GB2216145A - Protecting graphite based articles with silicon carbide - Google Patents

Protecting graphite based articles with silicon carbide Download PDF

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Publication number
GB2216145A
GB2216145A GB8901305A GB8901305A GB2216145A GB 2216145 A GB2216145 A GB 2216145A GB 8901305 A GB8901305 A GB 8901305A GB 8901305 A GB8901305 A GB 8901305A GB 2216145 A GB2216145 A GB 2216145A
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United Kingdom
Prior art keywords
heat treatment
coating
silicon
carbon
article
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
GB8901305A
Other versions
GB2216145B (en
GB8901305D0 (en
Inventor
Christopher Patrick Hyndman
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.)
Federal Mogul Technology Ltd
Original Assignee
T&N Technology 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 T&N Technology Ltd filed Critical T&N Technology Ltd
Publication of GB8901305D0 publication Critical patent/GB8901305D0/en
Publication of GB2216145A publication Critical patent/GB2216145A/en
Application granted granted Critical
Publication of GB2216145B publication Critical patent/GB2216145B/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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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
    • C23C14/00—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material
    • C23C14/58—After-treatment
    • C23C14/5806—Thermal treatment
    • 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
    • C23C14/00—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material
    • C23C14/58—After-treatment
    • 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
    • C23C14/00—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material
    • C23C14/58—After-treatment
    • C23C14/5846—Reactive treatment
    • 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
    • C23C4/18—After-treatment

Landscapes

  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Materials Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Plasma & Fusion (AREA)
  • Ceramic Products (AREA)
  • Crucibles And Fluidized-Bed Furnaces (AREA)

Abstract

A method of protecting graphite based articles such as for use in sintering crucibles comprises the steps of depositing a coating of a silicon based material on the article surfaces to be protected and finally heat treating the coated article at a minimum temperature of 1300 DEG C in the presence of carbon. The silicon coating may be deposited by a physical vapour deposition method or by plasma spraying. The carbon may be supplied from the furnace lining or from a furnace atmosphere having a gaseous carbon content or both. An optional heat treatment at 800-1300 DEG C in an inert atmosphere prior to the final heat treatment at a minimum of 1300 DEG C may also be carried out.

Description

Coatings The present invention relates to a method for increasing the life of graphite based articles and to a graphite based article having an extended life.
Graphite based articles such as containers are used for many tasks including the containment of molten metal or of other articles for heat treatment.
One use of graphite containers, for example, is in the sintering of sintered-reaction-bonded silicon nitride (SRBSN) or sintered silicon nitride (SSN) articles. The inside of the container is protected by a powder bed which is used to support the articles being sintered.
The out-side, however, is rapidly attacked by the gaseous carbon atmosphere in the furnace during sintering.
According to the present invention a method for the production of a protective coating on a graphite based article comprises the steps of depositing a coating of a silicon based material on the article surfaces to be protected and finally heat treating the coated article at a minimum temperature of 13000C in the presence of carbon.
Silicon coating thickness may initially lie in the range from 0.01 to 0.5 mm but may preferably lie within the thickness range 0.05 to 0.20 mm.
The silicon coating may be deposited by a physical vapour deposition method. Plasma-spraying is a preferred method of depositing the silicon.
Carbon may be provided from the substrate eg. from the graphite article itself or from a furnace atmosphere having a gaseous carbon content or both. High temperature vacuum furnaces having a carbon lining and carbon heating elements are suitable for this purpose.
A preferred temperature range for the production of the coating may lie in the temperature range from 1600 to 18500C and for a time of at least 15 minutes.
An optional heat treatment of a temperature lower than 0 0 1400 C, for example, between 800 and 1300 C in an inert atmosphere may be employed to drive off volatiles in the article. Such a heat treatment also serves to consolidate the initial silicon coating. A suitable inert atmosphere may be argon for example.
In order that the present invention may be more fully understood an example will now be described by way of illustration only.
A graphite crucible was prepared for coating with silicon on the outer surfaces. The preparation comprised abrading with glass beads to provide a key and ensuring that all traces of dust were removed. The surfaces were then plasma-sprayed with silicon powder having a mean particle size of approximately 40 micrometres and a typical composition of 96.5 Si/1.12 A1/0.4 Ca/1.44 Fe.
The silicon coating was applied to a thickness of 0.1 to 0.15 mm. This initial coating may lie in quite wide ranges depending upon the environment in which the crucible is to be used. After coating, the crucible was given a preliminary heat treatment at 11500C for 5 hours in argon which served to drive off volatile materials used in the graphite binder and also to consolidate the silicon coating. The crucible was then heated at 18000C for 5 hours in a "CONSARC" (trade name) furnace having a carbon lining and carbon heating elements.
A silicon carbide coating was formed on the outer surfaces of the crucible.
Crucibles so treated and subsequently used for the sintering of SRBSN or SSN articles have been found to have lives extended from about six months to several years. -.

