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81.
A series of sodium iron titanate (NFTO)–fluorocarbon composite coatings have been prepared with the liquid-phase blending method. The effects of two types of NFTO, NFTO platelets, and NFTO whiskers, on the tribological and corrosion behaviors of the composite coatings, are systematically studied. The results show that the addition of NFTO can significantly enhance the friction-reducing and wear resistance performances of the fluorocarbon coating. Under dry sliding, the minimum specific wear rate is 1.67 × 10−4 mm3/Nm for the platelet-filled composite coatings and 1.15 × 10−4 mm3/Nm for the whisker-filled composite coatings, respectively, showing a decrease of 83.5 and 88.6% than that of pure coating. Under a simulated seawater environment, the minimum specific wear rate is 5.44 × 10−5 mm3/Nm for the platelet-filled composite coatings and 0.84 × 10−5 mm3/Nm for the whisker-filled composite coatings, respectively, showing a decrease of 90.5 and 98.5% than that of pure coating. The morphologies of worn surfaces, wear debris, and transfer films are analyzed, and the corresponding wear resistance mechanisms are discussed. The electrochemical impedance spectroscopy certifies a remarkably improved corrosion resistance of the composite coatings which have been immersed in 3.5 wt % NaCl solution for 30 days. The composite coating reinforced with 7.5 wt % platelets shows the highest resistance of 256.3 × 106 Ω·cm2, approximately two orders of magnitude higher than that of pure coating. © 2020 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48936. 相似文献
82.
83.
为解决采空区突发涌水给矿山安全生产带来的安全威胁,以齐大山铁矿为研究对象,以高密度电阻率法含水构造带理论模型的正演模拟研究为基础,运用高密度电阻率法对采场南帮含水构造带的异常范围进行了圈定;运用瞬变电磁法进行了二次探测,并对高密度电阻率法所圈定的异常范围进行了验证。研究表明:含水构造带显示为低阻异常特征,在高密度电阻率法探测成果图中显示的两处低阻异常与含水构造带理论模型的正演模拟结果一致;同时,在瞬变电磁法探测成果图中显示的低阻区域均在高密度电阻率法所圈定的低阻异常范围内,二者相互验证,这两处低阻异常均为含水构造带的地球物理异常特征的显示,表明采用高密度电阻率法和瞬变电磁法组合识别技术可实现对隐伏含水构造带的先导性探测。 相似文献
84.
《能源学会志》2020,93(4):1747-1754
The effect of ash on dielectric properties and micro-structure of high alkali coal at different temperature pyrolysis was studied, so as to provide theoretical basis for coal deep processing by microwave. An acid-washed method was adopted to remove ash in Zhundong coal for preparing coal chars at 700 °C–1300 °C. X-ray diffraction analysis was used to characterize the microcrystal structure. The thermal stability was characterized by thermogravimetric analyzer, and the dielectric properties were measured by a vector network analyzer. The results showed that when the pyrolysis temperature was below 1100 °C, the presence of ash hindered the development of carbon structure in raw coal char. The main reason is that the alkali metal oxides (K2O and Na2O) in the ash promoted the solution loss reaction during pyrolysis. The structure of the original carbon layer was damaged, thereby the graphitization degree, thermal stability and dielectric properties of raw coal char were weaker than the ash-free coal char. When the pyrolysis temperature reached 1300 °C, the minerals were completely melted. The reaction of phase transition of SiO2 in ash played a catalytic role on raw coal char structure, resulting in tighter arrangement of adjacent carbon layers. The raw coal char showed stronger dielectric properties and thermal stability. 相似文献
85.
Seyed Mohammadreza Miraboutalebi Mohammad Peydayesh Maryam Bagheri Toraj Mohammadi 《化学工程与技术》2020,43(6):1214-1223
The potential of a novel α-Fe2O3/polyacrylonitrile (PAN) hybrid composite adsorbent to eliminate methylene blue (MB) from aqueous solution was evaluated. PAN was selected as the base composite. The presence of α-Fe2O3 as nanophotocatalyst on the surface of PAN introduced an efficient photocatalytic hybrid composite adsorbent for degrading MB. Effects of α-Fe2O3 nanopowder loading, pH, temperature, MB initial concentration, solar light, and contact time were investigated. Langmuir, Freundlich, and Temkin isotherms were applied to analyze the adsorption behavior. The Freundlich equation provided the best correlation with experimental data. Pseudo-first-order, pseudo-second-order, and intraparticle models were employed. Thermodynamic studies indicated an endotherm and spontaneous adsorption process in a defined temperature range. 相似文献
86.
《International Journal of Hydrogen Energy》2020,45(13):7741-7750
Ni3Se2 and Co-doped Ni3Se2 cauliflower-like nanostructures are synthesized using a simple and feasible electrochemical deposition technique. Electrochemical measurements of the resultant nanostructures in 1 M KOH electrolyte solution revealed that the energy storage performance of the cauliflower-like Ni3Se2 nanostructures was considerably improved by cobalt doping. Particularly, 6 wt% Co-doped Ni3Se2 electrodes exhibited remarkable high specific capacity (179.34 mAh g−1) and excellent stability with capacity retention of 85.9% over 1000 cycles because of their high electrical conductivity. Furthermore, to verify the feasibility of the optimized Co-doped Ni3Se2 electrodes for practical applications, Zn ion batteries were constructed by using a Zn plate as the anode and the Co-doped Ni3Se2 nanostructures as the cathode. The constructed Zn ion battery achieved high energy and power densities of 199.34 W h kg−1 and 24,510 W kg−1 at the current densities of 1 and 20 A g−1, respectively. In addition, up to 2.2 electrons per formula unit of Ni3Se2 were successfully utilized, indicating considerably higher utilization of Ni2+/Ni3+ redox sites by Co doping the selenite. This work demonstrated an effectual strategy for rational design of highly robust, low-cost flexible electrodes for energy storage devices. 相似文献
87.
