WO2012088637A1

WO2012088637A1 - Low metal ceramic based automobile friction material and production method thereof

Info

Publication number: WO2012088637A1
Application number: PCT/CN2010/002214
Authority: WO
Inventors: 刘伯威; 刘美玲; 刘咏; 黄伯云
Original assignee: 湖南博云汽车制动材料有限公司; 中南大学
Priority date: 2010-12-30
Filing date: 2010-12-30
Publication date: 2012-07-05

Abstract

A low metal ceramic based automobile friction material consists of the following components: 15-30wt% of binding matrix, 25-50wt% of reinforcing fiber, 10-20wt% of friction modifier and 10-30% of filler. The binding matrix comprises a major part of ceramic binder and a minor part of organic binder. The network structure is formed when the first dehydration reaction happens under the circumstance of heating the ceramic binder under hot press molding. The network structure is crosslinked with the sea island structure of the organic binder. When the temperature is raised to 500℃ above in the application, the ceramic binder is dehydrated and crosslinked for the senond time. The structure of the friction material tends to be ceramic-like, which can effectively maintain the high temperature cohesive force, increase the porosity, reduce high temperature wear loss and decline, improve the braking stability and decrease the braking noise. The reinforcing fiber added to the binding matrix can reduce the damage on coupled parts and prolong the service life. The small amount of organic binder added can reduce equipment input and production cost. The automobile friction material is simple to produce, convenient to operate and suitable for industrial production. It is a novel high-performance environment-friendly friction material, and can replace the existing half-metal or less-metal resin based friction material.

Description

Low cermet based automotive friction material and preparation method thereof

The invention relates to a brake pad friction material and a preparation method thereof for an automobile brake system, in particular to a low cermet based automobile friction material and a preparation method thereof; and belongs to the technical field of friction materials.

Background technique

Automotive brake pads are the key components of Class A of automotive brake systems. Their performance is directly related to the safety and reliability of vehicle operation. Currently used semi-metal or metal-based resin-based friction materials, when the car is in continuous or emergency braking, the temperature of the brake pads and brake disc surface is as high as 500~ 700 °C, and the organic binder in the brake pads, Resin rubber and other poor temperature resistance, decomposition begins at about 200 °C, and decomposes at a high temperature of 500 °C or higher, releasing water, gas and small molecular organic matter, forming a film on the friction surface, making it dry. Friction becomes mixed friction or wet friction, the friction coefficient is significantly reduced, and there is a hidden danger of brake failure, which is extremely dangerous for high-speed heavy-duty vehicles. At the same time, due to the large amount of thermal decomposition of the resin, the bonding effect is reduced, and the high temperature wear of the material is intensified, resulting in a significant decrease in the service life of the brake pad. The traditional approach is to use a variety of fibers, mineral fiber, ceramic fiber, aramid fiber, polypropylene fiber, etc. instead of reducing the amount of steel fiber, reducing its density, thermal conductivity, and increasing porosity, thus delaying to some extent. The friction coefficient drops sharply at high speed and low temperature. Although the braking comfort performance of a variety of hybrid reinforcing fiber friction materials is remarkably improved, the use of a resin as a main binder results in problems such as cracking at high temperatures and poor wear resistance at high temperatures.

Summary of the invention

The object of the present invention is to overcome the deficiencies of the prior art and provide a low cermet-based automobile with simple preparation process and convenient operation, and the prepared friction material has stable braking performance, small thermal decay, long service life and low cost. Friction material and preparation method.

A low cermet based automotive friction material of the present invention consists of the following components in weight percent:

Bonding substrate 1 5~30,

Reinforcing fiber 25~50,

Friction performance modifier 1 0~20,

Filler 1 0-30,

The bonding matrix is composed of an inorganic ceramic binder and an organic binder in a weight ratio of (1~6):1;

The reinforcing fiber is composed of steel fiber and auxiliary reinforcing fiber in a ratio of 1:1 by weight Composition

The friction property modifier is composed of a friction increasing agent and an antifriction agent in a ratio of 3:7 by weight.

