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

Definitions

• the invention relates to a protective layer for surfaces of metallic textile machine parts, in particular spinning machine parts, which protective layer consists of ceramic particles of at least two different, non-metallic elements embedded in a metallic matrix.
• the object of the invention is therefore to provide a protective layer for the highly stressed components of textile machines, which better meets the requirements with regard to abrasion resistance than the known protective layers.
• one hard particle consists of a carbide phase and the other consists of an oxidic phase.
• the disadvantages of the low toughness of oxidic hard materials can be largely compensated for.
• This embedding and the adhesive strength of the protective layer on the component or substrate can be improved if the oxidic particles were generated during the coating process using the HVC (high-speed flame spraying) process.
• the HVC process is a flame spray process developed in recent years in which the spray particles reach speeds that are above the speed of sound (Sulzer Technical Review (STR) 4/1988, page 4-10).
• Nickel or cobalt-based alloys that contain at least chromium as alloy components have proven to be a suitable metal matrix for the coating.
• the carbidic phase preferably consists of tungsten carbides, which advantageously consist of at least 70% tungsten carbide (WC).
• the tungsten carbides at least partially by carbides of the metals titanium (Ti), tantalum (Ta), vanadium (Va) and / or To replace niobium (Nb).
• the oxidic component of the protective layer which makes up up to 5% by weight, is preferably in the form of chromium oxides, in particular as chromium oxide (Cr2O3).
• the proportion of the oxidic phase can be varied for the HVC process by a suitable choice of the gas parameters - in particular the ratio between oxygen and fuel gas in the flame spray jet.
• the fuel gases used are primarily propane (C3H8), propylene (C3H6) or hydrogen (H2).
• the protective layer consists of a cobalt / chromium alloy as a metallic matrix and tungsten carbide (WC) as a carbide, and chromium oxide (Cr2O3) as an oxidic phase.
• One criterion for a high abrasion resistance of the protective layer is its surface roughness;
• the desired mean roughness values can be influenced in a targeted manner by suitable selection of the particle size of the wettable powder.
• Metallic materials based on iron, aluminum, copper or titanium are used as substrates.
• the surface to be coated is first degreased with the help of solvents and then sandblasted with granular material made of aluminum oxide (corundum, Al2O3).
• the grain size of Al2O3 is, for example, between 0.12 and 0.25 mm.
• the substrate is approximately 100 mm from the sandblasting source, which accelerates the grains at a pressure of approximately 3 bar.
• wettable powder which consists of% by weight 86% tungsten carbide (WC) and 14% of CoCr 30 cobalt base alloy consists.
• the particle size distribution of the wettable powder depends on the desired surface roughness of the surface provided with a protective layer in the sprayed state.
• the layer is applied in a system as shown in the mentioned article from STR 4/88.
• a fuel gas stream is emitted for a powder of the fraction + 5 -25 ⁇ m 60 l / min propane and 500 l / min oxygen used, which is mixed with 20 l / min nitrogen as the carrier gas.
• the powder is introduced in an amount of 14 g / min into the gas jet, with velocities between the substrate and pul fashionendem gas jet of 30-60 m / min and temperature of 2900 o C.
• the distance between the spraying system and substrate is about 250 mm.
• the spraying process in which the spray gun, controlled by a robot, sweeps the surface to be coated line by line, is maintained until a layer thickness of 20-50 ⁇ m is reached.
• the layer essentially consists of a metallic matrix of Co, Cr mixed crystals in which about 80% by weight of tungsten carbides and 5% by weight of chromium oxides are embedded; both Tungsten carbides have a share of about 72% in WC, while the chromium oxides, which - as can be found in metallographic tests or by X-ray fine structure analysis based on the distribution of the phases - formed during the coating process, are present as Cr2O3 alone.
• the Ra values of the protective layer in the sprayed state in the present case are 1.5-2.0 ⁇ m.
• the layers have high adhesive strength.

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)
• Spinning Or Twisting Of Yarns (AREA)

Applications Claiming Priority (2)

Publications (1)

Family

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Family Applications (1)

Country Status (3)

Cited By (2)

Families Citing this family (2)

Citations (5)

• 1989
  • 1989-10-11 CH CH3704/89A patent/CH679047A5/de not_active IP Right Cessation
• 1990
  • 1990-08-29 EP EP90810650A patent/EP0423063A1/fr not_active Withdrawn
  • 1990-09-26 JP JP2256781A patent/JPH03126856A/ja active Pending

Patent Citations (5)

Non-Patent Citations (2)

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