INTERNATIONAL JOURNAL OF REFRACTORY METALS & HARD MATERIALS
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2013
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IF 1.858
Pingping Liu,Fang Peng,Fangming Liu,Haikuo Wang,Chao Xu,Qiming Wang,Xiaoling Zhou,Wenwen Yin,Shuai Yin,Yong Li,Duanwei He
In this work, we present a novel method to sinter tungsten bulk material under high pressure without any additives. The sintering temperatures were greatly reduced in our experiments. The sintered samples can achieve near-full densification (relative density of 99.5%), and have fracture toughness of about 50% higher than that from the traditional methods, without sacrificing hardness. Moreover, the grain sizes of the sintered samples maintained in the initio range. The sintering kinetics, microstructure evolutions, and relationships of mechanical properties versus pressure–temperature conditions were also discussed.
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JOURNAL OF ALLOYS AND COMPOUNDS
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2015
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IF 2.999
Huali Hao,Wei Mo,Yonghu Lv,Shulong Ye,Ruinan Gu,Peng Yu
The influence of trace elements on the powder metallurgy of Cu was investigated. It was found that 1 wt. % of Ti can effectively increase the green density of the compacts and facilitate the subsequent sintering process, thus resulting in increased sintered density. Although 1 wt. % of W added into the Cu leads to similar increasing of green density, W significantly retarded the sintering process and has a negative effect on the sintered density. Moreover, intermetallic Cu 4 Ti were formed, which not only creates a short-circuit diffusion path for Cu but also forms liquid phases during sintering. However, it was hardly dissolved between W and Cu.
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METALLURGICAL AND MATERIALS TRANSACTIONS B-PROCESS METALLURGY AND MATERIALS PROCESSING SCIENCE
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2024
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IF 2.4
Zhang Xu,Zhang Liqi,Huang Bowen,Yang Yusheng,Zhao Zengwu
Materials like metallic iron and its alloys are essential to daily living and industrial production. The benefits of using electrolysis technology to prepare iron and its alloys are great efficiency, controllability, and environmental protection. This study focuses on the feasibility of the electrochemical method for the direct preparation of metallic iron and Si–Fe alloys in iron ores with high fluoride content. The electrochemical behavior of Fe(II) and Fe(III) in molten SiO 2 –CaO–CaF 2 slag on tungsten electrodes was investigated by using cyclic voltammetry and square wave voltammetry methods. It was determined that the reduction of Fe(II) ions follows a one-step two-electron transfer process: Fe(II) + 2e − → Fe(0). The reduction of Fe(III) involves a two-step electron transfer process: Fe(III) + e − → Fe(II) and Fe(II) + 2e − → Fe(0), respectively. The Fe(II)/Fe(0) process is an irreversible reaction controlled by diffusion. The diffusion coefficient of Fe(II) is D Fe(II) = 1.5 × 10 −6 cm 2 s −1 . The cathodic deposits of iron were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM) combined with energy dispersive X-ray spectroscopy (EDS). The findings indicate that the production of Fe 2 Si alloy through electrolysis is more favorable when Fe(II) is present in the slag, while the production of metallic iron is more favorable when Fe(III) is present in the slag. This work provides a basis for the electrochemical direct preparation of Fe–Si alloy and metallic iron in high fluorine iron ore.
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ACS Applied Nano Materials
·
2024
·
IF 5.3
Shuen Chen,Gengchang Lai,Xiaoyi Zhang,Xiaoxiao Feng,Liping Tong,Chenglong Peng,Xingchen He,Yang Li,Jiahong Wang
Phosphorus is an ideal anode material for high-rate lithium-ion batteries due to its high theoretical specific capacity and moderate operating potential. However, phosphorus undergoes tremendous volume expansion and low electrical conductivity during lithium storage, affecting its actual lithium storage performance. The formation of P–C bonds is an effective strategy to inhibit the volume expansion and maintain stable electrical contact between phosphorus and the current collector. Herein, high strength metal nanoparticles, such as molybdenum nanoparticles, are introduced into the ball milling process to reinforce P–C bonding and enhance the lithium storage performance. As a result, the BP/Mo/CNTs anode provides a high-rate capacity of 984 mAh g–1 at 8.0 A g–1 and high capacity retention of 90.3% after 300 cycles at 0.5 A g–1. To demonstrate the universality of this method, BP/W/CNTs nanocomposites were prepared by tungsten-assisted ball milling. This facile strategy provides a practical approach for the formation of abundant covalent bonds to improve the electrochemical performance of composites.
