ISSN:
1573-4803
Source:
Springer Online Journal Archives 1860-2000
Topics:
Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
Notes:
Abstract The phase diagram of the Cr-W-O system at 1000° C was established by metallographic and X-ray identification of the phases present after equilibration in evacuated silica capsules. Two ternary oxide phases, CrWO4 and Cr2WO6 were detected. The oxygen potential over the three-phase mixtures, W+Cr2O3 s+CrWO4, WO2.90+CrWO4+Cr2WO6 and Cr2O3+CrWO4+Cr2WO6, were measured by solid state cells incorporating Y2O3 stabilized ZrO2 electrolyte and Ni+NiO reference electrode. The Gibbs' energies of formation of the two ternary phases can be represented by the following equations $$\begin{gathered} W(s) + \tfrac{1}{2} Cr_2 O_3 (s) + \tfrac{5}{4} O_2 (g) \to CrWO_4 (s) \hfill \\ \Delta G^0 = - 172 047 + 48.725T ( \pm 230) cal mol^{ - 1} \hfill \\ Cr_2 O_3 (s) + WO_3 (s) \to Cr_2 WO_6 (s) \hfill \\ \Delta G^0 = - 3 835 + 0.235{\rm T} ( \pm 500) cal mol^{ - 1} \hfill \\ \end{gathered}$$
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00552303