In the low cermet-based automotive friction material of the present invention, the inorganic ceramic binder is magnesium phosphate; the organic binder is selected from phenolic resin or rubber; and the magnesium phosphate has a particle size of 350 to 400 mesh; The phenolic resin has a particle size of 180 to 200 mesh; and the rubber has a particle size of 20 to 40 mesh. In the low cermet-based automotive friction material of the present invention, the steel fiber has a diameter of 62 to 100 μm; and the auxiliary reinforcing fiber is selected from the group consisting of copper fiber, mineral fiber, ceramic fiber, carbon fiber, aramid fiber, and polypropylene fiber. At least two of the copper fibers; the diameter of the copper fibers is 100 to 150 μm; the length of the mineral fibers is 300 to 800 μm, and the diameter is less than 5 μm; the length of the ceramic fibers, carbon fibers, aramid fibers, and polypropylene fibers It is 300 to 500 microns and has a diameter of less than 5 microns.

In the low cermet-based automotive friction material of the present invention, the friction increasing agent is selected from at least one of zirconium silicate, alumina, chromite, pyrite; the anti-wear agent is selected from the group consisting of molybdenum disulfide. And at least one of barium sulfide, graphite and mica; the raw material of the friction increasing agent and the antifriction agent has an average particle size of 40 to 74 μm.

In the low cermet-based automotive friction material of the present invention, the filler is at least one selected from the group consisting of zinc powder, calcium carbonate, cashew nut shell powder or barium sulfate; the zinc powder, calcium carbonate, cashew nut shell powder or barium sulfate The particle size is 100~150 microns.

The invention relates to a method for preparing a low cermet based automotive friction material, comprising the following steps:

Step 1: Ingredients

According to the design of the low cermet-based automotive friction material, the distribution ratio of each component is equal to the weight of each component;

Step 2: Forming

The mixture obtained in the first step is placed in a hot stamping die, and the pressing pressure is 200-300 kgf/cm ² , the hot pressing temperature is 160-200 ° C, the exhaust is 4 to 10 times, and the holding time is pressed to calculate the thickness of the blank. The thickness of the millimeter is kept at 55~65s;

The third step: heat treatment

The compact obtained in the second step is heated to 140 ° C at a heating rate of 1 to 2 ° C / min, and after heating for 1 hour, the temperature is further increased to 160 to 180 ° C, and the temperature is maintained for 4 hours; then, 0.5 to 1 ° C / minute. The heating rate is heated to 210 ° C, kept for 4 hours, and cooled to room temperature with the furnace;

Step 4: Surface treatment

The billet obtained in the third step is heated to 650~700 ° C for high temperature ablation surface According to the cooling of the furnace, a low cermet-based automotive friction material is obtained.

The invention adopts the above-mentioned process method and group distribution ratio, most of the ceramic binder magnesium phosphate is used in the bonding matrix, and a small part of the traditional organic binder-resin and rubber, that is, the matrix is mainly inorganic ceramic phase. Metal fiber such as steel fiber, copper fiber, organic fiber such as aramid fiber, polypropylene fiber, inorganic fiber such as mineral fiber, carbon fiber or ceramic fiber is added as a reinforcing component in the bonded matrix; its working mechanism and advantages are simple As described below:

In the preparation process of the low cermet-based automobile friction material of the invention, the magnesium phosphate salt undergoes a dehydration reaction by heat during hot press forming, and its own magnesium-phosphorus-oxygen bond network structure is formed, melted, impregnated with the material, and resin The island structure formed by heat curing of the rubber is crosslinked. During the use of friction materials, when high-speed heavy load or emergency brake continuous braking occurs, the temperature of the pair of parts and the friction material rises rapidly to above 500 °C. At this time, the organic binder resin rubber is almost When the weight loss is exhausted, the friction coefficient begins to decrease, and the decay phenomenon occurs. The composite salt has secondary dehydration and cross-linking, the network structure is further tight, and the friction material structure tends to be ceramic. Due to the friction-increasing performance of the ceramic. The tendency for the coefficient of friction to decrease is slowed down, tending to stabilize, and the material decay is reduced. At the same time, the high-temperature adhesion of the material maintains the material structure tightly, and the high-temperature internal bond strength is maintained, reducing the wear of the material at high temperatures. In addition, this network structure can also promote the formation of porous structures, increase porosity, increase brake stability, and reduce brake noise. In particular, the addition of a small amount of resin and rubber can continue to follow the molding process and production equipment of resin-based automotive brake pads, reducing equipment investment and production costs.

