1,720,965 research outputs found
Feasibility tests for an internal combustion engine valve prepared with a Ti-47Al-2Nb-2Cr-1B intermetallic alloy
No full textTransformation toughening of Zirconia ceramics for biomedical application - a computational model
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A critical analysis of fracture toughness determination methods in glass or glass-ceramic matrix composites
No full textThe production of glass or glass-ceramic matrix composites is a promising method to obtain, from a brittle and flaw sensitive material, significant fracture toughness improvements. Fracture propagation in glass is modified by the presence of a secondary phase, which could be ceramic or metallic, particulate or fibrous. Fracture toughness becomes the fundamental property to be investigated, and an exact determination method is needed. In this work several determination methods are briefly explained, particularly relating to glass matrix composites. Chevron notch beam flexural method appears to be the most accurate and flexible, but experimental conditions are complex. Direct indentation methods appear useful for particulate reinforced glasses, but need a calibration step. Flexural tests on indented specimens appear to be promising, in spite of calibration need, as experimental apparatus is simple and indent-induced cracks are undoubtedly sharp, thus approximating the actual flaws in glasses
Post-hot-pressing and high-temperature bending strength of reaction-bonded Si3N4/MoSi2 and Si3N4/WSi2 composites
No full textJOURNAL AMERICAN CERAMIC SOCIET
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
Ni3Al intermetallic compound as second phase in Al2O3 ceramic composites
No full textSeveral metals have been proposed as second phases in ceramic matrix composites in order to improve their fracture toughness. Unfortunately, the use of metals is limited by low melting temperature, as for Al and Ag, poor oxidation resistance, as for Ni, Mo and W, and decrease of mechanical strength as temperature increases. In these respects, high temperature structural intermetallics show better properties. This work presents the preparation and the characterization of a Ni3Al reinforced-alumina. A ceramic composite containing 10 vol% Ni3Al powder was prepared by hot-pressing at 1350°C for 1.5 h green compacts of the mixture of ceramic and intermetallic powder. Microstuctural features were investigated by scanning electron microscopy (SEM). Elastic modulus, flexural strength and fracture toughness were measured at room and high temperatures and correlated to the micro structural characteristics of the material. A toughening mechanism due to plastic deformation of the intermetallic particles during crack propagation was seen to operate both at room and at high temperature
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
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