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Black phosphorus (BP), as a two-dimensional material, has exhibited unique optoelectronic properties due to its anisotropic plasmons. In the present work, we theoretically propose a radiative thermal switch (RTS) composed of BP gratings in the context of near-field radiative heat transfer. The simply mechanical rotation between the gratings enables considerable modulation of radiative heat flux, especially when combined with the use of non-identical parameters, i.e., filling factors and electron densities of BP. Among all the cases including asymmetric BP gratings, symmetric BP gratings, and BP films, we find that the asymmetric BP gratings possess the most excellent switching performance. The optimized switching factors can be as high as 90% with the vacuum separation d=50 nm and higher than 70% even in the far-field regime d=1 µm. The high-performance switching is basically attributed to the rotatable-tunable anisotropic BP plasmons between the asymmetric gratings. Moreover, due to the twisting principle, the RTS can work at a wide range of temperature, which has great advantage over the phase change materials-based RTS. The proposed switching scheme has great significance for the applications in optoelectronic devices and thermal circuits.

Problems with gear shaft formed by cross wedge rolling (CWR), such as slip, disorder of tooth, material deficiency at two sides of the gear, have restricted the application of this craft to form gear shafts. In this paper, numerical simulation on the process of gear shaft formed by cross wedge rolling was carried out with the help of solidworks and deform 3d. Compared with the standard profile, there is margin on the profile of the gear shaft for further process. It’s proved that the traditional methods to make a gear shaft can be replaced by CWR. From curves of force in three directions, it is easy to conclude that radical force and tangential force are the main forces which are exerted on the dies and vary similarly in all stages.