Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
  • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
  • B23K20/00—Non-electric welding by applying impact or other pressure, with or without the application of heat, e.g. cladding or plating
  • B23K20/12—Non-electric welding by applying impact or other pressure, with or without the application of heat, e.g. cladding or plating the heat being generated by friction; Friction welding
  • B23K20/1215—Non-electric welding by applying impact or other pressure, with or without the application of heat, e.g. cladding or plating the heat being generated by friction; Friction welding for other purposes than joining, e.g. built-up welding
• • C—CHEMISTRY; METALLURGY
  • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
  • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
  • C23C26/00—Coating not provided for in groups C23C2/00 - C23C24/00

Definitions

• the invention relates to methods of joining materials by causing relative, frictional movement between respective surfaces of the materials while the materials are urged together. Such methods are involved in friction welding and friction surfacing in which a first component in relative motion either rotary (including orbital) or oscillatory (eg.linear) is caused to bear against a second component so as to join to it via a plasticised intermediate layer which is developed due to the relative motion under applied load.
• the two components may be of similar or different metals or alloys.
• the invention applies for example to both continuous drive and so-called inertia friction welding processes as utilised for joining materials together in well known rod or tube form, or in a stud to plate configuration (including friction surfacing) , or in a ring to cylinder format as in radial friction welding.
• Friction welding i ⁇ well known as a solid phase process in which a plasticised layer is developed (between the components to be joined) , which layer is maintained at an elevated temperature less than the melting point by the work done in rapid shear within the plasticised layer.
• a method of joining materials by causing relative, frictional movement between respective surfaces of the materials while the materials are urged together is characterised in that at least one of the surfaces is treated with an agent to remove contaminates.
• the invention is primarily concerned with treating the surface of one material (generally that one which does not flow significantly, or as much as the other, under the conditions of operation) with an agent so as to modify the properties of the surface and improve the bonding via the plasticised layer to the other component.
• the agent is preferably activated or energised by the frictional movement itself.
• the active agent may comprise a powder, paste, liquid, or gaseous atmosphere and is used to etch or dissolve a surface layer of the material to which it is applied to reduce or eliminate the natural oxide or other surface contaminate.
• a suitable paste is a flux compound Murex Aluminium Welding Saffire Flux such as is used in oxygas welding of steels.
• This flux may be pasted on to the metal or alloy to which a component is to be joined as in friction welding or a surface applied as in friction surfacing. At the elevated temperature of the friction welding process the flux is activated and chemically attacks the surface but a ⁇ the friction welding or surfacing operation progresses it is dispersed so as not to remain as a barrier between the components to be joined.
• the beneficial action of this flux is illustrated in an extreme case of depositing an aluminium member onto a similar aluminium plate by friction surfacing, where the interface region is no longer apparent where the flux paste has been applied, prior to friction surfacing to the substrate material.
• the surface treatment by an active agent may be carried out prior to the frictional joining process, the surface being protected by suitable means from significant further contamination or oxidation until the joining process is completed.
• the material to be surfaced may be etched in a suitable chemical re-agent and then friction welded or surfaced in the presence of the etchant or alternatively under a protective fluid layer (such as oil or water) or gaseous protection ⁇ uch as an inert gas or non reactive gas such as argon or nitrogen respectively.
• Sodium Fluoride may be used for ' stainless steel and nickel based alloys.
• the objective of the flux or etchant is to reduce the contaminated or oxide layers on the material such that the friction welding or friction surfacing process is more effective and higher bond strengths are achieved, even though one component is virtually not contributing directly to the plasticised intermediate layer which is formed.
• the active agent is removed at least on complfe'cion of the joining process.
• the plasticised material (which is largely developed by the consumable member) is at a sufficient temperature and pressure, together with relative movement, to disperse the active agent (if still present while frictioning) ⁇ o as to effect a reliable joint.
