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
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10S428/00—Stock material or miscellaneous articles
  • Y10S428/922—Static electricity metal bleed-off metallic stock
  • Y10S428/9335—Product by special process
  • Y10S428/937—Sprayed metal
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T428/00—Stock material or miscellaneous articles
  • Y10T428/12—All metal or with adjacent metals
  • Y10T428/12014—All metal or with adjacent metals having metal particles
  • Y10T428/12028—Composite; i.e., plural, adjacent, spatially distinct metal components [e.g., layers, etc.]
  • Y10T428/12063—Nonparticulate metal component
  • Y10T428/12139—Nonmetal particles in particulate component
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T428/00—Stock material or miscellaneous articles
  • Y10T428/12—All metal or with adjacent metals
  • Y10T428/12181—Composite powder [e.g., coated, etc.]
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T428/00—Stock material or miscellaneous articles
  • Y10T428/29—Coated or structually defined flake, particle, cell, strand, strand portion, rod, filament, macroscopic fiber or mass thereof
  • Y10T428/2982—Particulate matter [e.g., sphere, flake, etc.]
  • Y10T428/2991—Coated
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T428/00—Stock material or miscellaneous articles
  • Y10T428/29—Coated or structually defined flake, particle, cell, strand, strand portion, rod, filament, macroscopic fiber or mass thereof
  • Y10T428/2982—Particulate matter [e.g., sphere, flake, etc.]
  • Y10T428/2991—Coated
  • Y10T428/2993—Silicic or refractory material containing [e.g., tungsten oxide, glass, cement, etc.]

Definitions

• a flame spray powder comprises finely-divided core particles of a metal or a metal alloy coated with discrete particles of a ceramic or cermet that remains in solid phase at least 100F above the fusing or melting temperature of the metal.
• the average particle size of the ceramic is less than 25 percent of the average particle size of the metal and the amount used is insufficient to totally cover the surface of the metal particles so that on the average in the range of 5 to 75 percent of the surface area of the metal particles is exposed to ambient conditions.
• this new ceramic clad metal powderin When used in flame spraying, this new ceramic clad metal powderin one embodiment forms a flame spray coating where the ceramic is in the continuous phase and the coating is relatively soft and abradable, and in another embodiment the metal of the coating is in the continuous phase and the coating is relatively hard and erosion resistant.
• U.S. Pat. No. 3,322,515 issued to Dittrich et al., May 30, 1967 and assigned to the assignee of the present invention discloses that rather than using the wire rod flame spray method and separately introducing a second material in powder form as disclosed in U.S. Pat. No. 3,084,064 powders formed of two or more materials can be used and in one embodiment proposes that aggregates be formed by cladding a core powder with a second powder.
• the aggregate powders basically comprise two metal components one of which will exothermically react with the other when subjected to the flame spray.
• Flame spraying involves the heat softening of a heat fusible material such as a metal or ceramic and the propelling of the softened material in particulate form against the surface to be coated to which the heat fusible material bonds.
• a flame spray gun is usually used for the purpose and with one type, heat fusible material is supplied in powder form to the gun.
• Such powders are of quite small particle size, e.g., below 100 mesh U.S. standard screen size to about one micron.
• a flame spray gun normally utilizes a combustion or plasma flame to effect melting of a powder but other heating means such as electric arcs, resistant heaters or induction heaters can also be used, alone or in combination.
• the carrier gas for the powder can be one of the combustion gases or it can be compressed air.
• the primary plasma gas is generally nitrogen or argon. Hydrogen or helium is usually added to the primary gas.
• the carrier gas is generally the same as the primary plasma gas although other gases such as hydrocarbons are used in special cases.
• the nature of the coating obtained by flame spraying a metal powder can be quite specifically controlled by proper selection of the composition of the powder, control of the physical nature of the powder and the use of select flame spraying conditions. It is well known and common practice to flame spray a simple mixture of a ceramic powder and a metal powder. Hard coatings that are useful may be produced with mixtures. Many ceramic powders such as boron nitride or silicon carbide do not have normal melting points and cannot be satisfactorily sprayed in mixtures. Others such as tungsten carbide or zirconium diboride tend to oxidize and decompose when heated to melting point in the flame.
