EP0233574A2 - Verfahren zur Überwachung des Sauerstoffgehaltes in einem agglomerierten Molybdänpulver - Google Patents

Verfahren zur Überwachung des Sauerstoffgehaltes in einem agglomerierten Molybdänpulver Download PDF

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Publication number
EP0233574A2
EP0233574A2 EP87101816A EP87101816A EP0233574A2 EP 0233574 A2 EP0233574 A2 EP 0233574A2 EP 87101816 A EP87101816 A EP 87101816A EP 87101816 A EP87101816 A EP 87101816A EP 0233574 A2 EP0233574 A2 EP 0233574A2
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EP
European Patent Office
Prior art keywords
molybdenum
powder
oxygen
oxygen content
agglomerated
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.)
Granted
Application number
EP87101816A
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English (en)
French (fr)
Other versions
EP0233574B1 (de
EP0233574A3 (en
Inventor
Joseph E. Ritsko
David J. Port
David L. Houck
Frank D. Kenney
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.)
Osram Sylvania Inc
Original Assignee
GTE Products Corp
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Filing date
Publication date
Priority claimed from US06/831,200 external-priority patent/US4684400A/en
Priority claimed from US06/831,201 external-priority patent/US4624700A/en
Application filed by GTE Products Corp filed Critical GTE Products Corp
Publication of EP0233574A2 publication Critical patent/EP0233574A2/de
Publication of EP0233574A3 publication Critical patent/EP0233574A3/en
Application granted granted Critical
Publication of EP0233574B1 publication Critical patent/EP0233574B1/de
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C1/00—Making non-ferrous alloys
    • C22C1/10—Alloys containing non-metals
    • 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
    • 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
    • C23C8/00—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals
    • C23C8/06—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using gases
    • C23C8/08—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using gases only one element being applied
    • C23C8/10—Oxidising
    • C23C8/16—Oxidising using oxygen-containing compounds, e.g. water, carbon dioxide

