JOURNAL OF POROUS MATERIALS
·
2016
·Vol. 23
·期 4
·867-875
·
IF 1.385
Guo Xingzhong,Song Jie,Ren Jing,Yang Fanger,Kanamori Kazuyoshi,Nakanishi Kazuki
Yttria-stabilized zirconia monoliths with well-defined macropores and high porosity have been successfully fabricated via sol–gel process accompanied by phase separation. Propylene oxide acts as an acid consumer to mediate sol–gel process, and poly (ethylene oxide) is used to induce phase separation. Ethylene glycol is applied as chelating agent, and formamide serves as drying control chemical additive to inhibit cracking during drying stage. Proper proportion of the starting compositions allows the generation of well-defined macroporous YSZ monoliths with co-continuous skeletons and porosity as high as more than 60 %. The dried gels are amorphous and crystalline of ZrO 2 precipitates after heat treatment between 400 and 1200 °C without formation of monoclinic ZrO 2 , which indicating a wide application prospects.
研究领域:
材料科学
·
化学工程
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DOI
高影响因子
JOM
·
2019
·Vol. 72
·期 4
·1687-1693
·
IF 2.305
Xia Yang,Zhao Jinlong,Dong Zhaowang,Guo Xueyi,Tian Qinghua,Zhang Siwen,Liu Yong
Ultra-high pure metallic zirconium powder was successfully obtained through a two-step gradient reduction of nano-ZrO 2 in Ar atmosphere. The first reduction by Mg was to remove ~ 85% oxygen, followed by a heat-treatment step to control the particle size and specific surface area of the powder, and the final reduction by calcium was to further purify the powder and decrease oxygen to an extremely low level (0.068 wt.%). The oxygen level in the final powder meets the standard specification of Zr sponge (ASTM B349/B349M-16). Processing parameters, including the reduction temperature, the amount of Mg and MgCl 2 and the heat treatment temperature, were investigated. Thermodynamic modeling with the assistance of HSC Chemistry software was carried out to understand the reduction reaction. This study offers a novel process for producing ultra-high pure metallic zirconium powder with the potential to replace the conventional Kroll process.
研究领域:
材料科学
·
冶金学
✓ 已验证
DOI
高影响因子
JOURNAL OF ALLOYS AND COMPOUNDS
·
2025
·
IF 6.3
Zhuohao Qiu,Gaoyuan Chen,Xixi Bao,Jitao Xu,Chengyi Chu,Guangjian Peng,Jianjun Guo,Yuchuan Cheng,Aihua Sun
Barium titanate ceramics exhibit great potential in ceramic capacitors due to their excellent dielectric properties. However, with the highly integrated advancement in electronic components, the preparation of high-capacitance ceramic capacitors with complex structural design has been the focus in current research. In this study, the complex structural barium zirconium titanate is first prepared through direct ink writing (DIW) technique. Subsequently, based on the regulation of zirconium substitution on the phase transition temperature of barium titanate, we reasonably designed zirconium-substituted barium titanate ceramics with varying stoichiometric ratios to regulate the three-phase transition temperatures of zirconium titanate ceramics, and following optimized the sintering temperature of the over-substituted barium zirconium titanate, thus improving the dielectric properties of the barium titanate. The results demonstrate that the solid content of 65 % exhibited the optimal forming precision and the highest densification. Additionally, the over-substituted zirconia alter the phase structure of barium titanate, increasing the proportion of tetragonal phase and subsequently elevating the dielectric constant of the specimens. Notably, among all sintering temperatures tested, the specimen sintered at 1400 °C display the highest proportion of tetragonal zirconia-barium titanate and an optimal dielectric constant. This research offers valuable technical and theoretical insights for the preparation and utilization of zirconium-substituted barium titanate ceramics with intricate structures.
研究领域:
材料科学
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电子工程
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产品关联
DOI
高影响因子
Materials Today Communications
·
2021
·
IF 3.383
Shijiao Zhao,Rui Xu,Jingtao Ma,Changsheng Deng,Xing Cheng,Xingyu Zhao,Shaochang Hao,Jianjun Li
Zirconium nitride is an increasingly attractive material, owning to its wide range of applications. Nitridation with carbon as a reductant is a commonly used process for the preparation of transition metal nitrides. In this study, the nitridation of carbon-containing zirconia gels was studied as a method to synthesize zirconium nitride. The behavior of the gel upon heat treatment was investigated online. The evolution of the microstructure during nitridation was investigated using high-resolution transmission electron microscopy (HRTEM). The relationships between the gaseous species, crystalline phases, microstructure, and chemical elements of the resulting materials were established. The results showed that NH 3 , CH 2 O, CO 2 , CO, H 2 O, and HCN were the gaseous products in the nitridation process. Nucleation of the nanograins started with zirconium oxynitride . Transformation from oxynitride to nitride led to the occurrence of open-mouth-like defects on the particles. The enrichment of N atoms was accompanied by a core-shell structure. Finally, a systematic nitridation mechanism involving five stages was proposed. This study is important for understanding the nitridation process and controlling the structure and properties of transition metal nitrides.
