Abstract: The disclosure relates generally to mold compositions and methods of molding and the articles so molded. More specifically, the disclosure relates to mold compositions, intrinsic facecoat compositions, and methods for casting titanium-containing articles, and the titanium-containing articles so molded.

Abstract: Titanium-containing articles having improved surface finishes and methods for changing the surface of titanium containing articles, for example by removing overstock, are provided. One example method includes passing a fluid at high pressure across a surface of an titanium aluminide alloy-containing article, for example, a turbine blade, at high linear speed and deforming the surface of the titanium aluminide alloy-containing article, and removing material from the surface of the titanium aluminide alloy-containing article. Though aspects of the invention can be used in fabricating high performance turbine blades, the methods disclosed can be applied to the treatment of any titanium-containing article for which it is difficult to obtain an improved surface finish.

Abstract: The disclosure relates generally to mold compositions and methods of molding and the articles so molded. More specifically, the disclosure relates to mold compositions and methods for casting titanium-containing articles, and the titanium-containing articles so molded.

Abstract: The present disclosure relates to a titanium-containing article casting mold composition comprising calcium aluminate and an X-ray or Neutron-ray detectable element. Furthermore, present embodiments teach a method for detecting sub-surface ceramic inclusions in a titanium or titanium alloy casting by combining calcium aluminate, an element more radiographically dense than the calcium aluminate, and a liquid to form a slurry; forming a mold having the calcium aluminate and the radiographically dense element from the slurry; introducing a titanium aluminide-containing metal to the radiographically dense element-bearing mold; solidifying said titanium aluminide-containing metal to form an article in the mold; removing the solidified titanium aluminide-containing metal article from said mold; subjecting the solidified titanium aluminide-containing article to radiographic inspection to provide a radiograph; and examining said radiograph for the presence of the radiographically dense element on or in the article.

Abstract: Titanium-containing articles having improved surface finishes and methods for improving surface finishes on titanium containing articles are provided. One method includes passing an abrasive medium across a surface of an titanium aluminide alloy-containing article, for example, a turbine blade, at high linear speed; deforming the surface of the titanium aluminide alloy-containing article with the abrasive medium and reducing a surface roughness of the surface of the titanium aluminide alloy-containing article and improving the surface finish of the surface. Surface finishes of 20 microinches Ra or less can be obtained. Though aspects of the invention can be used in fabricating high performance turbine blades, the methods disclosed can be applied to the treatment of any titanium-containing article for which it is difficult to obtain an improved surface finish.

Abstract: A casting apparatus is presented. The casting apparatus includes a first chamber and a second chamber. The first chamber includes a crucible and a sealed discharge outlet. The second chamber includes a casting mold for casting a plurality of filaments of a superalloy composition. The second chamber further includes a discharge inlet aligned with the sealed discharge outlet of the first chamber. The casting apparatus further includes a first port for applying a positive pressure to the first chamber and a second port for applying a vacuum to the second chamber. The sealed discharge outlet includes a hermetic seal comprising a material having a melting temperature equal to or greater than a melting temperature of the superalloy composition.

Abstract: One embodiment is a method. The method includes providing a casting apparatus including a first chamber and a second chamber, wherein the first chamber is isolated from the second chamber. The method includes charging an alloy composition into a crucible present in the first chamber and melting the alloy composition in the crucible to form a molten alloy composition. The method includes discharging the molten alloy composition into a casting mold present in the second chamber; applying a positive pressure to the first chamber to create a first chamber pressure; and applying a vacuum to the second chamber to create a second chamber pressure, wherein the first chamber pressure is greater than the second chamber pressure. The method further includes casting a filament or a turbine component from the molten alloy composition in the casting mold. An apparatus for casting a filament or a turbine component is also provided.

Abstract: A lamp is provided with an axially and radially graded structure to reduce the possibility of thermal stresses, cracks, and other defects in the lamp. In one embodiment, a system includes a ceramic lamp having a ceramic arc envelope and an end structure coupled to the ceramic arc envelope, wherein the end structure is graded both axially and radially into a plurality of regions. In another embodiment, a system includes a lamp having a layered end structure with a plurality of layers disposed one over another and that extend in both axial and radial directions relative to an axis of the lamp, wherein the plurality of layers include different materials having different coefficients of thermal expansion, Poisson's ratios, or elastic moduli, or a combination thereof.

Abstract: A casting apparatus is presented. The casting apparatus includes a first chamber and a second chamber. The first chamber includes a crucible and a sealed discharge outlet. The second chamber includes a casting mold for casting a plurality of filaments of a superalloy composition. The second chamber further includes a discharge inlet aligned with the sealed discharge outlet of the first chamber. The casting apparatus further includes a first port for applying a positive pressure to the first chamber and a second port for applying a vacuum to the second chamber. The sealed discharge outlet includes a hermetic seal comprising a material having a melting temperature equal to or greater than a melting temperature of the superalloy composition.

Abstract: Coatings suitable for use as protective oxide-forming coatings on Nb-based substrates exposed to high temperatures and oxidative environments. The coatings contain chromium and/or molybdenum, preferably contains silicon, and optionally contains niobium, titanium, hafnium, iron, rhenium, tantalum, and/or tungsten, which in combination form multiple intermetallic phases, which in combination form one or more intermetallic phases that promote the formation of a slow-growing oxide scale. Depending on the particular coating composition, the intermetallic phases may be: a silicon-modified Cr2Nb Laves phase and optionally a chromium solid solution phase, a CrNbSi intermetallic phase, and/or an M3Si intermetallic phase where M is niobium, titanium, and/or chromium; or M5Si3, MSi2 and/or M3Si2 where M is molybdenum, niobium, titanium, chromium, hafnium, iron, rhenium, tantalum, and/or tungsten.

