Method and apparatus for casting near-net shape articles

An apparatus for casting an article, said apparatus comprising:

• (a) a means for forming a molten material, said molten material comprising at least one of a metal and an alloy;
• (b) a means for pouring said molten material from said means for forming said molten material, wherein said means for pouring said molten material includes a cup for receiving said molten material in a superheated state;
• (c) a mold assembly for receiving said molten material from said cup, said mold assembly comprising a ceramic shell for containing said molten material, said ceramic shell defining a cavity therein for accepting said molten material, and at least one face coat of a refractory material disposed on an inner surface of said ceramic shell in said cavity such that said face coat is interposed between said solid shell and said molten material, said refractory material comprising at least one of hafnia, erbia, zircon, yttria, ceria, zirconia, and a stabilized zirconia, wherein said face coat contacts said molten material, and wherein said molten material solidifies within said ceramic shell to form a near-net shape of said article;
• and
• (d) a heater assembly for heating said mold to a predetermined temperature and controlling a temperature of said mold, said heater assembly being proximate to an outer surface of said mold.

A method of casting a near-net shape article, the method comprising the steps of:

• (a) forming a molten material comprising at least one of a metal and an alloy;
• (b) pouring the molten material into a cup;
• (c) maintaining the molten material in a superheated state within the cup;
• (d) receiving the molten material from the cup in a mold assembly, wherein the mold assembly comprises a solid shell for containing the molten material, the solid shell having a face coat disposed on an inner surface of the solid shell that contacts the molten material, the face coat comprising at least one of an oxide, a silicide, a silicate, an oxysulfide, and a sulfide and containing at least one of a rare earth metal, a refractory metal, and combinations thereof;
• and
• (e) solidifying the molten material in the mold assembly to form the near-net shape article.

A method of casting a near-net shape article from at least one alloy comprising silicon and at least one of niobium, molybdenum, titanium, and chromium, the method comprising the steps of:

• (a) providing the at least one alloy comprising silicon and at least one of niobium, molybdenum, titanium, and chromium;
• (b) forming a molten material comprising the alloy;
• (c) pouring the molten material into a cup;
• (d) maintaining the molten material in a superheated state within the cup;
• (e) receiving the molten material from the cup in a mold assembly, wherein the mold assembly comprises a ceramic shell having a cavity for receiving the molten material and at least one face coat of a refractory material disposed on an inner surface of the ceramic shell in the cavity, wherein the refractory material comprises at least one of hafnia, erbia, zircon, yttria, zirconia, and stabilized zirconia;
• and
• (f) solidifying the molten material in the mold assembly to form the near-net shape article.

A near-net shape article comprising at least one alloy, the at least one alloy comprising silicon and at least one of niobium, molybdenum, titanium, and chromium, wherein the near-net shape article is cast by:

• (a) forming a molten material comprising the at least one alloy;
• (b) pouring the molten material into a cup;
• (c) maintaining the molten material in a superheated state within the cup;
• (d) receiving the molten material from the cup in a mold assembly, wherein the mold assembly comprises a ceramic shell and at least one face coat of a refractory material disposed on an inner surface of the ceramic shell in the cavity, wherein the refractory material comprises at least one of hafnia, erbia, zircon, yttria, zirconia, and stabilized zirconia;
• (e) heating the mold assembly to a temperature at which the molten material is in a fluid state;
• and
• (f) solidifying the molten material in the mold assembly to form the near-net shape article.