Diagrams stability

Figure Bl.7.9. (a) Stability diagram for ions near the central axis of a quadnipole mass filter. Stable trajectories occur only if the and values lie beneath tire curve, (b) Stability diagram (now as a fiinction of U and F) for six ions with different masses. The straight line miming tlirough the apex of each set of curves is the operating line, and conesponds to values of UIVthat will produce mass resolution (reproduced with pennission of Professor R March, Trent University, Peterborough, ON, Canada).

The Mathieu equation for the quadnipole ion trap again has stable, bounded solutions conesponding to stable, bounded trajectories inside the trap. The stability diagram for the ion trap is quite complex, but a subsection of the diagram, correspondmg to stable trajectories near the physical centre of the trap, is shown in figure Bl.7.15. The interpretation of the diagram is similar to that for tire quadnipole mass filter. 

Figure Bl.7.15. Stability diagram for ions near the eentre of a quadnipole ion trap mass speetrometer. The enelosed area refleets values for and that result in stable trapping trajeetories (reprodueed with pennission of Professor R Mareh, Trent University, Peterborough, ON, Canada).

Determining Susceptibility of NijSj Formation Using a Stability Diagram... 

Figure 4-119. Stability diagram with region B indicating the more corrosive condition.

Figure 15.17 Stability diagrams for the systems (a) metal (M)-sulfur-oxygen (idealized), (b) Cu-S-O and (c) Pb S-O.

Fig. 7.41 A typical coal gasifier atmosphere at 871 °C plotted in the M-O-S thermodynamic stability diagram for elements commonly present in stainless steels and high temperature alloys...

The thermodynamic phase stability diagrams appear to be preferred by corrosion scientists and technologists for the evaluation of gas-metal systems where the chemical composition of the gaseous phase consisting of a single gas or mixture of gases has a critical influence on the formation of surface reaction products which, in turn, may either stifle or accelerate the rate of corrosion. Also, they are used to analyse or predict the reason for the sequence of formation of the phases in a multi-layered surface reaction product on a metal or alloy. 

A detailed explanation of the construction of thermodynamic phase stability diagrams may be found in References 22-25. In this section the basic principles of construction and interpretation for the specific situation of gas-metal equilibria will be addressed using a hypothetical system. 

Fig. 7.67 Phase stability diagram for a metal-sulphur-oxygen (M-S-O) system at I 000 K. (For the thermodynamic data AC 000 for the various across-boundary reactions, see Table 7.37)...

Table 7.37 Data for the construction of thermodynamic phase stability diagram M-S-0 at 1 000 K...

Therefore, the calculated coordinates of the triple point for the coexistence of MO, MS and A/SO4 are logPso2 = +2 and logpo = - 12 and the slope of the MO/MSO4 boundary is - y. The straight line from point B having slope — y gives the boundary line (i) between the stability areas of MO and A/SO4. This completes the construction of the phase stability diagram forM-S-O at 1000 K. 

Fig. 7.68 Thermochemical stability diagram for the system Fe-S-O at I 000 K showing the relative corrosion potentials of the atmospheres in conventional coal combustion (A), fluidised bed combustion (B), conventional coal gasification (C) and coal gasificiation using nuclear heat (D) (after Gray and Starr )...

Fig. 7.69 Thermochemical stability diagram for the 310 stainless-steel-S-O system at 750°C (from Gray and Starr after Natesan and Chopra ")...

Fig. 7.70 Phase stability diagram for the Cr-O-S system on Incoloy 800H at 1 023 K showing thermodynamic and kinetic boundaries (after Natason )...

Phase Stability Diagrams with a Liquid Phase... 

Fig. 7.72 A thermodynamic phase stability diagram for Al-O-S species in the eqilibrium with liquid Na2S04 at 1 000°C as a function of the oxygen activity and the acidity of the salt (after...

In recent work phase stability diagrams were used to evaluate the effect of molten Na2S04 on the kinetics of corrosion of pure iron between 600° C and 800° C by drawing a series of superimposed stability diagrams for Na-O-S and Fe-O-S at 600°C, 700° C and 800°C and thus to account for the differences in the corrosion behaviour as a function of temperature. 

Phase Stability Diagrams and the Formation of Volatile Halides... 

These isothermal diagrams can be used to consider the phase stability areas for more than one metal in contact with a common atmosphere and thus to assess the condensed phases which can be stable under the prevailing conditions. Figure 7.75 shows a stability diagram having phase areas for Co-S-O solid lines) and for Cu-S-O system broken lines). From this diagram it can be seen clearly that at 950 K at certain gas mixtures, pure metals Co and... 

Fig. 7.76 Superimposed simplified thermodynamic stability diagrams for three elements with oxygen and sulphur at 871°C. The shaded rectangle indicates possible activity ranges in coal gasification atmospheres (after Stringer )...

Fig. 7.77 Thermodynamic stability diagram for the Fe-Ni-Cr system at 1 143 K, assuming metal activities to be unity.-, phase boundaries involving Fe —phase boundaries involving Ni ----, phase boundaries involving Cr. The location of environments 1, 2, 3, and 4 are...

Fig. 7.78 Thermodynamic stability diagram for some oxides and sulphides at 1 000 K (after...

Fig. 7.79 Five possible reaction paths on a schematic thermodynamic phase stability diagram, and the corresponding distribution of phases in the reaction systems (after Stringer...

Fig. 7.80 A schematic thermodynamic phase stability diagram for the A-C-O system, showing three reaction paths. Paths 2 and 3 are only possible if gaseous diffusion in pores in the oxide product results in a carbon activity increase through the scale, as shown in Fig. 7.81 (after...

Because of the financial importance of this process to steel producers (about one-third of all the steel produced in the world is subsequently galvanised) a great deal of research has been carried out throughout the world to establish the true equilibrium phase boundaries in the Fe,, -Zn( system and the critical temperature of stability of the f phase. Since the AG -7 diagrams or the phase stability diagrams could not account for these discrepancies in this system, AG ,-concentration curves were used for... 

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