研究领域:
材料科学
·
化学工程
✓ 已验证
DOI
高影响因子
RSC Advances
·
2018
·Vol. 8
·期 72
·41603-41611
·
IF 2.936
Benxue Liu,Min Gao,Xiaochan Liu,Yongshuai Xie,Xibin Yi,Luyi Zhu,Xinqiang Wang,Xiaodong Shen
Zirconia (ZrO2) aerogels are potential candidates for use at temperatures higher than those attainable with silica aerogels. However, fabricating a robust ZrO2 aerogel with a high thermal stability is still a challenge. The extreme electronegativity of Zr makes the hydrolysis and polycondensation of zirconium precursors difficult to control, leading to poor structural integrity and unsatisfactory physical properties. In the present research, we prepared a ZrO2 aerogel by using a synthetic zirconium precursor, namely polyacetylacetonatozirconium (PAZ), and ammonia hydroxide as the gel initiator. The ammonia hydroxide catalyzes the cross-linking of PAZ via promotion of the dehydration between hydroxyls in PAZ and the acetylacetonate group in PAZ binds the zirconium ion firmly upon the addition of ammonia hydroxide to avoid a gel precipitate. A monolithic ZrO2 aerogel with a large diameter size of 4.4 cm and high optical transmittance was achieved after drying. The surface area and pore volume of the as-dried ZrO2 aerogel were as high as 630.72 m2 g−1 and 5.12 cm3 g−1, respectively. They decreased to 188.62 m2 g−1 and 0.93 cm3 g−1 after being heat-treated at 1000 °C for 2 h. The best mechanical performances of the ZrO2 aerogels showed a compressive strength of 0.21 ± 0.05 MPa and a modulus of 1.9 ± 0.3 MPa with a density of 0.161 ± 0.008 g cm−3. Both pore structures and mechanical performances varied according to the ammonia hydroxide gel initiator used. The thermal insulating properties of the ZrO2 aerogel performed better than a silica aerogel blanket with a thermal conductivity of 0.020 W (m−1 K−1).
研究领域:
材料科学
·
化学工程
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产品关联
DOI
PubMed
高影响因子
JOURNAL OF SOL-GEL SCIENCE AND TECHNOLOGY
·
2015
·Vol. 76
·期 3
·482-491
·
IF 1.532
Liu Hongjing,Liu Benxue,Wang Xinqiang,Zhu Luyi,Feng Cong,Zhang Guanghui,Xu Dong
Abstract Polycrystalline zirconia fibers with dense surface and good flexibility were achieved from polyaceticzirconium (abbreviated as PEZ) precursor fibers followed by steam pretreatment and post-calcination.
PEZ was synthesized via a one-pot solid–liquid reaction between basic zirconium carbonate and glacial acetic acid in methanol. Rheological behavior of the precursor sol with different concentrations was investigated, the power law model was used to describe the rheological behavior more accurately, and the relationship between the rheology and the spinnability of sol was discussed particularly. For the polymeric structure of PEZ, acetic acid was used as chelating agent and the carboxyl group was acted as a bidentate bridging ligand, which was speculated by FT-IR analysis. The effect of the pretreatment atmosphere on the evolution of the precursor fibers and the microstructure of the final fibers was discussed. The acetate group was removed in the form of molecules, and the final fibers preheated under steam atmosphere had better densification and flexibility than those were not. In addition, crystallization process, phase composition and thermal decomposition were investigated by XRD, Raman spectra and TG/DSC. Graphical Abstract The preheated atmosphere exerts an important influence on the densification and flexibility of zirconia fibers. Under steam atmosphere, acetate group in the precursor fibers is removed in the form of molecules and zirconia fibers sintered at 1050 °C for 2 h have a dense surface. However, zirconia fibers not subjected to the steam pretreatment have a large number of voids on the surface due to the decomposition of the organics. Furthermore, the fibers preheated under steam atmosphere have better flexibility than those were not. Therefore, pretreatment under steam atmosphere is essential for the preparation of the dense and flexible fibers.
