EP0028475A1 - Poudre pour la pulvérisation thermique et procédé pour la formation de joints abrasables au moyen de ladite poudre - Google Patents

Poudre pour la pulvérisation thermique et procédé pour la formation de joints abrasables au moyen de ladite poudre Download PDF

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Publication number
EP0028475A1
EP0028475A1 EP80303683A EP80303683A EP0028475A1 EP 0028475 A1 EP0028475 A1 EP 0028475A1 EP 80303683 A EP80303683 A EP 80303683A EP 80303683 A EP80303683 A EP 80303683A EP 0028475 A1 EP0028475 A1 EP 0028475A1
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EP
European Patent Office
Prior art keywords
powder
particles
powder according
nickel
microns
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP80303683A
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German (de)
English (en)
Inventor
Emilija Adamovic
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Viridian Inc Canada
Original Assignee
Sherritt Gordon Mines Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Sherritt Gordon Mines Ltd filed Critical Sherritt Gordon Mines Ltd
Publication of EP0028475A1 publication Critical patent/EP0028475A1/fr
Withdrawn legal-status Critical Current

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    • 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
    • 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
    • B22F1/00—Metallic powder; Treatment of metallic powder, e.g. to facilitate working or to improve properties
    • B22F1/18—Non-metallic particles coated with metal

