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
  • C23C30/00—Coating with metallic material characterised only by the composition of the metallic material, i.e. not characterised by the coating process
• • 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

Definitions

• the invention relates to a surface coating, a granular mixture for supply to a plasma coating and a method for coating a surface.
• DE 41 12 156 AI discloses a surface coating in which diamond particles are embedded in a matrix as a wear layer.
• a surface coating is produced by supplying suitable powders to a plasma torch, which are sprayed onto a substrate by the plasma torch.
• the plasma torch is supplied with carbon-containing gas or a carbon-containing liquid as the starting material.
• strong carbide formers are added with the powder, which form carbides from excess carbon in the matrix.
• the coating is suitable, among other things, for coating tools, such as screwdrivers, and is characterized by excellent wear properties.
• the invention proposes a surface coating with a hard metal grain which comprises a phase containing at least one hard metal in a first matrix containing at least one binder, the hard metal grain being arranged in a second matrix which contains at least one binder.
• hard metal grain means any particulate form of hard metal that consists of one or more hard materials, such as tungsten, titanium, chromium, molybdenum, tantalum carbide, with a binder.
• the binder can comprise a binder metal.
• a binder metal can be chosen from the iron group, for example.
• cobalt, nickel and iron come into consideration.
• brass can also be used as a binding metal.
• several different binder metals can also be used.
• the hard metal grain can be obtained from any known method, such as sintering or casting. In particular, recycled hard metals can also be used.
• the surface coating according to the invention is therefore characterized in that it has at least two different die phases.
• the one matrix phase comprises hard metal grains with the hard metal containing phase, which are located in the first matrix, while the second matrix phase primarily comprises the second matrix, in which the carbide grains are arranged. Individual hard metals can be dissolved in the second matrix phase. While the former matrix phase thus primarily has a granular, hard-metallic character, the second matrix phase can be recognized in that it essentially has the form of a solidified binder.
• Such a surface coating can be produced by a coating process in which a hard metal grain and a binder for the second matrix are applied to the surface by means of a plasma coating process.
• the necessary binder for the second matrix can be provided entirely from the carbide grit supplied.
• a portion of the carbide grain fed in can be melted during the coating process and binders can thus be made available. It is also possible to obtain the binder according to the invention for the second matrix by melting the coated or to be coated surface.
• the properties of the surface coating produced in this way can be mastered relatively easily if, in addition to the hard metal grain, the binder for the second matrix is supplied in particle form to the plasma coating device.
• the plasma coating device can have a granular mixture containing a hard metal grain and having a Content of further particles, which comprise a binder for the second matrix, are supplied.
• the binder for the second matrix is at least partially liquefied during the coating process, so that the hard metal grain is sufficiently embedded in the binder.
• the hard metal grain can be applied with the coating process in such a way that it does not melt or does not melt entirely. Smaller carbide grains and a certain surface area can melt and deliver binders.
• the characteristics of the hard metal grain embedded in the surface coating can be influenced by a suitable choice of the residence times and the position at which the hard metal grain of the plasma coating device is applied.
• the first matrix in such a method has a primarily granular, hard-metal character, but is formed with softer structures on its surface area or on the area of contact with the second matrix.
• this usually does not apply to the hard metal particles themselves.
• the first matrix and the second matrix can be fused into one another at least in a transition region. This requires a particularly intimate bond of the hard metal grain in the second matrix and thus an extraordinary hardness of the surface coating according to the invention.
• the coated or the uncoated surface is preferably not heated above 120 ° C., so that the surface is retained in its original hardness. This can be ensured by suitable cooling, for example by cooling nozzles.
• the binder of the first matrix preferably comprises at least one component which is identical to the binder of the second matrix.
• At least one of the binding metals comprises cobalt or brass.
• the hard metal grain is well embedded if the sum of the cobalt and brass contents in the materials supplied to the plasma coating device or in the entire surface coating does not exceed 14% by volume. A value of 12% by volume is particularly advantageous.
• the brass content is less than 7% by volume. as advantageous to achieve a sufficiently hard surface coating.
• the granular mixture or the surface coating according to the invention can have a tungsten content of 90% by volume to 80% by volume, preferably from 88% by volume to 87% by volume. This tungsten content is advantageously provided by the hard metal grain.
• the considerations described above relate to both the granular mixture and the coating process and the surface coating formed thereby.
• the surface coating if the named substances are present in the prescribed amounts, has particularly advantageous properties, i.e. for example, it is extremely hard with reasonable manufacturing costs.
• Sintered hard metal can be used as the hard metal grain. This nestles into the binder in a surprisingly good way and in this way forms a relatively hard surface coating.
• recycled hard metal can also be used. This can reduce the total cost of surface coating. In addition, such recycling is also advantageous from an environmental point of view.
• the hard metal used has a cobalt content
• at least part of this cobalt can be used to form the binder. This reduces the total cost of the surface coating, since existing cobalt is used anyway. This cost reduction is particularly advantageous in the case of recycled hard metal.
• the method according to the invention is particularly suitable for the use of a hard metal grain in which the grain is less than 90 ⁇ m. It is particularly suitable for a grain size that is smaller than 45 ⁇ m. With such a grain size, sufficiently large grains are stored in the surface coating, which guarantee a high wear resistance of the surface coating. This especially in connection with temperatures of max. 120 ° C, as already described above. In this way, for example, a surface coating of 25 ⁇ m can be ensured.
• a uniform and adjustable coating quality can be ensured by determining the cobalt content of the hard metal grain before coating and additionally adding cobalt to the coating process in order to achieve a desired cobalt content To achieve coating.
• the cobalt content of the second matrix can be adjusted in this way. It is understood that such a procedure is also advantageous for other binder materials.
• a granular mixture of a hard metal grain and brass powder is applied to a plasma coating device.
• the carbide grit contains 5.70% carbon, 0.01% sulfur, 0.07% nickel, 0.01% iron, 0.02% titanium, 0.04% niobium, 0, 13% tantalum and 6.89% cobalt in tungsten. These percentages refer to the total amount of tungsten.
• the grain size is entirely less than 45 ⁇ m.
• the brass powder comprises 78.5% copper and the rest zinc with about 0.2% impurities.
• a sieve analysis showed that 0.5% of the powder was larger than 160 ⁇ m and 55.05% larger than 40 ⁇ m.
• Cobalt was added to the granular mixture so that the granular mixture had a total of 6% cobalt, 6% brass and the remainder the other constituents of the hard metal grain. This granular mixture was applied to a plasma coater.
• the process enables a surface coating with a hardness of approx. 61 Rockwell or 2000 'Vickers to be achieved.

Priority Applications (5)

Applications Claiming Priority (2)

Publications (1)

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Family Applications (1)

Country Status (5)

Citations (9)

Family Cites Families (14)

• 1998
  • 1998-08-12 DE DE19836392A patent/DE19836392A1/de not_active Withdrawn
• 1999
  • 1999-08-07 EP EP99952333A patent/EP1117849B1/de not_active Expired - Lifetime
  • 1999-08-07 WO PCT/DE1999/002476 patent/WO2000009774A1/de active IP Right Grant
  • 1999-08-07 AT AT99952333T patent/ATE254674T1/de not_active IP Right Cessation
  • 1999-08-07 DE DE59907817T patent/DE59907817D1/de not_active Expired - Fee Related
  • 1999-08-07 DE DE19981545T patent/DE19981545D2/de not_active Expired - Fee Related
  • 1999-08-07 AU AU64626/99A patent/AU6462699A/en not_active Abandoned

Patent Citations (9)

Non-Patent Citations (1)

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