Effect of Enhanced Grain Refinement in Friction Welded SUS316L Alloy

To investigate the solid state weldability on SUS316L alloy, this work was carried out. Friction welding as a solid state welding was introduced and conducted at a rotation speed of 2,000 rpm and a friction pressure of 25 MPa on tube typed specimens. After this work, the grain boundary characteristic distributions such a grain size, shape and misorientation angle of the welds were clarified by electron backscattering diffraction method. The application of friction welding on SUS316L resulted in a significant refinement of the grain size in the weld zone (6.03 μm) compared to that of the base material (57.55 μm). Despite the grain refinement, the mechanical properties of the welds indicate relatively low or similar to the base material. These mechanical properties are due to dislocation density in the initial material and grain refinement in the welds

Soft luminescent solar concentrator film with organic dye and rubbery matrix

We propose a soft luminescent solar concentrator (LSC) with superior light propagation. The rubbery poly(ethylene-co-vinyl acetate) (EVA) was adopted to replace the conventional brittle poly(methyl methacrylate) (PMMA). We analyzed the transmittance, photoluminescence efficiency, crystallinity, and surface properties of LSC to understand the optical and structural properties of the LSC. In addition, we modified the optical slab model to provide insights into the optical phenomenon in plate-type LSC devices; we evaluated the solar absorption efficiency of the glass and emitting layers. We also evaluated the solar concentration performances of the LSC devices by measuring the photocurrent density generated using a monocrystalline silicon solar cell. We compared the transporting ability of emitted light into an edge by calculating the collection efficiency based on the concentration factor and optical efficiencies (absorption and photoluminescence). The concentration factor, optical efficiency, and collection efficiency of the EVA-LSC with 4000 ppm of Lumogen F Red 305 were 0.31, 3.1, and 40%, respectively. The overall optical properties of the EVA-LSC were comparable to those of the PMMA-LSC. Moreover, the light decay property of EVA-LSC was superior by 1.2 times than PMMA-LSC. Therefore, we suggest EVA can replace PMMA and be used for flexible and large-area LSC applications