A method to modify the shape of a channel in a metallic substrate is described. The method includes the step of applying at least one metallic coating on selected portions of an interior surface of the channel, so as to alter the heat transfer characteristics of the channel during passage of a coolant fluid therethrough. Related articles that contain the modified channels are also described, such as gas turbine engine components.

An aluminum alloy brazing sheet has high strength, corrosion resistance and elongation, and includes an aluminum alloy clad material. The material includes a core material, one surface of which is clad with a sacrificial material and an other surface of which is clad with an Al—Si-based or Al—Si—Zn-based brazing filler metal. The core material has a composition containing 1.3 to 2.0% Mn, 0.6 to 1.3% Si, 0.1 to 0.5% Fe and 0.7 to 1.3% Cu, by mass, with the balance Al and impurities. The sacrificial material has a composition containing more than 4.0% to 8.0% Zn, 0.7 to 2.0% Mn, 0.3 to 1.0% Si, 0.3 to 1.0% Fe and 0.05 to 0.3% Ti, by mass, with the balance Al and impurities. At least the core material has a lamellar crystal grain structure. Elongation of material is at least 4% and a tensile strength after brazing is at least 170 MPa.

An aluminum alloy brazing sheet has high strength, corrosion resistance and elongation, and includes an aluminum alloy clad material. The material includes a core material, one surface of which is clad with a sacrificial material and an other surface of which is clad with an Al—Si-based or Al—Si—Zn-based brazing filler metal. The core material has a composition containing 1.3 to 2.0% Mn, 0.6 to 1.3% Si, 0.1 to 0.5% Fe and 0.7 to 1.3% Cu, by mass, with the balance Al and impurities. The sacrificial material has a composition containing more than 4.0% to 8.0% Zn, 0.7 to 2.0% Mn, 0.3 to 1.0% Si, 0.3 to 1.0% Fe and 0.05 to 0.3% Ti, by mass, with the balance Al and impurities. At least the core material has a lamellar crystal grain structure. Elongation of material is at least 4% and a tensile strength after brazing is at least 170 MPa.

In this flat extruded aluminum multi-port tube, the corrosion-resistance, at inner surfaces of a plurality of flow passages independently and parallelly extending in the tube axial direction, is effectively enhanced. In a flat extruded aluminum multi-port tube 10 formed by an extrusion by employing an aluminum tube material and an aluminum sacrificial anode material having an electrochemically lower potential than the aluminum tube material, the aluminum sacrificial anode material is exposed to form a sacrificial anode portion 18 at least in a part of an inner circumferential portion in each of the plurality of flow passages 12.

In this flat extruded aluminum multi-port tube, the corrosion-resistance, at inner surfaces of a plurality of flow passages independently and parallelly extending in the tube axial direction, is effectively enhanced. In a flat extruded aluminum multi-port tube 10 formed by an extrusion by employing an aluminum tube material and an aluminum sacrificial anode material having an electrochemically lower potential than the aluminum tube material, the aluminum sacrificial anode material is exposed to form a sacrificial anode portion 18 at least in a part of an inner circumferential portion in each of the plurality of flow passages 12.

A composite material can include a carrier material that is coated, at least over part of the surface, with a corrosion protection layer made of an aluminum alloy. The composite material can provide a defined, effective, durable corrosion protection and simultaneously have a high recycling potential. The aluminum alloy of the corrosion protection layer can have the following composition in % by weight: TABLE-US-00001 0.8 ≦ Mn ≦ 1.8 Zn ≦ 0.05 Cu ≦ 0.05 Si ≦ 1.0 Cr ≦ 0.25 Zr ≦ 0.25 Mg ≦ 0.10
remainder aluminum and unavoidable impurities, individually a maximum of 0.05% by weight, in total a maximum of 0.15% by weight.

A composite material can include a carrier material that is coated, at least over part of the surface, with a corrosion protection layer made of an aluminum alloy. The composite material can provide a defined, effective, durable corrosion protection and simultaneously have a high recycling potential. The aluminum alloy of the corrosion protection layer can have the following composition in % by weight: TABLE-US-00001 0.8 ≦ Mn ≦ 1.8 Zn ≦ 0.05 Cu ≦ 0.05 Si ≦ 1.0 Cr ≦ 0.25 Zr ≦ 0.25 Mg ≦ 0.10
remainder aluminum and unavoidable impurities, individually a maximum of 0.05% by weight, in total a maximum of 0.15% by weight.

A heat pipe or a bundle of heat pipes for transporting geothermal heat in a well is provided. As the temperature rises at one end of the heat pipe, the operating fluid turns to a vapor which absorbs the latent heat. The hot vapor within the heat pipe flows to the cooler end of the heat pipe where it then condenses and releases the latent heat. The condensed fluid then flows back to the hot side of the heat pipe and the process repeats itself.

A heat pipe or a bundle of heat pipes for transporting geothermal heat in a well is provided. As the temperature rises at one end of the heat pipe, the operating fluid turns to a vapor which absorbs the latent heat. The hot vapor within the heat pipe flows to the cooler end of the heat pipe where it then condenses and releases the latent heat. The condensed fluid then flows back to the hot side of the heat pipe and the process repeats itself.

A surface treatment method for aluminum heat exchangers including (a) a step wherein a chemical conversion coating film is formed on the surface of an aluminum heat exchanger by subjecting the aluminum heat exchanger to chemical conversion using a chemical conversion agent; (b) a step wherein the aluminum heat exchanger, the surface of which has been provided with a chemical conversion coating film in step (a), is brought into contact with a hydrophilizing agent that contains a hydrophilic resin; and (c) a step wherein a hydrophilized coating film is formed on the surface of the aluminum heat exchanger by baking the aluminum heat exchanger, which has been subjected to a contact treatment in step (b). The chemical conversion agent used in step (a) contains zirconium and/or titanium in an amount of 5-5,000 ppm by mass in total, vanadium in an amount of 10-1,000 ppm by mass and a metal stabilizer in an amount of 5-5,000 ppm by mass. In addition, the chemical conversion agent used in step (a) has a pH of 2-6.