Patent Grant
9416240
1. Technical Field
The present invention relates to a friction material and, more particularly, to a low-wear microporous friction material with a high stability coefficient and a manufacturing method thereof.
2. Description of Related Art
Since their advent, microporous materials have been effective to some extent in lowering the friction temperature of friction pairs. In actual use, however, microporous materials have certain drawbacks such as uneven pore sizes, inconsistent wear resistance between batches, and an instable friction coefficient under wet conditions. The present invention not only can lower the brake temperature to protect the mating materials from thermal damage attributable to an excessively high brake temperature, but also can control the pore size of the material disclosed herein, reduce the wear rate of the material, and thereby extend the material's service life. The present invention also ensures that the friction coefficient of the material is not reduced under wet conditions. Thus, the present invention provides an effective way to deal with high-speed, heavy-load, and frequent braking.
One objective of the present invention is to overcome the above-mentioned defects of the prior art and provide a low-wear microporous friction material with a high stability coefficient and a manufacturing method thereof.
This objective of the present invention can be achieved through the following technical solutions: A low-wear microporous friction material with a high stability coefficient is characterized in that the formula of the material is as follows:
It is preferable that the formula of the material is as follows:
The GM-15 resin is a commercially available modified phenolic resin.
The rubber is a nitrile powder rubber.
The shaping aid includes but is not limited to 4-t-butyl thiophenol zinc, zinc pentachlorothiophenol, or an acrylate copolymer.
The sintering aid includes but is not limited to an organic silicone resin, dimethicone, or polytetrafluoroethylene.
The foaming aid includes but is not limited to azodicarbonamide, N,N-dinitroso pentamethylenetetramine, or azobisisobutyronitrile.
The carbon fiber is commercially available chopped carbon fiber.
The KEVLAR is commercially available aramid pulp.
A manufacturing method of a low-wear microporous friction material with a high stability coefficient is characterized in that the method comprises the following steps:
(1) weighing the raw materials (i.e., the constituents):
(2) adding the above constituents into a high-speed rake mixer and mixing the constituents, wherein the mixing time is 2˜50 min; reacting the mixed material in a shaping mold at room temperature ˜120° C. and under a pressure of 200˜500 kg/cm2 for 20˜300 sec; and then sintering the shaped friction sheet at high temperature, wherein the sintering temperature is 160-260° C., and the sintering time is 2-20 hours. Thus, a microporous friction material is obtained. The reaction pressure in the shaping mold is preferably 250˜300 kg/cm2, the reaction time is preferably 100˜200 sec, the sintering temperature is preferably 180-220° C., and the sintering time is preferably 10˜12 hours.
Typically, a microporous friction material produced by a prior art technique has micropore sizes of 1-4 μm, a porosity of 5%-20%, and an average wear rate of 0.35 cm3/MJ. When subjected to a wet condition in a bench test, with μaverage<0.20, the stability coefficient of the friction coefficient of such a material is less than 80% on an MM1000 tester.
Compared with the existing microporous friction materials, the present invention achieves the following: by adjusting the hydrophilicity of the friction material disclosed herein and controlling the surface tension of the material, the friction coefficient of the material is kept from lowering under wet conditions and is rendered stable in dry and wet conditions. In the prior art, by contrast, the friction coefficient of a friction material decreases rapidly to below 0.2 in wet conditions. By employing the technique of the present invention, the friction coefficient of the disclosed friction material is kept above 0.25 under wet conditions, and the stability coefficient of the friction coefficient can reach 85% or above on an MM1000 tester.
Compared with the prior art, the present invention also achieves the following: by adding the foaming aid, the pore size of the microporous material disclosed herein is controlled at 0.5-1 μm . Since abrasive particles contributing to friction are typically greater than 2 μm in diameter (60%), these abrasive particles will not clog the micropores and can be easily discharged, thereby reducing the probability of abrasive wear and avoiding the generation of metal inlays.
