Classifications

• • 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
  • C23C4/00—Coating by spraying the coating material in the molten state, e.g. by flame, plasma or electric discharge
  • C23C4/04—Coating by spraying the coating material in the molten state, e.g. by flame, plasma or electric discharge characterised by the coating material
  • C23C4/06—Metallic material
  • C23C4/08—Metallic material containing only metal elements
• • 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
  • C23C4/00—Coating by spraying the coating material in the molten state, e.g. by flame, plasma or electric discharge
  • C23C4/12—Coating by spraying the coating material in the molten state, e.g. by flame, plasma or electric discharge characterised by the method of spraying
  • C23C4/129—Flame spraying

Definitions

• the invention relates to a method for applying solder to a workpiece surface by means of flame spraying, the solder being melted by a fuel-oxygen flame and atomized with the aid of a propellant gas and applied to the workpiece surface.
• the surfaces of the workpieces can be coated with solder, brought into contact with one another and heated to the melting temperature of the solder in order to achieve a metallic bond.
• the solder is fed, for example in wire form, to a flame spray gun and passed axially through the acetylene-oxygen flame.
• the molten solder is then caught by a jet of compressed air, atomized and thrown onto the prepared workpiece surface, on which the atomized solder forms a coherent layer and adheres to the workpiece surface.
• solder layers that have been produced in this way often do not have the desired quality.
• Analysis of a solder layer applied to a workpiece surface by flame spraying shows that its composition differs from that of the solder prior to flame spraying, i.e. differs from the composition of the solid solder.
• some of the alloy elements are missing from the applied solder layer - in particular alloy elements with low melting temperatures.
• the solder layer applied to the workpiece surface is oxidized. As a result of this change in the solder, the strength of soldered connections, which are produced according to the described method, drops.
• the invention is therefore based on the object of specifying a method of the type described at the outset, in which the composition of a solder layer which was applied to a workpiece surface by flame spraying differs as little as possible from that of the corresponding solid solder.
• This object is achieved in that an inert gas is used as the propellant gas and a fuel-oxygen ratio is set in which the fuel fraction is greater than the fuel fraction required for a neutral flame setting.
• an inert gas is used as the propellant gas jet and a specific ratio of the amount of fuel to the amount of oxygen is set. It was found that the composition of the solder layer sprayed on by the process according to the invention differs only slightly from that of the corresponding solid solder. This effect may be due to the fact that the use of an inert propellant and by setting a reducing flame, burn-off of alloy elements and oxidation of the molten solder can be prevented.
• soldered connection between a part soldered onto this workpiece surface and the workpiece has good strength.
• the prerequisite for this is that the solder has been applied in a sufficient layer thickness.
• the melting temperature of the solders is not increased by the flame spraying process according to the invention. Overall, this process results in solder layers with very good soldering properties. This method is particularly advantageous if large-area, complex-shaped components have to be charged with solder before soldering.
• the inert atomizing gas is brought up to the molten solder on all sides, ie after the solder has passed through the fuel-oxygen flame.
• the inert gas also has the function of forming a protective gas jacket around the molten and atomized solder.
• the inert gas and the fuel-oxygen ratio according to the invention thus create conditions under which the interaction of the molten solder with oxygen is minimal.
• any gas that is inert to the molten solder can be considered as an inert gas.
• gases are, for example, the noble gases.
• argon or helium are therefore used as the propellant. Because of its low cost, its availability and its inert properties, the use of nitrogen as a propellant has also proven particularly useful. According to the invention, nitrogen is therefore preferably used as the propellant gas.
• acetylene is advantageously used as fuel. It is advantageous if, according to a preferred embodiment of the invention, an acetylene-oxygen mixture is used in which the ratio of the amount of acetylene to the amount of oxygen (Nm ') is between 1: 0.8 and 1: 1.15.
• a mixing ratio of 1: 0.9 is set.
• the method according to the invention is suitable for applying all types of solder materials.
• the burn-off of alloy elements with low melting points is effectively suppressed by the method according to the invention, the application of the method according to the invention to solders containing such alloy elements is particularly advantageous.
• this surface is expediently subjected to a pretreatment.
• the surface is prepared by blasting. Glass, for example, can be used as the abrasive.
• the workpiece surface is roughened by blasting. In this way, a metallically pure, fissured and larger surface compared to the untreated workpiece is created and thus optimal conditions for the effectiveness of the adhesive mechanism between surface and solder layer are created.
• a wire-shaped hard solder (diameter 3 mm) is placed in a flame spray gun in the central channel inserted and with a wire feed speed of approx. 0.55 m / min. promoted.
• An acetylene-oxygen mixture is introduced and burned in a channel of the flame spray gun which surrounds the central channel in a ring shape (mixture ratio of amount of acetylene to amount of oxygen approx. 1: 0.9).
• the acetylene-oxygen flame surrounding the solder melts the solder.
• the molten solder is atomized by the propellant. Nitrogen is used as the propellant gas, which is conducted in a channel coaxial with the acetylene-oxygen channel.
• the nitrogen forms a closed annular propellant jacket around the acetylene-oxygen flame and the molten solder. Protected by the nitrogen jacket, the atomized solder is thrown onto the prepared workpiece surface. A spray distance between the flame spray gun and the workpiece of approx. 160 mm is maintained. The relative speed between the flame spray gun and the workpiece is approximately 25 m / min. An analysis of the solder layer showed that its composition differs only slightly from that of the corresponding solid solder.

Landscapes

• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Physics & Mathematics (AREA)
• Plasma & Fusion (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Materials Engineering (AREA)
• Mechanical Engineering (AREA)
• Metallurgy (AREA)
• Organic Chemistry (AREA)
• Coating By Spraying Or Casting (AREA)

Applications Claiming Priority (2)

Publications (1)

Family

ID=6260067

Family Applications (1)

Country Status (2)

Cited By (2)

Families Citing this family (1)

Citations (9)

• 1985
  • 1985-01-17 DE DE19853501410 patent/DE3501410A1/de not_active Withdrawn
• 1986
  • 1986-01-08 EP EP86100175A patent/EP0189053A1/fr not_active Ceased

Patent Citations (9)

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