Integrated high-performance and accurate shaping technology of low-cost powder metallurgy titanium alloys: A comprehensive review

The practical engineering applications of powder metallurgy (PM) Ti alloys produced through cold compaction and pressure-less sintering are impeded by poor sintering densification, embrittlement caused by excessive O impurities, and severe sintering deforma-tion resulting from the use of heterogeneous powder mixtures. This review presents a summary of our previous work on addressing the above challenges. Initially, we proposed a novel strategy using reaction-induced liquid phases to enhance sintering densification. Near- complete density (relative density exceeding 99%) was achieved by applying the above strategy and newly developed sintering aids. By focusing on the O-induced embrittlement issue, we determined the onset dissolution temperature of oxide films in the Ti matrix. On the basis of this finding, we established a design criterion for effective O scavengers that require reaction with oxide films before their dissol-ution. Consequently, a ductile PM Ti alloy was successfully obtained by introducing 0.3wt% NdB6 as the O scavenger. Lastly, a powder- coating strategy was adopted to address the sintering deformation issue. The ultrafine size and shell-like distribution characteristics of coating particles ensured rapid dissolution and homogeneity in the Ti matrix, thereby facilitating linear shrinkage during sintering. As a result, geometrically complex Ti alloy parts with high dimensional accuracy were fabricated by using the coated powder. Our fundament-al findings and related technical achievements enabled the development of an integrated production technology for the high-performance and accurate shaping of low-cost PM Ti alloys. Additionally, the primary engineering applications and progress in the industrialization practice of our developed technology are introduced in this review.

Assessment of the performance of the TOPGNSS and ANN-MB antennas for ionospheric measurements using low-cost u-blox GNSS receivers

Low-cost GNSS receivers have recently been gaining reliability as good candidates for ionospheric studies. In line with these gains are genuine concerns about improving the performance of these receivers. In this work, we present a comprehensive investigation of the performances of two antennas(the u-blox ANN-MB and the TOPGNSS TOP-106) used on a low-cost GNSS receiver known as the u-blox ZED-F9P. The two antennas were installed on two identical and co-located u-blox receivers. Data used from both receivers cover the period from January to June 2022. Results from the study indicate that the signal strengths are dominantly greater for the receiver with the TOPGNSS antenna than for the receiver with the ANN-MB antenna, implying that the TOPGNSS antenna is better than the ANN-MB antenna in terms of providing greater signal strengths. Summarily, the TOPGNSS antenna also performed better in minimizing the occurrence of cycle slips on phase TEC measurements. There are no conspicuous differences between the variances(computed as 5-min standard deviations) of phase TEC measurements for the two antennas, except for a period around May-June when the TOPGNSS gave a better performance in terms of minimizing the variances in phase TEC. Remarkably, the ANN-MB antenna gave a better performance than the TOPGNSS antenna in terms of minimizing the variances in pseudorange TEC for some satellite observations. For precise horizontal(North and East) positioning, the receiver with the TOPGNSS antenna gave better results, while the receiver with the ANN-MB antenna gave better vertical(Up) positioning. The errors for the receivers of both antennas are typically within about 5 m(the monthly mean was usually smaller than 1 m) in the horizontal direction and within about 10 m(the monthly mean was usually smaller than 4 m) in the vertical direction.

Effect of titanium on the sticking of pellets based on hydrogen metallurgy shaft furnace:Behavior analysis and mechanism evolution

Direct reduction based on hydrogen metallurgical gas-based shaft furnace is a promising technology for the efficient and low-carbon smelting of vanadium-titanium magnetite.However,in this process,the sticking of pellets occurs due to the aggregation of metal-lic iron between the contact surfaces of adjacent pellets and has a serious negative effect on the continuous operation.This paper presents a detailed experimental study of the effect of TiO2 on the sticking behavior of pellets during direct reduction under different conditions.Results showed that the sticking index(SI)decreased linearly with the increasing TiO2 addition.This phenomenon can be attributed to the increase in unreduced FeTiO3 during reduction,leading to a decrease in the number and strength of metallic iron interconnections at the sticking interface.When the TiO2 addition amount was raised from 0 to 15wt%at 1100°C,the SI also increased from 0.71%to 59.91%.The connection of the slag phase could be attributed to the sticking at a low reduction temperature,corresponding to the low sticking strength.Moreover,the interconnection of metallic iron became the dominant factor,and the SI increased sharply with the increase in re-duction temperature.TiO2 had a greater effect on SI at a high reduction temperature than at a low reduction temperature.

