A Study of the Effect of Tungsten Oxide on W, WC Powder and Alloy Properties

Jiang Cijin,Shen Paul,Wang Huan 한국분말야금학회 2006 한국분말야금학회 학술대회논문집 Vol.2006 No.1

This is about the effects deoxidization, carbonization and alloying preparation on fine grain W, WC, and grade YG8 powder reduced by "yellow tungsten oxide" and "blue tungsten oxide". The result indicates that yellow tungsten has single composition and blue tungsten oxide has complex composition. With this feature, yellow tungsten oxide got better uniformity and concentration distribution on fine particle size W and WC powder than blue tungsten oxide's. The grade alloy YG8 that made of this W or WC powder has uniform alloy construction, concentrated WC grain distribution and better alloy properties.

리튬 이차전지용 텅스텐 산화물 전해 도금 박막 제조

이준우,최우성,신헌철,Lee, Jun-Woo,Choi, Woo-Sung,Shin, Heon-Cheol 한국재료학회 2013 한국재료학회지 Vol.23 No.12

Tungsten oxide films were prepared by an electrochemical deposition method for use as the anode in rechargeable lithium batteries. Continuous potentiostatic deposition of the film led to numerous cracks of the deposits while pulsed deposition significantly suppressed crack generation and film delamination. In particular, a crack-free dense tungsten oxide film with a thickness of ca. 210 nm was successfully created by pulsed deposition. The thickness of tungsten oxide was linearly proportional to deposition time. Compositional and structural analyses revealed that the as-prepared deposit was amorphous tungsten oxide and the heat treatment transformed it into crystalline triclinic tungsten oxide. Both the as-prepared and heat-treated samples reacted reversibly with lithium as the anode for rechargeable lithium batteries. Typical peaks for the conversion processes of tungsten oxides were observed in cyclic voltammograms, and the reversibility of the heat-treated sample exceeded that of the as-prepared one. Consistently, the cycling stability of the heat-treated sample proved to be much better than that of the as-prepared one in a galvanostatic charge/discharge experiment. These results demonstrate the feasibility of using electrolytic tungsten oxide films as the anode in rechargeable lithium batteries. However, further works are still needed to make a dense film with higher thickness and improved cycling stability for its practical use.

초음파 볼밀링 공정에 의한 용매 점도 특성에 따른 텅스텐계 합금 분쇄 거동

류근혁,소형섭,윤지석,김인호,이근재,Ryu, KeunHyuk,So, HyeongSub,Yun, JiSeok,Kim, InHo,Lee, Kun-Jae 한국분말재료학회 (*구 분말야금학회) 2019 한국분말재료학회지 (KPMI) Vol.26 No.3

Tungsten heavy alloys (W-Ni-Fe) play an important role in various industries because of their excellent mechanical properties, such as the excellent hardness of tungsten, low thermal expansion, corrosion resistance of nickel, and ductility of iron. In tungsten heavy alloys, tungsten nanoparticles allow the relatively low-temperature molding of high-melting-point tungsten and can improve densification. In this study, to improve the densification of tungsten heavy alloy, nanoparticles are manufactured by ultrasonic milling of metal oxide. The physical properties of the metal oxide and the solvent viscosity are selected as the main parameters. When the density is low and the Mohs hardness is high, the particle size distribution is relatively high. When the density is high and the Mohs hardness is low, the particle size distribution is relatively low. Additionally, the average particle size tends to decrease with increasing viscosity. Metal oxides prepared by ultrasonic milling in high-viscosity solvent show an average particle size of less than 300 nm based on the dynamic light scattering and scanning electron microscopy analysis. The effects of the physical properties of the metal oxide and the solvent viscosity on the pulverization are analyzed experimentally.

Block‐Copolymer‐Assisted One‐Pot Synthesis of Ordered Mesoporous WO_3−<i>x</i>/Carbon Nanocomposites as High‐Rate‐Performance Electrodes for Pseudocapacitors

Jo, Changshin,Hwang, Jongkook,Song, Hannah,Dao, Anh Ha,Kim, Yong‐,Tae,Lee, Sang Hyup,Hong, Seok Won,Yoon, Songhun,Lee, Jinwoo WILEY‐VCH Verlag 2013 Advanced functional materials Vol.23 No.30