Definitions

  • This invention relates to a method for introducing a controlled level of oxygen into agglomerated molybdenum metal powder and in particular, into agglomerated molybdenum plasma spray powder.
  • Flame spraying and plasma spraying are common techniques for the application of protective and wear resistant coatings of various metals, ceramics, and cermets, usually to metal surfaces (substrates).
  • the piston ring industry commonly uses molybdenum coating on rings for internal combustion engines.
  • an electric arc or an oxyacetylene flame melts the end of a continuous coil of molybdenum wire and a gas propels it onto a substrate for example, the war surface of a cast iron piston ring where it splats and solidifies, forming the coating in successive layers.
  • the coatings produced by this technique contain large quantities of oxygen, typically from about 7% to about 8% in solution and as various molybdenum oxides. The large quantities of oxygen in the molybdenum apparently harden the coating.
  • US Patent 4,146,388 describes and claims molybdenum plasma spray powders and a process for producing the powders of molybdenum having an oxygen content of from about 0.5 to about 15% by weight oxygen.
  • the process involves passing molybdenum particles through a plasma with oxygen or oxides of molybdenum to produce the oxygen containing (oxidized) powder.
  • a method for introducing a controlled level of oxygen into agglomerated molybdenum metal powder involving contacting the powder with a relatively dilute solution containing a sufficient amount of oxidizing agent for a sufficient time to increase the oxygen content of the powder followed by removing the resulting partially oxidized powder from the resulting solution.
  • a method for introducing a controlled level of oxygen into agglomerated molybdenum metal powder involving heating the powder at sufficient temperature for a sufficient time in the presence of water vapor, and a non-oxidizing atmosphere with the amount of the non-oxidizing atmosphere being controlled to produce a partially oxidized molybdenum powder.
  • a method for introducing a controlled level of oxygen into agglomerated molybdenum plasma spray powder involves forming a relatively uniform mixture of agglomerated powders containing essentially of molybdenum and one or more oxygen containing compounds of molybdenum wherein the mixture has an oxygen content of greater than about 10% by weight and reducing the mixture at a sufficient temperature for a sufficient time to remove a portion of the oxygen therefrom and form a molybdenum powder having an oxygen content of no greater than about 10% by weight.
  • Figure 1 is a plot of nitrogen flow rate versus weight percent oxygen in the oxidized molybdenum powder (second aspect of the invention).
  • the desired oxygen content is from about 1% to about 15% and preferably from about 7% to about 10% by weight. At levels lower than this, the hardness of the plasma coating is not improved. At levels higher than this range, coating integrity or bond strength is compromised.
  • US Patent 4,146,388 discloses a process for producing molybdenum spray powders containing oxygen by the plasma melting process or in conjunction with the plasma melting process. By the process of this invention the oxygen level in molybdenum powders is controlled in preparation for plasma coating applications.
  • the molybdenum powder has been previously agglomerated and sintered by well known methods.
  • the preferred molybdenum powder of this invention is supplied by the Chemical and Metallurigcal Division of GTE Products Corporation under the designation SA-101.
  • the oxygen content of conventional molybdenum powders which preferably consist essentially no greater than about 0.05% by weight oxygen can be increased by contacting the powder with a relatively dilute solution containing a sufficient amount of an oxidizing agent, which is preferably hydrogen peroxide for a sufficient time to raise the oxygen content to the desired level.
  • an oxidizing agent which is preferably hydrogen peroxide for a sufficient time to raise the oxygen content to the desired level.
  • the oxidizing agent must be present in a sufficient amount to raise the oxygen to the desired level, but not in excess amounts to cause the reaction to be uncontrolled.
  • a dilute solution of the oxidizing agent affords better control and avoids excessive oxidized
  • the solution contains preferably from about 1% to about 10% by weight of the oxidizing agent.
  • the oxidation can be controlled.
  • the resulting partially oxidized molybdenum powder is then separated from the resulting solution by any standard technique such as filtration.
  • the oxygen content of conventional molybdenum powders which preferably consist essentially of less than about 0.05% by weight oxygen can be increased by heating the agglomerated and sintered powder at a sufficient temperature for a sufficient time in the presence of water vapor and a non-oxidizing atmosphere with the amount of the non-­oxidizing atmosphere being controlled to produce a partially oxidized molybdenum powder.
  • the heating can be done by any standard method for heating metal powders.
  • Preferred methods involve the use of a rotary calciner or a fluidized bed.
  • Heating temperatures are generally from about 700°C to about 900°C with from about 750°C to about 850°C being preferred.
  • the heating time depends on the temperature and on the type of equipment used.
  • the slope of the calciner tube can be adjusted to vary the length of time that the powder remains in the calciner.
  • Water is introduced into the furnace to provide the necessary moisture for the process.
  • the preferred non-oxidizing atmosphere is nitrogen.
