Thesis - Oztek_Muzaffer_T_200508_MA

3.1.3.4. Effect of Milling Time and Ball to Powder Ratio
Two samples of LaNi 5 were milled in the Spex8000 Mixer Mill with a BPR of 1:1
for 10 and 30 minutes, respectively. Each sample was analyzed for hydriding at constant
temperature after a single activation cycle. The% H absorbed by the samples, along with
the results presented in the previous sections, are given in Table 1. The data indicate that
LaNi 5 was best activated with the Spex8000 Mixer Mill with a BPR of 10:1 for 10
minutes.
During ball milling, some of the material was stuck on the milling media. In the
Spex8000M mill with 10:1 ball to powder ratio, the amount of LaNi 5 lost was 30% of the
initial amount. To avoid material loss, samples for larger scale experimentation were
prepared with a lower BPR. BPR and milling time were 1.7:1 and 30 minutes,
respectively. Those samples were also analyzed using the DSC. The DSC analyses
included the activation cycle, followed by the constant temperature hydriding and were
repeated five times. The average percent hydrogen capacity at about 5 atm of H 2 was
calculated to be 0.76%.
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