Microstructure evolution and strengthening mechanism of high -performance powder metallurgy TA15 titanium alloy by hot rolling

Hot deformation of sintered billets by powder metallurgy(PM)is an effective preparation technique for titanium alloys,which is more significant for high-alloying alloys.In this study,Ti–6.5Al–2Zr–Mo–V(TA15)titanium alloy plates were prepared by cold press-ing sintering combined with high-temperature hot rolling.The microstructure and mechanical properties under different process paramet-ers were investigated.Optical microscope,electron backscatter diffraction,and others were applied to characterize the microstructure evolution and mechanical properties strengthening mechanism.The results showed that the chemical compositions were uniformly dif-fused without segregation during sintering,and the closing of the matrix craters was accelerated by increasing the sintering temperature.The block was hot rolled at 1200℃ with an 80%reduction under only two passes without annealing.The strength and elongation of the plate at 20–25℃ after solution and aging were 1247 MPa and 14.0%,respectively,which were increased by 24.5%and 40.0%,respect-ively,compared with the as-sintered alloy at 1300℃.The microstructure was significantly refined by continuous dynamic recrystalliza-tion,which was completed by the rotation and dislocation absorption of the substructure surrounded by low-angle grain boundaries.After hot rolling combined with heat treatment,the strength and plasticity of PM-TA15 were significantly improved,which resulted from the dense,uniform,and fine recrystallization structure and the synergistic effect of multiple slip systems.

Development in oxide metallurgy for improving the weldability of high -strength low-alloy steel-Combined deoxidizers and microalloying elements

The mechanisms of oxide metallurgy include inducing the formation of intragranular acicular ferrite(IAF)using micron-sized inclusions and restricting the growth of prior austenite grains(PAGs)by nanosized particles during welding.The chaotically oriented IAF and refined PAGs inhibit crack initiation and propagation in the steel,resulting in high impact toughness.This work summarizes the com-bined effect of deoxidizers and alloying elements,with the aim to provide a new perspective for the research and practice related to im-proving the impact toughness of the heat affected zone(HAZ)during the high heat input welding.Ti complex deoxidation with other strong deoxidants,such as Mg,Ca,Zr,and rare earth metals(REMs),can improve the toughness of the heat-affected zone(HAZ)by re-fining PAGs or increasing IAF contents.However,it is difficult to identify the specific phase responsible for IAF nucleation because ef-fective inclusions formed by complex deoxidation are usually multiphase.Increasing alloying elements,such as C,Si,Al,Nb,or Cr,con-tents can impair HAZ toughness.A high C content typically increases the number of coarse carbides and decreases the potency of IAF formation.Si,Cr,or Al addition leads to the formation of undesirable microstructures.Nb reduces the high-temperature stability of the precipitates.Mo,V,and B can enhance HAZ toughness.Mo-containing precipitates present good thermal stability.VN or V(C,N)is ef-fective in promoting IAF nucleation due to its good coherent crystallographic relationship with ferrite.The formation of the B-depleted zone around the inclusion promotes IAF formation.The interactions between alloying elements are complex,and the effect of adding dif-ferent alloying elements remains to be evaluated.In the future,the interactions between various alloying elements and their effects on ox-ide metallurgy,as well as the calculation of the nucleation effects of effective inclusions using first principles calculations will become the focus of oxide metallurgy.

