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Duhamel Cécilie Caballero Jacqueline Couvant Thierry Crépin Jérôme Gaslain Fabrice Guerre Catherine Le Hong-Thaï Wehbi Mickaël 《Oxidation of Metals》2017,88(3-4):447-457
Oxidation of Metals - The present work focuses on the intergranular oxidation of Alloy 600 and its weld material Alloy 82 after exposure in simulated primary water at 340–360 °C... 相似文献
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Zeolite Beta particles with size of 0.1, 0.5 and 1 μm were employed as molds for the synthesis of microporous carbon. After infiltration and pyrolysis of propylene at 800 °C for 2 h, zeolite/carbon composites were obtained and further subjected to acid extraction of the zeolite precursor. The initial zeolite samples, zeolite/carbon composites and carbon replicas were studied by XRD, TG analysis, SEM/TEM, DLS, N2 adsorption measurements and chemical analysis. The experimental data revealed that the carbon replicas faithfully replicate the zeolite morphology and possess higher micropore volume than that of the parent zeolite molds. The use of zeolite molds of different sizes resulted in carbons with fairly different pore structure. Thus, larger (0.5 and 1 μm) zeolite crystals provided replicas with a pore structure possessing mainly micropores, whereas the carbon replication of 0.1 μm zeolite aggregates built of much smaller crystallites resulted in a material with lower micropore volume and substantial contribution of mesopores to the total pore volume. The different pore structure of the latter carbon was found to be a result of the larger external surface area of the nanosized mold, loss of crystallinity during the preparation procedure and the presence of interparticles porosity. 相似文献
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P. E. Leger M. Sennour F. Delloro F. Borit A. Debray F. Gaslain M. Jeandin M. Ducos 《Journal of Thermal Spray Technology》2017,26(7):1445-1460
Aluminum (Al) powders with spherical and irregular particle shapes were mixed with two alumina (Al2O3) powders with either a spherical or an angular particle shape to achieve high-performance cold-sprayed coatings onto steel. Two effects of the aluminum particle shape were observed. First, coating microstructure observation showed impinging heterogeneity depending on particle shape. Second, particle jet differences depending on particle morphology were shown by velocity maps. From the latter, SEM and XRD, three effects of the alumina particle shape were also shown, i.e., higher in-flight velocity of angular particles, fragmentation of spherical hollow particles and embedding of alumina particles with aluminum. Numerical simulation of particle impacts was developed to study the densification of Al coating due to Al2O3 addition through elucidation of Al-Al2O3 interaction behavior at the scale of the coating. Al/Al and Al/Al2O3 interfaces were investigated using TEM to understand coating strengthening effects due to alumina addition at the scale of the particle. As a whole, Al and Al2O3 particle shape effects were claimed to explain coating mechanical properties, e.g., microhardness and coating–substrate bond strength. This study resulted in specifying criteria to help cold spray users in selecting powders for their applications, to meet economic and technical requirements. 相似文献
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