Claims (13)

1. A method for the production of a protective coating on a graphite based article, the method comprising the steps of depositing a coating of a silicon based material on the article surfaces to be protected and finally heat treating the coated article at a minimum temperature of 13000C in the presence of carbon.
2. The method according to Claim 1 wherein the heat treatment lies in the range 1600 to 1850 0C.
3. The method according to either Claim 1 or Claim 2 wherein the silicon coating thickness lies in the range from 0.01 to 0.50 mm.
4. A method according to Claim 3 wherein the thickness lies in the range from 0.05 to 0.20 mm.
5. A method according to any one preceeding claim wherein the silicon coating is deposited by a physical vapour deposition method.
6. A method according to Claim 5 wherein the silicon coating is deposited by plasma spraying.
7. A method according to any one preceeding claim wherein there is a heat treatment in the 0 temperature range between 800 and 1300 C in an inert atmosphere prior to the final heat treatment at a minimum of 13000C.
8. A method according to any one preceeding claim wherein the final heat treatment is performed at about 18000C.
9. A method according to any one preceeding claim wherein at least part of the carbon is supplied from a furnace lining.
10. A method according to Claim 7 wherein the heat treatment is carried out at 1150 0C.
11. A graphite based article having a protective coating when made by the method of any one of Claims 1 to 10.
12. A method substantially as hereinbefore described with reference to the accompanying specification.
13. A graphite based article having a protective coating substantially as hereinbefore described with reference to the accompanying specification.
GB8901305A 1988-02-23 1989-01-20 Coatings Expired - Lifetime GB2216145B (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB888804174A GB8804174D0 (en) 1988-02-23 1988-02-23 Coatings

Publications (3)

Publication Number Publication Date
GB8901305D0 GB8901305D0 (en) 1989-03-15
GB2216145A true GB2216145A (en) 1989-10-04
GB2216145B GB2216145B (en) 1992-06-03

Family

ID=10632201

Family Applications (2)

Application Number Title Priority Date Filing Date
GB888804174A Pending GB8804174D0 (en) 1988-02-23 1988-02-23 Coatings
GB8901305A Expired - Lifetime GB2216145B (en) 1988-02-23 1989-01-20 Coatings

Family Applications Before (1)

Application Number Title Priority Date Filing Date
GB888804174A Pending GB8804174D0 (en) 1988-02-23 1988-02-23 Coatings

Country Status (1)

Country Link
GB (2) GB8804174D0 (en)

Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB967933A (en) * 1961-10-23 1964-08-26 Gen Electric Co Ltd Improvements in or relating to methods of preparing crystalline silicon carbide
GB1002790A (en) * 1963-01-18 1965-08-25 Siemens Planiawerke Ag Improvements in or relating to carbon bodies
FR2236962A1 (en) * 1973-07-13 1975-02-07 Toshiba Ceramics Co Silicon carbide coating prodn. on graphite - by heating in an atmosphere of silicon vapour
GB1452773A (en) * 1972-11-24 1976-10-13 Westinghouse Electric Corp Silicon carbide-coated graphite members
GB2122179A (en) * 1982-06-18 1984-01-11 Us Energy Producing silicon carbide bodies
EP0171858A2 (en) * 1984-08-14 1986-02-19 AGIP S.p.A. Method of making silicon carbide and coatings of silicon carbide on carbonaceous substrates
EP0228166A1 (en) * 1985-12-24 1987-07-08 Ford Motor Company Limited Method of making graphite forming dies

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4617232A (en) * 1982-04-15 1986-10-14 Kennecott Corporation Corrosion and wear resistant graphite material

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB967933A (en) * 1961-10-23 1964-08-26 Gen Electric Co Ltd Improvements in or relating to methods of preparing crystalline silicon carbide
GB1002790A (en) * 1963-01-18 1965-08-25 Siemens Planiawerke Ag Improvements in or relating to carbon bodies
GB1452773A (en) * 1972-11-24 1976-10-13 Westinghouse Electric Corp Silicon carbide-coated graphite members
FR2236962A1 (en) * 1973-07-13 1975-02-07 Toshiba Ceramics Co Silicon carbide coating prodn. on graphite - by heating in an atmosphere of silicon vapour
GB2122179A (en) * 1982-06-18 1984-01-11 Us Energy Producing silicon carbide bodies
EP0171858A2 (en) * 1984-08-14 1986-02-19 AGIP S.p.A. Method of making silicon carbide and coatings of silicon carbide on carbonaceous substrates
EP0228166A1 (en) * 1985-12-24 1987-07-08 Ford Motor Company Limited Method of making graphite forming dies

Non-Patent Citations (3)

* Cited by examiner, † Cited by third party
Title
GB1452773 A is equivalent to US3925577 *
JP63-186865 A *
JP73-026597 B *

Also Published As

Publication number Publication date
GB2216145B (en) 1992-06-03
GB8901305D0 (en) 1989-03-15
GB8804174D0 (en) 1988-03-23

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Date Code Title Description
PCNP Patent ceased through non-payment of renewal fee

Effective date: 19930120