Metallurgical performance evaluation of space-weathered Chang’e-5 lunar soil

Space metallurgy is an interdisciplinary field that combines planetary space science and metallurgical engineering.It involves systematic and theoretical engineering technology for utilizing planetary resources in situ.However,space metallurgy on the Moon is challenging because the lunar surface has experienced space weathering due to the lack of atmosphere and magnetic field,making the mi-crostructure of lunar soil differ from that of minerals on the Earth.In this study,scanning electron microscopy and transmission electron microscopy analyses were performed on Chang’e-5 powder lunar soil samples.The microstructural characteristics of the lunar soil may drastically change its metallurgical performance.The main special structure of lunar soil minerals include the nanophase iron formed by the impact of micrometeorites,the amorphous layer caused by solar wind injection,and radiation tracks modified by high-energy particle rays inside mineral crystals.The nanophase iron presents a wide distribution,which may have a great impact on the electromagnetic prop-erties of lunar soil.Hydrogen ions injected by solar wind may promote the hydrogen reduction process.The widely distributed amorph-ous layer and impact glass can promote the melting and diffusion process of lunar soil.Therefore,although high-energy events on the lun-ar surface transform the lunar soil,they also increase the chemical activity of the lunar soil.This is a property that earth samples and tradi-tional simulated lunar soil lack.The application of space metallurgy requires comprehensive consideration of the unique physical and chemical properties of lunar soil.

Unscented Kalman filter for a low-cost GNSS/IMU-based mobile mapping application under demanding conditions

For the last two decades,low-cost Global Navigation Satellite System(GNSS)receivers have been used in various applications.These receivers are mini-size,less expensive than geodetic-grade receivers,and in high demand.Irrespective of these outstanding features,low-cost GNSS receivers are potentially poorer hardwares with internal signal processing,resulting in lower quality.They typically come with low-cost GNSS antenna that has lower performance than their counterparts,particularly for multipath mitigation.Therefore,this research evaluated the low-cost GNSS device performance using a high-rate kinematic survey.For this purpose,these receivers were assembled with an Inertial Measurement Unit(IMU)sensor,which actively transmited data on acceleration and orientation rate during the observation.The position and navigation parameter data were obtained from the IMU readings,even without GNSS signals via the U-blox F9R GNSS/IMU device mounted on a vehicle.This research was conducted in an area with demanding conditions,such as an open sky area,an urban environment,and a shopping mall basement,to examine the device’s performance.The data were processed by two approaches:the Single Point Positioning-IMU(SPP/IMU)and the Differential GNSS-IMU(DGNSS/IMU).The Unscented Kalman Filter(UKF)was selected as a filtering algorithm due to its excellent performance in handling nonlinear system models.The result showed that integrating GNSS/IMU in SPP processing mode could increase the accuracy in eastward and northward components up to 68.28%and 66.64%.Integration of DGNSS/IMU increased the accuracy in eastward and northward components to 93.02%and 93.03%compared to the positioning of standalone GNSS.In addition,the positioning accuracy can be improved by reducing the IMU noise using low-pass and high-pass filters.This application could still not gain the expected position accuracy under signal outage conditions.

Analysis of Oxygen Consumption in Lead and Zinc Metallurgy

This article analyzes the role of oxygen in lead zinc metallurgy,including shortening the metallurgical process,promoting energy conservation and environmental protection,improving metallurgical strength,enhancing raw material adaptability,and enhancing comprehensive recovery efficiency.This article introduces different lead zinc metallurgical processes and their oxygen consumption characteristics,including oxygen enriched side blowing lead smelting,oxygen bottom blowing lead smelting,oxygen enriched top blowing lead smelting,flash smelting lead,oxygen pressure leaching zinc smelting,and atmospheric pressure oxygen leaching zinc smelting.It is pointed out that oxygen enhanced metallurgy is the direction for the transformation and upgrading of lead zinc metallurgy.

Rational design and low-cost fabrication of multifunctional separators enabling high sulfur utilization in long-life lithium-sulfur batteries

