Continuous
polypyrrole (PPy) shells were coated on silicon carbide
(SiC) nanowires to form core–shell nanostructures, and the
thicknesses of the shells were efficiently tuned through controlling
the rate of polymerization. Compared with the composites loaded with
pure SiC nanowires, the values of ε′ and ε″
for the composites loaded with PPy@SiC nanowires were strengthened
remarkably along with the increased thickness of the shells. The electromagnetic
absorption (EA) bandwidths lower than −10 and −20 dB
can be monitored in the area of 3.67–18.00 and 4.13–18.00
GHz, when 5 wt % of PPy@SiC nanowires were loaded in the composite.
Meanwhile, the effective EA bandwidth can reach 6.88 GHz, and the
strongest reflection loss is −58.6 dB.
Controlled cold rolling impacts on microstructure and mechanical properties of the rare earth Ce-modified SAF 2507 super duplex stainless steel (SDSS) are investigated towards a better application and development prospective over the pristine SDSS. Rolling was performed at room temperature with the deformation level in a range of 30% -90%. A large amount of dislocations into the ferrite phase turned out, and their density increased with the deformation. While, emergence of dislocation plugs group, ferrite grains get refined to nanometer scale during the deformation process. In addition to deformed bands within austenite, formation of α′-martensitic phases and significant increment in their volume fraction are detected and attributed to deformation-induced martensitic transformation. Elongation of the ferrite and austenite microstructures along the deformation direction under the action of high strain also resulted in fibers formation gradually. Correspondingly, significant increase in the strength index while decrement in the plasticity index are observed. Moreover, cold rolling deformation not only affects the tensile fracture morphology but also switches it from a typical ductile to a ductile and quasi-cleavage mixed fracture.
High-order Bessel beams are of great interest for most stable long-range optical quantum communications due to their unique nondiffraction, self-healing, and orbital angular-momentum-carrying capabilities. Until now, metasurfaces based on Bessel beam generators are mostly static and focused on generating zero-order Bessel beams. A moiré meta-device made of two cascaded metasurfaces is a simple, effective strategy to dynamically manipulate the wavefront of electromagnetic (EM) waves by mutual rotation between the two metasurfaces. Here, an all-dielectric moiré meta-device integrated with the functions of an axicon and a spiral phase plate to generate terahertz Bessel beams is designed. Not only the order, but also the nondiffraction length of the generated Bessel beam can be continuously tuned. As a proof of concept of the feasibility of the platform, the case of tuning order is experimentally demonstrated. The experimental results are in good agreement with the theoretical expectations. In addition, we also numerically proved that the nondiffraction length of the Bessel beam can be adjusted with the same approach. The moiré meta-device platform is powerful in dynamically manipulating the wavefront of EM waves and provides an effective strategy for continuously controlling the properties of the Bessel beam, which may find applications in optical communications, particle manipulation, and super-resolution imaging.
Stress relief treatments were carried out separately with a pneumatic chipping hammer, ultrasonic peening treatment, and heat treatment for metal active-gas welding (MAG) welded joints of 2205 duplex stainless steel. The effects of these methods on the residual stress, microstructure, mechanical properties and corrosion resistance of welded joints were studied. Results show the stress state of the weld and the surrounding area was effectively improved by the pneumatic chipping hammer and ultrasonic peening treatment, and the residual stress field of the surface layer changed from tensile stress to compressive stress. On the contrary, low-temperature stress relieving annealing had no obvious effect on stress distribution. After the pneumatic chipping hammer and ultrasonic peening treatment, the welded joints were machined and hardened. Correspondingly, strength and hardness were improved. However, the heat treatment only led to a slight decrease in strength and hardness due to the static recovery of the welded joint structure. All stress relief methods effectively improved the corrosion resistance of welded joints, with the ultrasonic peening treatment giving the best performance.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.