Thermodynamic assessment of the system ZrO2–CaO–MgO using new experimental results

Serena, S.; Saínz, M.A.; Aza, S. De; Caballero, A.

doi:10.1016/j.jeurceramsoc.2004.02.011

Cited by 8 publications

(14 citation statements)

References 42 publications

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“…For the calculation of the activity of SiO 2 which is required for the growth of a magnesium silicate on magnesia stabilised zirconia the knowledge of the activity of MgO in the zirconia is required. In Figure 7 the phase diagram of the system ZrO 2 MgO is shown according to the assessment of Serena et al 14. It can be seen, that MgO has a high solubility in cubic zirconia, c‐ZrO 2 , and that the stability range of this phase is extended to much lower temperatures in the solid solution.…”

Section: Discussionmentioning

confidence: 98%

“…Therefore, the activity of MgO in this metastable state must be higher than unity, when the reference state of pure MgO at this temperature is used. In fact, when the dataset of Serena et al 14 is used for the calculation of this metastable equilibrium between cubic and tetragonal zirconia, the activity of MgO has a value of a MgO = 1.04. This value is inserted into the mass‐action law, equation (4), in order to find the minimum value of the activity of SiO 2 which is required to form a magnesium silicate.…”

Section: Discussionmentioning

confidence: 99%

“…The reason for this different behaviour of the MgO‐ and the CaO‐stabilised zirconia can already be anticipated from a comparison of the phase diagrams of zirconia with the respective stabilising oxide. The phase diagram of the system ZrO 2 CaO is shown in Figure 9 which has been calculated with the dataset of Serena et al 14. In contrast to the system ZrO 2 MgO, calcia and zirconia form intermediate oxides, Ca 6 Zr 19 O 44 and CaZrO 3 , respectively, which indicates an increased affinity between calcia and zirconia.…”

Section: Discussionmentioning

confidence: 99%

“…In fact, the activity of CaO is drastically reduced when the ZrO 2 concentration exceeds a value of 50 mol%. In Figure 10 the decadic logarithm of the CaO activity is shown as a function of the composition at a temperature of 1400 °C which has been calculated with the dataset of Serena et al 14. For a zirconia ceramics containing 7.3 mol% CaO the activity of calcia is given by the plateau of the two‐phase region c‐ZrO 2 /t‐ZrO 2 in the diagram.…”

Section: Discussionmentioning

confidence: 99%

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Interfacial Reactions in TRIP‐Steel/ZrO₂ Composites

Franke

Ksyta

Seifert

2011

steel research int.

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The interfaces between stainless TRIP steel and three types of zirconia ceramics were investigated after sintering the samples for 48 h at 1400 °C. The samples were prepared by embedding compact pieces of ceramics into steel powder and densifying them with a spark plasma equipment. In all experiments the same steel was used but the zirconia ceramics was stabilised with CaO, MgO, or non‐stabilised, respectively. It was found that no reaction product was formed in the samples with non‐stabilised or CaO‐stabilised ceramics. At the interface of MgO‐stabilised zirconia and steel, a layer of forsterite, Mg2SiO4, was formed. The silicate layer resulted from the reaction of MgO which was dissolved in the zirconia with Si which was an impurity in the steel. In a thermodynamic analysis the reasons are explained which lead to the formation of a silicate in the samples with MgO‐stabilised zirconia. Accordingly, thermodynamic calculations are in accord with the absence of a reaction layer in the cases of the non‐stabilised and the CaO‐stabilised zirconia, even though the Gibbs energy of formation of calcium silicates is much higher than that of the corresponding magnesium silicates. The maximum impurity level for silicon in the given steel is calculated which avoids the formation of a silicate layer at the interface of the MgO‐stabilised ceramics.

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Section: Discussionmentioning

confidence: 98%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

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Interfacial Reactions in TRIP‐Steel/ZrO₂ Composites

Franke

Ksyta

Seifert

2011

steel research int.

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“…MgO and CaZrO 3 are compatible phases and do not form a liquid phase up to temperatures higher than 2060 • C. 4,5 These materials have been suggested as chrome-free refractories for cement kilns to replace not only magnesia-chromite, but also the magnesia-oversaturated spinel now used as an alternative. MgOspinel bricks are highly resistant to thermal shock, non-sensitive against reducing/oxidizing conditions, but are vulnerable to thermal overload.…”

Section: Introductionmentioning

confidence: 99%