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MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING
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2025
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IF 7
Yu He,Shengwei Xin,Baoru Sun,Xuecheng Cai,Yapeng Lin,Lingwei Kong,Xun Shen,Congcong Du,Xiaoyuan Yuan,Kangkang Wen,Tongde Shen
Metals are often soft while ceramics are often hard. To make metals as hard as ceramics has been long-awaited in metals and ceramics communities. In this study, bulk nanocrystalline (NC) tungsten-1 wt% yttrium-0.7 wt% titanium (WYT) was fabricated via mechanical alloying followed by high-temperature/high-pressure sintering. The high pressure directly inhibits grain growth by suppressing atomic diffusion and indirectly inhibits grain growth by lowering sintering temperature, enabling the synthesis of dense NC WYT bulks with an average grain size of ∼ 9.0 nm. The high temperature causes annealing- and segregation-induced structural relaxation of grain boundaries (GBs) in sintered bulk NC WYT, resulting in GBs with a small excess volume of only ∼ 0.005 nm, one fifth that of bulk NC tungsten. The small grain size and the relaxed GBs in the bulk NC WYT make it hard for GBs to emit dislocations, resulting in extremely high hardness of 23.2 ± 0.3 GPa, yield strength of 9.4 ± 0.3 GPa, and ultimate compressive strength of 13.1 ± 1.1 GPa. The hardness of metallic bulk NC WYT is comparable to that of ceramic tungsten carbide (WC) whereas the wear rate of bulk NC WYT is even lower than that of WC. The structure-relaxed GBs lower the thermodynamic driving force for grain growth and result in an extremely high thermal stability - no grain growth occurs in bulk NC WYT annealed at a high temperature of 1500 °C, which is above the recrystallization temperature of tungsten. The present strategy - multifunctional treatments of NC alloy powders by high-temperature/high-pressure - provides a huge potential to manufacture dense bulk NC materials with exceptional mechanical property and thermal stability for practical applications.
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JOURNAL OF THE AMERICAN CERAMIC SOCIETY
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2024
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IF 3.5
Yingying Zeng,Hao Liang,Jieru Pu,Lei Liu,Xiaolong Pan,Hao Luo,Zhenwei Niu,Wei Zhang,Liang Bian
Tungsten disilicide (WSi 2 ) is a promising material for high-temperature applications due to its excellent mechanical properties and superior thermal stability. This study aims to investigate the mechanisms underlying the performance enhancement of polycrystalline WSi 2 and tungsten silicide (W-Si) composites synthesized by high-temperature and high-pressure (HPHT) strategies, focusing on their phase composition and microstructure. The results show that high pressure can effectively reduce the synthesis temperature of the tungsten silicide system, with the phase composition and microstructure of the products being dominated by the treatment temperature. The high intergranular strain resulting from the reactive process and the HPHT environment facilitated the formation of high-density dislocations, including dislocation arrays and networks with multiple orientations, especially near the grain boundaries. Additionally, a 3-nm thick amorphous ribbons were identified between these boundaries. This microstructure, characterized by high-density dislocations and amorphous ribbons, confers exceptional mechanical properties and oxidation resistance. The differences in oxidation behavior between powder and bulk WSi 2 samples underscore the complex relationship between phase stability and material properties under varying processing conditions. These findings indicate that dislocations and amorphous ribbons can achieve in high-temperature ceramics with strong covalent bonding, which is essential for the design and synthesis of advanced W-Si-based ceramics.