In summary, the invention has simple preparation process and convenient operation, and the prepared magnesium phosphate composite salt ceramic-based low-metal automobile friction material has improved braking stability and anti-degradation property compared with the conventional resin-based low-metal friction material. Better wear resistance, no damage to the dual, long life and low cost. Suitable for industrial production, it is a new type of high performance environmentally friendly friction material that can replace existing semi-metal or metal-based resin-based friction materials.

detailed description

The invention will be further described below in conjunction with specific embodiments.

The invention provides one comparative example, the number is 1; the embodiment is 10, and the numbers are 2~1 1 respectively.

The following materials and the proportions of the present invention and the comparative examples were respectively used for the matching and adjustment.

Binder:

Granular magnesium phosphate having a particle size of 350 to 400, a phenolic resin having a particle size of from 1 to 80 to 200, and a nitrile rubber having a particle size of from 20 to 40; Reinforcing fiber:

Steel fiber with a diameter of 62 to 100 μm, copper fiber with a diameter of 100 to 150 μm, a length of 300 to 500 μm, aramid fiber of less than 5 μm in diameter (DuPont, Kevlar), length 300 to 800 μm, diameter less than 5 μm Mineral fiber (Lapinus), 300-500 micron in length, carbon fiber or polypropylene fiber less than 5 micrometers in diameter, 300-500 micrometers in length, ceramic fiber less than 5 micrometers in diameter, the ratio of steel fiber content to total fiber content is 1: 1;

Friction performance modifier:

Barium sulfide, graphite having an average particle diameter of 40 to 74 μm or zirconium silicate treated with a silicon germanium coupling agent;

Filler:

Calcium carbonate, barium sulfate, cashew nut shell powder, the average particle size of 100~150 microns; wherein: Comparative Example 1 and the preparation process parameters of Examples 2 to 4 are:

According to the designed friction material group, the components are weighed and mixed evenly; pressurized at 160 °C, 200kgf/cm ² for 6 minutes, and hot pressed, 4~10 times, to obtain the thickness 6 mm friction material blank;

The friction material body is heated to 140 ° C at a heating rate of 1 to 2 ° C / min, and after heating for 1 hour, the temperature is further increased to 160 ° C, and the temperature is kept for 4 hours; then heated at a heating rate of 0.5 to 1 ° C /min. After heating to 210 Torr for 4 hours, after the furnace is cooled to room temperature, the billet is heated to 650 ° C, subjected to high-temperature ablation surface treatment, and cooled with the furnace to obtain a low cermet-based automotive friction material.

Wherein: the preparation process parameters of the examples 5 to 8 are:

According to the designed friction material group, the components are weighed and mixed evenly; pressurized at 180 °C, 250kgf/cm ² for 6 minutes, and hot pressed, 4~10 times, to obtain a thickness of 6 mm friction material blank;

The friction material body is heated to 140 ° C at a heating rate of 1 to 2 ° C / min, and after heating for 1 hour, the temperature is further increased to 170 ° C, and kept for 4 hours; then heated at a heating rate of 0.5 to 1 ° C /min. After heating to 210 ° C for 4 hours, after the furnace is cooled to room temperature, the billet is heated to 680 ° C, subjected to high-temperature ablation surface treatment, and cooled with the furnace to obtain a low cermet-based automotive friction material.

Wherein: The preparation process parameters of Examples 9 to 11 are:

According to the designed friction material group, the components are weighed and mixed evenly; pressurized at 200 °C, 300kgf/cm ² for 6 minutes, and hot pressed, 4~10 times, to obtain a thickness of 6 mm friction material blank;

The friction material body is heated to 140 ° C at a heating rate of 1 to 2 ° C / min, and after heating for 1 hour, the temperature is further increased to 180 ° C, and kept for 4 hours; then heated at a heating rate of 0.5 to 1 ° C /min. After 210 Ό, keep warm for 4 hours, after the furnace is cooled to room temperature, The billet is heated to 700 ° C, subjected to a high temperature ablation surface treatment, and cooled with the furnace to obtain a low cermet based automotive friction material.

