Abstract: Potential difficulties in surface modification of a substrate are avoided by using a mixture that includes a ceramic powder, a brazing material and a flux. Exposure to an elevated temperature activates the flux and at least partially melts the brazing material. Upon cooling, the melt solidifies to bond the ceramic powder to the substrate surface an create the modification.

Abstract: Potential difficulties with corrosion in hear exchangers utilizing aluminum fins are avoided by using fin and tube constructions made by a method which includes the steps of providing a flattened tube (50) of ferrous material (80) and having an exterior coating (82) predominantly of aluminum providing at least one serpentine fin (56) of aluminum (86) and clad with a predominantly aluminum braze cladding (88); assembling (102) the fin (56) to the flattened tube (50); applying (94), (100), (104), a brazing flux to at least one of the fin (56) and the tube (50); raising (106) the temperature of the assembly to a level sufficient to at least partially melt the braze cladding (88); and maintaining the temperature for a sufficient period of time to achieve a brazed joint (60) between the fin (56) and the tube (50) but a time insufficient to convert the coating (82) and the cladding (88) to ferrous-aluminum intermetallic compound or intermediate phase.

Abstract: Potential difficulties with corrosion in heat exchangers utilizing aluminum fins are avoided by using fin and tube constructions made by a method which includes the steps of providing a flattened tube (50) of ferrous material (80) and having an exterior coating (82) predominantly of aluminum; providing at least one serpentine fin (56) of aluminum (86) and clad with a predominantly aluminum braze cladding (88); assembling (102) the fin (56) to the flattened tube (50); applying (94), (100), (104), a brazing flux to at least one of the fin (56) and the tube (50); raising (106) the temperature of the assembly to a level sufficient to at least partially melt the braze cladding (88); and maintaining the temperature for a sufficient period of time to achieve a brazed joint (60) between the fin (56) and the tube (50) but a time insufficient to convert the coating (82) and the cladding (88) to ferrous-aluminum intermetallic compound or intermediate phase.

Abstract: Potential difficulties with corrosion in heat exchangers utilizing aluminum fins are avoided by using fin and tube constructions made by a method which includes the steps of providing a flattened tube (50) of ferrous material (80) and having an exterior coating (82) predominantly of aluminum; providing at least one serpentine fin (56) of aluminum (86) and clad with a predominantly aluminum braze cladding (88); assembling (102) the fin (56) to the flattened tube (50); applying (94), (100), (104), a brazing flux to at least one of the fin (56) and the tube (50); raising (106) the temperature of the assembly to a level sufficient to at least partially melt the braze cladding (88); and maintaining the temperature for a sufficient period of time to achieve a brazed joint (60) between the fin (56) and the tube (50) but a time insufficient to convert the coating (82) and the cladding (88) to ferrous-aluminum intermetallic compound or intermediate phase.

Abstract: Potential difficulties with corrosion in heat exchangers utilizing aluminum fins are avoided by using fin and tube constructions made by a method which includes the steps of providing a flattened tube (50) of ferrous material (80) and having an exterior coating (82) predominantly of aluminum; providing at least one serpentine fin (56) of aluminum (86) and clad with a predominantly aluminum braze cladding (88); assembling (102) the fin (56) to the flattened tube (50); applying (94), (100), (104), brazing flux to at least one of the fin (56) and the tube (50); raising (106) the temperature of the assembly to a level sufficient to at least partially melt the braze cladding (88); and maintaining the temperature for a sufficient period of time to achieve a brazed joint (60) between the fin (56) and the tube (50) but a time insufficient to convert the coating (82) and the cladding (88) to ferrous-aluminum intermetallic compound or intermediate phase.

Abstract: Potential difficulties with corrosion resistance in air cooled condensers utilizing aluminum fins are avoided by using fin and tube constructions made by a method which includes the steps of providing a flattened tube (50) of ferrous material (80) and having an exterior coating (82) predominantly of aluminum; providing at least one serpentine fin (56) of aluminum (86) and clad with a predominantly aluminum braze cladding (88); assembling (102) the fin (56) to the flattened tube (50); applying (94), (100), (104), a brazing flux to at least one of the fin (56) and the tube (50); raising (106) the temperature of the assembly to a level sufficient to at least partially melt the braze cladding (88); and maintaining the temperature for a sufficient period of time to achieve a brazed joint (60) between the fin (56) and the tube (50) but a time insufficient to convert the coating (82) and the cladding (88) to ferrous-aluminum intermetallic compound or intermediate phase.

Abstract: This invention relates to a method of bonding together a plurality of ferrous metal members, the resulting assembly and a heat exchanger comprising the thusly bonded metal members in which the members are bonded to each other by assembling them with aluminum metal between and in contact with them, coating this assembly with a liquid bonding composition as disclosed in Simpelaar U.S. Pat. No. 3,301,688 comprising a liquid solvent and a zinc halide and heating this assembly thereby causing the aluminum to displace zinc from the zinc halide with the zinc thereby uniting with the ferrous metal to form a secure joint comprising an alloy of iron from the ferrous metal members and zinc displaced from the zinc chloride.

Abstract: A weldment heat exchanger having at least the surfaces contacted by the fluids between which heat is exchanged of stainless steel and comprising a tube bundle having spaced tubes through which one of the fluids flows and over the outer surfaces of which tubes a second fluid flows for exchange of heat between the fluids through the walls of the tubes, a first header-tank at one end of the bundle and a second header-tank at the opposite end of the bundle, the joints of the parts including those of the two header-tanks and the tubes being welded.