Definitions

  • This invention relates to thermal spray powders, that is to say powders which are sprayed by thermal spraying such as flame spraying onto a substrate to form a coating on the substrate to provide desired surface properties.
  • One use of such powders is to form a coating on a substrate to provide an abradable seal, that is to say a coating which seals the space between the substrate and an adjacent surface movable relative thereto, and which is abraded to a controlled extent by relative movement between the substrate and the adjacent surface.
  • a seal is initially formed by thermal spraying a powder onto the substrate to form a coating with a slightly greater thickness than the spacing between the substrate and the adjacent surface, so that the coating is abraded by relative movement between the substrate and the adjacent surface to a slightly lesser thickness corresponding to the spacing between the substrate and the adjacent surface so as to provide an efficient seal therebetween.
  • Such seals are used for example on turbine or compressor blades of gas turbine engines, such as those used in aircraft, to provide a seal between the blades and the turbine or compressor housing.
  • One of the problems in providing a suitable abradable seal is to produce a thermally sprayed coating which, on the one hand has sufficient structural strength which nevertheless is low enough to provide abradability, and which, on the other hand, has a sufficiently high resistance to erosion by particles impinging on the abradable seal coating during use.
  • the seal coating is subjected to impingement by abrasive particles entrained in the air and ingested by the engine.
  • Powders used to form abradable seal coatings usually include a metallic material to provide sprayability, structural strength and erosion resistance, and a non-metallic solid material to directly or indirectly provide structural weakness, that is to say abradability, in the seal coating.
  • the non-metallic solid material should have good lubricity, that is to say good low friction properties, and preferably also good heat insulating properties.
  • the non-metallic solid material may be ceramic material.
  • the properties of an abradable seal coating depend not only on the physical and chemical nature of the powder but also on the conditions under which the thermal spraying process is carried out.
  • the interaction between the physical and chemical properties of the powder and the spraying conditions is complex.
  • the basic variables involved with respect to the powder are the melting point, surface tension and specific surface area of the powder particles, all of which variables affect the degree to which a powder particle will be melted for a given heat input and also affect the configuration in which the particles are deposited on the substrate, for example with lamellar or spherical shape.
  • Another variable is the heat input during spraying which is mainly controlled by varying the amount of gas combusted and/or the velocity of the powder travelling through the flame or plasma in the thermal spray.
  • each powder particle has a central core of non-metallic solid material surrounded by a layer of metallic material, as described for example in United States patent No. 3,914,507.
  • Such powders are known as composite powders, with the powder particles being known as composite powder particles.
  • One composite powder of this kind which has been or nickel alloy, and abradable seal coatings formed by thermal m spraying such powders have been found to be potentially useful as abradable seal coatings on compressor or turbine blades of aircraft gas turbine engines.
  • At least about 95% of the particles should be less than about 150 microns (100 mesh Tyler equivalent) in size, since conventional thermal spray equipment can only satisfactorily spray powder with particles conforming to this size limitation.
  • conventional thermal spray equipment can only satisfactorily spray powder with particles conforming to this size limitation.
  • Conventionally, when spraying composite powder to form an abradable seal it has been the practice to use powders with particle sizes conforming to this size limitation, and with at least 70% by weight of the particles being less than 75 microns (200 mesh) since it has been believed that such a size distribution was required to produce an abradable seal coating with satisfactory properties.
  • nickel or nickel alloy composite powder has from about 50 to about 90% by weight, and preferably from about 55 to about 65%, of its particles greater in size then about 75 microns. Also, there should be less than about 10%, and preferably less than about 5% of the particles with a size below 45 microns (325 mesh).
  • This relatively coarse powder can be sprayed with conventional thermal spray equipment, and the lower specific area of the coarser powder of the present invention allows less heat transfer into each particle during spraying so that less melting and/or superheating of the nickel or nickel alloy occurs. This encourages the deposition of the composite alloy rather than lamellar form, and this in turn reduces the-contact area between individual powder particles in the seal coating, thereby increasing the abradability.
  • the powder of the present invention is less sensitive to inadvertent errors during the spraying operation than the prior art finer powders so far as minor variations of desired spraying conditions affecting heat input are concerned.
  • the ratio of nickel or nickel alloy to non-metallic central core is preferably in the range of from about 78:22 to about 90:10, preferably in the range of from about 80:20 to about 80:18.
  • the nickel alloy may be nickel-chromium-aluminum (NiCrAl) alloy.
  • NiCrAl composite powder has previously been preposed for use in connection with prior art finer powders for forming abradable seal coatings, it has been found that the abradability of seal coatings formed from such powder tends to decrease when the seal coatings have been subjected to typical operating temperatures of an aircraft gas turbine engine, that is to say from about 650°C up to about 850°C. It has been believed that this loss of abradability was due to the gradual oxidation of the metallic content of the seal coating, with the oxides functioning to increase the strength of the bonds between metallic particles in the seal coating, and hence decrease abradability.
