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61.
《Journal of the European Ceramic Society》2021,41(13):6596-6605
This work focuses on identifying the rate-determining step of oxygen transport through La0.5Sr0.5Fe0.7Ga0.3O3-δ membranes with symmetric and asymmetric architectures. The best oxygen semipermeation fluxes are 3.4 10−3 mol. m-2.s-1 and 6.3 10−3 mol. m-2.s-1 at 900 °C for the symmetric membrane and asymmetric membrane with a modified surface. The asymmetric membrane with a modified surface leads to an increase of approximately 7 times the oxygen flux compared to that obtained with the La0.5Sr0.5Fe0.7Ga0.3O3-δ dense membrane without surface modification. This work also shows that the oxygen flux is mainly governed by gaseous oxygen diffusion through the porous support of asymmetric La0.5Sr0.5Fe0.7Ga0.3O3-δ membranes. 相似文献
62.
The microstructures and mechanical properties of the interconnected SiC–Si network reinforced Al–20Si composites solidified under high pressures were investigated. The results demonstrate that the complete interconnected SiC–Si network can be obtained by high pressure solidification, and the connected micron-sized pores are uniformly distributed in the interconnected SiC–Si network. The compressive strength and microhardness of the SiC/Al–20Si composites solidified under 3 GPa were 723 MPa and 229 HV0.05, respectively. Furthermore, the fracture process of SiC/Al–20Si composites was studied by in situ TEM tensile testing. The result shows that the crack first initiated and propagated at the Al/Si interface under an external load, and the SiC particles in the interconnected SiC–Si network can effectively hinder the crack propagation, thus enhancing the strength. 相似文献
63.
《Ceramics International》2021,47(22):31713-31723
Continuous carbon-fibre-reinforced Cs-geopolymer composite (Cf/CsGP) were prepared, and its in-situ conversion was investigated during high-temperature treatments. The effect of treatment temperature on the thermal evolution process and mechanical properties of the resulting products were systematically evaluated. The results indicated that the crystallization temperature of Cf/CsGP composite was considerably delayed because the amorphous structure of carbon fibres was not conducive as a nucleation substrate for pollucite derived from the CsGP matrix. Moreover, the integrity of the corresponding resulting products derived from the Cf/CsGP composite were damaged due to thermal shrinkage that occurred during the high-temperature treatment process. When treatment temperature was ≤1200oC, the mechanical properties of the corresponding products exhibited an upward trend, which was ascribed to the improvement of the densification degree of the resulting composite and well interface-bonding state between carbon fibres and pollucite. However, the mechanical properties of the resulting composites decreased with the treatment temperature continued increased from 1200 to 1400oC. This phenomenon was attributed to the impairment of fibre properties caused by interfacial reactions. 相似文献
64.
为改善涂层在真空、高温等苛刻条件下的摩擦学性能,利用中频直流磁控溅射技术在硅片和316L不锈钢上沉积了CrN和CrN/Ag涂层,利用扫描电镜、透射电镜和X射线衍射仪对涂层的成分及相结构进行了表征,通过划痕测试仪、纳米压痕仪和摩擦磨损试验机测试了涂层的力学及摩擦学性能。结果表明:添加Ag元素以后,CrN/Ag涂层硬度及承载能力有所减小,但结合强度增加;真空高温环境下CrN与CrN/Ag涂层摩擦因数随温度升高呈下降趋势,其中CrN涂层通过软化镀层减小剪切强度和阻力,从而减小摩擦因数,CrN/Ag涂层主要通过高温产生的热驱动力诱导表面Ag润滑膜的形成来减小摩擦因数;CrN涂层依靠自身剪切特性参与摩擦,而CrN/Ag涂层在真空高温下具有自润滑和持续润滑性能,作为自润滑零部件具有潜在的应用价值。 相似文献
65.
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67.
