Hydrogen Adsorption Isobars and the Effect of Sintering

It is shown in this section with the help of hydrogen sorption isobars on evaporated metal films sintered at various temperatures that the sorption process consists of absorption into the interior of the structure as well as of 

It is obvious that the isobars shown in Fig. 4 cannot be explained by adsorption. In the first place, the difference between the adsorption at —196° as obtained initially and the total sorption found at —196°, after obtaining the isobars, decreases little with increased temperature of sintering. Films sintered at 23° have about ten times the initial adsorption at — 196°C. of films sintered at 200° and about 175 times the 

C Presintered at 400°C. (Although this film was presintered in high vacuum at 400°C. for hour, additional sintering apparently occurred on reheating in the presence of hydrogen. The dotted line indicates the curve to be expected with decreasing temperature if no additional sintering had occurred.) 

In order to study the effect of absorption in the nickel-hydrogen system in more detail, Beeck et al. (11) have investigated the hydrogen sorption isobars between 20°K. and room temperature. As shown in Fig. 6, the solid curves represent the isobars for increasing and decreasing temperature. With increasing temperature (the part between 20 and 80°K. will be discussed later), sorption increases fast between 80 and 

It is of interest to note that in the measurement of the hydrogen absorption on the ascending isobar of Fig. 6, a sudden desorption of hydrogen took place, after raising the temperature, followed by a slow 

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