  • Abradable seal coatings made from powder in accordance with this further feature of the invention exhibit oxidation resistance and coating integrity (that is to say freedom from spalling) similar to that of conventional oxidation resistant alloys up to about 850°C. Unintentional pre- sence of u p to about 1% silicon and/or up to about 1% iron on the NiCrAl alloy may have an important influence in this Aspect of the coating performance.
  • a further advantage of this feature of the present invention is that such a chromium and aluminum content produces a favourable surface tension effect during thermal spraying which enables a seal coating of very desirable abradability to be formed.
  • Abrada- )ility is favoured by the deposition of the composite powder nto a substrate in a substantially spherical rather than .amellar form. It would have been expected that, since the presence of the alloying elements chromium and aluminum in the nickel lowers the melting point, the composite powder particles would tend to be present in lamellar form in the seal coating. It has been found that this is not the case, And it is believed that the amounts of chromium and aluminum in accordance with this feature of the -invention produce . surface tension effect which assists in causing the particles in the seal coating to be substantially spherical rather than lamellar.
  • the ion-metallic core material be ceramic, and suitable core materials in this respect are bentonite and rhyolite. Also, ach core preferably consists of a single core particle.
  • NiCrAl/bentonite powder having a weight ratio of N iCrAl to bentonite of 80:20 was produced by coating bentonite core particles with nickel in a manner as described in United States patent No. 3,062,680, such that each bentonite core particle was coated with a layer of nickel, the bentonite core particle.”sizes being less than 150 microns (100 mesh).
  • the nickel/bentonite powder was then alloyed with chromium and aluminum in a manner as described in United States patent No. 3,914,507 to form a NiCrAl composition of 92% nickel, 5% chromium and 3% aluminum.
  • NiCrAl/bentonite powder was then screened to produce a powder product with the size distribution of its particles in accordance with the invention, as follows:
  • the substrate (cylinder) was stationary, the gun being traversed across the end of the cylinder at a rate of 590 in/min (X direction) and movement in the Y direction being 0.25 in/pass.
  • the oxygen content and acetylene content was varied within the indicated ranges to obtain different combinations of abradability and erosion resistance.
  • the thickness of the coating produced in each case was 0.08 inch.
  • the ultimate tensile strength of each coating was measured by gluing the end of an uncoated cylinder to the surface of the coating, and pulling the two cylinders apart in a tensile machine until the coating fractured.
  • This ultimate tensile strength (UTS) test is used as an indication of abradability, as is customary in the art. A lower UTS value indicates better abradability.
  • the erosion resistance of each coating was measured by impinging a constant quantity of silica sand onto the coating for one minute, and the consequent weight loss was recorded to indicate the propensity for erosion in terms of an erosion number.
  • the values of the erosion number and ultimate tensile strength are indicated by the line marked 80/20(C) in Figure 1, with the dotted line showing target values of erosion number and ultimate tensile strength for abradable seal coatings on turbine blades of a typical aircraft gas turbine engine. It will be noted that such coatings can readily be provided with erosion number and abradability within the target values.
  • NiCrAl/bentonite powder was produced in the same manner as described above, except .that the powder was screened to produce a powder product with a particle size distribution in accordance with the prior art, as follows:
  • a number of abradable seal coatings were then formed from NiCrAl/bentonite powder in accordance with the invention and in the manner described above, and with the NiCrAl alloy containing 5% chromium and 3% aluminum.
  • the NiCrAl alloy contained 16% chromium and 5% aluminum.
  • Abradable seal coatings of both kinds were maintained at a temperature of about 800°C in air for a number of hours, and the ultimate tensile strength of a coating of each kind was measured from time to time in the manner previously described. The gain in weight of the seal coatings was also measured, the gain in weight being an indication of the amount of oxidation of the metallic content.
  • Figure 2 shows the increase in ultimate tensile strength of the abradable seal coatings over a 500 hour period. It will be noted that the increase in ultimate tensile strength, which represents decrease in abradability of the Ni5Cr3Al/ bentonite seal coating is much lower than that of the Nil6Cr5Al/ bentonite seal coating. Further, the increase in ultimate tensile strength of the Ni5Cr3Al/bentonite seal coating substantially ceases after about 200 hours, whereas the ultimate tensile strength of the Nil6Cr5Al/bentonite seal coating continues to increase.
  • the initial ultimate tensile strength of the Ni5Cr3Al/bentonite seal coating is less than that of the N il6Cr5Al/bentonite seal coating, and this is believed to be due at least partly to a beneficial surface tension effect of the chromium/aluminum composition in accordance with the preferred feature of the present invention.
  • Figure 3 shows that the Ni5Cr3Al/bentonite seal coating is in fact oxidized to a slightly greater extent than the Nil6Cr5Al/bentonite seal coating. As indicated earlier, it is believed that the smaller increase in abradability with time of the Ni5Cr3Al/bentonite seal coating is due to the formation of weaker oxides than those produced by the Ni16Cr5Al/bentonite seal coating.
  • Ceramic materials such as rhyolite, may be used as the core material if desired.