研究领域:
材料科学
·
化学工程
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产品关联
DOI
高影响因子
ELECTROCHIMICA ACTA
·
2021
·
IF 6.901
Na Li,Yaru Peng,Zeng Chen,Wenjuan Xiong,Jiaqi Sun,Yiming Chen,Putao Zhang,Meiyue Liu,Shengjun Li
The electro-deoxidation of MgO does not proceed efficiently due to the electrical insulation properties of MgO and large molar volume of metallic magnesium. In this experiment, an attempt was done to prepare Mg-Zr alloy from their oxides using the method of electro-deoxidation. The electrochemical mechanism of the deoxidation process of MgO, ZrO 2 and MgO-ZrO 2 composite was studied through cyclic voltammetry using metallic cavity electrode (MCE). There was an intermediate phase (Zr 3 O) in the reduction process of ZrO 2 . The electro-deoxidation of MgO occurred for MgO-ZrO 2 composite in CaCl 2 -NaCl molten salt. Moreover, the electro-deoxidation of MgO was promoted by the addition of polyvinyl butyral (PVB). The formation of metal phase Mg was confirmed by XRD, EDS, Raman spectroscopy, and inductively-coupled plasma spectroscopy. The electro-deoxidation products showed significant differences with the concentration of PVB and the ratio between MgO and ZrO 2 . The electro-deoxidation of MgO and ZrO 2 was favorable when the PVB concentration was 5.0% (wt.%). Pure metal phase of Mg-Zr alloys was formed when the molar ratio of MgO and ZrO 2 was 1:2. The atomic fraction of Mg in the electrolytic product was ca. 28.0 mol.%. This work shows that MgO could be directly electro-deoxidized to Mg without the formation of intermediate phase oxide.
研究领域:
材料科学
·
冶金工程
·
无机化学
·
电化学
·
金属合金制备
✓ 已验证
DOI
高影响因子
Journal of Zhejiang University-SCIENCE B
·
2021
·
IF 3.066
Zhiwei SU,Mingxing LI,Ling ZHANG,Chaoyang WANG,Leiqing ZHANG,Jingqiu XU,Baiping FU
Objective To coat a zirconia surface with silica-zirconia using a dip-coating technique and evaluate its effect on resin-zirconia shear bond strength (SBS). Methods A silica-zirconia suspension was prepared and used to coat a zirconia surface using a dip-coating technique. One hundred and eighty-nine zirconia disks were divided into three groups according to their different surface treatments (polishing, sandblasting, and silica-zirconia coating). Scanning electron microscopy (SEM), energy dispersive X-ray (EDX), and X-ray diffraction (XRD) were used to analyze the differently treated zirconia surfaces. Different primer treatments (Monobond N, Z-PRIME Plus, and no primer) were also applied to the zirconia surfaces. Subsequently, 180 composite resin cylinders (Filtek Z350) were cemented onto the zirconia disks with resin cement (RelyX Ultimate). The SBS was measured after water storage for 24 h or 6 months. The data were analyzed by two-way analysis of variance (ANOVA). Results SEM and EDX showed that the silica-zirconia coating produced a porous layer with additional Si, and XRD showed that only tetragonal zirconia was on the silica-zirconia-coating surface. Compared with the control group, the resin-zirconia SBSs of the sandblasting group and silica-zirconia-coating group were significantly increased ( P <0.05). The silica-zirconia coating followed by the application of Monobond N produced the highest SBS ( P <0.05). Water aging significantly reduced the resin-zirconia SBS ( P <0.05). Conclusions Dip-coating with silica-zirconia might be a feasible way to improve resin-zirconia bonding.
研究领域:
牙科学
·
材料科学
✓ 已验证
DOI
PubMed
高影响因子
SURFACE & COATINGS TECHNOLOGY
·
2013
·
IF 1.941
Songbai Liu,Kuo Jiang,Hongbo Zhang,Yi Liu,Li Zhang,Bingye Su,Yibao Liu
Ceramics with structure on nanometer-length scales have a thermal conductivity much lower than their coarser-grained ceramics. But the relatively low activation energy for grain growth of nanoparticles limits the stability of nano-material at high temperatures. The objective of the present study was to investigate the preparation of the composite powders of nano (La,Gd) 2 Zr 2 O 7 and nano (Zr,Gd)O 2 − δ by a sol-spray pyrolysis method. The XRD results indicated that the reaction products of 0.2LaO 1.5 –xGdO 1.5 –(0.8 − x)ZrO 2 (0.15 ≤ × ≤ 0.25) ternary system were composed of pyrochlore (La,Gd) 2 Zr 2 O 7 and cubic (Zr,Gd)O 2 phases. The composition with 0.2LaO 1.5 –0.2GdO 1.5 –0.6ZrO 2 had a grain size much smaller than the lower GdO 1.5 content counterpart for both the (La,Gd) 2 Zr 2 O 7 and (Zr,Gd)O 2 − δ phases. The relationship between grain size and GdO 1.5 content was explained in terms of lattice matching.
