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Research on additive manufacturing (AM) is being actively conducted in various fields in order to efficiently manufacture complex three-dimensional structures. In particular, metal powder feedstock and lasers are being used by the manufacturing industry to fabricate mechanical components and parts, such as propellers, fuel nozzles, and vehicle equipment. We developed an approach, scanning- directed energy deposition (S-DED), in which a high-throughput DED method with a scanning nozzle was established that could create metal beads of exceptional quality with high productivity using metal powder. The S-DED nozzle was designed based on a numerical simulation of the particle fluid flow, which was verified through a deposition experiment. Before the simulation, the deposition efficiency and shape of the bead were assumed according to the shape of the nozzle and the distance between the nozzle and the surface of the base material. The optimal inlet supply angle was determined by changing the powder flow inside the nozzle; the optimal number of outlet channels was determined by analyzing the amount of powder deposited by the laser beam irradiated on the base material. It was found that the laser beam improved the productivity by shaping the existing Gaussian beam into an 8 × 3 square flat-top beam. As a result of the simulation, it was proved that the angle of the inlet (that supplied powder to the nozzle) influenced the flow of powder finally captured in the laser beam. Based on the simulation, the angle of inlet was selected as 75°, and the number of outlet and cooling channels was five and three, respectively. A cross section of the specimen was analyzed using a single bead and multiple layers.

A conical form of nano-sized quantum cluster was formed on the surface of p-type crystalline silicon [111] wafer by anode electrochemical etching in HF-based solution. The conical surface is highly effective in absorbing sunlight and transporting photoelectrons to semiconductor material. These are because each cone has a graded band gap with the energy level in the range from 1.1 to 3 eV which can be considered as consisting of quantum dots in different sizes. Since the boron concentration on the surface of each cone gradually decreases from top to bottom, a continuously varying electrical field is created along the cone height. This electric field is forcing photoelectrons generated in the cone to move rapidly to the direction perpendicular to wafer surface. Hence the drift time of photoelectrons can be less than their recombination time within the thin layer close to the bottom of the cone.

Fe2O3 coated plate mica(Fe2O3/mica) for infrared reflectance red pigment was prepared under hydrothermal treatment. Fe2O3 was perfectly coated on mica via the difference of surface charge between Fe2O3 and mica particles at pH 3. Fe2O3/mica was then calcined at 800 oC to stabilize the coated layer on mica. The infrare (IR) reflectance pigments were characterized by X-ray diffraction, FE-SEM, zeta potential, and a UV-Vis-NIR spectrophotometer. In particular, the CIE color coordinate and IR reflectance properties of Fe2O3/mica pigments were investigated in relation to the thickness variation of the Fe2O3 layer coated on mica of various lateral sizes. The isolation-heat red paints containing the pigments were prepared and optimized with a thinner, settling agent, and dispersant. Then, the films were made. The thermal property of isolation-heat on these films was observed through the relationship of the IR reflectance value, which was based on the variation of the Fe2O3 layer’s thickness coated on mica and mica’s lateral size as IR reflectance pigment. With an increase in IR reflectance on these films, the thermal property of isolation-heat was effectively enhanced.