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
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C29/00—Alloys based on carbides, oxides, nitrides, borides, or silicides, e.g. cermets, or other metal compounds, e.g. oxynitrides, sulfides
  • C22C29/02—Alloys based on carbides, oxides, nitrides, borides, or silicides, e.g. cermets, or other metal compounds, e.g. oxynitrides, sulfides based on carbides or carbonitrides
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C29/00—Alloys based on carbides, oxides, nitrides, borides, or silicides, e.g. cermets, or other metal compounds, e.g. oxynitrides, sulfides
  • C22C29/02—Alloys based on carbides, oxides, nitrides, borides, or silicides, e.g. cermets, or other metal compounds, e.g. oxynitrides, sulfides based on carbides or carbonitrides
  • C22C29/04—Alloys based on carbides, oxides, nitrides, borides, or silicides, e.g. cermets, or other metal compounds, e.g. oxynitrides, sulfides based on carbides or carbonitrides based on carbonitrides
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C29/00—Alloys based on carbides, oxides, nitrides, borides, or silicides, e.g. cermets, or other metal compounds, e.g. oxynitrides, sulfides
  • C22C29/02—Alloys based on carbides, oxides, nitrides, borides, or silicides, e.g. cermets, or other metal compounds, e.g. oxynitrides, sulfides based on carbides or carbonitrides
  • C22C29/06—Alloys based on carbides, oxides, nitrides, borides, or silicides, e.g. cermets, or other metal compounds, e.g. oxynitrides, sulfides based on carbides or carbonitrides based on carbides, but not containing other metal compounds
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
  • B22F2207/00—Aspects of the compositions, gradients
  • B22F2207/01—Composition gradients
  • B22F2207/07—Particles with core-rim gradient

Definitions

• the invention relates to a coating powder for use in various coating technologies, such as the different variants of thermal spraying, such as plasma spraying, for example.
• the coating powder according to the invention can be applied to various highly stressed components which are exposed to a wide variety of stresses, such as, for example, abrasive and erosive wear, corrosion and high temperatures or a wide variety of combinations of these stresses, and which are used in the most varied areas of technology .
• Application examples are coated components in vehicle construction, mechanical engineering, in chemical and petrochemical plants, and many other branches of industry.
• Various hard metal-like coating powders are widely used in technology. These are characterized in that a carbide hard material such as WC or Cr3C2 is embedded in a ductile binder matrix.
• the most important systems for coatings are WC-Co and Cr3C2-NiCr.
• WC-Co has a very high wear resistance. Use at elevated temperatures (up to a maximum of 450 ° C) and simultaneous chemical exposure is limited. Attempts have been made to improve the corrosion resistance in particular by using other binders such as Ni and alloy with chromium, which is only possible to a limited extent due to the low alloyability of the system.
• Cr3C2-NiCr on the other hand, can be used well at higher temperatures (up to 750-80u ° C) and corrosive loads. However, the wear resistance of the system is lower than that of WC-Co.
• DD 224 057 describes a coating powder based on TiC which, in addition to at least one of the metals Ni, Co, Cr, W and B and / or Si, also contains Mo or Mo 2 C and free carbon. Individual components, such as Mo 2 C, can be bound to the TiC. Because there is no composite powder with a hard metal-like microstructure and the individual powder components are very coarse, no highly wear-resistant layers can be produced.
• DE 41 34 144 describes a carbide wettable powder which is intended to protect the core from oxidation by coating with active carbon. Titanium carbide and titanium carbon itide are also mentioned as wettable powders to be coated in a matrix of metals from the group iron, nickel and cobalt.
• WO 87/04732 describes a method for producing a wear-resistant layer, made of a powdery material which contains 10-50% by mass of TiC and an Fe and / or Ni alloy or a Co alloy. The proportion of the hard material phase in these compositions is too small to significantly increase the wear resistance.
• US Pat. No. 4,233,072 uses mechanical mixtures of the composition 60-85% Mo, 10-30% of a NiCr alloy and 5-20% TiC for the coating of piston rings.
• the hard material content is also extremely low.
• EP 0 425 464 describes a roll for paper manufacture which is provided with several layers.
• the top layer is a hard metal-like layer whose hard material phase consists of tungsten, chromium, titanium, niobium or boron carbides or a mixture thereof, and whose metallic binder phase Ni, Co or Fe or their alloys with transition metals from IV VI.
