The B4C-ZrB2-SiC ternary composites with super hard and high toughness were obtained by arc melting in argon atmosphere. Microstructures were observed by SEM, and phase compositions were analyzed by XRD. The hardness ...
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The B4C-ZrB2-SiC ternary composites with super hard and high toughness were obtained by arc melting in argon atmosphere. Microstructures were observed by SEM, and phase compositions were analyzed by XRD. The hardness and fracture toughness of ternary composites are 28GPa and 4.5MPa-m1/2. The eutectic mole composition is 0.39B4C-0.25ZrB2-0.36SiC, and the eutectic lamellar microstructure is composed of B4C matrix with the lamellar ZrB2 and SiC grains.
Using steel slag and charcoal as raw materials, the steel slag/charcoal nano-/micro-composites with magnetic-resistance mixed loss mode were fabricated by a high-performance milling process, and then the composition, ...
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Using steel slag and charcoal as raw materials, the steel slag/charcoal nano-/micro-composites with magnetic-resistance mixed loss mode were fabricated by a high-performance milling process, and then the composition, phase structure, morphology, and electromagnetic (EM) characteristics of the products were characterized by XRD, EDS, SEM, and vector network analyzer, respectively. The results showed that EM characteristics of the products were strongly dependent on the content of the charcoal (WCharcoal). The real and imaginary parts of the permittivity of the steel slag/charcoal nano-/micro-composites significantly increased with the increasing WCharcoal. Among them, the steel slag/charcoal composites with WCharcoal=50wt% exhibited the best EM-wave absorption performance, with a maximum reflectivity value of -33.4dB, the effective bandwidth 15.2GHz(<-10dB) and 8.6 GHz (<-20 dB), respectively, which is a consequence of enhanced dielectric loss and a proper EM matching.
作者：
Fangjun XuGuangze TangXinxin MaSun MingrenLiqin WangKen YukimuraG.E.OzurSchool of Material Science & Engineering
Harbin Institute of Technology Harbin 150001 China National Key Laboratory of Science and Technology on Precision Hot Processing of Metals Harbin Institute of Technology Harbin 150001 China State Key Lab of Advanced Welding Production Technology Harbin Institute of Technology Harbin150001China School of Mechatronics Engineering Harbin Institute of Technology Harbin 150001 China School of Material Science & Engineering Harbin Institute of Technology Harbin 150001 China Institute of High Current Electronics 4 Academichesky Av. Tomsk 634055 Russia State Key Lab of Advanced Welding Production Technology
Harbin Institute of Technology Harbin150001China
In the present study, (1-x)(Sr_(0.88)Bi_(0.08))TiO_(3)-xBi(Mg_(0.5)Ti_(0.5))O_(3) (SBT-BMT) system was synthesized using conventional solid stateprocessing. X-ray diffraction (XRD) and SEM testings were employed to d...
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ISBN:
(纸本)9781457711626
In the present study, (1-x)(Sr_(0.88)Bi_(0.08))TiO_(3)-xBi(Mg_(0.5)Ti_(0.5))O_(3) (SBT-BMT) system was synthesized using conventional solid stateprocessing. X-ray diffraction (XRD) and SEM testings were employed to determine the phase constitution and microstructure of ceramics. SBT-BMT ceramics exhibited moderate dielectric permittivities ((epsilon)_(r)) (>1100 at RT) and low dielectric loss (0.07percent) over the temperature range from -20 to 200 deg C, with flat temperature coefficients of permittivity. In addition, SBT-BMT ceramics were observed to possess dielectric relaxation characteristics and energy densities, being on the order of 1.4 J/cm~(3) at 180 kV/cm was observed for the 0.8S_(0.88)B_(0.08)T-0.2BMT ceramics.
A novel way was used to prepare dense B4C ceramics at a lower temperature by reactive sintering from carbon and boron elemental powders. Spark Plasma Sintering (SPS) technique, a rapid and non-conventional powder cons...
