Abstract: A structural layer (30) may be bi-cast onto ligaments (62) extending from a porous cooling construction (20). The material of the structural layer may be optimized for high-temperature strength, while the material of the porous construction may be optimized for high thermal conductivity. A fugitive material (56) such as wax may be formed on the ligaments of the porous construction. A second fugitive material (58) such as ceramic may fill the remaining part of the porous construction. An investment casting shell (60) may be disposed around the porous construction and the fugitive materials. The first fugitive material may then be replaced with the material of the structural layer (30), and the second fugitive material may be removed to provide coolant paths (26). A second structural layer (52) may be bi-cast onto further ligaments (62) on a second side of the porous construction.

Abstract: A structural layer (30) may be bi-cast onto ligaments (62) extending from a porous cooling construction (20). The material of the structural layer may be optimized for high-temperature strength, while the material of the porous construction may be optimized for high thermal conductivity. A fugitive material (56) such as wax may be formed on the ligaments of the porous construction. A second fugitive material (58) such as ceramic may fill the remaining part of the porous construction. An investment casting shell (60) may be disposed around the porous construction and the fugitive materials. The first fugitive material may then be replaced with the material of the structural layer (30), and the second fugitive material may be removed to provide coolant paths (26). A second structural layer (52) may be bi-cast onto further ligaments (62) on a second side of the porous construction.

Abstract: A structural layer (30) may be bi-cast onto ligaments (62) extending from a porous cooling construction (20). The material of the structural layer may be optimized for high-temperature strength, while the material of the porous construction may be optimized for high thermal conductivity. A fugitive material (56) such as wax may be formed on the ligaments of the porous construction. A second fugitive material (58) such as ceramic may fill the remaining part of the porous construction. An investment casting shell (60) may be disposed around the porous construction and the fugitive materials. The first fugitive material may then be replaced with the material of the structural layer (30), and the second fugitive material may be removed to provide coolant paths (26). A second structural layer (52) may be bi-cast onto further ligaments (62) on a second side of the porous construction.

Abstract: A method of forming and/or assembling a multi-panel outer wall (14) for a component (12) in a machine subjected to high thermal stresses comprising providing such a component (12) that includes an inner panel wall (16) having an outer surface, and an array of interconnecting ribs (38) on the outer surface of the component (12). An intermediate panel (22) is provided and preferably preformed to a general outer contour of the component (12), and is positioned over the inner panel (16). An external pressure force is applied across a surface area of the intermediate panel (22) against the outer surface of the component (12) to contour the intermediate panel (22) according to a geometric configuration formed by the ribs (38) thereby forming cooling chambers (24) between the outer surface and ribs (38) of the component (12) and the intermediate panel (22).

Abstract: A turbine airfoil (31) with an end portion (42) that tapers (44) toward the end (43) of the airfoil. A ridge (46) extends around the end portion. It has proximal (66) and distal (67) sides. A shroud platform (50) is bi-cast onto the end portion around the ridge without bonding. Cooling shrinks the platform into compression (62) on the end portion (42) of the airfoil. Gaps between the airfoil and platform are formed using a fugitive material (56) in the bi-casting stage. These gaps are designed in combination with the taper angle (44) to accommodate differential thermal expansion while maintaining a gas seal along the contact surfaces. The taper angle (44) may vary from lesser on the pressure side (36) to greater on the suction side (38) of the airfoil. A collar portion (52) of the platform provides sufficient contact area for connection stability.

Abstract: A method of forming and/or assembling a multi-panel outer wall (14) for a component (12) in a machine subjected to high thermal stresses comprising providing such a component (12) that includes an inner panel wall (16) having an outer surface, and an array of interconnecting ribs (38) on the outer surface of the component (12). An intermediate panel (22) is provided and preferably preformed to a general outer contour of the component (12), and is positioned over the inner panel (16). An external pressure force is applied across a surface area of the intermediate panel (22) against the outer surface of the component (12) to contour the intermediate panel (22) according to a geometric configuration formed by the ribs (38) thereby forming cooling chambers (24) between the outer surface and ribs (38) of the component (12) and the intermediate panel (22).

Abstract: A structural layer (30) may be bi-cast onto ligaments (62) extending from a porous cooling construction (20). The material of the structural layer may be optimized for high-temperature strength, while the material of the porous construction may be optimized for high thermal conductivity. A fugitive material (56) such as wax may be formed on the ligaments of the porous construction. A second fugitive material (58) such as ceramic may fill the remaining part of the porous construction. An investment casting shell (60) may be disposed around the porous construction and the fugitive materials. The first fugitive material may then be replaced with the material of the structural layer (30), and the second fugitive material may be removed to provide coolant paths (26). A second structural layer (52) may be bi-cast onto further ligaments (62) on a second side of the porous construction.

Abstract: A turbine airfoil (31) with an end portion (42) that tapers (44) toward the end (43) of the airfoil. A ridge (46) extends around the end portion. It has proximal (66) and distal (67) sides. A shroud platform (50) is bi-cast onto the end portion around the ridge without bonding. Cooling shrinks the platform into compression (62) on the end portion (42) of the airfoil. Gaps between the airfoil and platform are formed using a fugitive material (56) in the bi-casting stage. These gaps are designed in combination with the taper angle (44) to accommodate differential thermal expansion while maintaining a gas seal along the contact surfaces. The taper angle (44) may vary from lesser on the pressure side (36) to greater on the suction side (38) of the airfoil. A collar portion (52) of the platform provides sufficient contact area for connection stability.

Abstract: A nickel-base casting alloy for use in gas turbine components consists essentially of the composition (in weight percent): carbon 0.02-0.15, chromium 14-18, cobalt 8-12, aluminum 0.5-1.5, titanium 2.0-3.5, niobium 3.5-6.0, tantalum 1.0-2.0, tungsten 1.0-3.0, molybdenum 3.0-6.0, boron 0.002-0.05, zirconium 0.01-0.1, balance nickel and incidental impurities. The alloy is characterized by a volume fraction of gamma prime of about 32%, an ultimate tensile strength in the range 990-1010 MPa over the temperature range 550.degree.-750.degree. C., and a mean coefficient of linear thermal expansion in the range 11.5-15.0 alpha(*E-06/.degree.C.).