The process of the decrease of the surface area due to crystallite growth in ceria at 943 K is described by a kinetic model involving oxygen and cerium diffusion. The experimentally found variations in the rate of crystallite growth are reported as a function of the content ( 10% cat.) of dopants, which are the cations Ca2+, Mg2+, Al3+, Y3+, Sc3+, ...
Kinetic of grain in a BaTiO3 powder was studied at 850°C in a various gaseous atmosperes and for different Ba/Ti ratios. The decrease in surface area from about 8m²/g to 2m²/g waas used to obtain the experimental rate of grain growth versus the partial pressure of water vapour (wich was found to accelerate the process) and versus the Ba/Ti ratio. A...
Le but de cette étude est de comprendre la transformation thermique d'un polysilazane en carbonitrure de silicium afin de maitriser la composition de la fibre céramique dont il est le précurseur. Les deux phénomènes qu'il convient d'éviter dans l'élaboration de telles fibres sont l'oxydation et la cristallisation qui provoque la perte totale de rés...
An equation for the decrease of stabilizer content in propellants is given, which describes the measured consumption of stabilizers such as diphenylamine, 2-nitrodiphenylamine, acardite II and ethylcentralite very well. The equation was obtained with a kinetic formulation for the stabilizer depletion, which combines the reactions of first and zero ...
To predict the safe operational service life (safe use time) and the safe service life in storage (safe storage time) of gun propellants (GP) and rocket propellants (RP) the consumption of stabilizer is often used. For this the measured data must be described with a kinetic model. Frequently an exponential decrease of the stabilizer content is take...
Gun propellants ana double base rocket propellant were tested to find out stabilizer consumption and molar mass degradation between 60 degree Celsius and 90 degree Celsius, in part between 40 degree Celsius and 110 degree Celsius. The stabilizer content was measured by reversed-phase high performance liquid chromatography (HPLC) with UV-detection, ...
Diagnostic and growth experiments were performed in a multi-filament CVD reactor using forced convection for the feed gas supply in order to investigate kinetic and gas dynamic effects during diamond deposition. An insight in these effects seems to be a prerequisite for large-area deposition of diamond by hot-filament CVD. Conditions of forced conv...
Chemical, thermal and mechanical stability are important parts in the quality and safety assessment of propellants and explosives. Decomposition reactions limit the safe use time, the socalled lifetime. With explosives consisting of nitric acid esters, stabilizer consumption and molar mass (molecular weight) decrease are very suitable methods to pr...
Vier zweibasige Raketenfesttreibstoffe und ein einbasi Treibladungspulver wurden hinsichtlich Stabilisatorver Molmassenabbau und Wärmeentwicklung zwischen 50 Grad C C, bzw. 40 Grad C und 110 Grad C untersucht. Die Stabi wurde mit der Hochleistungsflüssigkeitschromatographie Molmassenabnahme mit der Gelpermeationschromatographie Wärmeentwicklung mit...
Published in Journal of the experimental analysis of behavior
Transition-state choice behavior of pigeons was examined in two experiments designed to test predictions of melioration and the kinetic model. Both experiments began with an initial training condition during which subjects were maintained on concurrent variable-interval schedules. In Experiment 1, subjects were then exposed to concurrent variable-r...
