Fe-based bulk metallic glasses (BMGs) with high boron content have potential application as a coating material used in the framework for storing spent nuclear fuels to support their safe long-term disposal. The high glass forming ability (GFA) and large supercooled liquid region are therefore required for such Fe-based BMGs in either the glassy powder fabrication or the subsequent coating spraying. In order to meet these requirements, the influence of Nb content on the GFA of Fe57Cr10Zr8B18Mo7−xNbx (x=1–5, at.%) alloys was investigated, as Nb has positive roles in GFA and thermal stability of BMGs. The results indicate that a fully amorphous phase in the as-cast samples with 3 mm in diameter is obtained for both the Fe57Cr10Zr8B18Mo5Nb2 and Fe57Cr10Zr8B18Mo4Nb3 alloys. The corresponding supercooled liquid regions of the two BMGs are 78 K and 71 K, respectively. The mechanism for improving their GFA was analyzed based on the principle of metal solidification, the parameters for glass formation and thermal properties of the alloys. The compression strength and Vicker’s hardness of the two BMGs are 1,950 MPa and 1,310 HV, 2,062 MPa and 1,180 HV, respectively. The developed BMGs with high B content, good GFA, and very high hardness can be used as coating materials to the framework for spent nuclear fuels.
Graphene-based materials have attracted significant attention in many technological fields, but scaling up graphene-based technologies still faces substantial challenges. High-throughput top-down methods generally require hazardous, toxic, and high-boiling-point solvents. Here, an efficient and inexpensive strategy is proposed to produce graphene dispersions by liquid-phase exfoliation (LPE) through a combination of shear-mixing (SM) and tip sonication (TS) techniques, yielding highly concentrated graphene inks compatible with spray coating. The quality of graphene flakes (e.g., lateral size and thickness) and their concentration in the dispersions are compared using different spectroscopic and microscopy techniques. Several approaches (individual SM and TS, and their combination) are tested in three solvents (N-methyl-2-pyrrolidone, dimethylformamide, and cyrene). Interestingly, the combination of SM and TS in cyrene yields high-quality graphene dispersions, overcoming the environmental issues linked to the other two solvents. Starting from the cyrene dispersion, a graphene-based ink is prepared to spray-coat flexible electrodes and assemble a touch screen prototype. The electrodes feature a low sheet resistance (290 Ω □−1) and high optical transmittance (78%), which provide the prototype with a high signal-to-noise ratio (14 dB) and multi-touch functionality (up to four simultaneous touches). These results illustrate a potential pathway toward the integration of LPE-graphene in commercial flexible electronics. 相似文献
With the blossom of information industry, electromagnetic wave technology shows increasingly potential in many fields. Nevertheless, the trouble caused by electromagnetic waves has also drawn extensive attention. For instance, electromagnetic pollution can threaten information safety in vital fields and the normal function of delicate electronic devices. Consequently, electromagnetic pollution and interference become an urgent issue that needs to be addressed. Carbon nanotubes (CNTs) have become a potential candidate to deal with these problems due to many advantages, such as high dielectric loss, remarkable thermodynamic stability, and low density. With the appearance of climbing demands, however, the carbon nanotubes combining various composites have shown greater prospects than the single CNTs in microwave absorbing materials. In this short review, recent advances in CNTs-based microwave absorbing materials were comprehensively discussed. Typically, we introduced the electromagnetic wave absorption mechanism of CNTs-based microwave absorbing materials and generalized the development of CNTs-based microwave absorbers, including CNTs-based magnetic metal composites, CNTs-based ferrite composites, and CNTs-based polymer composites. Ultimately, the growing trend and bottleneck of CNTs-based composites for microwave absorption were analyzed to provide some available ideas to more scientific workers. 相似文献
The influence of applied magnetic field during annealing process as well as of Mg doping on the room-temperature magnetoelectric coupling effects in BaSrCo2-xMgxFe11AlO22 are experimentally studied through the magnetization, magnetodielectric, and magnetoelectric current measurements. Hexaferrite samples of Co2Y were found to be highly oriented by an applied magnetic field (Ho) during the annealing process, leading to an enhancement of the room-temperature magnetoelectric coupling effects. Although the substitution of nonmagnetic Mg ions in Co sites tends to reduce the ferromagnetism at macroscopic scale, a proper amount of Mg doping content facilitates the superexchange interaction between the adjacent magnetic blocks; meanwhile modulates the magnetic anisotropy in the samples. An appropriate adjustment of the competition between the anisotropy and the superexchange could enhance the magnetoelectric coupling at room temperature, which can be confirmed by the magnetic-field-induced dielectric constant and current density study. 相似文献
In order to obtain casein edible films with great packing performance, gelatin as the reinforcing additive with different ratios were loaded via two methods including layer- by- layer and blending. A comparative study on structure properties between double layers and blending films made from casein and gelatin was obtained by scanning electron microscopy and Fourier transform infrared spectroscopy. The difference between the films' packing characters were conducted by water vapor permeability (WVP), optical property, and mechanical properties (including tensile strength (TS) and elongation (EAB)). The results showed that the degree of films roughness increased and the structural stability decreased as the increase of gelatin additive ratio in both double layers and blending films. Thickness and WVP both displayed a trend of increasing first then decreasing at the dividing of gelatin instead of casein in 50%. Importantly, WVP values in double layers film with a largest value of 6.95 gm−1Pa−1s−1 was higher than blending films, observably (P < 0.05). Additionally, TS in blending film was increased by 23.44% than double layers film under the gelatin additive proportion of 70%, and EAB value in double layers film was larger by 207.65% than blending film under the gelatin additive proportion of 10%. 相似文献
In this study, we report the three-point flexural strength and fracture toughness of monolithic hafnium carbide up to 2000 °C. HfC with different grain sizes was consolidated using the spark plasma sintering method. Coarse-grained monoliths showed a weak dependence on the strain rate during high-temperature tests at 1600 °C–2000 °C. In contrast, results for the ceramics with a grain size below 20 μm indicated a positive dependence of the yield strength vs strain rate. This allowed us to identify the activation energy for high-temperature deformation in flexure as 370 kJ/mol. This level of activation energy is in satisfactory agreement with reports about the diffusion of C in hafnium carbide. 相似文献