Process for producing ceramic bearing components

• US 20030176270A1
• Filed: 01/27/2003
• Published: 09/18/2003
• Est. Priority Date: 01/25/2002
• Status: Active Grant

• Current Assignee: AB SKF, Global Precursor Ceramics GmbH
• Original Assignee: Ab Sfk
• Inventors: Gegner, Jurgen
• Granted Patent: US 7,163,650 B2
• Time in Patent Office: Days
• US Class Current: 501/96.2
• CPC Class Codes: C04B 35/589 obtained from Si-containing polymer precursors or organosilicon monomers
• CPC Class Codes: F16C 33/043 Sliding surface consisting mainly of ceramics, cermets or hard carbon, e.g. diamond like carbon [DLC]
• CPC Class Codes: F16C 33/30 Parts of ball or roller bearings

Abstract

A process for producing ceramic bearing components in which a material mixture is produced from an organometallic compound as a preceramic precursor and from silicon in element form or in the form of an alloy as a chemically reactive filler. The material mixture is subjected to reaction pyrolysis for conversion into a ceramic material.

Claims

1. Process for producing ceramic bearing components comprising:

producing a material mixture from an organometallic compound as a preceramic precursor and from silicon in element form or in a form of an alloy as a chemically reactive filler; and

subjecting the material mixture to reaction pyrolysis to convert the material mixture into a ceramic material.

2. Process according to claim 1, wherein the material mixture is produced from a cross-linking organometallic compound as the preceramic precursor.

3. Process according to claim 1, wherein the material mixture is produced from an organosilicon compound as the preceramic precursor.

4. Process according to claim 3, wherein the material mixture contains a silicone or polysiloxane as the preceramic precursor.

5. Process according to claim 3, wherein the material mixture contains a silicone resin or polysilsesquioxane as the preceramic precursor.

6. Process according to claim 1, wherein the material mixture contains a metal in element form, in the form of an alloy, in the form of an intermetallic phase or in the form of any chemical composition as the chemically reactive filler.

7. Process according to claim 6, wherein the material mixture contains a metal silicide as the chemically reactive filler.

8. Process according to claim 6, wherein the material mixture contains more silicon than metal.

9. Process according to claim 6, wherein the metal is a transition metal.

10. Process according to claim 8, wherein the metal is iron.

11. Process according to claim 6, wherein the metal is aluminum.

12. Process according to claim 1, wherein the chemically reactive filler is processed in powder form with a grain size in a range of about 1 micron to several dozen microns.

13. Process according to claim 1, wherein the material mixture contains an inert filler.

14. Process according to claim 1, wherein the material mixture contains fibers to improve mechanical properties.

15. Process according to claim 14, wherein the fibers in the material mixture are short fibers.

16. Process according to claim 1, wherein the material mixture contains zirconium oxide and/or aluminum oxide and/or silicon carbide and/or silicon nitride to improve mechanical properties and/or reaction kinetics.

17. Process according to claim 1, wherein the reaction pyrolysis is carried out at least partially in a chemically reactive gas atmosphere.

18. Process according to claim 1, wherein the reaction pyrolysis is carried out in a nitrogen atmosphere.

19. Process according to claim 1, wherein the reaction pyrolysis is carried out at least partially in a chemically inert gas atmosphere or in a vacuum.

20. Process according to claim 1, wherein the reaction pyrolysis is carried out at an overpressure.

21. Process according to claim 1, wherein the reaction pyrolysis is carried out at an overpressure of a few bars to a few 100 bar.

22. Process according to claim 1, wherein the reaction pyrolysis is carried out while varying pressure.

23. Process according to claim 1, wherein the reaction pyrolysis is carried out at a temperature between 1000°

C. and 1700°

C.

24. Process according to claim 23, wherein the reaction pyrolysis is carried out at a temperature between 1200°

C. and 1500°

C.

25. Process according to claim 23, wherein the temperature is varied during the reaction pyrolysis.

26. Process according to claim 1, including subjecting the material mixture to at least one heat treatment in the range from 400°

C. to 1000°

C. before the reaction pyrolysis.

27. Process according to claim 26, wherein the at least one heat treatment is carried out with a holding time of approximately 1 hour.

28. Process according to claim 1, including shaping the material mixture to a configuration approaching the bearing component and stabilizing the organometallic compound in the material mixture by curing before the reaction pyrolysis.

29. Process according to claim 28, wherein the curing is carried out by heat at a temperature between about 100°

C. to 300°

C.

30. Process according to claim 28, wherein the curing is carried out by radiation.

31. Process according to claim 28, wherein the curing is carried out under pressure.

32. Process according to claim 28, wherein upon curing a semifinished article of stable shape is produced from the material mixture, and including mechanical working the semifinished article before the reaction pyrolysis to produce the bearing components almost to a final state.

33. Process according to claim 1, wherein components of the material mixture are matched to one another to inhibit shrinkage or effect a controlled volume change which is oriented to further processing of the bearing component when the reaction pyrolysis is carried out.

34. Process according to claim 1, wherein the ceramic material is subjected to aftersintering following the reaction pyrolysis.

35. Process according to claim 1, wherein after carrying out the reaction pyrolysis, the ceramic material is mechanically finished.

36. Process according to claim 1, wherein after carrying out the reaction pyrolysis, the ceramic material is subjected to shot-peening.

37. Process according to claim 1, wherein the atomic ratio of metal to silicon is approximately 1:

2.