Spinel matrix composites

The cordierite and spinel matrix composites both showed strength improvements over the monolithics that were retained up to 1000°C. Measurements on the spinel matrix composite showed a significant decrease at 1200°C. 

Table 2.5 Summary of elevated temperature mechanical properties for zirconia, cordierite, and spinel matrix composites...

As mentioned previously, the main body of research on whisker-reinforced composites was concerned with alumina, mullite, and silicon nitride matrix materials. None the less, selected work examined zirconia, cordierite, and spinel as matrix materials.16-18 The high temperature strength behavior reported for these composites is summarized in Table 2.5. As shown, the zirconia matrix composites exhibited decreases in room temperature strength with the addition of SiC whiskers. However, the retained strength at 1000°C, was significantly improved for the whisker composites over the monolithic. Claussen and co-workers attributed this behavior to loss of transformation toughening at elevated temperatures for the zirconia monolith, whereas the whisker-reinforcement contribution did not decrease at the higher temperature.17,18... 

N. Wang, Z. Wang, and G. C. Weatherly, Formation of Magnesium Aluminate (Spinel) in Cast SiC Particulate-Reinforced A1 (A356) Metal Matrix Composites, Metall. Trans., 23A[5], 1423-1430 (1992). 

Zirconia-toughened ceramics (ZTCs). These are ceramic matrix composites. The matrix is alumina, mullite, or spinel. The reinforcements are tetragonal or monoclinic zirconia particles. 

Although olivine and spinel do not contain U or Th, these structure types have many technological applications in high radiation environments (e.g. Pells 1991, Ibarra 1996, Yu et al. 1994), such as the use of spinel as an inert matrix nuclear fuel (Boczar et al. 1997). Additionally, because there are so many data available on the structure and properties of olivine and spinel structure-types and compositions, this system is ideal for systematic studies of radiation effects. 

Figure 18.23 Mechanically coupled magnetoelectric composites, (a) Crain mixture (b) Thin-film heterostructure (from Ref [123]) (c) Sandwich structure (from Ref [130]) (d) Spinel ferro/ ferrimagnetic nanopillars embedded on a perovskite ferroelectric matrix (from Ref [137].)...

While the method is suitable for the production of various defined oxide phases, such as series of different spinels with different degree of substitution of cations in the structure, alternatively random compositions of mixed oxides can be synthesized to cover a wider range of different solids. The practical implementation of such a method is as follows measured amounts of activated carbon (volumetric measurement is sufficient, the deviations in weight are on the order of 1% for about 100 mg) are placed in small quartz containers (in our setup a 7 x 11 matrix is used however, any other format is also possible). A tray with these containers... 

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