<P><B>Abstract</B></P><P>An ordered mesoporous tungsten‐oxide/carbon (denoted as m‐WO<SUB>3−<I>x</I></SUB>‐C‐s) nanocomposite is synthesized using a simple one‐pot method using polystyrene‐<I>block</I>‐poly(ethylene oxide) (PS‐<I>b</I>‐PEO) as a structure‐directing agent. The hydrophilic PEO block interacts with the carbon and tungsten precursors (resol polymer and WCl<SUB>6</SUB>), and the PS block is converted to pores after heating at 700 °C under a nitrogen flow. The m‐WO<SUB>3−<I>x</I></SUB>‐C‐s nanocomposite has a high Brunauer–Emmett–Teller (BET) surface area and hexagonally ordered pores. Because of its mesoporous structure and high intrinsic density of tungsten oxide, this material exhibits a high average volumetric capacitance and gravimetric capacitance as a pseudocapacitor electrode. In comparison with reduced mesoporous tungsten oxide (denoted as m‐WO<SUB>3−<I>x</I></SUB>‐h), which is synthesized by a tedious hard template approach and further reduction in a H<SUB>2</SUB>/N<SUB>2</SUB> atmosphere, m‐WO<SUB>3−<I>x</I></SUB>‐C‐s shows a high capacitance and enhanced rate performance, as confirmed by cyclic voltammetry, galvanostatic charge/discharge measurements, and electrochemical impedance spectroscopy. The good performance of m‐WO<SUB>3−<I>x</I></SUB>‐C‐s is attributed to the high surface area arising from the mesoporous structure, the large interconnected mesopores, and the low internal resistance from the well‐dispersed reduced tungsten oxide and amorphous carbon composite structure. Here, the amorphous carbon acts as an electrical pathway for effective pseudocapacitor behavior of WO<SUB><I>3‐x</I></SUB>.</P>

CuO embedded silica nanoparticles for tungsten oxidation via a heterogeneous Fenton-like reaction

Kim, Kijung,Yi, Dong Kee,Paik, Ungyu Elsevier 2017 MICROELECTRONIC ENGINEERING Vol.183 No.-

<P><B>Abstract</B></P> <P>The Fenton reaction is used for the oxidation of tungsten via the production of hydroxyl radicals under acidic conditions. However, the narrow working pH range required for ideal reaction conditions limits the applications of these reactions. Herein, we developed a simple heterogeneous Fenton-like system for hydroxyl radical production over a broad pH range. Copper oxide nanoparticles (NPs) grown on the surface of silica NPs led to a heterogeneous Fenton-like reaction with hydrogen peroxide (H<SUB>2</SUB>O<SUB>2</SUB>), resulting in a high production rate of hydroxyl radicals in the range of acidic to neutral pH. The increased hydroxyl radical production rate at these pH values led to a high oxidation rate of tungsten. Furthermore, we applied this heterogeneous Fenton-like system to tungsten chemical mechanical planarization, resulting in high performance tungsten removal in acidic to neutral pH conditions.</P> <P><B>Highlights</B></P> <P> <UL> <LI> CuO embedded silica NPs was synthesized for enhanced tungsten oxidation. </LI> <LI> A heterogeneous Fenton-like system resulted in high production of hydroxyl radicals. </LI> <LI> High concentration of hydroxyl radicals resulted in high oxidation rate of tungsten. </LI> <LI> Cu-silica NPs resulted in high removal rate of tungsten in CMP process. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Water as DES-cosolvent on the morphology tuning and photochromic enhancement of tungsten oxide-molybdenum oxide nanocomposite

Olayinka Oderinde,Imtiaz Hussain,Mengmeng Kang,Yuanfeng Wu,Kalulu Mulenga,Ismaeel Adebayo,Fang Yao,Guodong Fu 한국공업화학회 2019 Journal of Industrial and Engineering Chemistry Vol.80 No.-

In this study, we report the utilization of different water contents (0–40 vol.%) as cosolvent to ethaline,ChCl:EG (deep eutectic solvent) at the mole ratio of 1:2 to prepare binary oxide of tungsten oxide-molybdenum oxide nanocomposite in an ambient environment, followed by characterization using XRD,FTIR, SEM, TEM, TGA, XPS and UV–vis spectroscopy. The as-prepared composite composed of aggregatedparticles at low temperature of 60 C, in the crystallite sizes ranging from~48.40 to 71.97 nm, with watercosolvent acting as bad solvent. Further characterizations revealed that the atomic percentage ratios oftungsten and molybdenum components increase with decrease in carbon content as the water contentincreases, while the morphology changes from cubic to prismatic polyhedral-like structures at lowtemperature, in addition to retaining ~73% of its original weight above 700 C. The UV–vis analysisrevealed broad absorption at 239–374 nm with a threshold value of 527 nm and can attain maximumphotochromic response in less 60 s on exposure to UV–vis light irradiation.

