Friction lining material and method for producing a friction lining material

Abstract

The invention relates to a method for producing a friction lining material as well as a friction lining material having a porous body, whose pores are filled with a filling material, said porous body being formed on the basis of petroleum coke.

Claims

1. A friction lining material having a porous body, whose pores are filled with a filling material, wherein the filling material comprises a metal portion of at least 5% wt and wherein the porous body has a porosity of 5 to 50%, a bulk density of 1.5 to 5 g/cm.sup.3 and comprises more than 50 wt % of petroleum coke.

2. The friction lining material according to claim 1, wherein the friction lining material comprises a porous body having a porosity of 10 to 30%, a bulk density of 2.0 to 2.5 g/cm.sup.3 and a metal portion of at least 10 wt %.

3. The friction lining material according to claim 1, wherein the friction lining material comprises a porous body having a porosity of 15 to 20%, a bulk density of 2.2 to 2.4 g/cm.sup.3 and wherein the metal portion comprises a copper portion of 20 to 30 wt %.

4. The friction lining material according to claim 1, wherein the friction lining material comprises a porous body having a porosity of 25 to 30%, a bulk density of 2.2 to 2.4 g/cm.sup.3 and wherein the metal portion comprises a copper portion of 25 to 45 wt %.

5. The friction lining material according to claim 1, wherein the friction lining material comprises a porous body having a porosity of 10 to 20%, a bulk density 1.9 to 2.4 g/cm.sup.3 and the metal portion comprises an aluminum alloy of 5 to 25 wt %.

6. A friction lining comprised of a friction lining material according to claim 1.

7. A method for producing a friction lining material, comprising the steps of compacting a mixture comprising petroleum coke and a binding agent containing carbon and subsequently pyrolizing the mixture at a temperature between 800 and 1500 C. in order to produce a porous body, then graphiting the porous body, and subsequently filling pores formed in the porous body with a molten filling material, wherein the molten filling material comprises a ceramic material.

8. The method according to claim 7, wherein synthetic resin, tar or pitch is used as a binding agent.

9. The method according to claim 7, wherein the filling material further comprises a semimetal.

10. The method according to claim 7, wherein the filling material further comprises a metal.

11. The method according to claim 7, wherein the ceramic material comprises silicon carbide or aluminum oxide.

12. The method according to claim 10, wherein the metal comprises copper.

13. The method according to claim 10, wherein the metal comprises a metal alloy.

14. The method according to claim 10, wherein the metal comprises an aluminum alloy.

15. A method for producing a friction lining material, comprising the steps of compacting a mixture comprising petroleum coke and a binding agent containing carbon and subsequently pyrolizing the mixture at a temperature between 800 and 1500 C. in order to produce a porous body, then graphiting the porous body, and subsequently filling pores formed in the porous body with a molten filling material, wherein the molten filling material comprises a semimetal material.

16. The method according to claim 15, wherein the filling material further comprises a semimetal.

17. The method according to claim 15, wherein the semimetal material comprises a material containing boron or silicon.

Description

(1) The friction curves are illustrated in FIGS. 1 and 2, respectively, the essentially horizontal friction curves representing the dynamic friction factor or sliding friction factor, which is attained at a continuous relative movement of the friction partners, and the maximum values of the friction curves representing the static friction factor, which is attained when friction partners, which form a friction pairing and which are each formed by a friction lining piece arranged on a steel plate, are pressurized by a tangential force, namely a force parallel to the friction plane, from a standstill.

(2) FIG. 1 illustrates the friction curve in a friction pairing between a conventional organic friction lining and a steel plate.

(3) FIG. 2 illustrates the friction curve in a friction pairing between a friction lining according to the invention and a steel plate.

(4) As the two FIGS. 1 and 2 clearly illustrate in comparison to each other, the friction curve shows an extreme increase of the friction factor in a conventional friction lining material when being converted from a dynamic to a static friction behavior, i.e. when the friction lining is pressurized from a standstill with a continuously increasing tangential force so that it tears away from the static friction after a continuous relative movement on the steel plate. Moreover, FIG. 1 clearly illustrates that a dynamic friction factor which is significantly larger than the dynamic friction factor before tearing away is attained after tearing away when the dynamic operation is continued.

