DE102012219303A1 - Friction and/or sliding liner, useful in brake disc, comprises plastic matrix containing graphite as filler, where the matrix in addition to the graphite comprises nanofiller and the graphite is combined with the nanofiller as microfiller - Google Patents

Abstract

The friction and/or sliding liner comprises a plastic matrix, which contains graphite (5-7%) as filler. The plastic matrix in addition to the graphite comprises a nanofiller. The graphite is combined with the nanofiller as microfiller.

Description

The invention relates to a friction and / or sliding coating with a plastic matrix containing graphite as filler. The invention further relates to the use of graphite in a friction and / or sliding coating. The invention further relates to a brake disc with a friction and / or sliding coating.

From the German patent application DE 29 23 051 A1 is a thermosetting adhesive for bonding brake pads known containing graphite. From the translation DE 697 29 939 T2 the European patent specification EP 0 892 896 B1 For example, friction materials having textured surfaces are known for use in clutch plate members, brake linings, transmissions, and the like, where the precisely shaped composite structures comprise a plurality of friction particles dispersed in a binder, such as natural and synthetic graphite. The German patent application DE 10 2006 003 908 A1 comprises a plain bearing body with a metal-containing sliding layer containing nanomaterial. The German patent DE 10 2006 039 638 B3 discloses the use of nanocomposites as a lacquer, adhesive, potting compound, coating, matrix resin for fiber-reinforced plastics, polymer foam or plastic moldings or for the production of such products. The German patent application DE 10 2005 042 138 A1 discloses composites of at least one thermoplastic polymer and at least one semi-metal oxide dispersed nanodispersed in the polymer.

The object of the invention is to increase the wear resistance of friction and / or sliding coatings with a plastic matrix containing graphite as a filler without undesirably impairing the mechanical strength.

The object is achieved in a friction and / or sliding coating with a plastic matrix containing graphite as a filler in that the plastic matrix contains at least one nanofiller in addition to the graphite. The friction and / or sliding linings are preferably technical friction and / or sliding linings for various applications in general mechanical engineering, agriculture, medical, safety or sanitary engineering. The invention particularly relates to brake linings and / or clutch linings for the automotive industry. According to a further aspect of the invention, the friction and / or sliding linings are used for wind power brakes. In the context of the present invention, it has surprisingly been found that the combination of nanofillers with graphite in the plastic matrix brings about a synergy effect which improves both the tribological and the mechanical properties in comparison to conventional friction and / or sliding linings. Nanofillers are particles whose size is in the nanometer range. The particles preferably comprise an average grain size greater than ten nanometers. At the same time, the particles preferably have a size of less than a hundred nanometers in at least one direction. The particles can have different geometries. Thus, the particles may have the shape of spheres, needles, crystals or tubes. The cured plastic matrix with the fillers is also referred to as a composite or composite material.

A preferred embodiment of the friction and / or sliding coating is characterized in that the nanofiller contains nanosilicate. In this case, synthetic, spherical or spherical nanosilicate is preferably used as the nanofiller. The nanosilicate is dispersed in the plastic matrix prior to introduction. The nanosilicates are particles of silicate whose order of magnitude is in the nanometer range.

Another preferred embodiment of the friction and / or sliding coating is characterized in that the plastic matrix contains two to fifteen percent, in particular about five or ten percent, nanosilicate. The percentages with respect to the fillers are preferably percentages by volume. The volume percentages are preferably based on a resin from which the plastic matrix is formed. A nanosilicate content of ten percent showed the greatest improvement in mechanical properties.

Another preferred exemplary embodiment of the friction and / or sliding lining is characterized in that the nanofiller contains nanoclays or montmorillonites. These are preferably organophilic nanoclays or montmorillonites. The organophilic nanoclays or montmorillonites (o-MMT) are preferably exfoliated before introduction into the plastic matrix. Montmorillonite is a mineral from the group of clay minerals.

Another preferred embodiment of the friction and / or sliding coating is characterized in that the plastic matrix contains from two to ten percent, in particular about five percent, Nanoclays or Montmorillonite. The percentages with respect to the fillers are preferably percentages by volume. The volume percentages are preferably based on a resin from which the plastic matrix is formed.

Another preferred embodiment of the friction and / or sliding coating is characterized in that the plastic matrix contains from two to fifteen percent, in particular about five or about ten percent, graphite. Graphite is a mineral and one of the natural manifestations of the chemical element carbon in its purest form. Graphite is used in a known manner as a solid lubricant through which the wear can be minimized. However, the addition of graphite alone in friction and / or sliding coatings has a negative effect on their mechanical properties.

Another preferred embodiment of the friction and / or sliding lining is characterized in that the graphite is combined as a microfiller with the nanofiller. A microfiller comprises particles in the micrometer range. For example, the graphite includes particles having a grain size of about twenty microns.