Abstract: Methods for making a reinforced refractory crucible for melting titanium alloys including providing a form, applying a facecoat to the form, the facecoat having at least one facecoat layer, applying a backing about the facecoat, the backing having at least one backing layer, applying at least one reinforcing element to at least a portion of the facecoat layer, the backing layer, or a combination thereof where the reinforcing element includes at least one composition selected from ceramic compositions, metallic compositions, and combinations thereof.

Abstract: One embodiment is a method. The method includes providing a casting apparatus including a first chamber and a second chamber, wherein the first chamber is isolated from the second chamber. The method includes charging a superalloy composition into a crucible present in the first chamber and melting the superalloy composition in the crucible to form a molten superalloy composition. The method includes discharging the molten superalloy composition into a casting mold present in the second chamber; applying a positive pressure to the first chamber to create a first chamber pressure; and applying a vacuum to the second chamber to create a second chamber pressure, wherein the first chamber pressure is greater than the second chamber pressure. The method further includes casting at least one filament from the molten superalloy composition in the casting mold. An apparatus for casting a plurality of filaments is also provided.

Abstract: The present invention provides a method for forming a refractory metal-intermetallic composite. The method includes providing a first powder comprising a refractory metal suitable for forming a metal phase; providing a second powder comprising a silicide precursor suitable for forming an intermetallic phase; blending the first powder and the second powder to form a powder blend; consolidating and mechanically deforming the powder blend at a first temperature; and reacting the powder blend at a second temperature to form the metal phase and the intermetallic phase of the refractory metal-intermetallic composite, wherein the second temperature is higher than the first temperature.

Abstract: Refractory crucibles capable of managing thermal stress and suitable for melting highly reactive alloys having a facecoat, a backing, and at least one retaining ring applied about at least a portion of the backing of the crucible, the retaining ring comprising a composition selected from the group consisting of conductive materials, non-conductive materials, and combinations thereof.

Abstract: A system, in certain embodiments, includes a high intensity discharge lamp having a composite leg. The composite leg includes a plurality of leg sections coupled together in series. The plurality of leg sections includes different materials, coefficients of thermal expansion, Poisson's ratios, or elastic moduli, or a combination thereof. A method, in certain embodiments, includes enclosing a high intensity discharge within a ceramic arc envelope. The method also includes reducing thermal stresses associated with the high intensity discharge via a composite leg extending outwardly from the ceramic arc envelope. The composite leg includes a plurality of leg sections coupled together in series. The plurality of leg sections includes different materials, coefficients of thermal expansion, Poisson's ratios, or elastic moduli, or a combination thereof.

Abstract: Crucibles for melting titanium alloys having a facecoat including at least one facecoat layer containing an oxide selected from scandium oxide, yttrium oxide, hafnium oxide, a lanthanide series oxide, and combinations thereof, and a backing including at least one backing layer where the crucible has a backing to facecoat thickness ratio of from about 6.5:1 to about 20:1.

Abstract: Nb—Si based alloy articles comprising a Nb—Si based alloy upon which is disposed an environmentally-resistant coating are described. They include a coating comprising at least one phase selected from the group consisting of M(Al,Si)3, M5(Al,Si)3, and M3Si5Al2, wherein M is one or more of Nb, Ti, Hf, Cr. Such coating can improve the environmental (e.g., in oxidation-promoting environments) resistance of a Nb—Si based alloy and alloy articles. Methods for preparing these articles are described as well.

Abstract: Reinforced crucibles for melting titanium alloys having a facecoat including at least one facecoat layer, a backing including at least one backing layer, and at least one reinforcing element applied to at least a portion of one or more of the facecoat layer, the backing layer, or a combination thereof where the reinforcing element includes at least one composition selected from ceramic compositions, metallic compositions, and combinations thereof.

Abstract: A coating suitable for use as protective oxide-forming coatings on Nb-based substrates, and particularly monolithic niobium-based alloys, exposed to high temperatures and oxidative environments. The coating contains aluminum, may further contain silicon, and optionally contains niobium, titanium, hafnium, and/or chromium, which in combination form one or more intermetallic phases that promote the formation of a slow-growing oxide scale. The intermetallic phases may be M(Al,Si)3, M5(Al,Si)3, and/or M3Si5Al2 where M is niobium, titanium, hafnium, and/or chromium.

Abstract: Coatings suitable for use as protective oxide-forming coatings on Nb-based substrates exposed to high temperatures and oxidative environments. The coatings contain chromium and/or molybdenum, preferably contains silicon, and optionally contains niobium, titanium, hafnium, iron, rhenium, tantalum, and/or tungsten, which in combination form multiple intermetallic phases, which in combination form one or more intermetallic phases that promote the formation of a slow-growing oxide scale. Depending on the particular coating composition, the intermetallic phases may be: a silicon-modified Cr2Nb Laves phase and optionally a chromium solid solution phase, a CrNbSi intermetallic phase, and/or an M3Si intermetallic phase where M is niobium, titanium, and/or chromium; or M5Si3, MSi2 and/or M3Si2 where M is molybdenum, niobium, titanium, chromium, hafnium, iron, rhenium, tantalum, and/or tungsten.