  • the amount of non-oxidizing atmosphere in the ambient atmosphere of the furnace is controlled.
  • the amount of the non-oxidizing gas can be controlled by controlling the flow rates. It has been found, for example, that when the flow rate of the non-oxidizing atmosphere, for example, nitrogen, is decreased, the oxygen content of the resulting partially oxidized molybdenum is increased. This will be apparent in the example that follows.
  • the resulting partially oxidized molybdenum powder is made up of essentially spherical particles.
  • the oxygen content of this powder ranges from about 3% to about 15% by weight.
  • X-ray analyses of the partially oxidized power generally shows molybdenum trioxide.
  • Undesirable molybdenum trioxide can be eliminated by using ammonia solution to dissolve it without disturbing other desirable properties of the powder.
  • the powder in the event that the oxygen content is too high, the powder can be subjected to standard reduction methods to reduce the oxygen content.
  • Molybdenum powder type SA-101 from GTE which has been spray dried and which is -200, +325 mesh (44 to 74 ⁇ m) is fed at the rate of about 12 pounds (5.4 kg) per hour into a 6" (152.44 mm) diameter rotating calciner at a temperature of about 800°C under a nitrogen atmosphere. Water is fed by a separatory funnel at the rate of about 20 to 30 cm3/min to provide the necessary moisture for the oxidation process.
  • the resulting powder is in the form of essentially spherical brown particles with a bulk density of from about 2.4 to about 2.8 g/cm3.
  • the oxygen containing compounds of molybdenum can be molybdenum dioxide, molbydenum trioxide, or ammonium paramolybdate.
  • any mixture of molybdenum and oxygen containing compounds of molybdenum can be used as long as the oxygen content of the agglomerated mixture is greater than about 10% by weight.
  • a typical composition of the mixture of molybdenum powders to be agglomerated consists essentially of in percent by weight about 40% molybdenum, about 50% molybdenum dioxide, and about 10% molybdenum trioxide with the oxygen content being about 15.8% by weight.
  • the mixture of molybdenum and the oxygen containing compound or compounds can be agglomerated by any of several methods well known in the art.
  • a preferred method involves generally forming a slurry of water, ammonia or ammonium hydroxide, molybdenum trioxide, molybdenum dioxide, and ultrafine (about 1 to 3 microns in diameter) molybdenum particles.
  • Ammonium paramolybdate is formed from the molybdenum trioxide and ammonium hydroxide and acts as the binder in this system.
  • the resulting slurry is then spray dried to remove the water and form the relatively uniform agglomerated mixture which consists of essentially spherical particles.
  • the above method of forming the agglomerated mixture is described in US Patent 3,973,948 which is hereby incorporated by reference.
  • Another method of forming the relatively uniform agglomerated mixture is by first forming a slurry as described above. The water is allowed to evaporate while the slurry is being continually stirred to break up the material. The resultant coarse moist powder is then forced through a 100 mesh screen and collected. The powder is then further dried with gentle agitation. The final agglomerated mixture is then screened from this dried mixture.
  • the resulting agglomerated mixture is then reduced at a sufficient temperature for a sufficient time to remove a portion of the oxygen and form a molybdenum powder having an oxygen content of no greater than about 10% and preferably from about 7% to 10% by weight.
  • the reduction can be done in a standard furnace in a dry hydrogen atmosphere.
  • the preferred temperatures are from about 700°C to about 1000°C.
  • the time depends on the temperature and on the nature of the equipment. However, typical times are from about 2 hours to about 4 hours.
  • the reduction can be done in a fluidized bed or rotary calciner.
  • the reducing conditions are adjusted to give the final desired oxygen content.
  • the advantages of using a fluidized bed or rotary calciner over the above described static bed reduction are that a bed depth problem is avoided resulting in a more uniform reduction than in the static bed furnace.
  • a fluidized bed or rotary calciner the reduction of the agglomerate takes place from the outside of the agglomerates to the inside resulting in the metal phase being on the outside of the agglomerates. This results in a more efficient melting of the agglomerates in the plasma application and therefore produces a harder coating.
  • the resulting powders with controlled oxygen levels are used in plasma spraying applications to produce coatings such as on piston rings.
  • An aqueous slurry is made up consisting essentially of about 85% solids, the solids consisting essentially of about 11% molybdenum trioxide, about 52% molybdenum dioxide, and about 36% molybdenum, the oxygen content of the solids being about 16.6%, and ammonia in an amount equal to about 87% of the molybdenum trioxide.
  • the slurry is dried in a conventional dryer to produce a relatively uniform agglomerated mixture consisting of particles which are essentially spherical in shape.
  • the mixture is reduced in dry hydrogen at about 800°C for about 2 hours resulting in a free-flowing molybdenum spray powder having an oxygen content of from about 7% to about 8%.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Physics & Mathematics (AREA)
  • Plasma & Fusion (AREA)
  • Manufacture Of Metal Powder And Suspensions Thereof (AREA)
  • Battery Electrode And Active Subsutance (AREA)
  • Catalysts (AREA)
EP87101816A 1986-02-12 1987-02-10 Verfahren zur Überwachung des Sauerstoffgehaltes in einem agglomerierten Molybdänpulver Expired - Lifetime EP0233574B1 (de)