• Sub-group of the PSE can be alloyed.
• the hard phase content can be up to 96%. Due to the insufficient microstructural formation in the coating powder, substrates coated with them show poor wear behavior, so that the field of application of such a layer remains limited to this special application.
• M.Yu. Zashlyapin et al. (Sashchitnye pokrytiya na metallakh, volume 20, 1986, p. 52-55) describe coating powders with TiCN as hard material phase and binders consisting of 75% by mass of Ni and 25% by mass of Mo, which in the composite powder contain 35-65% by mass. % are included. This corresponds to 65-78 vol .-% hard material phase in the coating powder.
• the sintered wettable powders consist of TiCN and a solid solution of TiCN and Mo in the nickel matrix. Due to the use of Mo as a starting material and the associated low content of non-metals, this powder is susceptible to oxidation and substrates coated with it show poor wear behavior.
• this hard metal-like coating powder to be proposed according to the invention it is to be achieved that, by conventional coating technologies, hard metal-like, extremely resistant layers can be produced on highly stressed components which, compared to known technical solutions, have improved combinations of properties such as high wear resistance at high temperature, high wear resistance with simultaneous high corrosive load, lower Have coefficient of friction at high temperature, and which can be easily adapted to different stress profiles by varying the composition.
• the coating powder according to the invention is characterized in that it has a microstructure similar to hard metal. At least two cubic hard material phases, which have a core-shell structure and form a hard material grain, are embedded in a metallic binder matrix composed of at least one or more of the elements Ni, Co and Fe. Said core-shell structure is formed by metallurgical reactions, dissolution and re-excretion processes during the sintering process in the production of coating powder.
• the task of the hard material phase in the shell is, in particular, to improve the poor wetting of the pure hard material TiC with the usual binding metals Ni, Co and Fe or their alloys.
• the metals Mo and W which are added in particular in the form of their carbides Mo 2 C or WC as starting powder in the production of coating powder, have proven to be particularly suitable.
• these carbides preferentially dissolve in the binder compared to TiC and separate as mixed carbides in the cooling phase of the sintering process (Ti.MoJC ⁇ x or (Ti.WJC ⁇ x as a shell around undissolved TiC grains.
• Nitrogen is advantageously added as a further alloy element. This is achieved by completely or partially replacing the titanium carbide, which is used as the starting material for the production of coating powder, with titanium carbonitride. It is known from developments for cutting materials that the Mo and / or W content in the binder phase can be increased in particular by increasing the nitrogen content (P. Etmayer et al., Int. J. Refractory Metals & Hard Materials, 1995, No 6, vol.13, p.343-351). The known fact that nitrogen is released from carbonitrides at elevated temperatures, such as also occur during thermal spraying, has so far prevented the use of nitrogen in commercial hard metal-like coating powders.
• the microstructure formation of the coating powder according to the invention protects the hard material phases from nitrogen losses during the spraying process.
• the use of nitrogen-containing coating powders is particularly advantageous when layers are produced from these which must have a low coefficient of friction.
• the elements Zr, Hf, V, Nb, Ta and Cr are also further alloy elements according to the invention. These can be used alone or together with nitrogen. Alloy elements such as AI, B and others are also advantageous in special applications.
• metallic alloy elements in the form of carbides are introduced during the production of the coating powder.
• Cr 3 C 2 , Cr 7 C 3 , Cr 23 C 6 , WC, W 2 C and M02C can, for example, still be detectable by X-ray phase analysis after the sintering process.
• the orthorhombic Cr 3 C 2 is detected, for example, after sintering from a certain amount by X-ray phase analysis.
• the carbide hard materials Cr 3 C 2 , Cr 7 C 3 , Cr 23 C 6 , WC, W 2 C and Mo 2 C oxidize in such a way that a free carbide of the metal is released when free carbon is released - if this is stable - and then the metal itself is formed (RFVoitovich, Okislenie karbidov i nitridov, Kiev, Naukova dumka, 1981).
• This forming metal is able to further alloy the metallic binder.
• This also has the effect that the alloy state of the binder is positively influenced and the oxygen content in the layer is reduced.
• the chromium formed by oxidation of the Cr 3 C 2 significantly increases the corrosion resistance of the binder. It is also important that all carbidic and carbonitridic starting materials used for coating powder production have a low oxygen content.