Tungsten oxide-modified ITO electrode for electrochromic window based on reversible metal electrodeposition

Ha Huu Do,Ha Huu Do,Wenwu Guo,Mahider Tekalne,Quyet Van Le,Thang Phan Nguyen,Jin Hyuk Cho,Sang Hyun Ahn,Soo Young Kim 대한금속·재료학회 2022 ELECTRONIC MATERIALS LETTERS Vol.18 No.1

Reversible metal electrodeposition (RME) windows are a promising material for electrochromic windows and electronic display applications. However, the lifetime of RME devices is a major drawback in the preparation of commercial and practical devices. In this study, we propose a new strategy to prolong the stability and improve the efficiency of RME devices. By using tungsten oxide, a well-known electrochromic material, to modify the surface of a transparent conductive electrode, superior, stable, and highly effective devices were prepared successfully. By applying a low potential of − 0.8 V to 0.5 V, the RME device can quickly switch between a bleached state and colored state with different colors changing from transparent to black and deep blue. The performance improvement of the RME device can be explained by the simultaneous reduction of tungsten oxide and metal ion deposition in the conductive substrate under an applied potential. Furthermore, the lifetime of the device increased significantly (over 1500 cycles) owing to the shielding role of tungsten oxide film in the acid medium, which is an indispensable component of reversible electrochromic devices.

성게모양 텅스텐 나노 산화물의 합성 및 슈퍼커패시터 특성 연구

정진주,김도형 한국물리학회 2013 새물리 Vol.63 No.2

Tungsten-oxide nanourchins (NUs) consisting of nanowires added to a spherical shell were prepared by using the hydrothermal synthesis method. The detailed morphology and crystallinity depended on the synthesis time and the synthesis temperature. The electrochemical (EC) properties of an EC double layer capacitor using tungsten-oxide NUs/PEDOT:PSS composite films and a 1-M H3PO4 electrolyte were examined. The capacitance of tungsten-oxide NUs with relatively longer nanowires was 50% higher than that with shorter nanowires. Controlling the morphologing of nanostructures is important for improving the performance of a supercapacitor. 습식법을 이용하여 속이 빈 구형태의 표면에 나노 선들이 방사형으로성장된 성게모양 나노 텅스텐 산화물을 합성하였다. 합성시간 및합성온도에 따른 나노 구조의 모폴로지 변화 및 슈퍼커패시터의 특성에미치는 모폴로지의 영향을 조사하였다. 슈퍼커패시터는 PEDOT:PSS와텅스텐 산화물 하이브리드 필름을 작동전극으로 하고, 스퍼터링 방법으로증착된 Au 필름을 집전체로,1-M H3PO4 수용액으로구성되었다. 합성조건 조절을 통해 얻은 긴 나노 선을 가진텅스텐산화물의 슈퍼커패시터 성능은 비 표면적 증가에 의해 상대적으로짧은 나노 선을 가진 텅스텐산화물의 충전용량에 비해 50% 높아졌다. 나노 구조물의 모폴로지 조절은 슈퍼커패시터 성능향상을 위해 매우중요한 요소이다.

Thermal Oxidation Mechanism of W-1.1wt% Ni Films Sputtered on Steel

Jae Chun Lee,Thuan Dinh Nguyen,Dong Bok Lee 한국물리학회 2009 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.54 No.3

W-1.1 wt.%Ni films having a β-W structure were deposited on a steel substrate by using the magnetron sputtering method. Their oxidation resistance in air was inferior at temperatures above 600℃ due mainly to the formation of tungsten oxides. They oxidized to an outer NiO layer that was formed by outward transport of Ni and an inner (WO3 + NiWO4)-mixed oxide layer that was formed by the inward diffusion of oxygen. At the same time, substrate elements, such as Fe and Cr, diffused outward toward the lm surface to be incorporated in the oxide layer. W-1.1 wt.%Ni films having a β-W structure were deposited on a steel substrate by using the magnetron sputtering method. Their oxidation resistance in air was inferior at temperatures above 600℃ due mainly to the formation of tungsten oxides. They oxidized to an outer NiO layer that was formed by outward transport of Ni and an inner (WO3 + NiWO4)-mixed oxide layer that was formed by the inward diffusion of oxygen. At the same time, substrate elements, such as Fe and Cr, diffused outward toward the lm surface to be incorporated in the oxide layer.

Performance enhancement of Pd-based hydrogen oxidation catalysts using tungsten oxide

Kwon, K.,Jin, S.a.,Lee, K.H.,You, D.J.,Pak, C. Elsevier Science Publishers 2014 CATALYSIS TODAY - Vol.232 No.-

Replacing Pt catalysts with less expensive materials is of critical importance for the commercialization of fuel cells. Pd, which is comparable to Pt in the hydrogen oxidation reaction (HOR) activity and of which price is about one third of Pt, is employed as an anode catalyst. In a half cell or a single cell, the HOR activity of Pd can be enhanced by alloying other elements such as Ru. However, there is still a performance gap compared to the state-of-the-art PtRu and this gap can be closed by using a co-catalyst, tungsten oxide. When PdRu or PdIr is coupled with WO<SUB>x</SUB>, there is a significant increase in cell performance, which indicates the promotion of HOR by WO<SUB>x</SUB>. Although tungsten oxide itself does not have enough catalytic activity for HOR, it seems to act as a hydrogen-storage medium through the formation of hydrogen tungsten bronze, so called the H spillover effect, leading to the enhancement of HOR at Pd alloy surfaces.