Phase diagram, hydrogen

Hydrogen phase diagram (pressure versus temperature). 

The phase diagrams of the uranium-zirconium and uranium-hydrogen systems employed in this work were those given by Rough and Bauer (15). The zirconium-hydrogen phase diagram used is a composite of data found in the various references to that system, and is presented in Figure 1. 

Figure 6.3 Thorium-hydrogen phase diagram [M2]. (Reprinted with permission from the copyright holder. Academic Press, Inc., New York, and Dr. G. G. Libowitz.)...

Sha3] Shapovalov, V.I., Poltoratskii, L.M., The Iron-Carbon-Hydrogen Phase Diagram , Steel USSR, 8(6), 356-357 (1978), translated from Erv. VUZ. Chem. Met., 6, 117-120 (1978) (Experimental, Phase Diagram, 14)... 

Fig. 1. Phase diagram of the potassium duoride—hydrogen duoride system.

Phase diagrams of adsorbed He particles show interesting features which have many similarities to the phase diagrams of adsorbed hydrogen systems. 

The hydrogen effect on ductility and the flow stress will be considered first on the example of non-alloyed titanium. The Ti - H phase diagram is given in Fig. 1, and Fig. 2 shows the temperature dependence of ductility of Ti-a H alloys, A , for several X values. Tensile tests were run at a rate e 10" s . Ductility of the commercial... 

Other ductility behavior showed alloys with x = 1-25 and 1.54 whose ductility A (T) jumped near 300°C, passed through a maximum at about 350°C, passed through a maximum at about 350°C, and again decreased at higher test temperatures. Points in Fig. 1 correspond to temperatures of anomalous Au(T) behavior for appropriate hydrogen contents. A clear correlation is observed between the ductility anomalies and special lines in the phase diagram, it i.e., all points fall at the boundaries of the two-phase regions or at the line equidistant from these boundaries. 

It is essentially a phase diagram which consists of a family of isotherms that relate the equilibrium pressure of hydrogen to the H content of the metal. Initially the isotherm ascends steeply as hydrogen dissolves in the metal to form a solid solution, which by convention is designated as the a phase. At low concentrations the behaviour is ideal and the isotherm obeys Sievert s Law, i.e.,... 

As discussed in Chapter 6, water forms strong hydrogen bonds and these lead to a number of important features of its atmospheric behavior. All three phases of water exist in the atmosphere, and the condensed phases can exist in equilibrium with the gas phase. The equilibria between these phases is summarized by the phase diagram for water. Fig. 7-9. 

As with the phase diagrams and Pourbaix diagrams, the theoretical standard hydrogen electrode also allows us to calculate the relative energies of intermediates in electrochemical reactions. As an example, we investigate the oxygen reduction reaction (ORR). We look at the four proton and electron transfer elementary steps ... 

As seen from the figure, the stability function does not become negative at any pressure when the hydrogen sulfide mole fraction lies anywhere between 0 and 1. The phase diagram calculations at 311.5 K are shown in Figure 14.11. As seen, the correct phase behavior is now predicted by the EoS. 

Data for the hydrogen sulfide-water and the methane-n-hexane binary systems were considered. The first is a type III system in the binary phase diagram classification scheme of van Konynenburg and Scott. Experimental data from Selleck et al. (1952) were used. Carroll and Mather (1989a b) presented a new interpretation of these data and also new three phase data. In this work, only those VLE data from Selleck et al. (1952) that are consistent with the new data were used. Data for the methane-n-hexane system are available from Poston and McKetta (1966) and Lin et al. (1977). This is a type V system. 

VLE data and calculated phase diagram for the hydrogen sulfide-water system [reprinted from Industrial Engineering Chemistiy Research with permission from the American Chemical SocietyJ. 

This work raises some interesting issues. The first is that the stoichiometry of a complex is not necessarily the most obvious. For example, it was reported initially that phthalic acid formed a 2 1 complex with alkoxystil-bazole [34], when in fact a careful study carried out by constructing a binary phase diagram (Fig. 11) revealed the complex to have a 1 1 ratio of the two components [35]. The reluctance of the system to form the more obvious 2 1 complex may relate to the presence of intramolecular hydrogen bonding or could even relate to the change in the pfCa of the second acid proton on com-plexation. 

The energy density of hydrogen can be doubled as compared to the 10,000 psi CH2 to 70 g/L by liquefaction to 20 K [49]. Five kilogram of hydrogen only requires 71L of volume, and this is equivalent on a volumetric basis to current vehicles. The phase diagram in Figure 10.26... 

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