研究领域:
材料科学
·
陶瓷学
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产品关联
DOI
高影响因子
ELECTROCHEMISTRY
·
2018
·Vol. 86
·期 4
·153-157
·
IF 1.074
Xiyun YANG,Jianfeng ZHANG,Shenghai YANG,Niuchang OUYANG
To understand the role of water on zirconium passivation in n-butanol solutions containing Bun4NBr, composition and corrosion properties of the passive film were studied using cyclic voltammetry, X-ray photoelectron and electrochemical impedance spectroscopy. Zirconium undergoes spontaneous passivation followed by pitting corrosion as a result of passivity breakdown by the aggressive attack of bromide anions. The passive film consists mainly of ZrO2, ZrO2·2H2O and a small amount of zirconium butoxide. The pitting potential shifts positively and pitting corrosion is seriously inhibited with the addition of a small amount of water. Water improves the pitting corrosion resistance of the passive film by changing the thickness and the relative ratio of OH−/O2−. The result is helpful to electrosynthesize zirconium butoxide with high energy efficiency.
研究领域:
材料科学
·
电化学
✓ 已验证
产品关联
DOI
高影响因子
Materials
·
2024
·Vol. 17
·期 22
·5426
·
IF 3.1
Zengqing Sun,Xiaoyu Li,Jinxin Xing,Min Gan,Zhiyun Ji,Yong Lyu
In this study, 12 mol% ceria-stabilized tetragonal zirconia polycrystal ceramics with xNd2O3(where x equals 0, 0.1, 0.2, 0.3, 0.4, 0.5, and 0.7) were synthesized via the solid-state method, and the effects of Nd2O3doping amounts on the mechanical properties and microstructure were studied. The results show that with an increase in the Nd2O3doping amount, the grain size of the ceramics was reduced from 2.93 μm to 0.69 μm. The hardness and strength of the ceramics increased significantly, while the fracture toughness decreased. The reduction in fracture toughness was attributed to the reduction in tetragonal grain size, which suppressed the tetragonal–monoclinic phase transformation caused by stress. Additionally, as the content of Nd2O3increased, the formation of cubic zirconia accelerated, but no second phase was observed. Most importantly, when the doping amount of Nd2O3reached 0.3 mol%, the comprehensive mechanical characteristics of the ceramics were optimal. This provides a research basis for the preparation of nanoscale 12 mol% ceria-stabilized tetragonal zirconia polycrystal ceramics.
研究领域:
材料科学
·
陶瓷工程
✓ 已验证
产品关联
DOI
PubMed
高影响因子
MICROPOROUS AND MESOPOROUS MATERIALS
·
2015
·
IF 3.453
Shengxue Wang,Wei Li,Song Wang,Jinming Jiang,Zhaohui Chen
Hierarchical porous lanthanum zirconate (La 2 Zr 2 O 7 , LZO) monoliths have attracted numerous attentions as adsorption, catalysis, especially in high-temperature and high water-vapor-containing environments. Herein, La 2 Zr 2 O 7 monoliths with hierarchially distributed pores have been synthesized via a spontaneous route based on a non-alkoxide sol–gel process accompanied by phase separation. Nitrates of Zr(IV) and La(III) were used as precursors, propylene oxide and formamide were used as gelation inducers, and polyethylene glycol was used as phase separation inducer. The mechanisms of Zr(IV)/La(III) binary gelation process and competitive reaction between gelation and phase separation have been discussed. Zr(IV)/La(III) binary gels exist in the form of Zr(IV)-rich gel networks coupled with La(III)-rich discrete entities. The size of the pores can be controlled by adjusting the amount of gelation and separation inducers. The surface area of the as-prepared La 2 Zr 2 O 7 monoliths is 89 m 2 /g. La 2 Zr 2 O 7 monoliths are amorphous and heating in air at more than 600 °C leads to the formation of pyrochlore structure La 2 Zr 2 O 7 . With further increase in temperature, the crystalline degree of LZO monoliths increased. After heat treatment, the macroporous skeleton can be well retained. However, the macropores became slightly smaller and the solid skeleton became fragile. Sintering of the continuous skeleton occurred after heat treatment.
研究领域:
材料科学
·
化学工程
✓ 已验证
DOI
高影响因子
危险品化学品经营许可证（带存储）