Journal of Powder Materials

Research Articles

Effect of TiO₂ Content on High-Temperature Degradation Behavior of Nd₂O₃ and Yb₂O₃ Doped YSZ Composite Materials: Gye-Won Lee, Seonung Choi, Tae-jun Park, Jong-il Kim, In-hwan Lee, Yoon-seok Oh; J Powder Mater. 2024;31(5):431-436. Published online October 31, 2024; DOI: https://doi.org/10.4150/jpm.2024.00269

Abstract PDF: Hot section components of gas turbines are exposed to a high operating temperature environment. To protect these components, thermal barrier coatings (TBC) are applied to their surfaces. Yttria-stabilized zirconia (YSZ), which is widely used as a TBC material, faces limitations at temperatures above 1200℃. To mitigate these issues, research has focused on adding lanthanide rare earth oxides and tetravalent oxides to prevent the phase-transformation of the monoclinic phase in zirconia. This study investigated the effects of varying TiO2 content in Nd2O3 and Yb2O3 co-doped YSZ composites. Increasing TiO2 content effectively suppressed formation of the monoclinic phase and increased the thermal degradation resistance compared to YSZ in environments over 1200℃. These findings will aid in developing more thermally stable and efficient TBC materials for application in high-temperature environments.

Inter-laminar Strength of NITE-SiC/SiC Composites With Various Fiber Reinforcing Architecture: Jong-il Kim; J Powder Mater. 2024;31(5):437-444. Published online October 31, 2024; DOI: https://doi.org/10.4150/jpm.2024.00248

Abstract PDF: The mechanical performance of SiC/SiC composites is significantly influenced by the architecture of fiber reinforcement. Among the various fabrication methods, the nano-powder infiltration transition/eutectic (NITE) process is a promising technique that is capable of achieving a dense and stoichiometric SiC matrix. The reinforcement architecture, such as cross-ply (CP) or woven prepreg (WP), is determined during the preform stage of the NITE process, which is crucial in determining the mechanical properties of SiC/SiC composites. In this study, the tensile test and double notch shear (DNS) test were conducted using NITE-SiC/SiC composites to investigate the effect of the fiber reinforcing architecture on the fracture mechanism of SiC/SiC composites. The tensile strength and maximum shear strength of both CP and WP specimens were nearly identical. However, other mechanical properties, particularly those of CP specimens, exhibited significant variability. A comparison of fracture surfaces and load-displacement curve analyses from the DNS tests revealed that the cross points of the longitudinal or transverse fibers act as obstacles to both deformation and crack propagation. These obstacles were found to be more densely distributed in WP specimens than in CP specimens. The variability observed in the mechanical properties of CP specimens is likely due to size effects caused by the sparser distribution of these obstacles compared to the WP specimens.

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