Materials Science Forum Vol. 950

Abstract: Solid Oxide Fuel Cell (SOFC) systems are considered to be the most competitive green energy technology in the future because of their high energy conversion rates, low emissions and multiple fuels available. High temperature heat exchanger plays an important role in the system. The process system requires the design of heat exchangers to achieve operating temperature (700-800 °C), cross-temperature (>500°C) and low pressure drop in the smallest space, which is a challenge to the choice of materials. In this paper, the performances (Tensile strength, yield strength, linear expansion coefficient, and thermal conductivity coefficient) and price of high temperature alloy materials (304H, 310S, incoloy800H and Incoloy625) in the current application environment are compared. The applicable material (310S) of heat exchanger is determined. It provides a material basis for research and development of high temperature heat exchangers in SOFC system and commercialization.

Abstract: It is calculated the effective anisotropic stiffness tensor of the representative volume element in 2.5D woven composites by energy method. The Multi-point constraints are applied to periodic boundary conditions. Compared with the static tensile tests, the validity of present method is verified.

Abstract: Segmented carbon filaments produced by catalytic decomposition of 1,2-dichloroethane over Ni-Mo (8 wt.% Mo) self-organizing catalyst were subjected to functionalization in two different regimes. The structure, textural properties and chemical composition of surface were studied using SEM, Raman spectroscopy, adsorption (BET) and XPS. It was shown that oxidation of carbon nanomaterial in concentrated HNO₃ results in enhancement of O-containing groups concentration (from 2.2 to 6.8 wt.%), increase in specific surface area (from 224 to 280 m²/g) and slight structural disorder of graphitic material (increase of I_D/I_G ratio from 2.15 to 1.84).

Abstract: Lanthanum and zirconium oxides are well known to be applied as an additive to improve the properties of the commercial alumina. Such modified aluminas are widely used in different catalytic fields including three-way catalysis. In the present research we have paid attention to the possible effects of the doping on the catalytic performance and stability of bimetallic Pd-Rh catalysts. The samples were prepared via an incipient wetness impregnation of the commercial supports, tested in CO oxidation under prompt thermal aging regime and characterized by physicochemical methods.

Abstract: In the present work, the impact of the rhodium deposition on the thermal stability of ceria-based catalysts was studied. The samples were prepared by an incipient wetness impregnation of the support with aqueous solution of rhodium nitrate. The loading of Rh was 0.1 and 1 wt.%. The textural characteristics of the samples were examined by a low-temperature nitrogen adsorption. It was shown that the addition of rhodium intensifies the process of ceria agglomeration, which leads to the lower values of specific surface area along with increased average pore diameter after the aging at 1000 °C. Stability of the catalysts was investigated by means of a prompt thermal aging procedure. The high-loaded catalyst (1 wt.% Rh/CeO₂) was more active than the 0.1 wt.% Rh/CeO₂ sample, while the stability of both the catalysts was excellent. It should be emphasized that the alumina-based reference samples with the similar rhodium loading were significantly less active and poorly stable.

Abstract: This research aim to improve the machining properties of the EDM for cemented carbide. The new methods were designed and proposed to use the ultrasonic vibration technique. Two types of USEDM systems were produced. One had a low frequency of 29 kHz with a large vibration amplitude, while the other had a high frequency of 59 kHz with a small amplitude. The Cu-W tool electrode was synchronized with the devised vibration system, and several discharge generation conditions were carried out on the cemented carbide material. The results showed that the highest machining efficiencies were obtained from the ultrasonic low frequency of 29 kHz with a large vibration amplitude. The MRR, TWR and surface roughness of the ultrasonic low frequency with the large vibration amplitude were better than the high frequency system with the small amplitude system. It was clarified that the ultrasonic vibration with the large amplitude could assist the material removal behavior of the discharge.

Abstract: This study presents the dynamic response analyze of a simply supported and isotropic functionally graded (FG) double curved panel under mechanical loading. The aim of the research was to investigate mechanical behavior in a FGM curved panel due to different excitation mode of dynamic loading. The novelty of this research is an investigation of von Mises equivalent stress distribution in double curved panel due to different excitation mode. Computed results are found to agree well with the results reported in the literature. Moreover, influence of volume fraction of the material is studied.