still lacking.Herein,we report a general approach to synthesize a series of three-dimensional(3D)honeycomb-like M-N_xC(M=Mn,Fe,Co,Cu,or Ni) containing metal single atoms.Experimental results indicate that 3D M-N_(xCs) exhibit a greatly enhanced dielectric loss compared with that of the NC matrix.Theoretical calculations demonstrate that the density of states of the d orbitals near the Fermi level is significantly increased and additional electrical dipoles are induced due to the destruction of the symmetry of the local microstructure,which enhances conductive loss and dipolar polarization loss of 3D M-N_(xCs),respectively.Consequently,these 3D M-N_(xCs) exhibit excellent electromagnetic wave absorption properties,outperforming the most commonly reported absorbers.This study systematically explains the mechanism of dielectric loss at the atomic level for the first time and is of significance to the rational design of high-efficiency electromagnetic wave absorbing materials containing metal single atoms.

Selective preparation of light aromatic hydrocarbons from catalytic fast pyrolysis vapors of coal tar asphaltene over transition metal ion modified zeolites

The catalytic cracking of coal tar asphaltene(CTA)pyrolysis vapors was carried out over transition metalion modified zeolites to promote the generation of light aromatic hydrocarbons(L-ArHs)in a pyrolysisgas chromatography/mass spectrometry(Py-GC/MS)micro-reactor system.The effects of ultra stable Y(USY),Co/USY and Mo/USY on the selectivity and yield of L-ArHs products and the extent of deoxygenation(Edeoxygenation),lightweight(Elightweight)from CTA pyrolysis volatiles were investigated.Results showed that the yields of L-ArHs are mainly controlled by the acid sites and specific surface area of the catalysts,while the deoxygenation effect is determined by theirs pore size.The Eligltweight of CTA pyrolysis volatiles over USY is 9.65%,while the Edeoxygenation of CTA pyrolysis volatiles over Mo/USY reaches 20.85%.Additionally,the modified zeolites(Mo/USY and Co/USY)exhibit better performance than USY on L-ArHs production,owing to the synergistic effect of metal ions(Mo,Co)and acid sites of USY.Compared with the non-catalytic fast pyrolysis of CTA,the total yield of L-ArHs obtained over USY(4032 mg·kg^(-1)),Co/USY(4363 mg·kg^(-1))and Mo/USY(4953 mg·kg^(-1))were increased by 27.03%,38.19%and 54.78%,respectively.Furthermore,the possible catalytic conversion mechanism of transition metal ion(Co and Mo)modified zeolites was proposed based on the distribution of products and the characterizations of catalysts.

Development of low-cost high-strength stainless steel for new-energy bus frames

Along with strict environmental regulation, new-energy vehicles are becoming increasingly popular due to their low emissions, and they will inevitably replace existing fossil-fuel-based buses in China. To achieve a lightweight bus body ,high-strength steels are commonly used for the bus frame,but these grades are susceptible to corrosion. From the perspective of ＂lower life-cycle cost＂, high-strength stainless steel is a better bus structure choice than high-strength carbon steels, since stainless steel bus frames last 10-15 years without requiring any maintenance. The low-cost high-strength stainless steels developed by Baosteel are introduced,the yield and tensile strengths of which can be controlled to within the range of 350-700 MPa and 900-1 200 MPa,respectively, and the elongation values are above 30%. Measurements of the toughness and fatigue resistance of these high-strength stainless steels and their joints indicate that the structural integrity requirements for bus frames can be met. The results of salt spray corrosion studies indicate that stainless steels will substantially increase the service life of bus frames in wet and icy winter conditions where deicing with CaC12 is necessary for road safety. The results of our investigation clearly indicate that high-strength stainless steel is a potential bus-frame material that makes it possible to achieve substantial weight savings, excellent corrosion resistance, and prolonged operational life.

A Design Modification Approach to Utilize the Benefits of Metal Additive Manufacturing Adoption

Existing Metal Additive Manufacturing processes are fast approaching a matured stage in which a wide range of possibilities are available for the incorporation of the rapid fabrication technology to current industrial practices. In terms of design conventions, the limitless geometrical freedom allows complex structures including cellular internal grids and lattices to be formed without additional tooling. Repair parts and leveraging components can also be produced on demand when required especially for military assets where large volume of inventory is constantly maintained to ensure operational readiness. In this exemplary work, a feasibility study on using stainless steel material with integrated cellular design to manufacture a guide bracket found on a military vehicle via Selective Laser Melting process was conducted. The results showed appreciably better mechanical performance in using a stainless steel honeycomb as compared to the aluminum alloy used for the original component together with a faster production route through SLM.

