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MB2(M=Ti,Zr,Hf)是ⅣB族过渡金属的硼化物,化学气相淀积(CVD)是制备MB2类薄膜材料和保护涂层的最有效技术之一。对MB2类材料CVD制备的热力学进行了简要分析。阐述了反应前驱体的选择和应用。对近年来MB2类材料的CVD合成制备的最新研究报道进行了整理和总结,对MB2类材料的CVD制备发展进程进行了概括。从CVD过程的设备工艺到产物的表征,从显微结构的定性研究到晶格常数匹配的定量分析,均进行了简要的阐述。最后,对CVD工艺制备MB2类材料的发展和应用前景进行了展望。 相似文献
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Xiao-Fei Wang Xin-Gang Wang Qing-Qing Yang Hong-Liang Dong Cheng Zhang Guo-Jun Zhang Dan-Yu Jiang 《Journal of the American Ceramic Society》2021,104(6):2436-2441
Medium-entropy (Ti,Zr,Hf)C ceramics were prepared by hot pressing a dual-phase medium-entropy carbide powder with low oxygen content (0.45 wt%). The results demonstrate that the medium-entropy (Ti,Zr,Hf)C ceramics sintered at 2100°C had a relative density of 99.2% and an average grain size of 1.9 ± 0.6 μm. The flexural strength of (Ti,Zr,Hf)C carbide ceramics at room temperature was 579 ± 62 MPa. With an increase in temperature to 1600°C, the flexural strength showed an increase up to 619 ± 57 MPa, and had no significant degradation even up to 1800°C. The high-temperature flexural strengths of (Ti,Zr,Hf)C were obviously higher than those of the monocarbide ceramics (TiC, ZrC, and HfC). The primary strengthening mechanism in (Ti,Zr,Hf)C could be attributed to the high lattice parameter mismatch effects between TiC and ZrC, which not only inhibited the fast grain coarsening of (Ti,Zr,Hf)C ceramics, but also increased the grain-boundary strength of the obtained ceramics. 相似文献
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《Journal of the European Ceramic Society》2002,22(11):1847-1855
The objective of this work was to lower the sintering temperature of lead zirconate titanate (PZT) without reducing the piezoelectric performance. PZT was sintered using PbO–WO3 additive of eutectic composition, which assists the densification process by liquid-phase formation. Sintering was carried out from 1075 to 1125 °C between 1 and 4 h. Density, dielectric properties and piezoelectric properties were measured. Microstructure and fracture mechanism have been studied by SEM. At the mildest sintering conditions, the additive has a positive effect on dielectric and piezoelectric properties. The liquid-phase sintering leads to a denser material without additional grain growth. PZT with PbO–WO3 additive is mechanically weaker than pure PZT. The liquid phase leads to weaker grain boundaries and the material cracks in intergranular fracture, whereas pure PZT has a mixture of intergranular and transgranular fracture, and PZT sintered conventionally at 1260 °C has transgranular fracture. 相似文献
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Ba(Zr0.3Ti0.7)O3薄膜的结构及性能 总被引:1,自引:0,他引:1
用溶胶-凝胶法分别在Pt/Ti/SiO2/Si和LaNiO3/Pt/Ti/SiO2/Si衬底上制备了锆钛酸钡[Ba(Zr0.3Ti0.7)O3,BZT]薄膜.相结构及介电性能研究表明:衬底和薄膜厚度对BZT薄膜性能具有显著影响.制备在LaNiO3/Pt/Ti/SiO2/Si衬底上的BZT薄膜具有(100)面的择优取向,其介电常数及介电损耗则随着薄膜厚度的增加而降低.对制备在Pt/Ti/SiO2/Si衬底上的BZT薄膜,在薄膜厚度低于500nm时,其介电常数随薄膜厚度增加而增加,大于500nm时又有所减小. 相似文献
