Casting processes, casting apparatuses therefor, and castings produced thereby

A directional solidification process for producing a casting, the process comprising:

• providing a mold with a cavity and a continuous solid facecoat on a surface within the cavity and formed from a facecoat slurry applied to the surface, the facecoat consisting essentially of at least 60 weight percent of a first phase containing yttria, the balance of the facecoat being essentially a binder phase consisting essentially of an inorganic material;
• introducing a molten quantity of a metal alloy into the cavity of the mold so that the molten metal alloy contacts the facecoat;
• immersing the mold in a liquid coolant to cool and solidify the molten quantity of the metal alloy and form a casting of the metal alloy, during which an oxide layer forms on a surface of the casting, the facecoat becoming sufficiently adherent to the oxide layer such that at least a portion of the facecoat detaches from the surface of the mold and remains tightly adhered to the surface of the casting in the event the casting contracts during cooling;
• removing the mold from the liquid coolant;
• and then
• removing from the mold the casting with the oxide layer and at least the remnant portion of the facecoat thereon.