• Examples of application are the use of fluxes for the friction surfacing of aluminium and its alloys, and similar materials with a tenacious oxide film and in the joining of soft materials to hard material ⁇ as in the friction bonding of copper and its alloy ⁇ , or other suitable soft materials, to a steel cylinder as in the case of shell banding.
• the above examples relate to active, chemical type agents for treating the surface of the substrate.
• physical (non-active) type agents or agents not necessarily relying on chemical action can be utilised.
• one well known problem is in friction welding or friction surfacing to cast iron type materials, due to smearing or spreading of the carbon content across the interface - thereby reducing the friction and associated heating produced at the interface, and causing the intermediate layer to be generated which prevents or reduces the effective bonding.
• a scouring agent may be added to the consumable in a ⁇ ufficient quantity to a ⁇ sist in the break up of any such free carbon layer, but not so much as to interfere significantly with the joint to be establi ⁇ hed.
• This technique may also be used to improve the bonding in for example friction surfacing of coated sub ⁇ trates.
• friction ⁇ urfacing galvanised steel difficulty is experienced in generating ⁇ ufficient friction at the interface due to the low frictional properties of the zinc layer which is smeared across the surface by the frictioning action.
• suitable particulates may be used, such as alumina or silica, for reducing or disper ⁇ ing the coating layer of low frictional properties.
• the scouring agent may be distributed through out the cross section of the consumable member a ⁇ for example in an MMC type material. However, to reduce any unwanted scouring material in the region of the interface it is preferable for the scouring agent to be concentrated towards a periphery of a consumable.
• the materials to be deposited in friction surfacing include metals and their alloys, and compound materials formed of metals and non-metals such a ⁇ metal matrix composite ⁇ (MMC) .
• MMC metal matrix composite ⁇
• Active agent ⁇ both chemical and phy ⁇ ical according to the invention may conveniently be incorporated in the consumable member by mean ⁇ of in ⁇ erts and the like in holes in the con ⁇ umable member ⁇ .
• Such hole ⁇ may be filled with powders or pastes or flux cored wires and so forth to provide active chemicals for reducing surface oxides or other contaminants and to provide active physical agents for cleaning or scouring surfaces, either separately or in combination.
• Figure 2 illustrates the results of friction surfacing of stainless steel on to a spheroidal graphite iron sub ⁇ trate; and, Figure 3 is a magnified version of Figure 2.
• Figure 1 illustrates the result of providing an E1B aluminium ⁇ urface on a SIB aluminium substrate, at x500 enlargement.
• a Murex Aluminum Welding Saffire Flux wa ⁇ provided as a paste on the aluminium substrate and a conventional friction surfacing process was then carried out.
• the flux was activated and chemically attacked the ⁇ urface of the substrate as de ⁇ cribed earlier.
• the flux is disper ⁇ ed re ⁇ ulting, a ⁇ seen in Figure 1, with an absence of any discontinuity or lack of bond in ⁇ - the vicinity of the interface.
• Figure 2 illustrate ⁇ the result of providing a stainless steel deposit on a spheroidal graphite (SG) iron substrate.
• SG spheroidal graphite
• a consumable member of stainless steel was provided containing less than 5% ceramic (alumina) .
• the deposit is bonded to the SG iron base over most of the cross section of the deposit although the outer edges are not bonded as is well known in friction surfacing without recourse to techniques to increase the pressure at the edges.
• Figure 3 shows the interface of Figure 2 at higher 5 magnification where the stainle ⁇ s steel layer exhibits no continuous discontinuity between itself and the substrate.
• the free carbon layer is clearly broken up giving satisfactory bond strength between the stainless steel deposit and the SG iron substrate. It is also noted that 0 the alumina particulate in the consumable member is also dispersed and does not form a barrier between the stainless steel and the SG iron.
• a suitable form of particulate bearing member can be produced from bar stock with an insert containing the 5 desired scouring agent, preferably set towards the periphery of the member.
• the insert may be a bore of 3mm or even 4mm diameter at some 8-9mm from the centre, giving a relative cross section of less than 2% and less that 3% respectively of 0 that of the bar.

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• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Materials Engineering (AREA)
• Metallurgy (AREA)
• Organic Chemistry (AREA)
• Pressure Welding/Diffusion-Bonding (AREA)

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Publications (1)

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Cited By (3)

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Citations (5)

• 1990
  • 1990-08-20 GB GB909018226A patent/GB9018226D0/en active Pending
• 1991
  • 1991-08-16 WO PCT/GB1991/001396 patent/WO1992003247A1/en active Application Filing
  • 1991-08-16 DE DE19914191962 patent/DE4191962T1/de not_active Withdrawn
• 1993
  • 1993-01-18 GB GB9300890A patent/GB2261623B/en not_active Expired - Fee Related

Patent Citations (5)

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