ADVANCED SYNTHESIS OF LIGHT METALS

The synthesis, processing and mechanical properties of the light metals, aluminum,magnesium and titanium Produced by advanced techniques are reviewed. Synthesis techniques to be addressed will include rapid solidification, spray deposition, mechanical alloying, plasma Processing and vapor deposition.

金属与聚合物异种材料连接研究现状及发展

金属/聚合物复合结构在保持较高力学性能的基础上可实现工程轻量化,实现金属/聚合物的高效连接具有重要的学术价值与实践意义。本文以金属/聚合物复合结构在工程轻量化中的应用为出发点,对胶接、机械连接与焊接在内的金属/聚合物连接技术的特点进行分析,重点介绍了激光焊、感应焊、电阻焊、超声波焊、搅拌摩擦焊等焊接技术在金属/聚合物连接中的应用,阐述了金属/聚合物复合结构的连接机理,并对金属/聚合物复合结构连接技术的未来进行了展望。

基于E-YOLOX的实时金属表面缺陷检测算法

针对现有基于深度学习的金属表面缺陷检测方法存在泛化能力差、检测速度低等问题,提出一种新的检测算法E-YOLOX。该算法采用新的特征提取网络ECMNet,并使用深度卷积减少网络参数;以线性逆瓶颈残差网络提升特征提取能力,在正向传播过程中保留更多高维张量内的流形分布于低维子空间的关键特征;以扩张跨阶段局部网络结构多样化神经网络的梯度流路径,使深层神经网络更高效地学习和收敛。同时,提出一种新的数据增强方法边缘Cutout,在训练过程中自适应生成掩膜覆盖图像的随机区域,提升网络的检测和泛化能力。实验结果表明,E-YOLOX-l在铝型材表面缺陷数据集AL6-DET上检测精度达到了77.2%的mAP,在钢材表面缺陷数据集GC10上检测精度达到了36.8%的mAP,较基准模型YOLOX-l分别提高3.6%和1.7%,同时参数量减少55%,计算量减少49%,检测速度达到57 FPS,提高了21 FPS。与相关算法对比,该算法取得较高的检测精度,且在精度和速度之间达到较好的均衡。

车用纤维金属层板构件冲压变形行为研究

纤维金属层板(fiber metal laminate,FML)是一种新型轻量化混杂材料,逐渐被应用于汽车等运载装备领域,但其成形过程受多种参数影响,成形过程中的应力应变分布规律尚不清楚。选用T300碳纤维铝合金复合层板为研究对象,利用ABAQUS有限元软件对其冲压成形过程进行模拟,并进行了精度验证。主要研究了FML在预浸料种类、层板厚度和层板数等因素的影响下,应力分布及壁厚变化规律。结果表明,建立的FML冲压模型计算精度准确,预浸料种类主要影响纤维层的应力分布和壁厚变化,层板厚度和层板数对各层的壁厚变化产生影响,通过减薄层板厚度或增加层板数可以缓解过度减薄问题,层板厚度和层数也会影响铝合金层的应力分布,随着厚度和层数的增加,铝合金层的应力分布趋于均匀。

DN-YOLOv5的金属双极板表面缺陷检测算法

为解决氢燃料电池中金属双极板表面缺陷尺寸小,缺陷对比不明显、种类多造成的难以检测,易误检漏检以及缺陷检测模型复杂度太大难以部署等问题,提出一种改进版的金属双极板缺陷检测算法DN-YOLOv5,来探究缺陷检测在冲压成形的金属双极板视觉检测工作台场景下进行快速精准检测的可行性,从而实现智能检测,提升检测效率。本研究着重于修改YOLOv5主干网络Backbone部分,添加网络中模块数量,加入NAM注意力机制和使用深度可分离卷积模块来替代原来CSP/CBS主干网络卷积模块,并引入SIoU对损失函数重新进行了定义,极大的提升了主干网络的轻量化程度。结果表明,本算法的map@0.5可达0.988,每秒检测传输帧率为9.98,模型参数量降低了52.13%,在测试集75张缺陷图像中真检率达到了99.74%。该方法在保证模型较高检测率的同时,显著降低了模型复杂度和参数计算量。此外,该算法结合新的检测尺度设计特征融合网络,提升网络的小目标、多目标检测能力。该算法具有良好的稳定性和鲁棒性,综合性能较好,满足部署移动端场景进行缺陷检测的轻量化需求。