The lithium-sulfur(Li-S)battery with an ultrahigh theoretical energy density has emerged as a promising rechargeable battery system.However,the practical applications of Li-S batteries are severely plagued by the sluggish reaction kinetics of sulfur species and notorious shuttling of soluble lithium polysulfides(LiPSs)intermediates that result in low sulfur utilization.The introduction of functional layers on separators has been considered as an effective strategy to improve the sulfur utilization in Li-S batteries by achieving effective regulation of LiPSs.Herein,a promising self-assembly strategy is proposed to achieve the low-cost fabrication of hollow and hierarchically porous Fe_(3)O_(4)nanospheres(p-Fe_(3)O_(4)-NSs)assembled by numerous extremely-small primary nanocrystals as building blocks.The rationally-designed p-Fe_(3)O_(4)-NSs are utilized as a multifunctional layer on the separator with highly efficient trapping and conversion features toward LiPSs.Results demonstrate that the nanostructured p-Fe_(3)O_(4)-NSs provide chemical adsorption toward LiPSs and kinetically promote the mutual transformation between LiPSs and Li_(2)S_(2)/Li_(2)S during cycling,thus inhibiting the LiPSs shuttling and boosting the redox reaction kinetics via a chemisorption-catalytic conversion mechanism.The enhanced wettability of the p-Fe_(3)O_(4)-NSs-based separator with the electrolyte enables fast transportation of lithium ions.Benefitting from these alluring properties,the functionalized separator with p-Fe_(3)O_(4)-NSs endows the battery with an admirable rate performance of 877 mAh g^(−1)at 2 C,an ultra-durable cycling performance of up to 2176 cycles at 1 C,and a promising areal capacity of 4.55 mAh cm^(−2)under high-sulfur-loading and lean-electrolyte conditions(4.29 mg cm^(−2),electrolyte/ratio:8μl mg^(−1)).This study will offer fresh insights on the rational design and low-cost fabrication of multifunctional separator to strengthen electrochemical reaction kinetics by regulating LiPSs conversion for developing efficient and long-life Li-S batteries.

Intelligent SLAM Algorithm Fusing Low-Cost Sensors at Risk of Building Collapses

When firefighters search inside a building that is at risk of collapse due to abandonment or disasters such as fire,they use old architectural drawings or a simple monitoring method involving a video device attached to a robot.However,using these methods,the disaster situation inside a building at risk of collapse is difficult to detect and identify.Therefore,we investigate the generation of digital maps for a disaster site to accurately analyze internal situations.In this study,a robot combined with a low-cost camera and twodimensional light detection and ranging(2D-lidar)traverses across a floor to estimate the location of obstacles while drawing an internal map of the building.We propose an algorithm that detects the floor and then determines the possibility of entry,tracks collapses,and detects obstacles by analyzing patterns on the floor.The robot’s location is estimated,and a digital map is created based on Hector simultaneous localization and mapping(SLAM).Subsequently,the positions of obstacles are estimated based on the range values detected by 2D-lidar,and the position of the obstacles are identified on the map using the map update method in semantic SLAM.All equipment are implemented using low-specification devices,and the experiments are conducted using a low-cost robot that affords near-real-time performance.The experiments are conducted in various actual internal environments of buildings.In terms of obstacle detection performance,almost all obstacles are detected,and their positions identified on the map with a high accuracy of 89%.

Ceramic particles reinforced copper matrix composites manufactured by advanced powder metallurgy:preparation, performance, and mechanisms

Copper matrix composites doped with ceramic particles are known to effectively enhance the mechanical properties,thermal expansion behavior and high-temperature stability of copper while maintaining high thermal and electrical conductivity.This greatly expands the applications of copper as a functional material in thermal and conductive components,including electronic packaging materials and heat sinks,brushes,integrated circuit lead frames.So far,endeavors have been focusing on how to choose suitable ceramic components and fully exert strengthening effect of ceramic particles in the copper matrix.This article reviews and analyzes the effects of preparation techniques and the characteristics of ceramic particles,including ceramic particle content,size,morphology and interfacial bonding,on the diathermancy,electrical conductivity and mechanical behavior of copper matrix composites.The corresponding models and influencing mechanisms are also elaborated in depth.This review contributes to a deep understanding of the strengthening mechanisms and microstructural regulation of ceramic particle reinforced copper matrix composites.By more precise design and manipulation of composite microstructure,the comprehensive properties could be further improved to meet the growing demands of copper matrix composites in a wide range of application fields.

