Thesis - Oztek_Muzaffer_T_200508_MA

determined by the start and end of a hydrogen-helium peak pair. The flow rate through
the reactor was monitored with a Fisher Scientific digital flowmeter.
Dehydriding of the hydrided samples was accomplished by heating the reactor
with heating tape up to 150 ºC under argon flow and analyzing the exit stream for
hydrogen using the GC. As soon as no hydrogen was detected in the stream, the heating
system was turned off to allow cool down to room temperature for the subsequent
experiments.
2.2.2.2. Activation procedure
Samples ball milled in stainless steel vials with lower ball to powder ratios and longer
milling times were activated in a high pressure reactor. Approximately 200 grams of
milled alloy were placed in a Pyrex Petri dish that was then transferred into a 2000 mL
capacity Parr Pressure Reactor. Pressure was monitored with one Omega type px303
pressure transducer with a range up to 34 atm. Temperature in the reactor was regulated
by a Love Controls Series 2600 type controller. Pressure and thermal data were acquired
with a Dell GX240 PC using Lab View software through a National Instruments board.
Samples were heated up to 250 ºC under a hydrogen pressure of approximately 20 atm.
After the system reached equilibrium, the heating system was turned off and the system
was allowed to cool under hydrogen pressure. After cooling, the system was vented and
a heating cycle was run to remove absorbed hydrogen.
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