Upon consideration of the SiO2–Al2O3 phase diagram in Figure 10.26, for each pair of the f...

Upon consideration of the SiO2–Al2O3 phase diagram in Figure 10.26, for each pair of the fol- lowing list of compositions, which would you judge to be the more desirable refractory? Justify your choices.

(a) 20 wt% Al2O3–80 wt% SiO2 and 25 wt% Al2O3–75 wt% SiO2

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(b) 70 wt% Al2O3–30 wt% SiO2 and 80 wt% Al2O3–20 wt% SiO2

Figure 10.26 The silica–alumina phase diagram; ss denotes solid solution.