Thermodynamic and experimental study of TiAgCu alloys

Cours : Istanbul, carrefour diplomatique : l’établissement des ambassades permanentes européennes La pénétration ottomane en Europe, à partir du milieu du xive siècle, s’accompagne, bien entendu, de relations de guerre avec les États chrétiens européens, mais aussi de relations qu’on peut qualifier de diplomatiques. Elles sont naturellement amenées par les limites des capacités militaires du conquérant, aux prises avec des adversaires qui ne sont pas inertes, qui nouent entre eux (ainsi d’ail..

Force measurements during posterior calvarial vault osteodistraction : A novel measurement method

Posterior calvarial vault osteodistraction (PCVO) has become increasingly popular in the correction of craniosynostosis. When compared to cranioplasty, PCVO offers a shorter, less invasive operation, greater intracranial volume advancement and a lower rate of relapse. In general, distraction protocols are based primarily on clinical observations rather than systematic research. Faster distraction protocols may reduce complications. However, distraction protocols producing higher forces can increase complications. Thus, we need to understand these forces in order to improve distraction protocols and devices. We developed a force measurement method that can be used on PCVO devices. Here, we present preliminary data about the forces developed during PCVO. We measured the forces in four bicoronal craniosynostosis patients during PCVO. We observed a linear-like trend between the force increase and the distraction distance within distraction sessions. We also observed a step-wise force increase between distraction sessions and found that the distraction force relaxed rapidly shortly after the distraction session. The mean maximum pre distraction force for one distracter was 20.4 N, while the mean maximum end-distraction force for one distracter was 57.6 N. Our data suggests that current treatment protocols might be re-evaluated favouring shorter distraction distances and more frequent distraction sessions. (C) 2017 European Association for Cranio-Maxillo-Facial Surgery. Published by Elsevier Ltd. All rights reserved.Peer reviewe

Sociophonetic variation in a long-term language contact situation: /l/-darkening in Welsh-English bilingual speech

This study investigates /l/-darkening in the Welsh and English speech of bilinguals in North Wales. Although it is claimed that /l/ is dark in all syllable positions in northern varieties of both languages, there have been no quantitative investigations of this feature which consider cross-linguistic phonetic differences, the differing nature of language contact between North East and North West Wales, and differences in the way both languages are acquired by speakers. The dataset of 32 Welsh-English bilinguals, aged 16-18, was stratified by speaker sex, home language, and area. Tokens of /l/ in word-initial onset and word-final coda positions were analysed acoustically. The results show cross-linguistic differences in onset position and that such differences were found to be greater in the speech of female participants and those from North West Wales. Differences were also found between Welsh-dominant and English-dominant communities. These results are discussed with reference to the influence of extra-linguistic factors on speech production and the possible social meaning associated with dark /l/

Stability and formation kinetics of TiN and silicides in the Ti/Si3N4 diffusion couple

Reactions in Ti/Si3N4 and TiN/Si diffusion couples annealed in the temperature range of 1000-1200°C were studied theoretically as well as experimentally with SEM/EPMA technique. Isothermal sections of the Ti-Si-N system were calculated using the most recent thermodynamic data. Calculations showed that TiN and Si react with each other and form Si3N4 and TiSi2, parallel to the experimental studies. Correspondingly, results from the Ti/Si3N4 couple were in good accordance with calculated phase equilibria

On the Metallurgy of Active Brazing

Advanced ceramics like silicon nitride are increasingly used as structural components in demanding high temperature applications as well as in electronics industry. Complex, multicomponent structures for engineering applications generally. The interfacial microstructures formed when Si3N4 is brazed with Ag-Cu-Ti braze alloys have been discussed in several recent studies. In order to resolve which chemical reactions are possible under various joining conditions and thereby to be able to control the brazing of Si3N4 the reactions in brazing has to be studied using both microstructural and thermodynamics. In this work the earlier determined ternary Ti-Ag-Cu and Ti-Is-N systems have been applied to the brazing of silicon nitride with AgCuTi alloys. Using direct brazing experiments at various temperatures and thermodynamic analyses performed by combining the most recent available thermodynamic data and experimental information the chemical reactions controlling the brazing process are determined and a description of the am is presented. It is shown that the miscibility gap found in the ternary Ti-Ag-Cu system exists during brazing and divides the liquid braze into Ag-rich (Ll) and Ti- and Cu-rich (L2) liquid. The liquid L2 segregates at the ceramic interface and reacts with the silicoa quaternary Ti-Si-Cu-N compound

Stability and formation kinetics of TiN and silicides in the Ti/Si3N4 diffusion couple

Reactions in Ti/Si3N4 and TiN/Si diffusion couples annealed in the temperature range of 1000-1200°C were studied theoretically as well as experimentally with SEM/EPMA technique. Isothermal sections of the Ti-Si-N system were calculated using the most recent thermodynamic data. Calculations showed that TiN and Si react with each other and form Si3N4 and TiSi2, parallel to the experimental studies. Correspondingly, results from the Ti/Si3N4 couple were in good accordance with calculated phase equilibria