Dry self-lubricating dense material; a mechanical part formed from said material; a method of manufacturing said material

1. A material, which is dense, with a density of ≧90%, bulk dry self-lubricating, with a coefficient of friction of <0.3, constituted by a matrix that endows it with suitable strength, with a R m of ≧400 MPa in a medium to high temperature range of 300° C.≦θ≦600° C.; said matrix including particles of solid lubricant in its volume.

2. The material according to claim 1 , wherein the diameter of said particles of solid lubricant is in the range 5 μm to 100 μm.

3. The material according to claim 1 , wherein said particles of solid lubricant are present in an amount of 1% to 30% by volume.

4. The material according to claim 1 , selected from the group consisting of:

a martensitic stainless steel containing particles of boron nitride;

a cobalt-based alloy containing particles of boron nitride and/or graphite; and

nickel or a nickel-based alloy containing particles of graphite.

5. The material according to claim 1 , able to be obtained by powder metallurgy techniques.

6. A mechanical part selected from the group consisting of a bushing, a pivot, and a spindle, the part being formed from a material according to claim 1 .

7. A method of manufacturing a material according to claim 1 , the method comprising:

forming an intimate mixture of a powder which is the matrix precursor, particles of lubricant and an organic binder;

molding said intimate mixture by pressing or injecting into a mold;

removing the molded blank from said mold;

debinding said blank;

densifying said debound blank by sintering.

8. The method according to claim 7 , wherein said powder, the matrix precursor, is constituted by grains with an equivalent diameter in the range 20 μm to 70 μm.

9. The method according to claim 7 , wherein said particles of lubricant comprise grains of boron nitride with an equivalent diameter in the range 5 μm to 30 μm.

10. The method according to claim 7 , wherein said particles of lubricant comprise grains of metal-coated graphite with an equivalent diameter in the range 30 μm to 90 μm.

11. The method according to claim 7 , wherein said intimate mixture of powder, particles and binder is obtained in three steps:

mixing said powder, particles and said binder at a temperature in the range 150° C. to 200° C.;

cooling said mixture until it solidifies;

grinding said solidified mixture.

12. The method according to claim 7 , wherein said molding is implemented by injection molding, advantageously at a temperature in the range 150° C. to 200° C., for 15 to 60 seconds.

13. The method according to claim 7 , wherein said debinding comprises a first chemical treatment followed by a second heat treatment, said second heat treatment advantageously being continued to pre-sinter said blank.

14. The method according to claim 13 , wherein said debinding includes a first chemical treatment using hexane in the liquid phase then in the vapor phase.

15. The method according to claim 14 , wherein said debinding includes a second heat treatment carried out in a suitable protective gas, between 110° C. and 450° C.

16. The method according to claim 7 , wherein densification by sintering is carried out in a vacuum or in a low partial pressure of a suitable protective gas, between 1100° C. and 1500° C.

17. The method according to claim 7 , further comprising:

machining said densified debound blank.

18. The method according to claim 7 , further comprising:

at least one supplemental heat treatment intended to harden said densified debound and optionally machined blank.

19. The material according to claim 1 , wherein said particles of solid lubricant are present in an amount of 10% to 20% by volume.