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ISBN:
(纸本)9780470927151
A novel way was used to prepare dense B4C ceramics at a lower temperature by reactive sintering from carbon and boron elemental powders. Spark Plasma Sintering (SPS) technique, a rapid and non-conventional powder consolidation method, was employed. The densification, microstructure and mechanical property of the as-prepared B4C ceramics were investigated. The reactive sintering process could be divided into two stages, corresponding to synthesis (1300∼1700°C) and densification (1700∼1900°C), respectively. At those stages, boron first reacted with carbon to form B4C, and then the in-situ densification of the as-synthesized B4C occurred and was enhanced by increasing sintering temperature. B4C ceramics with grain size of several hundred nanometers and high densification (98%) were obtained at 1800°C, a lower sintering temperature as compared with general hot press. Due to the high densification and purity as well as fine texture, the SPS-sintered B4C ceramics had high Vickers hardness (48.8GPa), Young's modulus (264.5GPa), fracture toughness (3.9MPa·m1/2) and flexure strength (450MPa).
In the present work, tetragonal BaTiO3 particles down to 20 nm have been synthesized by low temperature aqueous co-precipitation method through composition control. Field emission scanning electron microscopy (FE-SEM)...
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In the present work, tetragonal BaTiO3 particles down to 20 nm have been synthesized by low temperature aqueous co-precipitation method through composition control. Field emission scanning electron microscopy (FE-SEM) images indicated that the precipitates contained fine (about 20-30 nm) faceted particles. The Raman spectra revealed that tetragonal phase appeared with the increase in Ba/Ti ratio in the precursor solution. The appearance of tetragonal phase in BaTiO3 nanoparticle was related with the lattice defect revealed by lattice parameter and lattice strain calculated by XRD results. The lattice defect can be modified through composition control.
The Fe2O3 nanoparticles activated V2O5 nanotubes were achieved via a hydrolysis method. The TEM and SEM images of the nanotubes indicated that the Fe2O3 nanoparticles with the particle size of about 15 nm were dispers...
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ZnO-B2O3-SiO2 additive with 0.55: 0.35: 0.10 molar ratio was added to Ba0.3Sr0.7TiO3 ceramics in order to lower the sintering temperature. The densification behavior, crystalline structure, microstructure, dielectric ...
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ZnO-B2O3-SiO2 additive with 0.55: 0.35: 0.10 molar ratio was added to Ba0.3Sr0.7TiO3 ceramics in order to lower the sintering temperature. The densification behavior, crystalline structure, microstructure, dielectric properties and breakdown strength of ceramics were studied. When 9 wt.% additive was mixed with pure Ba0.3Sr0.7TiO3 powder, the densification temperature of samples decreased from 1350°C to 1100°C compared with no additive system, and the sintered ceramics revealed dielectric properties at room temperature as follows: dielectric constant Εr = 413, dielectric loss tanδ = 0.00231 under 1 kHz and the breakdown strength Eb = 9.2 kV/mm.
Lead free textured K_(0.5)Na_(0.5)NbO_(3) piezoelectric ceramics have been prepared by reactive-templated grain growth method by using NaNbO_(3) with different morphologies as templates. The NaNbO_(3) template particl...
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ISBN:
(纸本)9781457711626
Lead free textured K_(0.5)Na_(0.5)NbO_(3) piezoelectric ceramics have been prepared by reactive-templated grain growth method by using NaNbO_(3) with different morphologies as templates. The NaNbO_(3) template particles with different edge length (10-20 (mu)m) and thickness (0.5-2.5 (mu)m) was synthesized through controlling Bi_(1.5)Na_(x-1.5)Nb_(x)O_(3x+3) precursor's layer numbers x from 2 to 6 by two-step molten salt methods. The crystalline phases and microstructure of textured K_(0.5)Na_(0.5)NbO_(3) were characterized by X-ray diffraction and scanning electron microscopy, respectively. It shows that all the K_(0.5)Na_(0.5)NbO_(3) ceramics are orthorhombic perovskite structure with {001} orientation. By using the template particles with a ratio of edge length to thickness (l/h)(velence)approx10, the textured ceramics with optimized piezoelectric properties was prepared. The results indicate that the enhanced properties of textured ceramics are concerned with the template morphology.
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