摘要:
A filler material is melted into a metallic substrate having a defect under conditions chosen to preclude cracking. In a preferred embodiment of the invention, a laser beam is operated at a relatively low power density and at a relatively large diameter for an extended length of time to produce a molten pool with a low aspect ratio.
摘要:
A containerless method of producing a crack free metallic article of near-net shape includes melting a filler material into a metallic substrate or seed under conditions chosen to preclude cracking. In a preferred embodiment of the invention, a laser beam is operated at a relatively low power density and at a relatively large beam diameter at the substrate surface for an extended length of time to produce a molten pool with a low aspect ratio. Near-net shape is achieved by applying the process in a closed-loop, multi-axis material deposition system.
摘要:
A containerless method of producing a crack free metallic article of near-net shape includes melting a filler material into a metallic substrate or seed under conditions chosen to preclude cracking. In a preferred embodiment of the invention, a laser beam is operated at a relatively low power density and at a relatively large beam diameter at the substrate surface for an extended length of time to produce a molten pool with a low aspect ratio. Near-net shape is achieved by applying the process in a closed-loop, multi-axis material deposition system.
摘要:
A method is provided for casting an article such as a blade having an attachment root and an airfoil, the airfoil having a proximal end and a distal end. The method comprises introducing a molten alloy into a mold; and varying a composition of the introduced alloy during the introduction so as to produce a compositional variation.
摘要:
A refractory metal core for use in a casting system has a coating for providing oxidation resistance during shell fire and protection against reaction/dissolution during casting. In a first embodiment, the coating includes at least one oxide and a silicon containing material. In a second embodiment, the coating includes an oxide selected from the group of calcia, magnesia, alumina, zirconia, chromia, yttria, silica, hafnia, and mixtures thereof. In a third embodiment, the coating includes a nitride selected from the group of silicon nitride, sialon, titanium nitride, and mixtures thereof. Other coating embodiments are described in the disclosure.
摘要:
A high modulus component, such as an aircraft engine turbine blade, is formed from a base metal that has a high modulus crystallographic orientation that is aligned with the primary, i.e. radial, direction of the turbine blade. The base metal is Ni, Fe, Ti, Co, Al, Nb, or Mo based alloy. Alignment of a high modulus direction of the base metal with the primary direction provides enhanced high cycle fatigue life.
摘要:
A casting system for forming a gas turbine engine component is provided. The casting system, in a first embodiment, comprises a shaped refractory metal sheet having a plurality of features for forming a plurality of film cooling passages, which features are formed from refractory metal material bent out of the sheet. The casting system for forming a gas turbine engine component in a second embodiment comprises a metal wall having an airfoil shape and a refractory metal core adjacent the metal wall and having a shape corresponding to the shape of the metal wall.
摘要:
This invention involves a cloning or expression vector comprising a gene which encodes 5-enolpyruvylshikimate-3-phosphate synthase (EPSPS) polypeptide which, when expressed in a plant cell contains a chloroplast transit peptide which allows the polypeptide, or an enzymatically active portion thereof, to be transported from the cytoplasm of the plant cell into a chloroplast in the plant cell, and confers a substantial degree of glyphosate resistance upon the plant cell and plants regenerated therefrom.The EPSPS coding sequence may be ligated to a strong promoter, such as the 35S promoter from cauliflower mosaic virus, to create a chimeric gene. Such genes can be inserted into plant transformation vectors, and subsequently introduced into plant cells. Plant cells transformed using such genes and plants regenerated therefrom have been shown to exhibit a substantial degree of glyphosate resistance.
摘要:
High modulus turbine shafts and high modulus cylindrical articles are described as are the process parameters for producing these shafts and cylindrical articles. The shafts/articles have a high Young's modulus as a result of having high modulus crystal texture along the longitudinal axis of the shaft/article. The shafts are produced from directionally solidified seeded single crystal cylinders that are axisymmetrically hot worked before a limited recrystallization process is carried out at a temperature below the recrystallization temperature of the alloy. The disclosed process produces an intense singular texture and results in shaft or cylindrical article with a Young's modulus that is at least 40% greater than that of conventional nickel or iron alloys or conventional steels.
摘要:
A method for casting comprising: providing a seed, the seed characterized by: an arcuate form and a crystalline orientation progressively varying along an arc of the form; providing molten material; and cooling and solidifying the molten material so that a crystalline structure of the seed propagates into the solidifying material.