Fernanda Monedeiro Viorica Railean-Plugaru Maciej Monedeiro-Milanowski Pawe Pomastowski Bogusaw Buszewski 《International journal of molecular sciences》2021,22(9)
Considering the advent of antibiotic resistance, the study of bacterial metabolic behavior stimulated by novel antimicrobial agents becomes a relevant tool to elucidate involved adaptive pathways. Profiling of volatile metabolites was performed to monitor alterations of bacterial metabolism induced by biosynthesized silver nanoparticles (bio-AgNPs). Escherichia coli, Enterococcus faecalis, Klebsiella pneumoniae and Proteus mirabilis were isolated from pressure ulcers, and their cultures were prepared in the presence/absence of bio-AgNPs at 12.5, 25 and 50 µg mL−1. Headspace solid phase microextraction associated to gas chromatography–mass spectrometry was the employed analytical platform. At the lower concentration level, the agent promoted positive modulation of products of fermentation routes and bioactive volatiles, indicating an attempt of bacteria to adapt to an ongoing suppression of cellular respiration. Augmented response of aldehydes and other possible products of lipid oxidative cleavage was noticed for increasing levels of bio-AgNPs. The greatest concentration of agent caused a reduction of 44 to 80% in the variety of compounds found in the control samples. Pathway analysis indicated overall inhibition of amino acids and fatty acids routes. The present assessment may provide a deeper understanding of molecular mechanisms of bio-AgNPs and how the metabolic response of bacteria is untangled. 相似文献
68.
Muzhang Huang Xiangyang Liu Yingjie Feng Chunlei Wan Wei Pan Jun Yang Xiaohui Zhao 《Journal of the European Ceramic Society》2021,41(1):526-534
Understanding the effect of nonstoichiometry on material properties is of critical importance for the Thermal Barrier Coatings (TBCs) application. In this work, the effect of nonstoichiometry was systematically investigated in Y3NbO7, a recently identified promising TBCs material for next-generation gas turbine engines. The results show that the nonstoichiometry effect mediates the microstructure, mechanical properties, thermophysical properties, oxygen ionic conductivity and optical transmittance. The results suggest that the oxygen ionic conductivity is correlated to the mass diffusion in the oxygen-deficient fluorite oxides Y1-xNbxO1.5+x. The stoichiometric composition Y3NbO7, with the lowest thermal conductivity and slowest mass diffusion in Y1-xNbxO1.5+x series, is optimal for the TBCs application, which can be of relevance for TBCs material design and coating fabrication. 相似文献
69.
本文在环氧涂料中添加玄武岩鳞片,提高其防腐蚀性能。针对玄武岩鳞片的团聚问题,通过机械力化学改性工艺,采用正硅酸四乙酯、HY-311型钛酸酯偶联剂、E-44型环氧树脂对玄武岩鳞片进行杂化包覆,结果表明,杂化包覆后玄武岩鳞片的沉降时间从2h提高至96 h。杂化包覆玄武岩鳞片添加量为20%涂层的性能最优,附着力为13.40 MPa,耐盐雾时间为2000 h,在3.5%NaCl溶液中浸泡2000 h后,0.01 Hz的阻抗模值仍然有5.15×109 Ω·cm2。 相似文献
70.
《Ceramics International》2022,48(18):25984-25995
Design of architectured composites with layered-ordered structure can solve the strength-toughness mismatch problem of structural materials. In the present study, heterostructure Ti6Al4V/TiAl laminated composite sheets with different thicknesses of interface layer and TiAl composite layer were successfully produced by hot-pressing technology. The effects of interface regulation and laminated structure on their mechanical properties, crack propagation, and fracture behavior were studied. The results indicated that compressive strength of the sheets increased with the decrease in interface thickness. Compressive strength of TiAl composite sheet with thicker composite layer reached 1481.55 MPa at the arrester orientation with sintering holding time of 40 min, which was 25.96% higher than that of the sheet obtained at 120 min. Analysis indicated that the interface area transferred stress through slip bands and through-interface cracks. Compressive strength at the divider orientation reached 1443.06 MPa, which was 45.78% higher than that of the sheet obtained at 120 min. In this case, the interface area transferred stress through slip bands and along-interface cracks. For TiAl composite sheets with thinner composite layer, compressive strength was further improved to 1631.01 MPa and 1594.66 MPa at the arrester and divider orientations with sintering holding time of 40 min, respectively. The ductile metal layer exerted a significant toughening effect. Both interface regulation and laminated structure transformation could enhance the hetero-deformation induced (HDI) strengthening and improve the comprehensive mechanical properties of the composite sheets. 相似文献