Papers by Keyword: Beryllium Oxide

Abstract: Surface modification of Fe2O3 by adding BeO was synthesized and calcined at different temperatures of 200-600 °C. The adsorbents were characterized by using XRD, N2 adsorption-desorption isotherm prior to performing CO2 adsorption and desorption studies. The CO2 adsorption data were analyzed using adsorption isotherm models such as Langmuir, Freundlich, Temkin, and Dubinin-Radushkevich. BeO/Fe2O3-300 that calcined at 300 °C showed the most efficient adsorbent with physisorption and chemisorption were measured at 5.85 and 45.88 mg/g respectively. The CO2 adsorption notably best fitted with Freundlich isotherm with R2 = 0.9897 and calculated adsorption capacity closest to experimental data. This implies the CO2 adsorption process was governed by multilayer adsorption on the heterogeneous surface of the adsorbent. The mean free energy of adsorption (E=3.536 kJ/mol) from Dubinin-Radushkevich and heat of adsorption (bT=3.219 kJ/mol) from the Temkin model support that the adsorption process is physical phenomena.

Abstract: The effect of beryllium hardening has been studied. Beryllium is sintered by method of hot isostatic pressing (HIP), depending on the temperature of powders pressing. The research results of electron microscopic studies were the base for demonstrating formation of the hydraulic phase at the grain boundary of sintered beryllium and influence of the reinforcing phase on the mechanical properties of the HIP blank. The dependence of beryllium precision elastic limit and conventional yield strength from the size of the reinforcing particles of beryllium oxide has been found. The obtained equation provides a description of the “dispersion-grain-boundary" mechanism of isostatic pressed Beryllium hardening.

Abstract: Beryllium and carbon are foreseen as materials for plasma facing components of future fusion devices. Erosion, re-deposition and thermal annealing events arising from heat-loads during reactor operation will produce mixed material layers and compounds on the plasma facing surfaces, leading to changes in the material properties. In order to mimic the erosion/deposition and compound formation processes, carbon layers have been evaporated onto beryllium plates and annealed in the 373 to 1073 K range for 90 min. Ion beam measurements revealed a smooth beryllium and carbon interdiffusion at the samples interface up to 773 K. A carbide formation reaction front became apparent for higher temperatures in scanning electron microscopy observations, with the volume fraction of Be₂C crystals resulting also evident in X-ray diffraction patterns. The annealing route induced delamination of large surface areas of the samples through telephone cords blistering, attributed to strain energy release. At 973 and 1073 K, cracking occurred preferentially along the blisters boundaries and evolved in time, leading to their final removal. This fracture behaviour seems caused by the different thermal expansion coefficients of the phases. The superficial films remain unchanged at lower temperatures. The results prove that the compound formation promotes by itself the occurrence of dust emission events in tokamaks.