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  • 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)
  • Turbine Rotor Nozzle Sealing (AREA)
  • Powder Metallurgy (AREA)
EP80303683A 1979-11-06 1980-10-17 Poudre pour la pulvérisation thermique et procédé pour la formation de joints abrasables au moyen de ladite poudre Withdrawn EP0028475A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
CA339229 1979-11-06
CA000339229A CA1141569A (fr) 1979-11-06 1979-11-06 Poudres composites a deposer par projection pour l'obtention de revetements de scellement usinables

Publications (1)

Publication Number Publication Date
EP0028475A1 true EP0028475A1 (fr) 1981-05-13

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Family Applications (1)

Application Number Title Priority Date Filing Date
EP80303683A Withdrawn EP0028475A1 (fr) 1979-11-06 1980-10-17 Poudre pour la pulvérisation thermique et procédé pour la formation de joints abrasables au moyen de ladite poudre

Country Status (3)

Country Link
EP (1) EP0028475A1 (fr)
JP (1) JPS5687603A (fr)
CA (1) CA1141569A (fr)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0144769A1 (fr) * 1983-11-07 1985-06-19 Hazelett Strip-Casting Corporation Couche matricielle sur convoyeurs flexibles pour la coulée, procédé et appareil pour la formation de couches matricieles
EP0272197A2 (fr) * 1986-12-15 1988-06-22 United Technologies Corporation Particules abrasives de carbure de silicium à revêtement multiple
CN1043364C (zh) * 1995-06-13 1999-05-12 中国石油化工总公司 一种耐蚀涂层用的超合金粉末及其制造耐蚀合金涂层的方法
CN1043355C (zh) * 1995-06-13 1999-05-12 中国石油化工总公司 一种耐蚀涂层用的超合金粉末及其制造耐蚀合金涂层的方法

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
ES2340037T3 (es) * 2003-12-17 2010-05-28 Sulzer Metco (Us) Inc. Turbo maquina con capa ceramica de abrasion..
CA2784665C (fr) * 2010-01-26 2018-05-22 Sulzer Metco (Us), Inc. Composition abrasable et procede de fabrication
US10378450B2 (en) 2014-05-27 2019-08-13 United Technologies Corporation Chemistry based methods of manufacture for MAXMET composite powders

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
BE674204A (fr) * 1964-12-30 1966-04-15
US3254970A (en) * 1960-11-22 1966-06-07 Metco Inc Flame spray clad powder composed of a refractory material and nickel or cobalt
US3655425A (en) * 1969-07-01 1972-04-11 Metco Inc Ceramic clad flame spray powder
US3743533A (en) * 1971-10-28 1973-07-03 G Yurasko Flame spraying
US3914507A (en) * 1970-03-20 1975-10-21 Sherritt Gordon Mines Ltd Method of preparing metal alloy coated composite powders
FR2388776A1 (fr) * 1977-04-26 1978-11-24 Sherritt Gordon Mines Ltd Poudre mixte a revetement metallique et son procede de preparation

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3254970A (en) * 1960-11-22 1966-06-07 Metco Inc Flame spray clad powder composed of a refractory material and nickel or cobalt
BE674204A (fr) * 1964-12-30 1966-04-15
US3655425A (en) * 1969-07-01 1972-04-11 Metco Inc Ceramic clad flame spray powder
US3914507A (en) * 1970-03-20 1975-10-21 Sherritt Gordon Mines Ltd Method of preparing metal alloy coated composite powders
US3743533A (en) * 1971-10-28 1973-07-03 G Yurasko Flame spraying
FR2388776A1 (fr) * 1977-04-26 1978-11-24 Sherritt Gordon Mines Ltd Poudre mixte a revetement metallique et son procede de preparation

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0144769A1 (fr) * 1983-11-07 1985-06-19 Hazelett Strip-Casting Corporation Couche matricielle sur convoyeurs flexibles pour la coulée, procédé et appareil pour la formation de couches matricieles
EP0272197A2 (fr) * 1986-12-15 1988-06-22 United Technologies Corporation Particules abrasives de carbure de silicium à revêtement multiple
EP0272197A3 (en) * 1986-12-15 1989-10-11 United Technologies Corporation Silicon carbide abrasive particles having multilayered coating
CN1043364C (zh) * 1995-06-13 1999-05-12 中国石油化工总公司 一种耐蚀涂层用的超合金粉末及其制造耐蚀合金涂层的方法
CN1043355C (zh) * 1995-06-13 1999-05-12 中国石油化工总公司 一种耐蚀涂层用的超合金粉末及其制造耐蚀合金涂层的方法

Also Published As

Publication number Publication date
CA1141569A (fr) 1983-02-22
JPS5687603A (en) 1981-07-16

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Inventor name: ADAMOVIC, EMILIJA