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对比了熔体快淬合金和常规熔铸合金Zr0.9Ti0.1(Ni,Co,Mn,V)2.1的微结构和电化学性能. XRD分析表明: 熔体快淬合金在退火前后的晶体结构与铸态合金一样,都为面心立方结构,由Laves C15主相组成;随快淬速度的增加,快淬合金中的非晶成份增多. 电化学测试表明:快淬合金有较好的活化性能,经6~8次循环即可完全活化,但其最大放电容量较低,小于270 mA×h/g;而退火后的快淬合金需经30次循环才能完全活化,其最大放电容量皆为340 mA×h/g左右,高于铸态合金和退火前的快淬合金;在电流密度为300 mA/g下充放电循环,发现退火后的快淬合金循环稳定性明显高于铸态合金电极,并且随快淬速度增加,循环稳定性越好. 相似文献
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Yixuan Chen Jie Jian Jianguo Chen Jinrong Cheng 《Journal of the American Ceramic Society》2021,104(9):4687-4694
Ternary ceramics of (0.87−x)BiFeO3–xPbTiO3–0.13Ba(Zr0.5Ti0.5)O3 (BF–xPT–0.13BZT, 0.27 ≤ x ≤ 0.37) were prepared by the traditional solid state reaction methods. X-ray diffraction results display that BF-xPT-0.13BZT ternary ceramics of x ≥ 0.29 exhibit the perovskite structure with dominant tetragonal (T) phases mixed with a small amount of rhombohedral (R) phases. Scanning electron microscopy (SEM) images reveal that the average grain size of BF-xPT-0.13BZT ternary ceramics is in a range of 10–11 μm, increasing first and then decreasing with the increase of PbTiO3 (PT) content. The low tanδ of about 0.015 and high Curie temperature Tc of above 450°C were obtained for BF-xPT-0.13BZT ternary ceramics. Moreover, the fluctuation of piezoelectric coefficient d33 is less than ±10% over a broad temperature range of 30°C–400°C. BF-xPT-0.13BZT ternary ceramics for x = 0.33 possess the maximum Tc and d33 of 470°C and 320 pC/N respectively, with the room temperature resistivity of about 1011 Ω·cm. These results indicate that BF-xPT-0.13BZT ternary ceramics for x = 0.33 with both excellent piezoelectric properties and high Curie temperature have promising applications in high-temperature piezoelectric devices. 相似文献
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Qing-Qing Yang Xin-Gang Wang Ping Wu Xiao-Fei Wang Cheng Zhang Guo-Jun Zhang Dan-Yu Jiang 《Journal of the American Ceramic Society》2022,105(2):823-829
We report for the first time the synthesis of a core-shell structured composite powder with a core of Zr(Ti,Ta)C and a shell of Ti,Ta(Zr)C at 1700°C and investigate the formation mechanism for the core-shell structure. The medium-entropy (Ti,Zr,Ta)C ceramics with fine grains (1.1 ± 0.4 μm) and relative density of 94.8% was prepared by hot-pressing at 2100°C. The flexural strength of (Ti,Zr,Ta)C at 1000°C (493 ± 21 MPa) was close to the room temperature (511 ± 52 MPa). As the temperature increased from 1600°C to 1800°C, the flexural strength was increased significantly, with an ultra-high flexural strength of 725 ± 32 MPa at 1800°C. The existence of the core-shell structure in the powder suppressed the grain growth due to the sluggish diffusion effect. The ultra-high strength of (Ti,Zr,Ta)C ceramics was attributed to its fine microstructures, high fracture toughness, and the reinforced the grain boundary strength. 相似文献
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Ba掺杂对Pb(Zr,Ti,Sb)O_3压电陶瓷Curie温度与压电性能的影响 总被引:1,自引:1,他引:0