Another preferred embodiment of the friction and / or sliding coating is characterized in that the plastic matrix is formed of epoxy resin. The epoxy resin is preferably a two-component system containing a hardener in addition to the resin, for example, an ether. The addition of the hardener triggers crosslinking by polyaddition. The inventive addition of graphite as microfiller and of at least one nanofiller, the properties of the epoxy resin in the cured state can be particularly advantageously improved.

The invention further relates to the use of graphite in combination with at least one nanofiller in a friction and / or sliding coating, in particular in a previously described friction and / or sliding coating.

The invention further relates to a brake disc with a previously described friction and / or sliding coating.

The invention particularly particularly relates to a wind power brake with a previously described friction and / or sliding lining, in particular with a previously described brake disk.

Further advantages, features and details of the invention will become apparent from the following description in which, with reference to the drawings, various embodiments are described in detail.

Show it:

1 a bar graph showing the influence of montmorillonite in combination with graphite as a filler on the wear;

2 a bar graph showing the influence of montmorillonite in combination with graphite as a filler on the mechanical properties;

3 a bar graph showing the influence of nanosilicate in combination with graphite as filler on the wear, and

4 a bar chart showing the influence of nanosilicate in combination with graphite as a filler on the mechanical properties.

The invention relates to friction and / or sliding coatings with a plastic matrix. Microplastic fillers, such as graphite, can be incorporated into the plastic matrix to minimize wear. However, microfillers, such as graphite, have a negative impact on the mechanical properties.

Nanofillers have the potential to improve the mechanical and tribological properties of composite materials with a plastic matrix. In the context of the present invention, various nanofillers were tested. The use of organophilic montmorillonites and of synthetic, spherical nanosilicate has proven to be particularly advantageous. Organophilic montmorillonite, abbreviated as o-MMT, must be exfoliated before it exhibits improved mechanical properties in the composite material, which is also referred to as a composite. Nanosilicate must be dispersed for the same purpose.

For the plastic matrix, an epoxy resin was used in the context of the present invention, which is sold under the technical name Ancarez RZ 4020 by the German company Air Products GmbH. It is a bisphenol-A diclycidyl ether (BADGE). The hardener used is a 3-aminoethyl-3,5,5-trimethylcyclohexylamine, which is also marketed by Air Products GmbH under the name Ancamine 3473.

The organophilic montmorillonite used was a product of the American company Nanocor Incorporated, which is marketed under the trade name Nanomer I.30E. This product is modified by seven percent wt octadecylamine and has a particle size of ten microns prior to exfoliation.

As a synthetic, spherical nanosilicate, a product of the German company NANO Resins AG is used, which is sold under the trade name Nanopox ^® F 400. The term Nanopox is protected by trademark law. The synthetic, spherical nanosilicate was used in the form of particles with an average particle size of twenty nanometers.

In making the composites or composite materials, the various components were mixed with the fillers. The nanoclays or montmorillonite was mixed with the epoxy resin by shear mixing, preferably at speeds of 10,000 revolutions per minute. For introducing the nanosilicate into the epoxy resin standard mixing processes were used, preferably at 500 revolutions per minute.

The mechanical properties of the cured composite were tested by conventional tests. To determine the tensile strength and the associated modules was in accordance with DIN 53455 proceed. With respect to the three-point bending strength and the associated modules was according to DIN 53452 proceed.

With regard to the tribological properties, known tests for determining the abrasive wear with a static coefficient of friction and a dynamic coefficient of friction have also been used. A surface pressure of one megapascal was applied at a test temperature of 60 degrees Celsius and a sliding speed of 6.6 meters per second.

The results of the experiments are in the 1 to 4 shown in the form of bar charts, each one x-axis 1 and a y-axis 2 exhibit. The 1 and 2 show the influence of montmorillonite in combination with graphite on the wear and the mechanical strength of the composite material. The 3 and 4 show the influence of synthetic, spherical nanosilicate in combination with graphite on the wear and the mechanical strength of the composite material.

In the 1 and 3 is on the y-axis 2 in each case a measure of the wear in cubic millimeters per megajoule applied. In the 2 and 4 is on the y-axis 2 a measure of mechanical strength is plotted in Newtons per square millimeter.

In 1 shows a bar 4 a wear value of 414 for pure epoxy resin. The value 414 the unit is cubic millimeters per megajoule. In the following, the associated unit will not be repeated for the sake of simplicity. A beam 5 represents a wear value of 349 which is achieved by adding five percent graphite. A beam 6 shows a value of 346 which is achieved by adding five percent o-MMT. A beam 7 shows a value of 218 which is achieved by adding five percent graphite plus five percent o-MMT.

By an arrow 8th is in 1 indicated that the sole addition of graphite or o-MMT has a rather small effect on the wear. By another arrow 9 It is suggested that the combination of o-MMT with graphite has an unexpected significant positive impact on wear.

In 2 are by bars 11 to 14 the average tensile strengths in Newton per square millimeter determined in the tests are shown. Through more bars 15 to 18 the mean bending stiffnesses are shown in Newton per square millimeter. The bars correspond 11 to 14 Tensile strength values of 64 . 38 . 29 and 25 Newton per square millimeter. The bars 15 to 18 correspond to bending stiffnesses of 109 . 79 . 60 and 65 Newton per square millimeter.