• Such a distribution of the alloy elements is also within the meaning of the present invention.
• Ti C, N
• Mo or W an accumulation of Mo or W can be observed.
• these values are well above the specified limit values.
• Several shell phases can also be detectable in special alloy variants.
• the volume ratio between the hard material phases and the binder phase in the coating powder according to the invention can be varied within wide limits, but a sufficiently high wear resistance of the layers is only achieved if the volume fraction of the hard materials, based on the starting materials before sintering, is> 60% by volume is.
• both individual hard materials such as TiC, TiN, Ti (C, N), Mo 2 C, WC, and Cr 3 C 2
• complex hard materials such as (Ti, Mo) C and (W, Ti) C
• single hard materials are preferably used.
• the carbon content of the titanium-containing hard materials is in the range from 4 to 21% by mass, the nitrogen content is a maximum of 17% by mass.
• TiC or Ti (C, N) this corresponds to all compositions of the complete mixed crystals from TiC to approximately TiC 0 3 N 0 7 . In the corresponding ratio, TiC and TiN can also be used as starting materials.
• the volume fraction of these titanium-containing hard materials is 50-95% by volume, preferably 60-85% by volume. If a third hard material phase is used, its proportion is at most 35% by volume, preferably at most 25% by volume. The proportion of the second hard material phase responsible for the formation of the core-shell structure results from the respective differences.
• the alloying elements such as W, Mo, Cr, are preferably added as carbides and can dissolve during the sintering process in the production of coating powder both in the cubic hard material phases and partly in the binder phase.
• the core-shell structure of the cubic hard material phases that characterizes the coating powder is transferred to the layer and can be detected in the layer.
• Another advantage of the coating powders according to the invention is that they can be processed almost equally well with the most varied process variants of thermal spraying.
• the coating powder according to the invention can by different coating powder production technologies, which include a sintering process as the most important technological step, such as Sintering and breaking.
• a sintering process as the most important technological step
• coating powder particles of irregular morphology are produced with the technology of sintering and breaking.
• the preferred technology for producing the wettable powders according to the invention is therefore agglomeration and sintering.
• a spray drying process is advantageously used for the agglomeration.
• the spray drying parameters are to be chosen so that granules with a high green density are formed, which are compacted by a simple sintering process in which the core-shell structure of the hard material phases can form in the binder matrix.
• the high green density of the spray drying granules is also important for the sintering of individual granules to be kept to a minimum.
• the sintering leads to a change in the phase composition in the coating powders due to the metallurgical reactions, dissolution and re-excretion processes, the changes in the elemental compositions are insignificant.
• the size of the hard material particles with core-shell structure in the sintered coating powder is ⁇ 10 ⁇ m, but preferably ⁇ 5 ⁇ m. After sintering, the lightly sintered coating powder is processed by a gentle grinding process and then fractionated according to the requirements for its application in one of the coating technologies mentioned.
• the grain size of the coating powder according to the invention must be adapted to the requirements of the respective coating technology, and can therefore be in a wide range from 10-250 ⁇ m.
• Binder proportion are premixed dry, dispersed in water and then in a wheelchair Stainless steel containers with carbide balls intimately mixed.
• the suspension is mixed with 1.5% by mass of an adapted binder composed of polyvinyl alcohol and polyethylene glycol and then granules are produced in a spherical shape by spray drying.
• the binder is driven out together with the sintering in a one-stage tempering.
• Debinding and tempering are carried out in flat graphite crucibles under argon at a heating rate of 5 K / min to 600 ° C and 10 K / min up to the sintering temperature at 1320 ° C, which is followed by an isothermal holding time of 30 min.
• Figure 1 shows the metallographic cross section of a coating powder particle with a magnification of 3000 times. The grain-shell structure of the hard material particles can be clearly seen.
• the sintered powders are subjected to gentle grinding and then fractionated according to the requirements for use in the various coating technologies.
• the preferred grain size for use in high-speed flame spraying or detonation spraying is 20-45 ⁇ m.
• the d10 for this powder was 20 ⁇ m, the d90 for 42 ⁇ m.
• the powder with the grain size 20-45 microns with a detonation spray system "Perun P" (Paton Institute, Ukraine) with a barrel with a length of 660 mm and 21 mm in diameter to layers with a layer thickness of about 250 microns on steel substrates are suitable for the abrasion test.