• the ceramic When softer coatings are desired the ceramic is usually not melted to any extent during the spraying and accidental entrapment of the unmelted ceramic powder particles is relied on. If greater heat is used to melt the ceramic, if the ceramic has a melting point, this may be too much heat for the metal and may cause oxidation of the metal and produce too hard a coating. In the case of the metal-clad ceramic particles, as is taught in the U.S. Pat. No. 3,254,970, in practice the powder usually comprises a major portion of ceramic because it is difficult to obtain very thick cladding layers of the metal onto the ceramic and the sprayed coating produced therefrom often does not have suitable properties for the application, for example the proper degree of abradability.
• the ceramic which has a low thermal conductivity may effectively insulate the metal core particles from the flame.
• coatings produced by flame spraying with this powder were totally unsatisfactory.
• the PLMG method is carried out by placing about one-half gram of powder on a l-inch by 3-inch glass slide.
• the powder is evenly distributed and then a mirror is gently placed on top of the powder to make a cover glass. It is fastened with tape with the reflector side of the mirror facing the powder.
• This slide is then placed in a metallurgical microscope. Light is passed through the glass slide across the powder and reflected back off the mirror. When viewed under normal reflected light, a dull outline of the powder is visible. When polarized light is used the mirror appears grey, the exposed metal shows dark and the ceramic is very bright. Examination of the specimen in a plain polarized light requires a polarizing prism and analyzer.
• the ceramic appears bright and the mirror and exposed metal are darkened. If the ceramic is not sensitive to polarized light, experimentation with incident light may be required to contrast the ceramic with the metal.
• the core and coating particles will usually appear to have a generally globular to spherical shape.
• the amount of exposed metal can be determined.
• a square grid is superimposed on the image magnified 150 times. This may be done by using an appropriate eye piece reticle or by placing a grid on a photograph, with the grid 1 inch by 1 inch comprising squares each 0.1 inch square.
• the grid must be positioned so that the particles are within the outer lines of the grid.
• the area of the particle is estimated. With the grid in the same position, the metal surface area is also estimated by counting the squares t'rlled by dark areas. Dividing the estimated dark area by the particle area gives the percent of the exposed metal surface. This procedure is usually carried out on 25 to 30 particles selected at random.
• the ceramic powder should remain in solid phase, that is, it should not melt, soften, vaporize or decompose significantly at a temperature at least 100 F above the melting or fusing temperature of the core metal.
• the third material will usually be less than 25 percent of the size of the core particles. It may be either a metal or ceramic in an amount in the range of 0.5 to 15% of the volume of the amount of metal core. As an example, when the core is nickel, cobalt or iron, or an alloy thereof, it is preferable to mix fine aluminum powder with the ceramic powder before bonding the mix to the core particles.
• the ceramic cladding powder is preferably bonded to the metal core particles with a resinous binder although other types of bonding methods can be used.
• the metal core particles will usually have a size in the range of minus 100 mesh (U.S. standard screen size) to 3 microns, preferably of l4O to +3 25 mesh.
• the ceramic coating particles will usually have the size of less than 25% of the size of the core particles.
• the nmount of the ceramic powder will usually be in the range of 1 to 30 volume percent of the volume of the core particles so that incomplete cladding of the core particles is assured.
• the cladding is accomplished by mixing the core particles, the ceramic cladding particle and the resinuous binder, carricd in a suitable solvent, together followed by removing ofthe solvent and the breaking up of any agglomerates that may have been formed. Upon drying the binder is present in an amount between 0.05 and 5 volume percent of the volume of the core particles.
• Any one of many types of binders can be used such as starches, sugars, celluloses, polyamides, rubbers, urethanes, phenols, polyesters, epoxies, acetates and the like.
• the water soluble polyvinyl alcohols, the inorganic and organic silicates and organic resins such as the phenolics and vinyls are perhaps preferred.
• the incomplete ceramic cladding can be achieved without a binder by other known methods such as vapor deposition.
• Ceramic is used broadly, such as is described by W. D. Kingery, Introduction to Ceramics, John Wiley & Sons, Inc., New York (1960). Ceramics are usually compounds although carbon, especially the higher temperature form of graphite, is now considered a ceramic. Usually ceramics are resistant to high temperatures. Preferably the ceramics used have a melting point, if any, or are stable, at least 100 F. above the melting point of the metal of the core particles.
