13 research outputs found
Real-time monitoring of the silicidation process of tungsten filaments at high temperature used as catalysers for silane decomposition
The scope of this work is the systematic study of the silicidation process affecting tungsten filaments at high temperature (1900ºC) used for silane decomposition in the hot-wire chemical vapour deposition technique (HWCVD). The correlation between the electrical resistance evolution of the filaments, Rfil(t), and the different stages of the their silicidation process is exposed. Said stages correspond to: the rapid formation of two WSi2 fronts at the cold ends of the filaments and their further propagation towards the middle of the filaments; and, regarding the hot central portion of the filaments: a initial stage of silicon dissolution into the tungsten bulk, with a random duration for as-manufactured filaments, followed by the inhomogeneous nucleation of W5Si3 (which is later replaced by WSi2) and its further growth towards the filaments core. An electrical model is used to obtain real-time information about the current status of the filaments silicidation process by simply monitoring their Rfil(t) evolution during the HWCVD process. It is shown that implementing an annealing pre-treatment to the filaments leads to a clearly repetitive trend in the monitored Rfil(t) signatures. The influence of hydrogen dilution of silane on the filaments silicidation process is also discussed
Characterisation of Advanced and Free-Machining Titanium Alloys by Synchrotron Radiation
Mensch-Technik-Kooperation und Fahrzeuginnenraum
Kraftfahrzeuge ermöglichen unserer Gesellschaft Mobilität. Mit ihrer Hilfe können Menschen und Güter von einem Ursprungs- zu einem Zielort bewegt und menschliche Bedürfnisse z. B. nach Nahrung, Anerkennung und Selbstverwirklichung gestillt werden. Erreicht werden kann dieses Stillen von Bedürfnissen aber nur durch eine enge Kooperation zwischen Menschen (innerhalb und außerhalb der Fahrzeuge) sowie dem technischen System. So wirken zum Beispiel Fahrende mit Hilfe von Bedienhandlungen zur Längs- und Quersteuerung (d. h. Beschleunigen/Bremsen, Richtungswechsel) auf das Kraftfahrzeug ein