Zirconia interphase

M. Holmquist, R. Lundberg, O. Sudre, A. G. Razzell, L. Molliex, J. Benoit, and J. Adlerbom, Alumina/alumina composite with a porous zirconia interphase - Processing, properties and component testing, J. Eur. Ceram. Soc., 20 599-606 (2000). 

Colomban, P., Bruneton, E., Lagrange, J.L., Mouchon, E., Sol-gel mullite matrix-SiC and -mullite 2D woven fabrics composites with or without zirconia containing interphase. Elaboration and properties, J. Eur. Ceram. Soc., 16, 301, 1996. 

Fig. 8. Regular blocks of mullite lattice fringes inside the zirconia grain interphase, (end of the triangles that are arrowed). Therefore, the HREM method can support, in this case, the idea of solid solubility of mullite inside the zirconia boundary [25]...

The zirconia/mullite interphase has been examined indicating a coherent relation between both types of crystals, as is shown in Fig. 8. Only the A labeled grain shows this coherency while the B grain oriented with respect to the other does not show this effect. Therefore, the HREM allows us to distinguish the critical orientations of crystals at interphases. Domains of closure interpenetrating into the zirconia are visible at the boundary [25]. 

The crystallization of the amorphous zirconia is likely to result in a drastic decrease of the copper/zirconia interfacial area which certainly contributes to the loss of activity observed upon crystallization. Our investigations provide further support for the crucial role of the interfacial area in copper/zirconia catalysts. Further work focusing on the structural and chemical properties of this interphase and its role in methanol synthesis is presently undertaken. 

The chemical reactions between carbon and at the interphase and the reactions between ZrB, ZrC, SiC, and O, at the porous layer lead to consumption by oxidation of ceramic matrix, and causes a decrease in the pore size because of the difference in the density of boron oxide, silica, and zirconia, with the boride and carbide ceramics ... 

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