激光表面处理对工业级锆基块体非晶合金弯曲变形和缺口韧性的影响

目的 改善块体非晶合金的弯曲力学性能,同时考虑航空结构材料选材的经济性,研究激光表面处理工艺对工业级Zr49.7Ti2Cu37.8Al10Er0.5块体非晶合金弯曲变形和缺口韧性的影响规律。方法 采用低纯原料和低真空制备条件获得工业级Zr49.7Ti2Cu37.8Al10Er0.5块体非晶合金试样,考虑到弯曲条件下试样受到拉伸和压缩2种正应力状态,研究不同处理工艺和激光处理表面对试样弯曲变形和缺口韧性的影响。结果 当激光处理表面位于弯曲试样的2个侧表面时,其对试样的塑性变形能力和断裂强度没有明显的影响,但会显著降低试样的缺口韧性,从(56.4±3.4)MPa·m1/2降低到(26.2±4.8)MPa·m1/2;激光处理表面位于弯曲试样的受拉侧时,试样的弯曲断裂强度从2 150 MPa降低到1 800 MPa;当激光处理表面位于弯曲试样的受压侧时,试样的弯曲断裂强度从2 150 MPa提高到2 550 MPa,但对其缺口韧性无明显的影响。结论 激光表面处理在工业级Zr49.7Ti2Cu37.8Al10Er0.5块体非晶合金试样表面引起的成分变化和引入的残余应力状态对其弯曲力学行为和缺口韧性的影响,与试样的受力情况紧密相关。残余应力与外载应力的正向耦合能够放大外载应力的作用效果,表面和心部的成分差异也有可能作为应力集中点出现,导致裂纹源的形成,降低试样的断裂强度。

增材制造金属点阵结构性能研究进展

点阵结构是一种三维规则排列的多孔结构,具有高比强度、高比刚度及优异的散热性能,是结构功能一体化设计的主要载体。由于点阵结构零件的结构复杂,传统加工方法无法直接制备。增材制造技术是一种通过分层制造方式构建三维实体零件的新型制造技术,在复杂结构制造方面具有独特优势。通过增材制造点阵结构零件可以极大地降低制件重量,提高综合力学性能,在航空航天、能源、车辆工程等领域展现出巨大的技术优势。本文对增材制造金属点阵结构、极小曲面结构、拓扑优化结构等复杂零件结构相关研究进行了总结与归纳,从力学性能、轻量化、能量吸收、散热吸声等应用方向进行了综述,最后总结并展望了金属增材制造点阵结构的优势与发展方向。

氰化尾渣制轻集料同步处理重金属探索试验研究

针对某金矿全泥氰化尾渣理化性质和污染物特点,以达到GB/T 30760—2014《水泥窑协同处置固体废物技术规范》中水泥熟料中重金属铅量限制要求为目的,探索采用自研药剂协同热处理氰化尾渣轻集料载体中重金属铅的可行性。试验考察了不同净化剂类型、净化剂投加量、预焙烧温度及时间、焙烧温度及时间等因素对铅去除效果的影响,并确定最佳反应条件。试验结果表明:采用1#净化剂和2#净化剂协同热处理后的轻集料均可以满足标准要求;轻集料配方A确定的最佳反应条件为预焙烧温度450℃,预焙烧时间1 h,焙烧温度1200℃,焙烧时间0.5 h,1^(#)净化剂投加量1.5%;轻集料配方B确定的最佳反应条件为预焙烧温度400℃,预焙烧时间30 min,焙烧温度1175℃,焙烧时间20 min,选择2#净化剂,投加量1.5%,生产成本约为100元/t。

Lightweight Design:Friction‑Based Welding between Metal and Polymer

The heterojunctions between metal and polymer have become the effective ways to produce the lighter,safer and more environmental friendly vehicles for the manufacturing fields of automotive and aerospace.The state-of-the-art frictionbased welding techniques are characterized by low peak temperature,severe plastic deformation,energy efficiency and nonpollution,which can simultaneously realize the mechanical and chemical bonding,improving mechanical performances.In this review,the current progress about friction-based welding techniques is summarized,containing technical development,welding tool design,microstructural characteristic,process optimization,surface modification and joining mechanism.The conclusions and prospects are presented,which focus on the practical implications for the manufacturing sectors and recommendations for further research and development.The purpose of this review is to elucidate the benefits of friction-based welding techniques so that these methods may be better exploited and industrialized.