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In Situ Fluorination of Free Graphite in Powder Metal Alloys

IP.com Disclosure Number: IPCOM000077254D
Original Publication Date: 1972-Jul-01
Included in the Prior Art Database: 2005-Feb-25
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Martin, JT: AUTHOR [+2]

Abstract

A self-lubricating bearing surface is provided in a sintered iron base Powdered metal part by mixing metal powder and graphite powder, forming and sintering the part and fluorinating the free graphite at the surface to form polycarbon monofluoride.

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In Situ Fluorination of Free Graphite in Powder Metal Alloys

A self-lubricating bearing surface is provided in a sintered iron base Powdered metal part by mixing metal powder and graphite powder, forming and sintering the part and fluorinating the free graphite at the surface to form polycarbon monofluoride.

Iron powder and graphite powder are pressed into a desired form and thereafter sintered in an appropriate atmosphere. The sintering process is conducted in two stages, initially the part is placed in a vessel and heated to 1300 degrees F for 15 minutes followed by a 2000 degrees F temperature for 45 minutes.

The sintering is treated to convert graphite at the surface to polycarbon monofluoride C(F(x)) by:
1) Placing the sintering in a nickel lined reaction vessel.
2) Purging the vessel with helium introduced at the rate of

50cc per minute to remove moisture and oxygen.
3) Heating the vessel to 200 degrees C during the purge.
4) Slowly introducing fluoride at a partial pressure of 25

TORR in helium, while raising the vessel temperature to 600

degrees C.
5) Continuing the reaction for several hours or until a white

polycarbon monofluoride is formed at graphite locations

in the alloy.

As described above, graphite was blended into the powdered metal mix before compacting. Graphite could also be introduced by being rubbed or mechanically worked into a porous sintered surface. Fluorination of graphite particles embedded in a surface is not limited to iron-graphite...