GB697908A - Improvements in or relating to porous materials - Google Patents

Abstract

697,908. Making porous material. NATIONAL RESEARCH DEVELOPMENT CORPORATION. April 6, 1951 [April 6, 1950; June 3, 1950], Nos. 8757/50 and 14040/50. Class 83 (ii). [Also in Groups I, VIII and XXVIII] Porous material comprises wire-like members laid up in a single ply or layer, or in two or more superposed plies or layers, the or each ply being one member thick, the ply, at least in the case of a single ply material, having adjacent members contiguous with one another, and being subsequently deformed so as to produce pores between them through the ply or each of them and joined one to another. In a particular embodiment soft iron wires 1 of 16 S.W.G. spaced by wires 2 of 36 S.W.G. are stacked in plies and lightly rolled to deform the wires, Fig. 2, forming pores 3. Copper foil sheet is then laid on the stack and the whole placed in a controlled-atmosphere brazing furnace. After brazing the stack is coldrolled and then rebrazed. The pores are then reduced to the required size by further cold rolling, Fig. 3. In a modification, a single ply is formed by feeding members through rollers which crimp and guide them in spaced relationship, thereafter subjecting them to a tacking operation as by gluing or brazing, before proceeding with the brazing and other steps aforementioned. For the production of multi-ply sheets the plies, with members of adjacent plies in angular relationship are fed through cold rolls and tacked. In a further modification wire-like members are fed on to a rotating frame, which is rotated about a different axis after each revolution so that the members in adjacent plies will be in non-parallel relationship. The assembly thus formed is brazed and cut along the sides of the frame, each side of the assembly thus constituting a unit compact upon which further deformation or brazing processes may be carried out if required. A porous walled tube, Fig. 5, comprises several layers of a ply consisting of alternate round and half-round section 16 S.W.G. mild steel wire, the half round section wire being twisted about 8 times to the inch, and the assembly brazed and rolled. Where the members are of synthetic resins or rubbers the joining may be arranged to take place during and by virtue of the curing operation. The material is of use in making turbine and like blades, or parts of turbines, com. pressors, combustion apparatus, heat exchangers, and other components of gas turbine plant, de-icing and boundary-layer removal plant in aircraft, and porous walled fluid ducts.