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Nanomaterials
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2024
·Vol. 14
·期 8
·722
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IF 4.4
Zhengtang Cai,Kaipeng Zheng,Chun Ma,Yu Fang,Yuyang Ma,Qinglin Deng,Han Li
Compared to SnTe and PbTe base materials, the GeTe matrix exhibits a relatively high Seebeck coefficient and power factor but has garnered significant attention due to its poor thermal transport performance and environmental characteristics. As a typical p-type IV–VI group thermoelectric material, W-doped GeTe material can bring additional enhancement to thermoelectric performance. In this study, the introduction of W, Ge1−xWxTe (x= 0, 0.002, 0.005, 0.007, 0.01, 0.03) resulted in the presence of high-valence state atoms, providing additional charge carriers, thereby elevating the material’s power factor to a maximum PFpeakof approximately 43 μW cm−1K−2, while slightly optimizing the Seebeck coefficient of the solid solution. Moreover, W doping can induce defects and promote slight rhombohedral distortion in the crystal structure of GeTe, further reducing the lattice thermal conductivityκlatto as low as approximately 0.14 W m−1K−1(x= 0.002 at 673 K), optimizing it to approximately 85% compared to the GeTe matrix. This led to the formation of a p-type multicomponent composite thermoelectric material with ultra-low thermal conductivity. Ultimately, W doping achieves the comprehensive enhancement of the thermoelectric performance of GeTe base materials, with the peak ZT value of sample Ge0.995W0.005Te reaching approximately 0.99 at 673 K, and the average ZT optimized to 0.76 in the high-temperature range of 573–723 K, representing an increase of approximately 17% compared to pristine GeTe within the same temperature range.
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PubMed
高影响因子
CHEMICAL ENGINEERING JOURNAL
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2025
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IF 13.2
Haoming Xu,Imtiaz Haider,Yuhua Zheng,Wenli Li,Serge Zhuiykov,Yanbin Cui
Flexible electrochromic devices (ECDs) are garnering significant interest as they have potential applications in free-form displays and wearable electronics. Typically, liquid electrolytes were used to prepare ECDs. However, liquid electrolytes are susceptible to leakage, especially when cracks develop during their use. Solid electrolytes can avoid such leakage and use for the assembly of solid-state ECDs. This study aims to create a solid-state ECD with a solid polymer electrolyte (SPE) via a solution casting method. Tungsten trioxide (WO 3 ), lithium bis((trifluoromethyl)sulfonyl) azide (LiTFSI) and polyvinyl alcohol (PVA) were used as electrochromic (EC) material, ion source and solid-state ion source container, respectively. Furthermore, succinonitrile (SN) and phosphoric acid (H 3 PO 4 ) were added into PVA/LiTFSI to increase the ionic conductivity, which allowed Li + to move to the WO 3 layer at a faster rate. The resulting SPE exhibited an electrochemical window of 4.0 V, room temperature ionic conductivity of 3.4 × 10 -4 S/cm, a glass transition temperature of 38 °C, and high mechanical flexibility (500 % strain at a stress of 2 MPa). The assembled solid-state flexible ECDs demonstrated an optical contrast of 41 % at 650 nm, responses of coloration to 49 % in 17 s and bleaching to 90 % in 43 s, coloration efficiency of 70.12 cm 2 /C and less than 5 % degradation of optical contrast after 1000 cycles. This work presents a simple approach to fabricating flexible and transparent solid-state ECDs without the risk of liquid leakage.
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Advanced Optical Materials
·
2025
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IF 7.2
Haopeng Jing,Chunjian Wang,Kun Li,Ran Jiang,Jumei Zhou,Hongtao Cao,Hongliang Zhang
Electrochromic devices (ECD) have become a hot research topic in the field of green buildings due to their excellent energy efficiency and thermal management capabilities. Currently, challenges such as difficulties in large-area preparation, high costs, and degradation of electrochromic performance over time have hindered their widespread application. A strategy incorporating a dual-phase nanocrystalline structure of WO 3 and TiO 2 ·H 2 O is proposed, in which specific synthesis parameters are precisely controlled to tailor the microstructure and composition of the films, enabling the fabrication of large-area WO 3 -PB ECD with UV-rejuvenation electrochromic performance. As a result, the as-prepared WO 3 -PB ECD exhibits an optical modulation of 75.6% and a remarkable cycle life exceeding 13,000 cycles. The electrochromic performance degradation caused by long cycles can be restored via UV irradiation. Utilizing UV light to restore the performance of these WO 3 -PB ECDs promotes sustainable and environmentally friendly development, highlighting their important practical value.
