Dynamic response and fracture of high strength boride/alumina ceramic composite were investigated by split Hopkinson pressure bar (SHPB) experiment in this paper. The compressive stress-strain curves and dynamic compr...
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Dynamic response and fracture of high strength boride/alumina ceramic composite were investigated by split Hopkinson pressure bar (SHPB) experiment in this paper. The compressive stress-strain curves and dynamic compression strength of the composites were tested. The surface's microstructure of fractured composites were examined by using scanning electron microscope (SEM) to investigate the fracture mechanism. The results show that boride/alumina has high dynamic compressive strength and high Young's modulus. The main fracture mode of the material is the fracture of the ceramic grains. The micro-voids and flaws, generated during the sintering and manufacturing of material and mechanical process of specimen, decrease the strength of the material because they provide the source of crack expansion when the material undergoes the dynamic loadings.
The effect of particle morphology of α-Al2O3 on sintering property of its compact is investigated in this paper. The morphology of α-Al2O3 particles and its compact were studied by SEM and TEM, and line-shrinkage ra...
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The effect of particle morphology of α-Al2O3 on sintering property of its compact is investigated in this paper. The morphology of α-Al2O3 particles and its compact were studied by SEM and TEM, and line-shrinkage rate, density and water absorption rate were measured respectively. The results showed that the expansion of compact at elevated temperature brought harm to densification and formation of homogenous structure of the compact and the sintering property of compact was influenced by the morphology of α-Al2O3 particles in different degrees.
Permittivity and dielectric strength determine the energy storage density of a material. Although a composite can be molded easier, its lower energy storage density prevents the material from applications since the po...
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In the present study, the processing-properties relationships of the ZrO2/(Ni+Al2O) 3) composites are examined. Dense composites were prepared either by pulse electrical current sintering (PECS) at 1350C for 5 minutes...
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In the present study, the processing-properties relationships of the ZrO2/(Ni+Al2O) 3) composites are examined. Dense composites were prepared either by pulse electrical current sintering (PECS) at 1350C for 5 minutes or by pressureless sintering (PLS) at 1600C for 1 h. The size of Ni particles is as small as 30 nm to 50 nm. Though the size of ZrO2 grains in the matrix increases as alumina and nickel particles are added, the strength of the ZrO2/(Ni+Al2O3) composites is significantly higher than that of monolithic ZrO2.
After combining the PVDF and BST powders with different particle sizes, the anti-voltage strengths of composites was tested. Although the concentrates of ceramic were all the same, their anti-voltage strengths were di...
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Highly oriented plate-like rod/tube arrays of ZnO are synthesized by a solution-based approach at low temperature. The ZnO rod/tube arrays grow oriented vertically on silicon substrate and the intersectant ZnO nanoshe...
Highly oriented plate-like rod/tube arrays of ZnO are synthesized by a solution-based approach at low temperature. The ZnO rod/tube arrays grow oriented vertically on silicon substrate and the intersectant ZnO nanosheets stand on the backbones of ZnO rods/tubes. The constructions of plate-like rod or tube arrays depend on the processing conditions. The growth mechanisms are investigated based on the nucleation and growth process. The initial ZnO film formed on substrate is crucial for the growth of ZnO rods/tubes perpendicular to the substrate. The nanosheets grow around the ZnO rods/tubes by the secondary nucleation and growth process. The ZnO tubes are formed by the etching of the ZnO polar faces. The novel ZnO structures are expected to have great potential for electronics, photoelectronics, sensors, and catalysis etc.
BaCO3 whiskers exhibiting different morphologies were fabricated by a simple precipitation reaction of barium chloride with sodium carbonate in the absence and presence of poly-（styrene-alt-maleic acid） （PSMA） as ...
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BaCO3 whiskers exhibiting different morphologies were fabricated by a simple precipitation reaction of barium chloride with sodium carbonate in the absence and presence of poly-（styrene-alt-maleic acid） （PSMA） as a crystal growth modifier at room temperature. The as-prepared products were characterized by scanning electron microscopy （SEM）,transmission electron microscopy （TEM）,and X-ray diffraction （XRD）. The influences of experimental parameters on the size and morphology of BaCO3 whiskers were investigated and discussed. It was found that the as-prepared BaCO3 whiskers are single crystals with diameter ranging from 100 to 300?nm,and grow along the crystallographic a-axis or [100] direction. BaCO3 whiskers with different morphologies,such as branching and dendritic structure,can be obtained depending on the experimental conditions. With increasing PSMA concentration,the diameter of BaCO3 whiskers decreases.
Based on the 35# steel, the manufacture of boronized material, structure and composing of the boronized layer under microwave field were studied. Compared with the normal thermal mode, the layer under microwave field ...
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Based on the 35# steel, the manufacture of boronized material, structure and composing of the boronized layer under microwave field were studied. Compared with the normal thermal mode, the layer under microwave field has differences in forming, structure and so on, besides, it is much more thicker in the same condition. The layer's fast formation dues to the boracic atom's fast diffusion.
Samples of LiNi0.95-xCoxAl0.05O2（x=0.10 and 0.15） and LiNiO2,synthesized by the solid-state reaction at 725?℃ for 24?h from LiOH·H2O,Ni2O3,Co2O3,and Al（OH）3 under an oxygen stream,were characterized by TG-DT...
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Samples of LiNi0.95-xCoxAl0.05O2（x=0.10 and 0.15） and LiNiO2,synthesized by the solid-state reaction at 725?℃ for 24?h from LiOH·H2O,Ni2O3,Co2O3,and Al（OH）3 under an oxygen stream,were characterized by TG-DTA,XRD,SEM,and electrochemical tests. Simultaneous doping of cobalt and aluminum at the Ni-site in LiNiO2 was tried to improve the cathode performance for lithium-ion batteries. The results showed that co-doping （especially,5% Al and 10% Co in atomic fraction） definitely had a large beneficial effect in increasing the capacity （186.2?mA·h/g of the first discharge capacity for LiNi 0.85 Co 0.1 0Al 0.05 O2） and cycling behavior (180.1?mA·h/g after 10 cycles for LiNi0.95-xCoxAl0.05O2) compared with 180.7?mA·h/g of the first discharge capacity and 157.7?mA·h/g of the tenth discharge capacity for LiNiO2,respectively. Differential capacity versus voltage curves showed that the co-doped LiNi0.95-xCoxAl0.05O2 had less intensity of the phase transitions than the pristine LiNiO2.
Al2O3/WC-10Co/ZrO2 cermets were prepared by a hot-pressing process by using WC-10Co nanocomposite powder, Y2O3 stabilized nanocrystalline ZrO2 powder and submicron Al2O3 powder. The influences of sintering temperature...
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Al2O3/WC-10Co/ZrO2 cermets were prepared by a hot-pressing process by using WC-10Co nanocomposite powder, Y2O3 stabilized nanocrystalline ZrO2 powder and submicron Al2O3 powder. The influences of sintering temperature on the microstructure, grain size and properties were investigated according to the density, fracture toughness, Rockwell A hardness (HRA), hysteresis loops and scanning electron microscopy (SEM) micrographs of fractured surfaces of the specimens. The results show that the composite powders (WC-10Co(50%)/Al2O3(40%)/ZrO2(10%)) after being high-energy ball-milled for 48 h was hot-pressing sintered at 1450°C, then submicron Al2O3/WC-10Co/ZrO2 cermets with an average grain size of less than 1 μm and better properties of 97.5% in relative density, 7.4468 MPa·m1/2 in fracture toughness, HRA 94.0 is achieved.
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