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Microstructure, properties and oxidation behavior of the glass-ceramic basedcoating on near-α titanium alloy
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Thermal cycling of Crofer22APU-sealant-anode supported electrolyte joined structures for planar SOFCs up to 3000 h
No full textThermal cyclic tests in air were performed for Crofer22APU/glass-ceramic/Anode-Supported-Electrolyte (ASE) joined samples for a total period of 3000 hours. Different cooling rates from the SOFC operating temperature of 800°C to room temperature were carried out. Large and elongated voids were observed to develop just below the Cr2O3/Cr-Mn spinel layer of the Crofer22APU. Diffusion of Al to the areas just below the protective oxide layer led to formation of Al2O3 on the surface of the voids. The emergence of CaAl2Si2O8 as a new phase in the glass-ceramic was attributed to the diffusion of Ca away from the interfacial areas thus decreasing the proportion of Ca to Al and Si. The glass-ceramic sealant maintained good adherence with the Crofer22APU and the ASE without presence of any crack even after 3000hrs of exposure
Microstructure characterisation of erosion resistant coatings on carbon bonded carbon fibre composites
No full textMicrostructure and properties characterization of the double layered glass-ceramic coating onnear-α titanium alloy
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Microstructure, mechanical properties and oxidation behavior of the TiAl(Si,Ag) coating on near-α titanium alloy
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Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
He-irradiation effects on glass-ceramics for joining of SiC-based materials
No full textCaO-Al2O3 (CA) and SiO2-Al2O3-Y2O3 (SAY) glass-ceramics are promising candidates for SiC/SiC indirect joints. In view of their use in locations where high radiation level is expected (i.e. fusion plants) it is important to investigate how radiation-induced damage can modify the material microstructure. To this aim, pellets of both types were irradiated with 5.5 MeV 4He+ ions at an average temperature of 75 °C up to a fluence of almost 2.3x10^18 cm^ -2. This produces a displacement defect density that increases with depth and reaches a value of about 40 displacements per atom in the ion implantation region, where the He-gas reaches a concentration of several thousands of atomic parts per million. X-ray diffractometry and scanning electron microscopy showed no change in the microstructure and in the morphology of the pellet surface. Moreover, a transmission electron microscopy investigation on cross-section lamellas revealed the occurrence of structural defects and agglomerates of He-bubbles in the implantation region for the CA sample and a more homogeneous He-bubble distribution in the SAY pellet, even outside the implantation layer. In addition, no amorphization was found in both samples, even in correspondence to the He implantation zone. The radiation damage induced only occasional micro-cracks, mainly located at grain boundaries (CA) or within the grains (SAY
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