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Glass Fiber Reinforced Polymer (GFRP) is widely used as aerospace material requiring high specific strength, specific stiffness, and excellent mechanical and chemical properties. To apply the already approved composite materials to other processes, an equivalency test that compares the mechanical properties of the composite materials based on the database is required. For the successful completion of the equivalency test, it is important to control the factors affecting the mechanical properties. The resin content and density of the specimens are manufactured differently according to the process. The effect of these factors on the change of mechanical properties required for equivalency qualification has not been sufficiently reported. In this study, an equivalency test was performed on the GFRP applied to the aircraft radome based on the procedure of the equivalency test and acceptance test proposed by the National Center for Advanced Materials Performance. The causes of problems occurring between equivalency tests were analyzed. It was confirmed that the resin content, density, and voids of the specimen affect the mechanical properties. As the resin content decreases, the density and voids were controlled, and it was confirmed that the average strength and modulus increase by 13.12 and 6.78%, respectively. The equivalency qualification was completed by applying an improved process in which these factors were controlled.

The study aimed to investigate the impact of oxygen vacancies on the reliability of perovskite-structured ceramics. In particular, the focus was on anti-ferroelectric (PbLa)(ZrTi)O3, commonly known as PLZT, which exhibits excellent DC-bias characteristics, making it a promising material for high-power capacitors. To address the issue of oxygen vacancies, Dy3+ was introduced as a donor by substituting it into (Pb0.82La0.12)(Zr0.86Ti0.14)O3. As the substitution of Dy3+ increased, there was a decrease in the dielectric constant. However, this was accompanied by an increase in both breakdown voltage and reliability characteristics. [ABSTRACT FROM AUTHOR]

Composite specimens with resin contents of 33.5%, 35.4%, and 35.9%, respectively, were manufactured by controlling the type of subsidiary material used in the bagging process for a composite material having the same composition. The effect of controlling the resin content on the microstructure and mechanical properties of composite specimens was investigated. The flow of resin and air during the cure process was inferred and explained by connecting it with the microstructure. Specifically, the behavior of the resin determined the thickness, density, and void of the composite laminate, which acted as a factor causing the difference in mechanical properties of the composite materials. As the resin content increased, there was no significant difference in tensile strength, but Young's modulus decreased. In the case of the compression test, there was a difference in mechanical properties due to the combined effect of the reinforcement and the resin. The maximum compressive strength value was shown in the process with low void content, and Young's modulus tended to decrease as the resin content increased. In the bagging process, the subsidiary material controlled the flow of resin and air, and caused a difference in microstructure, affecting the change of mechanical properties. [ABSTRACT FROM AUTHOR]

It is necessary to develop a low‐loss dielectric material based on the low‐temperature co‐fired ceramic (LTCC) process, which is essential for expanding 5G service. LTCC is designed by mixing SiO2 and glass to secure low dielectric constant. The density, porosity, and average diameter of pores of the sintered specimen are analyzed and evaluated to confirm the change in sintering behavior according to the mixing composition ratio of SiO2 and glass and the heating rate. When the ratio of the mixed filler is 35 vol%, the density is the highest at 2.30 g cm−3, the porosity is the lowest at 4.59%, and the diameter of the pores is also the smallest at about 5.80 μm. Therefore, it is selected as the optimal mixing ratio. When the heating rate is used as a variable, the density is high in 1, 3, and 5 °C min−1, and the porosity and pore diameter are small. However, it is confirmed that as the heating rate increases, the density gradually decreases, while the porosity as well as pore diameter increases. As a result of analyzing the sample under the optimal conditions, the dielectric constant 3.64 and loss 0.01 are shown in 30 GHz. [ABSTRACT FROM AUTHOR]

(Pb, La)(Zr, Ti)O3 (PLZT) with antiferroelectric properties can be applied as a capacitor whose capacitance increases in a high electric field. From this, we obtained a high sintering density at 950 °C by adding low-temperature sintering additives, 8.0 wt% of PbO and 2.5 wt% of ZnO, simultaneously to a (Pb0.88, La0.12)(Zr0.86, Ti0.14)O3 composition. The change in electrical characteristics was confirmed in terms of Sn4+ substitution, resulting in no change in the sintering density by Sn4+ substitution. However, as the amount of Sn4+ substitution increases, the dielectric constant gradually decreases from 1300 to 700, and the grain size decreases from about 4 to 1 µm in terms of microstructure. In the crystal structure analysis, the general formation of a single perovskite structure was confirmed. The results of the hysteresis curve measurement revealed that the breakdown electric field increases from 4 to 9 kV·mm−1 as the amount of Sn4+ substitution gradually increases. However, polarization decreases in the same way as the permittivity trend. The composition exhibits excellent electrical properties when the ratio of Sn4+ is 0.4: a high energy storage density of 3.5 J·cm−3, energy efficiency of 80%, and breakdown electric field of about 8.5 kV·mm−1. [ABSTRACT FROM AUTHOR]

Three types of In2O3 nanoparticles decorated with Au, Pd and Pt nanoparticles, respectively, were synthesized by thermal decomposition method, and the effects of metal nanoparticles on their phase, microstructure, chemical state, carrier types were investigated with XRD, SEM/TEM, and XPS. Additionally, sensing properties to CO gas, such as sensitivity, etc., were examined with sensing apparatus. Au-decorated In2O3 nanoparticles exhibited the highest sensitivity to CO gas, with S = 5.59 at a 10 ppm CO gas concentration at 50 °C compared to Pd or Pt-decorated In2O3 nanoparticles. This can be interpreted as a much higher adsorption of oxygen molecules on the In2O3 surface due to the high oxygen vacancies in the In2O3 lattice, which generates an electron depletion region in the outer layer of In2O3 to sharply increase the resistance or the spill-over effect due to Au nanoparticles on In2O3. Au nanoparticles were observed in the TEM images and confirmed by XPS analysis. [ABSTRACT FROM AUTHOR]