Prototyping low-cost automatic weather stations for natural disaster monitoring

Weather events put human lives at risk mostly when people might occupy areas susceptible to natural disasters.Deploying Professional Weather Stations(PWS)in vulnerable areas is key for monitoring weather with reliable measurements.However,such professional instrumentation is notably expensive while remote sensing from a number of stations is paramount.This imposes challenges on the large-scale weather station deployment for broad monitoring from large observation networks such as in Cemaden—The Brazilian National Center for Monitoring and Early Warning of Natural Disasters.In this context,in this paper,we propose a Low-Cost Automatic Weather Station(LCAWS)system developed from Commercial Off-The-Shelf(COTS)and open-source Internet of Things(IoT)technologies,which provides measurements as reliable as a reference PWS for natural disaster monitoring.When being automatic,LCAWS is a stand-alone photovoltaic system connected wirelessly to the Internet in order to provide real-time reliable end-to-end weather measurements.To achieve data reliability,we propose an intelligent sensor calibration method to correct measures.From a 30-day uninterrupted observation with sampling in minute resolution,we show that the calibrated LCAWS sensors have no statistically significant differences from the PWS measurements.As such,LCAWS has opened opportunities for reducing maintenance costs in Cemaden's observational network.

Accumulation behavior of heavy metals by Bidens pilosa L.from metallurgical slag:effects on plant physiology and absorption characteristics

Many of the abandoned mining and industrial land in villages and towns are seriously polluted by heavy metals in China,it is necessary for sustainable development to adopt efficient and economical ways to restore the ecology of abandoned mining and industrial land.Pollution level of topsoil contaminated with metallurgical slag from nonferrous metal smelting waste site in Baoding,North China and the heavy metals(HMs)accumulation behavior of Bidens pilosa L.(B.pilosa,native pioneer plant)were studied.Two selected study sites were mainly contaminated by As(270~434 mg/kg),Cd(63~95 mg/kg),Pb(5496~24504 mg/kg)and Zn(4500~21300 mg/kg),which exceed the national standard severely.Investigation of multi-metal accumulation in different parts of B.pilosa indicated that the absorption of toxic metals varied by types,concentration and species of HMs under stress conditions,soil property and plant tissues.The results showed that B.pilosa had excellent ability to accumulate HMs under different HMs stress condition,with the highest accumulation concentration of 85 mg/kg for As,380 mg/kg for Cd,4000 mg/kg for Pb,and 7500 mg/kg for Zn in roots under experimental conditions,respectively.The growth trend of B.pilosa declined with the increase of HMs stress concentration in tested soils.HMs stress led to different degrees of plant toxicity and obstruction of physiological metabolism.Among the plant physiological index,Chla and ChlT decreased 28.0%and 28.1%,37.3%and 35.5%under different stress treatments,respectively.Indicators related to physiological metabolic strength and stress resistance of plant,such as MDA(Malondiadehyde),CAT(catalase),SOD(superoxide dismutase)and SP(soluble protein),all increased with the increase of HMs stress concentration.

影响工业还原罐内铝热法炼镁过程还原效率的因素

在工业还原罐内进行铝热还原炼镁试验,分析影响还原效率的因素。结果表明:结晶镁的氧化和燃烧以及原料混合不均匀是导致还原效率降低的主要原因;原料混合不均匀导致贫铝区和MgO剩余,促进生成12CaO·7Al_(2)O_(3)和CaO·Al_(2)O_(3);对于富铝区域,MgO和CaO同时被还原,生成Mg_(2)Ca相。辐射传热和化学反应吸热是影响还原速率的关键因素;提高加热温度能够迅速提高球团层的温度,进而使球团获得足够的反应速度;此外,球团中含镁量越高,需要的反应时间越长。

化工冶金跨行业耦合二氧化碳循环利用技术

双碳战略是国家重大战略,也是推动国家经济高质量可持续发展的必由之路。我国碳达峰到碳中和时间短、任务重。我国化工冶金每年碳排放约36亿t,约占全国工业碳排放量的36%,此外化工冶金废气、固废、废热产生量大、堆存量多、难利用、循环利用率低。发展化工冶金低碳化转型和变革,是我国工业领域双碳目标实现的根本保证。我国化工冶金历时百年,已发展成熟,仅通过原料燃料替代及绿色工艺转型减碳容量有限,亟需开展化工冶金跨行业耦合与循环利用技术变革,深入推动工业领域减碳。我国化工冶金大多是孤立、非循环连续工艺过程,引起跨行业耦合难、循环利用难度大的问题。针对上述问题,首先分析了化工冶金行业碳排放治理现状及国家战略需求;其次,提出了废气与废热耦合热化学转化制高质气体、废气与废气耦合定向催化制高端化学品、废气与固废耦合制低碳材料3个减碳增效策略。结合其技术发展现状和趋势,提出了拟重点发展的化工冶金跨行业耦合二氧化碳循环利用技术,以期为工业低碳绿色发展提供支撑。