《Ceramics International》2020,46(1):722-730
In this work, a new core-shell structure of antiferroelectric ceramic powder (Pb0.97La0.02Zr0.85Sn0.12Ti0.03O3-PLZST) coated with linear dielectric (Al2O3) has been successfully prepared to realize high energy density through tape-casting process. According to the experimental results of electron microscope, the sol-gel derived Al2O3 layer was uniformly coated on the PLZST particles and the Al2O3 layer can be taken as the buffer layer to effectively refine the grain growth as well. Therefore, the modified PLZST particles were fine and uniform compared with the pure PLZST. It was found that the buffer layer could undertake higher electric field and the electric field applied to PLZST particles was weakened based on finite element analysis, which can avoid the premature breakdown of PLZST. And the actual measured breakdown strength was significantly enhanced from 22.2 kV/mm to 35.5 kV/mm. Correspondingly, an extremely high recoverable energy storage density of 5.3 J/cm3 was obtained for PLZST with 0.5%wt Al2O3, an 204% enhancement over the pure PLZST ceramics (2.6 J/cm3), and the corresponding efficiency was up to 88.3%. In addition, impedance spectroscopy measurement was carried out to further confirm the better insulation of the ceramic with Al2O3 buffer. 相似文献
88.
《Journal of the European Ceramic Society》2020,40(8):2811-2820
In this work, Amosic-3 SiC/SiC composites were irradiated to 10 dpa and 115 dpa with 300 keV Si ions at 300 °C. To evaluate its irradiation behaviour and investigate the underlying mechanism, nanoindentation, AFM, Raman and electron microscopy were utilized. Nanoindentation showed that although micromechanical properties declined after irradiation, hardness and Young’s modulus were maintained better under 115 dpa. AFM manifested differential swelling among PyC interface, fiber and matrix and SEM showed irradiation-induced partial interface debonding, which are both more obvious under 115 dpa. TEM revealed the generation and proliferation of amorphous regions, which is according with the decline and broadening of peaks in Raman spectra. The material was almost completely amorphous after irradiated to 10 dpa while recrystallization occurred under 115 dpa. All results mentioned above contribute to the decline of hardness and Young’s modulus and may explain why the micromechanical degradation was more significant under 10 dpa. 相似文献
89.
《Journal of the European Ceramic Society》2020,40(6):2338-2344
The high-temperature and high-performance piezoelectric ceramics are required urgently in the petrochemical, automotive, and aerospace industries. In this work, the (0.85-x)BiFeO3-xPbTiO3-0.15BaTiO3 (BF-PT-BT, x = 0.21, 0.22, 0.23, 0.24 and 0.25) piezoelectric ceramics with both high Curie temperature and large piezoelectric constant d33 were presented. X-ray diffraction analysis shows that BF-PT-BT ceramics exhibit dominant perovskite structure with the coexistence of tetragonal (T) and rhombohedral (R) phases. The c/a ratio, Curie temperature, piezoelectric constant, dielectric constant and loss of the BF-PT-BT ceramics for x = 0.23 are 1.06, 546 °C, 222 pC/N, 545 and 0.013, respectively. Room temperature piezoelectric constant of BF-PT-BT ceramics is much higher than those of PbTiO3, PbNb2O6 and other ABO3 perovskite compounds (BaZrO3, Bi(Zn, Ti)O3, PbZrO3 and Pb(Mg, Nb)O3) modified ternary BiFeO3-PbTiO3 ceramics with similar Curie temperatures. The piezoelectric constant is almost unchanged after BF-PT-BT ceramics was annealed at 450 °C for 30 min, which is due to the stable switched non-180° domain and transformed R phase by annealing treatment. 相似文献
90.
Yasir Ul Haq Imran Murtaza Sadaf Mazhar Naeem Ahmad Awais A. Qarni Zeeshan Ul Haq Shahid A. Khan Mahmood Iqbal 《应用聚合物科学杂志》2020,137(40):49197
Electric power system applications demand for high-temperature dielectric materials. The improved performance of polymer nanocomposites requires improvement in their thermal conductivity & stability, dielectric stability and processing technique. However, they often lose their dielectric properties with a rise in temperature. Here, we offer a solution by incorporating electrically conducting material (MXene) and semiconducting inorganic nanoparticles (ZnO NPs) into an insulating PMMA polymer matrix to maintain high dielectric constant, both at the room and high temperature. Therefore, to achieve desirable thermal and dielectric properties is the main objective of the present study based on the homogeneous distribution of the nanofillers by in-situ bulk polymerization assisted by strong sonication in the corresponding polymer. The introduction of MXene and ZnO NPs into the PMMA not only acquires a substantial increment in the dielectric constant, to attain a value 437, with minimum energy loss of 0.36 at 25 Hz, but also improves the thermal conductivity of PMMA up to 14 times by causing the reduction of thermal resistance, which is actually responsible for the poor thermal conductivity of amorphous pure PMMA polymer. More importantly, hybrid PMMA/4:2 wt% MXene:ZnO nanocomposite leads to an excellent thermal stability. Moreover, further characterization of the synthesized nanocomposites by FTIR, SEM and XRD leads to the evaluation of strong interaction of ternary components with PMMA matrix. 相似文献