Partial phase diagram of the ternary reciprocal system KF-AlF3-Al2O3-K2O
Résumé
A K2ZrF6 treatment improves the wettability of SiC (or C) fibers by aluminum alloys. A possible mechanism involves the formation of K3AlF6 followed by the dissolution of the alumina film. DTA analyses of K3AlF6-α-Al2O3 mixtures show that a temperature invariant transition occurs at 1132K, the solid containing trace amounts of KAlF4 and β-alumina at room temperature. Part of the ternary reciprocal system KF-AlF3-Al2O3-K2O is calculated, the Gibbs free energy of the liquid being described according to the CIS theory. The K3AlF6-Al2O3 isopteth section is given. It is characterized by a liquidus with a deep minimum at 1132K and 11.6 wt % alumina.