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Materials Today Communications
·
2025
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IF 4.5
Xiyang Liu,Lihua Guo,Jinpeng Zhang,Guoqiang Wang,Linyuan Lu,Jun Lin,Jinwei Zhan
Tungsten (W) stands out as one of the most promising matrix materials for cermet fuels in nuclear thermal propulsion (NTP) systems, with its effective thermal conductivity (ETC) being intricately linked to the economic viability and safety of reactors. This study investigated the influence of sintering temperature on the microstructure of nanoscale W powder using Spark Plasma Sintering (SPS). Based on the microstructural evolution observed at various temperatures, both a finite element (FE) model and an Artificial Neural Network (ANN) model were employed to assess the ETC of the W matrix, and the ETC was experimentally measured using the frequency-domain thermoreflectance (FDTR) method. The FE simulation results reveal a 7.5 % average relative error between modeled and measured ETC values at high sintering temperatures, demonstrating good consistency between simulation and experiment. Further analysis reveals that the porosity of the W matrix significantly affects its ETC. As the sintering temperature increases from 1273 to 1973 K, the porosity decreases from 32.48 % to 3.86 %, while the ETC increases from 46.07 to 160.71 W/(m·K). The ANN results demonstrate that the trained ANN model could accurately assess the ETC of the W matrix, with a regression coefficient of 0.9983 for the trained dataset and 0.9922 for the tested dataset. Based on the relationship between porosity and ETC, an optimized formula has been developed for predicting the ETC of the W matrix with an R² value of 0.9954 and an RRMSE of 2.37 %. The ANN model established in this study provides an accurate method for predicting the ETC of W and offers new insights and references for predicting the ETC of other materials.
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TRANSACTIONS OF THE INDIAN INSTITUTE OF METALS
·
2025
·Vol. 78
·期 4
·1-11
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IF 1.6
Chen Qijie,Liu Chencheng,Han Jiaxin,Cheng Yong,Chen Qingyun,Xiong Zhonggang
A new high-entropy MAX phase (V 0.2 Nb 0.2 Ta 0.2 Mo 0.2 W 0.2 ) 2 AlC was successfully synthesized at 1500 ℃ by nonpressure sintering one-step solid phase reaction method. The microstructure, crystal structure and oxidation behavior of high-entropy (V 0.2 Nb 0.2 Ta 0.2 Mo 0.2 W 0.2 ) 2 AlC MAX phase were investigated. Using thermogravimetry analysis to investigate the oxidative stability of (V 0.2 Nb 0.2 Ta 0.2 Mo 0.2 W 0.2 ) 2 AlC in air environment at high temperature from 0 to 1000 °C, there is no volume change from 0 to 400 °C, and the morphology still exhibits a typical layered structure, demonstrating thermal stability. Oxidation rate gradually decreases with the increase in temperature, and the K p3 value decreases to 0.86 × 10 –4 kg 2 m −4 s 2 at 1000 ℃. The microscopic morphology analysis at different temperatures shows that the surface defects of the matrix gradually form under high-temperature conditions, in which the formation of carbide and Al 2 O 3 layers hinds the further oxidation of the sample. The research provides a reference for the synthesis and thermal stability of new two-dimensional layered high-entropy MAX ceramics.
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APPLIED PHYSICS A-MATERIALS SCIENCE & PROCESSING
·
2025
·Vol. 131
·期 1
·1-16
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IF 2.8
Zheng Guangwei,Jiang Shukang,Zhang Fengqing,Yu Hongwen,Zhang Yanli L.
Choosing suitable photoanode materials is the most critical aspect for photoelectrochemical (PEC) water splitting. The low efficiency of PEC water splitting photoanodes restricts their widespread application for large-scale H 2 production. Herein, we prepared WO 3 photoanodes with controllable structures via hydrothermal-electrophoretic deposition and seed-mediated hydrothermal synthesis, achieving ex situ assembly and in situ growth on FTO glass substrates. Under simulated sunlight irradiation, the photoelectric current density of the WO 3 photoanode prepared by in situ hydrothermal synthesis exceeds 1.0 mA/cm² (at 1.23 V vs. RHE), significantly higher than that of the WO 3 photoanode prepared by ex situ assembly (which is less than 0.3 mA/cm² at 1.23 V vs. RHE). By contrast, the in situ preparation of the WO 3 photoanode using tungsten powder and H 2 O 2 as raw materials exhibits the enhanced photocurrent density of 1.27 mA/cm² at 1.23 V vs. RHE. The excellent PEC performance of the resulting sample could be attributed to the ordered charge transport channels from the two-dimensional (2D) nanoplates structure, the enhanced electron-hole pairs separation from the superior crystallinity of WO 3 and the strong binding between the WO 3 nanoplates and the FTO substrate. Additionally, the effect of calcination temperature on the PEC performance of the prepared WO 3 was further investigated. This work provides a way for the synthesis of environmentally friendly and cost-effective photoanodes for efficient photoelectrochemical water splitting.
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