• the spraying conditions optimized for this material were used.
• the spray distance was 120 mm with a detonation rate of 6.6 detonations / s.
• An acetylene / oxygen mixture in a volume ratio of 1.0 was used.
• the coating powder was fractionated; a particle size range of 20-45 ⁇ m was also used for spray tests.
• the morphology of this wettable powder according to the invention is shown in Figure 4.
• the coating powder was also processed under spray conditions analogous to embodiment 1 using the "Perun P" detonation spray system (Paton Institute, Ukraine) to give layers with a layer thickness of approximately 250 ⁇ m on steel substrates which are suitable for the abrasion test.
• the mass loss after 5904 m wear path was 68 mg, when converted to the volume loss 10.6 mm 3 .
• Hard material and 13.5% by volume binder were produced using the same method as in embodiment 1, a coating powder. There were differences in the sintering temperature, which was 1300 ° C here. The microstructure of this coating powder corresponds to that in exemplary embodiment 2. The coating powder was fractionated; particle sizes of 20-45 ⁇ m were also used for spray tests.
• the coating powder was also processed under spray conditions analogous to embodiment 1 using the "Perun P" detonation spray system (Paton Institute, Ukraine) to give layers with a layer thickness of approximately 250 ⁇ m on steel substrates which are suitable for the abrasion test.
• the mass loss after 5904 m wear path was 58 mg, when converted to the volume loss 8.9 mm 3 .
• the microstructure of this coating powder corresponds to that in exemplary embodiment 2.
• the coating powder was fractionated; particle sizes of 20-45 ⁇ m were also used for spray tests.
• the coating powder was also processed under spray conditions analogous to embodiment 1 using the "Perun P" detonation spray system (Paton Institute, Ukraine) to give layers with a layer thickness of approximately 250 ⁇ m on steel substrates which are suitable for the abrasion test.
• the mass loss after 5904 m wear path was 80 mg, when converted to the volume loss 12.1 mm 3 .
• Embodiment 5 Embodiment 5
• a coating powder from embodiment 1 was likewise applied to a steel substrate suitable for the abrasion test using a PT A-3000S plasma spraying system with an F4 burner in the atmosphere.
• a PT A-3000S plasma spraying system with an F4 burner in the atmosphere.
• an Ar / H 2 plasma (best results at 45 l / min Ar and 14 l / min H 2 ) with a plasma power of 38 kW was used.
• the mass loss after 5904 m wear path was 100 mg, when converted to the volume loss 16.4 mm 3 .
• a coating powder from exemplary embodiment 1 was also applied to steel substrates suitable for the abrasion test by high-speed flame spraying with a PT CDS spraying system with a gas mixture of hydrogen (600 l / min) and oxygen (300 l / min) at a spraying distance of 200 mm.
• the mass loss after 5904 m wear path was 94 mg, when converted to the volume loss 15.4 mm 3 .

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• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Materials Engineering (AREA)
• Mechanical Engineering (AREA)
• Metallurgy (AREA)
• Organic Chemistry (AREA)
• Physics & Mathematics (AREA)
• Plasma & Fusion (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Coating By Spraying Or Casting (AREA)
• Powder Metallurgy (AREA)
• Paints Or Removers (AREA)
• Manufacture Of Metal Powder And Suspensions Thereof (AREA)
• Materials For Medical Uses (AREA)

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• 1996
  • 1996-10-02 DE DE19640788A patent/DE19640788C1/de not_active Expired - Fee Related
• 1997
  • 1997-09-25 AT AT97912020T patent/ATE210205T1/de active
  • 1997-09-25 CA CA002267960A patent/CA2267960C/fr not_active Expired - Fee Related
  • 1997-09-25 US US09/269,819 patent/US6162276A/en not_active Expired - Lifetime
  • 1997-09-25 WO PCT/DE1997/002207 patent/WO1998014630A1/fr active IP Right Grant
  • 1997-09-25 EP EP97912020A patent/EP0948659B1/fr not_active Expired - Lifetime
  • 1997-09-25 BR BR9711858A patent/BR9711858A/pt not_active IP Right Cessation
  • 1997-09-25 JP JP51613398A patent/JP4282767B2/ja not_active Expired - Fee Related
• 1999
  • 1999-03-30 NO NO19991572A patent/NO321957B1/no not_active IP Right Cessation

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