In addition, according to the present invention, the pore sizes and porosity of the microporous material are respectively controlled at 0.2-1 μm and 15%-35% or above by changing the shaping temperature and the shaping pressure and by adding the shaping aid. With this technique, the wear to which the product is subject is greatly reduced, with an average wear rate lower than 0.16 cm3/MJ, and the service life of the product is thus doubled at least. In short, the friction material disclosed herein is a green low-carbon friction material.
The present invention will be described in detail below with reference to specific embodiments.
Embodiment 1
(1) Formulation of the Constituents:
(2) Preparation:
The above constituents were added stepwise into a high-speed rake mixer in proportion and mixed, wherein the mixing time was 25 min. Then, the mixed material was reacted in a shaping mold at 80° C. and under a pressure of 250 kg/cm2 for 150 sec. After that, the shaped friction sheet was sintered at high temperature, wherein the sintering temperature was 200° C. and the sintering time was 10 hours. Consequently, a microporous friction material was obtained.
The properties of the obtained friction material are as follows:
1. Physical and Mechanical Properties
2. Friction Properties
Embodiment 2
(1) Formulation of the Constituents:
(2) Preparation:
The above constituents were added stepwise into a high-speed rake mixer in proportion and mixed, wherein the mixing time was 30 min. Then, the mixed material was reacted in a shaping mold at 100° C. and under a pressure of 200 kg/cm2 for 200 sec. After that, the shaped friction sheet was sintered at high temperature, wherein the sintering temperature was 220° C. and the sintering time was 12 hours. Consequently, a microporous friction material was obtained.
The properties of the obtained material are as follows:
1. Physical and Mechanical Properties
2. Friction Properties
Embodiment 3
(1) Formulation of the Constituents:
(2) Preparation:
The above constituents were added stepwise into a high-speed rake mixer in proportion and mixed, wherein the mixing time was 30 min. Then, the mixed material was reacted in a shaping mold at 50° C. and under a pressure of 300 kg/cm2 for 100 sec. After that, the shaped friction sheet was sintered at high temperature, wherein the sintering temperature was 180° C. and the sintering time was 20 hours. Consequently, a macroporous friction material was obtained.
The properties of the obtained material are as follows:
1. Physical and Mechanical Properties
2. Friction Properties
Embodiment 4
(1) Formulation of the Constituents:
(2) Preparation:
The above constituents were added stepwise into a high-speed rake mixer in proportion and mixed, wherein the mixing time was 2 min. Then, the mixed material was reacted in a shaping mold at 120° C. and under a pressure of 200 kg/cm2 for 300 sec. After that, the shaped friction sheet was sintered at high temperature, wherein the sintering temperature was 260° C. and the sintering time was 2 hours. Consequently, a microporous friction material was obtained.
The properties of the obtained material are as follows:
1. Physical and Mechanical Properties
2. Friction Properties
Embodiment 5
(1) Formulation of the Constituents:
(2) Preparation:
The above constituents were added stepwise into a high-speed rake mixer in proportion and mixed, wherein the mixing time was 50 min. Then, the mixed material was reacted in a shaping mold at room temperature and under a pressure of 500 kg/cm2 for 20 sec. After that, the shaped friction sheet was sintered at high temperature, wherein the sintering temperature was 160° C. and the sintering time was 20 hours. Consequently, a microporous friction material was obtained.
The properties of the obtained material are as follows:
1. Physical and Mechanical Properties
2. Friction Properties
| Number | Date | Country | Kind |
|---|---|---|---|
| 2012 1 0316276 | Aug 2012 | CN | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/CN2012/082790 | 10/11/2012 | WO | 00 |
| Publishing Document | Publishing Date | Country | Kind |
|---|---|---|---|
| WO2014/032360 | 3/6/2014 | WO | A |
| Number | Name | Date | Kind |
|---|---|---|---|
| 6025405 | Snell Tung | Feb 2000 | A |
| 20040206441 | Lamport | Oct 2004 | A1 |
| Number | Date | Country |
|---|---|---|
| 1944498 | Apr 2007 | CN |
| 101024760 | Aug 2007 | CN |
| Number | Date | Country | |
|---|---|---|---|
| 20150218333 A1 | Aug 2015 | US |