The bars 11 and 15 according to the use of pure epoxy resin. The bars 12 and 16 show the influence of five percent graphite. The bars 13 and 17 show the influence of five percent o-MMT. The bars 14 and 18 show the influence of five percent o-MMT and five percent graphite on the mechanical properties. By an arrow 19 it is indicated that the mechanical properties do not deteriorate significantly by the addition of graphite in combination with montmorillonite.

In 3 put bars 21 to 27 Wear values of 414 . 349 . 348 . 312 . 240 . 164 and 152 Cubic millimeters per megajoule. The beam 21 shows the wear when using pure epoxy resin. The term pure epoxy resin means, as in the previous embodiment, that the epoxy resin no fillers are mixed. The bar 22 corresponds to an addition of five percent graphite. The bar 23 corresponds to an addition of five percent dispersed nanosilicate. The bar 24 corresponds to an addition of ten percent dispersed nanosilicate. The bar 25 corresponds to an addition of five percent dispersed nanosilicate and additionally five percent graphite. The bar 26 corresponds to an addition of ten percent dispersed nanosilicate and additionally five percent graphite. The bar 27 corresponds to an addition of ten percent dispersed nanosilicate and additionally ten graphite.

By an arrow 28 It is suggested that the sole addition of graphite or nanosilicate has a rather small influence on the wear. In contrast, when adding dispersed nanosilicate in combination with graphite, a significant influence on the wear can be found, as indicated by another arrow 29 is indicated.

In 4 are through the bars 31 to 37 the average tensile strengths in Newton per square millimeter determined in the tests are shown. Through more bars 41 to 47 the mean bending stiffnesses are shown in Newton per square millimeter. The bars correspond 31 to 37 Tensile strengths of 64 . 38 . 49 . 78 . 46 . 45 and 35 Newton per square millimeter. The bars 41 to 47 correspond to bending stiffnesses of 109 . 79 . 96 . 119 . 89 . 73 and 68 Newton per square millimeter.

The bars 31 and 41 correspond to the use of pure epoxy resin. The bars 32 and 42 show the influence of five percent graphite. The bars 33 and 43 show the influence of five percent nanosilicate. The bars 34 and 44 show the influence of ten percent nanosilicate. The bars 35 and 45 show the influence of five percent nanosilicate and five percent graphite. The bars 36 and 46 show the influence of ten percent nanosilicate and five percent graphite. The bars 37 and 47 show the influence of ten percent nanosilicate and ten percent graphite.

By an arrow 48 it is suggested that the mechanical properties can be improved by adding ten percent nanosilicate. By another arrow 49 it is indicated that the mechanical properties do not deteriorate significantly by adding graphite in combination with nanosilicate.

In summary, the addition of ten percent synthetic spherical nanosilicate to a graphite / epoxy resin blend reduced wear by 71 percent compared to pure epoxy resin. This effect could only be observed in combination of the two fillers.

The addition of synthetic, spherical nanosilicates also improved the mechanical properties of graphite-epoxy composites. A nanosilicate content of ten percent showed the greatest improvement in mechanical properties.

Adding Nanomer I.30E to a graphite-epoxy resin composite reduced wear by 40 percent compared to pure epoxy resin. The combination of graphite with Nanopox ^® F400 and Nanomer I.30E showed strong synergistic effects on wear behavior.

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QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 2923051 A1 [0002]
• DE 69729939 T2 [0002]
• EP 0892896 B1 [0002]
• DE 102006003908 A1 [0002]
• DE 102006039638 B3 [0002]
• DE 102005042138 A1 [0002]

Cited non-patent literature

• DIN 53455 [0027]
• DIN 53452 [0027]

Claims (10)

Friction and / or sliding coating with a plastic matrix containing graphite as a filler, characterized in that the plastic matrix in addition to the graphite contains at least one nanofiller. Friction and / or sliding coating according to claim 1, characterized in that the nanofiller contains nanosilicate. Friction and / or sliding coating according to one of the preceding claims, characterized in that the plastic matrix contains two to fifteen percent, in particular about five or ten percent, nano silicate. Friction and / or sliding coating according to one of the preceding claims, characterized in that the nanofiller contains nanoclays or montmorillonites. Friction and / or sliding coating according to one of the preceding claims, characterized in that the plastic matrix contains from two to ten percent, in particular about five percent, Nanoclays or montmorillonite. Friction and / or sliding coating according to one of the preceding claims, characterized in that the plastic matrix contains two to fifteen percent, in particular about five or about ten percent, graphite. Friction and / or sliding coating according to one of the preceding claims, characterized in that the graphite is combined as a microfiller with the nanofiller. Friction and / or sliding coating according to one of the preceding claims, characterized in that the plastic matrix is formed from epoxy resin. Use of graphite in combination with at least one nanofiller in a friction and / or sliding coating, in particular according to one of the preceding claims. Brake disc with a friction and / or sliding coating according to one of the preceding claims.

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