Applications Claiming Priority (6)

Application Number Priority Date Filing Date Title
US82880186A 1986-02-12 1986-02-12
US828801 1986-02-12
US06/831,200 US4684400A (en) 1986-02-20 1986-02-20 Method for controlling the oxygen content in agglomerated molybdenum powders
US831201 1986-02-20
US831200 1986-02-20
US06/831,201 US4624700A (en) 1986-02-20 1986-02-20 Method for controlling the oxygen content in agglomerated molybdenum powders

Publications (3)

Publication Number Publication Date
EP0233574A2 true EP0233574A2 (de) 1987-08-26
EP0233574A3 EP0233574A3 (en) 1989-07-26
EP0233574B1 EP0233574B1 (de) 1993-05-12

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EP87101816A Expired - Lifetime EP0233574B1 (de) 1986-02-12 1987-02-10 Verfahren zur Überwachung des Sauerstoffgehaltes in einem agglomerierten Molybdänpulver

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EP (1) EP0233574B1 (de)
DE (2) DE3785775T2 (de)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3837782A1 (de) * 1988-11-08 1990-05-10 Starck Hermann C Fa Sauerstoffhaltiges molybdaenmetallpulver sowie verfahren zu dessen herstellung
EP0374585A1 (de) * 1988-12-15 1990-06-27 Linde Aktiengesellschaft Verfahren zur Herstellung einer Oberflächenschicht aus Molybdän durch thermisches Spritzen

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB823407A (en) * 1956-07-25 1959-11-11 Hartmetllwerk Immelborn Veb Improvements in or relating to the production of metal powders
DE1071348B (de) * 1959-12-17
DE2312810A1 (de) * 1973-03-15 1974-09-19 Goetzewerke Legierung bzw. pulvergemisch zur herstellung von verschleissfesten schichten durch auftragschweissen
US3909241A (en) * 1973-12-17 1975-09-30 Gte Sylvania Inc Process for producing free flowing powder and product
DE2433814A1 (de) * 1974-07-13 1976-01-22 Goetzewerke Legierungspulver bzw. pulvergemisch fuer verschleissfeste spritzschichten
US4146388A (en) * 1977-12-08 1979-03-27 Gte Sylvania Incorporated Molybdenum plasma spray powder, process for producing said powder, and coatings made therefrom

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE1071348B (de) * 1959-12-17
GB823407A (en) * 1956-07-25 1959-11-11 Hartmetllwerk Immelborn Veb Improvements in or relating to the production of metal powders
DE2312810A1 (de) * 1973-03-15 1974-09-19 Goetzewerke Legierung bzw. pulvergemisch zur herstellung von verschleissfesten schichten durch auftragschweissen
US3909241A (en) * 1973-12-17 1975-09-30 Gte Sylvania Inc Process for producing free flowing powder and product
DE2433814A1 (de) * 1974-07-13 1976-01-22 Goetzewerke Legierungspulver bzw. pulvergemisch fuer verschleissfeste spritzschichten
US4146388A (en) * 1977-12-08 1979-03-27 Gte Sylvania Incorporated Molybdenum plasma spray powder, process for producing said powder, and coatings made therefrom

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
PROPERTIES OF OXYGEN-BEARING MOLYBDENUM COATINGS, Proceedings of the 9th International Thermal Spray Conference, The Hague (NL), 19-23 May 1980# *

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3837782A1 (de) * 1988-11-08 1990-05-10 Starck Hermann C Fa Sauerstoffhaltiges molybdaenmetallpulver sowie verfahren zu dessen herstellung
EP0368082A2 (de) * 1988-11-08 1990-05-16 H.C. Starck GmbH & Co. KG Sauerstoffhaltiges Molybdänmetallpulver sowie Verfahren zu dessen Herstellung
EP0368082A3 (en) * 1988-11-08 1990-07-25 Hermann C. Starck Berlin Gmbh & Co. Kg Oxygenated molybdenum metal powder and process for its preparation
US4976779A (en) * 1988-11-08 1990-12-11 Bayer Aktiengesellschaft Oxygen-containing molybdenum metal powder and processes for its preparation
US5037705A (en) * 1988-11-08 1991-08-06 Hermann C. Starck Berlin Gmbh & Co. Kg Oxygen-containing molybdenum metal powder and processes for its preparation
EP0374585A1 (de) * 1988-12-15 1990-06-27 Linde Aktiengesellschaft Verfahren zur Herstellung einer Oberflächenschicht aus Molybdän durch thermisches Spritzen

Also Published As

Publication number Publication date
DE233574T1 (de) 1987-12-17
EP0233574B1 (de) 1993-05-12
DE3785775T2 (de) 1993-08-12
DE3785775D1 (de) 1993-06-17
EP0233574A3 (en) 1989-07-26

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