2023年钼业年评

2023年钼产品价格较2022年上涨34%,创17年来新高。受此影响,国内外多家已停产或停止开发的钼企业重启生产及开发计划,使得国际国内钼产量增长约14%。国内外钼的应用、科技研发方面均有进步与突破,钼被越来越多地应用于新的领域并显现出优异的特性。

Fe含量对粉末冶金Cu-Fe合金显微组织与性能的影响

研究Fe含量对粉末冶金Cu-Fe合金显微组织及性能的影响。采用电火花等离子烧结、冷轧以及时效处理工艺制备4种不同铁含量(5%、10%、20%和40%,质量分数)的Cu-Fe合金。研究结果表明,随着Fe含量从5%(质量分数)增加到40%(质量分数),Fe相由离散球形分布演变为连续交错分布,Fe相尺寸从0.29μm增加到1.20μm;时效态的Cu-Fe合金的屈服强度从411.5 MPa提高到788.8 MPa,电导率从62.5%(IACS)降低到42.0%(IACS)。在以上结果的基础上,提出一种混合法则计算Cu基体、初级Fe相和次级Fe相对屈服强度的贡献,可较好地预测Fe含量高于10%(质量分数)合金的力学性能。

工程教育认证背景下冶金工程专业课程教学持续化改革与实践

在工程教育专业认证背景下,针对内蒙古科技大学冶金工程专业开展持续化教学改革。通过培养方案修订、具体课程考核与评价方式重新合理设置等措施以满足工程教育认证持续改进工作的要求。同时,以钢铁冶金工艺学课程为例阐释持续改进后的课程综合评价分析具体过程,以保证更优地完成课程目标达成工作及教学培养学生过程中的良好改进。

金工实习综合课件改革设计与应用

针对工科专业传统金工实习主要关注技术训练,缺少专业特色、缺乏综合能力的培养,设计金工实习“小车快跑”综合实习课件。该课件由不同工种完成不同功能的零部件,最后经装配钳工完成小货车的组装,并增加小型竞赛环节,验证综合实习课件完成效果。“小车快跑”综合课件实习加强了学生金工综合能力训练,提高了学生的协作精神,创新思维能力。实践证明,“小车快跑”综合实习课件显著提高了学生对金工实习的兴趣,可以更好地达到专业课程的目标要求。

一种高性能非蒸散型吸气剂的性能分析

非蒸散型吸气剂(NEG)是高真空和超高真空系统维持真空度的重要材料,具有高稳定性和高气体吸附性能,文章采用粉末冶金的方法制备出Zr_(59.46)V_(29.81)Al_(10.73)吸气剂,并基于小孔流导法搭建了一套吸气剂性能测试的高真空系统,分别测试了气体种类及工作温度对吸气剂性能的影响,实验结果表明:Zr_(59.46)V_(29.81)Al_(10.73)吸气剂对H_(2)、CO_(2)、N2都有很好的吸气性能,其对H_(2)的吸气性能远超N2和CO_(2),但它不吸收He等惰性气体,不同工作温度对吸气性能有很大差异,其最佳工作温度为200℃。利用X射线衍射图谱(XRD)和扫描电子显微镜(SEM)及能量色散图谱(EDS)对吸气剂进行晶相、形貌和成分分析,结果表明Zr_(59.46)V_(29.81)Al_(10.73)吸气剂表面呈现多孔状结构,其主要由α-Zr基固溶体、C15 Laves相及少量Zr_(x)Al_(y)化合物组成,多孔的结构及α-Zr基固溶体、C15 Laves相的高比例有利于吸气剂对活性气体的吸附,因此Zr_(59.46)V_(29.81)Al_(10.73)吸气剂展现出较好的性能。