(5) In comparison thereto, a friction curve can be identified in the friction lining material according to the invention, the increase of the dynamic friction factor on the static friction factor being significantly lower in said friction curve and a dynamic friction factor being attained after tearing away in said friction curve, said dynamic friction factor being only slightly higher than the dynamic friction factor before tearing away.

(6) The noticeable slight difference between the static friction factor and the dynamic friction factor in the friction lining material according to the invention underlines the low tendency to stick and slip so that oscillations, which are caused by sticking and slipping and which lead to disruptive noise emissions, can be prevented. Such noise emissions occur in particular in the operation of wind energy plants which are provided with an azimuth adjustment for the rotor arranged on the car. An azimuth braking device is provided for fixing the pivot position of the car and comprises brake calipers comprising brake pads, i.e. friction linings, said brake calipers interacting with annular brake disks made of steel.

(7) In addition to the advantage of a low tendency to stick and slip, the friction lining material according to the invention enables realizing an essentially constant or only slightly dispersed braking force due to the dynamic friction factor which slightly changes during operation, although the slightly dispersing braking force, independent of the usage conditions of the friction lining material according to the invention, always is of an advantage whenever a brake force is controlled, as in ABS systems, for example.

(8) In order to produce a first exemplary embodiment of a friction lining material, a porous body formed on the basis of petroleum coke having a middle particle size D.sub.50 of 100 m is mixed with a phenolic resin as a binding agent, is compacted as a molded piece for producing a porous body and subsequently pyrolized at 1400 C. The result is a porous body having a bulk density of 1.7 g/cm.sup.3 and a porosity of 17%. After the porous body has been infiltrated by molten copper at a temperature of 1300 C. and a pressure of 7.5 MPa, the result is a friction lining material having a bulk density of 2.27 g/cm.sup.3, a metal portion of 25% and a friction coefficient of =0.36.

(9) According to another exemplary embodiment of a friction lining material, a porous body formed on the basis of petroleum coke having a middle pore size D.sub.50 of 125 m which is mixed with pitch as a binding agent is produced and compacted into a molded piece. After a pyrolysis has been conducted at 1400 C., a porous body having a bulk density of 1.5 g/cm.sup.3 and a porosity of 27% is the result. After the porous body has been infiltrated by molten copper at a temperature of 1300 C. and a pressure of 7.5 MPa, the result is a friction lining material having a bulk density of 2.5 g/cm.sup.3, a metal portion of 42% and a friction coefficient of =0.44.

(10) According to a third exemplary embodiment of a friction lining material, a porous body formed on the basis of petroleum coke having a middle particle size D.sub.50 of 30 m is produced, a phenolic resin being used as a binding agent and the realized mixture being compacted to form a molded piece and subsequently being pyrolized at 950 C. The result is a porous body having a bulk density of 1.72 g/cm.sup.3 and a porosity of 16%.

(11) After the porous body has been infiltrated by a molten aluminum alloy (AlSil2) at a temperature of 600 C. and a pressure of 10 MPa, a porous body having a bulk density of 1.98 g/cm.sup.3, a metal portion of 17% and friction factor of =0.2.

(12) According to a fourth exemplary embodiment of a friction lining material, a porous body formed on the basis of petroleum coke having a particle size D.sub.50 of 30 m is produced, a phenolic resin being added to the porous body so as to produce a mixture. After the mixture has been compacted to form a molded piece and has been pyrolized at a temperature of 950 C., the thus formed porous body is graphited in another step at a temperature of 3000 C. Thus, a porous body having a bulk density of 1.85 g/cm.sup.3 and a porosity of 17% is produced.

(13) After the porous body has been infiltrated by a molten aluminum alloy (AlSil2) at a temperature of 600 C. and a pressure of 10 MPa, a friction lining material having a bulk density of 2.19 g/cm.sup.3, a metal portion of 15.5% and a friction factor of =0.11 is the result.