• Typical ceramics are carbides such as tungsten carbide, chromium carbide and titanium carbide; simple oxides such as aluminum oxide, Zirconium oxide, titanium oxide and chromium oxide; complex oxides such as magnesium zirconate, borosilicate glasses, diatomaceous earth and talcum powder; nitrides such as boron nitride, borides such as zirconium diboride, halides such as calcium fluoride, silicides such as chromium silicides, 61C.
• the core metal or alloy can include such metals as tungsten, titanium, tantalum, columbium, zirconium, nickel, cobalt, iron, aluminum, copper, tin, and alloys thereof.
• Typical core metals are: essentially pure molybdenum; titanium with six parts aluminum and four parts vanadium; nickel with 16 parts chromium and eight parts iron; monel (67 percent nickel 33 percent chromium); a cobalt alloy having 25.5 parts chromium, 10.5 parts nickel, 7.5 parts tungsten, 0.5 parts carbon with the balance cobalt; Type 316 or Type 431 stainless steel; aluminum with 12 parts silicon, and aluminum-bronze such as one with 9.5 parts aluminum, 1 part iron and the balance copper; and a Babbit of 7.5 parts antimony, 3.5 parts copper, 0.25 parts lead with the balance being tin.
• Example I Eighty-nine parts of a nickel-chromium alloy powder of 140 to +325 mesh was coated with 4 parts by weight of a 3 to 4 micron aluminum powder and 7 parts of a 325 mesh boron nitride powder (HTP grade-Carborundium Co., Latrobe, Pa.) using 5 parts of a phenolic varnish (Metcoseal AP Metco, Inc., Westbury, N.Y.) as a binder. The aluminum and boron nitride powders were first preblended, and the varnish was mixed with the alloy powder. The materials were then blended together using additional solvent as necessary. The solvent was removed by stirring, agglomerates were broken up and the clad powder was screened to l00 to +325 mesh. The yield was 94 percent based on original ingredients.
• the metal cores were 75 percent covered by the boron nitride and aluminum.
• flame sprayed at a flame temperature of about 5,500 F. Thermospray 5 P gun, Metco, Inc., acetylene gas and oxygen
• the coating hardness was measured on a superficial Rockwell Hardness Tester using a 15 kg load and a Va-inch-diameter ball.
• the spray distance in this case was 8 inches. An increase in the spray distance will increase the hardness.
• the composition of the coating was 49 volume percent boron nitride, 49 volume percent nickel-chromium alloy and 2 volume percent free aluminum. The balance of aluminum presumably combined exothermically with the nickel.
• Example II The nature of the coating, i.e., its abradability, erosion resistance and hardness, will vary with the spray parameters.
• the same clad powder as in Example I was sprayed with the same gun with the essential conditions changed being air and spray distance to give additional coating specimens: B, C and D.
• the coating of Example I is designated as specimen A.
• the conditions and results are given in Table I.
• the coatings were sprayed on l-inchby l-inchtime A-inch-thick flat pieces of mild steel. These coatings were ground flat and weighted. Then almost 0.03 inch of the coating thickness were ground off and the specimen weighted again. The difference in weight over the volume gave, fairly accurately, the density of the coating.
• the erosion resistance tests were carried out by spraying the coatings on l-inch by 2-inch by /rr-inch mild steel plates prepared by blasting with alumina grit (Metcolite F), upon which the erosion tests were carried out for one minute.
• the test coatings were blasted at a 45 angle with A1 0 type particles propelled by compressed air. The distance between the nozzle and the coating was about 4 inches.
• the weight loss was converted into volume using density.
• the specimen were l-inch by 3-inch plates coated to 0.05 inch and ground flat.
• the tests were conducted on a scribe test machine which moves a stylus back and forth on the coating to cut a scratch using a 0.35-inch-wide pointed probe and a 1,650-gram load on the probe. The tests were run for one minute each and the thickness loss measured.
• Coating B With Coating B the metal matrix was continuous whereas with Coating A the boron nitride was in the continuous phase.
• the B-type coating had a metallurgical structure that gave a high erosion resistance with less abradability.
• Coating C and D had a more continuous metal phase than Coating B and this tended to make a hard matrix and erosion resistant coating.