用传统固相法制备了组成为0.98Pb1.0–xBaxTi0.48Zr0.52O3–0.02PbSbO3(x=0.18~0.24)的Ba掺杂Pb(Zr,Ti,Sb)O3(PSZT)压电陶瓷。通过X射线衍射和Raman光谱研究了Ba掺杂PSZT陶瓷的结构,并测量和分析了Ba掺杂对PSZT压电陶瓷的Curie温度和压电性能的影响。结果表明:Ba掺杂影响PSZT陶瓷中四方相和三方相的转化过程、两相比例、晶粒大小并导致四方相的晶格畸变。随Ba含量(x)从0.18增加到0.24,PSZT陶瓷的Curie温度从189℃几乎线性下降到141℃;当Ba掺杂量为0.22时,PSZT陶瓷的Curie温度为156℃,压电应变常数d33为578pC/N,机电耦合系数Kp为0.63,机械品质因数Qm为37.3。 相似文献
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Yichen Wang Duo Yu Jie Yin Buhao Zhang Hangfeng Zhang Xuejian Liu Yulong An Michael J. Reece Zhengren Huang 《Journal of the American Ceramic Society》2022,105(10):6395-6406
The ablation behavior of (Hf–Ta–Zr–Nb–Ti)C high-entropy carbide (HEC-0) was investigated using a plasma flame in air for different times (60, 90, and 120 s) at about 2100°C. The effect of SiC content on the ablation resistance of HEC–xSiC composites (x = 10 and 20 vol%) was also studied. The linear ablation rate of HEC-0 decreases with increasing ablation time, showing the positive role of the oxide layer with a complex composition. The linear ablation rate of HEC–10 vol% SiC (0.3 µm s−1) is only a 10th of that of HEC-0, showing a significant improvement in ablation resistance, probably due to the formation of a protective oxide layer containing melted SiO2 and refractory Hf–Zr–Si–O oxides. 相似文献
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研究了Pb(Zr,Ti)O3/Terfenol-D(Tb1-xDyxFe2)合金叠层结构的磁电压特征.介电常数和磁导率随频率变化特征表明,复合样品的电-机械谐振和磁-机械谐振不在同一频率.电-机械谐振和磁-机械谐振均可以增强磁电耦合效果,电-机械谐振对磁电耦合的影响比磁-机械谐振的影响大得多.磁电压的相位差在电-机械谐振频率附近增加0.75π~π.在磁-机械谐振频率附近出现明显的突变.磁电压显示出中心线对称分布,样品的不同位置对磁电压输出的贡献不同.磁电压的不同分布是由于应变的分布方式和谐振模式造成的. 相似文献
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介绍了Ti(C,N)基金属陶瓷的基本组成和结构,综述了Ti(C,N)基金属陶瓷的研究现状,指出了未来的发展方向和应用。 相似文献
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BCZT基无铅压电陶瓷具有优良的压电性能,是国内外无铅压电陶瓷领域研究的新热点,本文主要介绍了近年来国内外在锆钛酸钡基钙钛矿型无铅压电陶瓷体系中所开展的研究工作。着重讨论BCZT基无铅压电陶瓷的组分及其掺杂特性的影响、并总结国内外就改善BCZT陶瓷缺点(烧结困难、距离温度低、温度稳定性差)方面所取得的进展。通过上述的研究发现结合掺杂及组分设计,在不牺牲优秀压电性能的前提下,获得良好的温度稳定性,使BCZT陶瓷在未来取代铅基陶瓷成为可能。 相似文献
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Navavan Thongmee Anucha Watcharapasorn Mark Hoffman Sukanda Jiansirisomboon 《Ceramics International》2012
The ceramic samples of compound (1 ? x)Pb(Zr0.52Ti0.48)O3–xBi3.25La0.75Ti3O12 (when x = 0, 0.03, 0.05, 0.07, 0.10, 0.15 and 0.20) were prepared by a solid-state mixed oxide method. X-ray diffraction analysis showed that complete solid solutions occurred for all compositions. Perovskite phase with tetragonal crystal structure and corresponding lattice distortion was observed. Scanning electron micrographs of sample surfaces showed equiaxed grains for all compositions. Ferroelectric measurements revealed that the addition of small amount of BLT (x = 0.03) showed high remanent polarization (~33.5 μC cm?2) and low coercive field (~2.74 kV mm?1). Further increasing BLT content could maintain ferroelectric properties of PZT–BLT ceramics. Based on this study, ferroelectric properties of this PZT–BLT ceramic system can be improved for being further used in ferroelectric memory applications. 相似文献