Thesis - Oztek_Muzaffer_T_200508_MA

V∆P m .
.
H ∆n AWt AWt
% H = =− =− RT
m s m s m s
where m H = mass of hydrogen
m s
∆n
AWt
V
∆P
R
T
= mass of sample
= change in number of moles of hydrogen
= atomic weight of hydrogen atom
= volume of sample cell
= change in pressure
= gas constant
= temperature
3.1.1. Mg 2 Ni
The Mg 2 Ni alloy was ball milled and a sample weighing approximately 110 mg
was loaded in the DSC and heated up to 250 ºC under 3.7 atm of H 2 . The thermogram
and the percent hydrogen and pressure curves for the initial hydriding step are given in
Figures 9 and 10, respectively. In the thermogram, two exothermic events were observed,
of which only the first one is accompanied by a pressure drop. The first peak indicated
uptake of hydrogen by the alloy at an onset temperature of 148 ºC. The amount of
hydrogen absorbed was slightly less than 3%. The smaller peak observed during cool
down was due to some phase change that did not involve absorption or release of gas.
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