• Example III Eight weight percent of a diatomaceous earth is clad on a cobalt alloy (25.5 Cr, 10.5 Ni, 7.5 W, 0.5C, balance cobalt) using the same cladding method as above described.
• the size of the alloy powder is -200 325 mesh.
• the diatomaceous earth has a size of less than one micron.
• Three percent aluminum flake powder having a size of 0.2 microns thick and 1 micron long is also added to the mixture.
• the binder used is as in Example I.
• the coating produced from this powder is capable of withstanding temperatures up to l,800 F.
• Example IV A 3 percent weight carbon, having a size of less than 1 3 microns is clad onto an aluminum powder of l70 325 mesh using organic silicate as the binder. This is combustionflame sprayed to produce a self lubricating and abradable coating.
• Example V v Talc Mg Si.,O (Ol-l) is clad onto an aluminum bronze powder of 270 15 microns using a resinuous binder. This powder will produce a self lubricating bronze coating suitable for bearing applications.
• Example VI Fifte en weight percent titanium oxide 0.1 micron to 1 micron is clad on a titanium alloy (6 Al. 4 V) 100 to 325 mesh using polyvinyl alcohol asa binder and water for solvent. If this is plasma flame sprayed on titanium alloy shafts used in jet engines it provides a wear resistance bearing surface which is lightweight and capable of high temperature operation.
• Example VII An aluminum oxide powder weight percent) 2 microns to 5 microns is clad onto an aluminum powder 270 to 400 mesh and combustion flame sprayed on steel to give an abrasion and corrosion resistance protective coating.
• Example VlII tungsten carbide particles (10 weight percent) 2 to 7 microns are clad onto Metco E self-fluxing alloy (1 C, 4 Si, 17 Cr, 3.5 B, 4 Fe, balance Ni). This will provide a very dense, hard, wear-resistance coating.
• Example IX Silicon carbide particles (5 weight percent) 5 to 10 microns are clad onto copper powder -l70 325 mesh and combustion flame sprayed on brake disks. This provides a wear and fade resistant, thermally conductive coating for automobile brakes.
• a flame spray powder comprising finely-divided core particles of a metal bonded to and coated with discrete particles of a ceramic that remains in solid phase at least 100 above the fusing temperature of said metal, said ceramic having an average particle size less than percent of the average particle size of said metal core and leaving exposed on the average in the range of 5 to 75 percent of the surface area of the metal core as determined by the PLMG method.
• the powder of claim 1 having a particle size in the range of -l00 mesh to 3 microns and wherein in the range of 10 to 50 percent of the surface of said core particles is exposed by said discrete particles which amount to in the range of l to 30 volume percent of the volume of the core particles.
• said discrete particles additionally include a material selected from the group comprising metals and ceramics and having an average particle size of less than 25 percent of the size of said metal core particles, the additional material being present in an amount in the range of 0.5 to 15 percent of the volume of the amount of said metal.
• a flame sprayed composition obtained by passing a metal-ceramic powder through a flame spray gun and melting at least the metal component thereof; and thereafter impinging the heated powder against a receptor surface, said powder comprising finely-divided core particles of a metal bonded to and coated with discrete particles of a ceramic that remains in solid phase at least F. above the fusing temperature of said metal, said ceramic having an average particle size less than 25 percent of the average particle size of said metal and leaving exposed on the average in the range of 5 to 75 percent of the surface are thereof as determined by the PLMG method.
• composition of claim 8 wherein said ceramic is in the continuous phase and said composition is relatively soft and abradable.

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• Chemical & Material Sciences (AREA)
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• Plasma & Fusion (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Materials Engineering (AREA)
• Mechanical Engineering (AREA)
• Metallurgy (AREA)
• Organic Chemistry (AREA)
• Coating By Spraying Or Casting (AREA)
• Other Surface Treatments For Metallic Materials (AREA)

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• 1969
  • 1969-07-01 US US838319A patent/US3655425A/en not_active Expired - Lifetime
• 1970
  • 1970-05-14 FR FR7017696A patent/FR2048433A5/fr not_active Expired
  • 1970-06-26 DE DE2031616A patent/DE2031616C3/de not_active Expired
  • 1970-07-01 JP JP45057690A patent/JPS5016811B1/ja active Pending

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