Abstract: A flat hollow body having a fluid channel inside thereof is made from two plates 2 serving as heat exchanger components, by brazing the plates at the peripheral edge portions thereof. The plate 2 comprises a core layer 21 of aluminum or aluminum alloy, and an Al—Si alloy layer 22 covering each of opposite sides of the core layer 21. The core layer 21 contains Si diffusing thereinto from the Al—Si alloy layer 22. The alloy layer 22 has a portion up to 1.65 mass % in Si content. The flat hollow body has high corrosion resistance.

Abstract: The heat exchanger according to the present invention includes a heat exchanger component in which a fluoride layer 10 is formed at the surface layer portion. It is preferable that the fluoride layer 10 falls within the range of from 2 nm to 10 &mgr;m in thickness. It is preferable that the component is at least one of a fin and a plate. Furthermore, it is preferable that the fluoride layer 10 is formed on a substrate via an intermediate layer 2. It is preferable that the intermediate layer 2 includes an anodized oxide layer 3 and/or a nickel plated layer 4. The heat exchanger is excellent in corrosion resistance against water, vapor and the like The heat exchanger is preferably used, especially, for a fuel cell.

Abstract: In brazing a first metal piece having a tubular joint portion of predetermined length at an end thereof and a second metal piece having a bore for inserting the extremity of the joint portion thereinto by replaced brazing with the extremity of the joint portion inserted in the bore, a plurality of axial grooves having a depth of 0,3 to 1,5 mm and arranged at a spacing of 5 to 30 mm in the circumferential direction are formed in the outer peripheral surface of joint portion of the first metal piece. Each of the grooves has one end extending to the outside of the bore of the second metal piece when the joint portion is inserted in the bore. The gas or residue of flux produced during brazing escapes through the grooves, whereby voids or like defects are prevented from occurring in the fillet of the brazed joint. Since the grooves are all filled up with the brazing filler metal, the brazed joint is given a sufficient bond strength and prevented from permitting leakage there-through.

Abstract: A heat exchanger made of aluminum includes a tube and a fin joined thereto by a fillet which is made primarily of zinc. The tube and the fin are each prepared from a material made of aluminum and nobler than the fillet by at least 0.325 V in terms of potential. The use of the material for forming the tube and the fin prevents cracks from developing in the vicinity of the interface between the fillet and the tube or the fin.

Abstract: A process for producing an intake manifold having a main pipe made of wrought aluminum material and having an open end, a closed end opposite to the open end, a plurality of holes formed in its peripheral wall and outward tubular projections integral with the peripheral wall and each formed around each of the holes, and a plurality of branch pipes made of wrought aluminum material and each having one end fitting in and joined to each of the tubular projections. The manifold is smooth-surfaced in its interior, diminished in resistance to air and improved in air intake efficiency. The manifold requires no finishing procedure unlike those prepared by casting.

Abstract: An intake manifold comprising a main pipe made of wrought aluminum material and having an open end, a closed end opposite to the open end, a plurality of holes formed in its peripheral wall and outward tubular projections integral with the peripheral wall and each formed around each of the holes, and a plurality of branch pipes made of wrought aluminum material and each having one end fitting in and joined to each of the tubular projections. The manifold is smooth-surfaced in its interior, diminished in resistance to air and improved in air intake efficiency. The manifold requires no finishing procedure unlike those prepared by casting.