In Examples 2 to 11, the ratio of the magnesium phosphate to the resin/rubber was (1 to 6):1. The friction materials prepared in Examples 2 to 8 and Comparative Example 1 were tested as follows:

1) Hardness, HRS; Rockwell hardness tester.

2) Porosity; using a porosity analyzer.

3) Shear strength (500 ° C, 3 min) in high temperature materials _; shear tester. The following performance was tested using a LINK NVH3900 bench tester:

4) Degradation performance (JASO C406-2000, 100km/h, 0.3g deceleration); 5) Braking performance (JASO C406-2000, 50 km/h, 100km/h,

130km/h);

6) Wear performance (SAE 2707,);

Table 1 shows the specific components of each of the examples and comparative examples.

Table 2 shows the test condition parameters.

Table 3 shows the test results of hardness, porosity, and shear strength in high temperature materials. Table 4 shows the results of the performance and decay tests.

Table 5 shows the results of the abrasion test.

Table 1

Table 2

Partial initial speed end speed initial disc brake deceleration

(km/h) km/h) temperature (°C) degree (g) number (N) running-in 50 4 100 0.25 100 town town road 50 4 150 0.25 200

(TB)1

Township road 80 4 200 0.35 200

(CB)1

Township road 100 4 125 0.40 200

(CB) 2

Town and town road 50 4 150 0.25 200

(TB) 2

Township road 100 4 125 0.40 200

(CB)3

Slope 80 4 350 0.35 50

(HDB)

table 3

No. Hardness (HRS) Porosity (%) Shear strength

(MPa)

1 72 9.2 2.1

2 68 9.8 2.3

3 70 10.5 2.4

4 72 11.2 2.6

5 75 11.8 2.9

6 77 12.0 3.0

7 80 12.5 3.1

8 82 13.1 3.1

9 72 9.2 2.2

10 74 9.8 2.4

11 76 12.3 2.7 Table 4

JASOC efficiency lOOkm/h 130km/h

Can 50km/h (min)

1 0.42 0.36 0.28 0.12

2 0.43 0.39 0.31 0.17

3 0.43 0.40 0.33 0.23

4 0.44 0.41 0.36 0.26

5 0.45 0.42 0.37 0.30

6 0.45 0.42 0.39 0.33

7 0.46 0.43 0.40 0.36

8 0.48 0.44 0.40 0.38

9 0.42 0.35 0.30 0.21

10 0.44 0.42 0.38 0.27

11 0.45 0.43 0.38 0.31

table 5

It can be seen from Tables 2 to 5 that the performance parameters of Examples 2 to 11 increase the Rockwell hardness, porosity and high-temperature shear strength of the friction material with the increase of the proportion of magnesium phosphate, but the friction material Hardness should not be too high, considering the impact The factor of dynamic comfort, so the hardness is recommended to be controlled within 80. At the same time, the ceramic binder will increase the hard and brittleness of the material to a certain extent, and reduce the mechanical properties such as the flexural strength and impact strength of the material. Therefore, it is necessary to control it to increase with the increase of the ceramic binder content. The braking performance is improved significantly, the high-speed friction coefficient is slowed down, the recession is obviously improved, and the lowest friction coefficient is raised above 0.35. No. 7 and No. 8 friction materials can be said to have almost no degradation, but in actual driving, high speed Emergency braking If the friction coefficient is too high, the instantaneous heat generated is too high, which will cause the material to be highly prone to thermal expansion, resulting in a dangerous situation. Therefore, the amount of the inorganic ceramic bonding agent should be controlled from this angle. From the point of view of wear, after a pure organic binder is subjected to a wear test cycle, the amount of wear is much larger than that after the addition of the inorganic binder. As the content of the ceramic binder increases, the wear amount is more than 3 and the wear amount is significantly reduced. Small, but after the proportion increases to 5, the trend of decreasing wear is slowed down. Therefore, the optimum ratio of inorganic ceramic binder to organic binder is (3 ~ 5): 1.

In summary, the magnesium phosphate composite salt ceramic-based low-metal automotive friction material produced by the technology of the present invention has improved braking stability, better resistance to degradation and wear resistance than conventional resin-based low-metal friction materials. It does not hurt the duality. It is a new type of high performance environmentally friendly friction material.

Claims

Rights request

1. A low cermet based automotive friction material consisting of the following components in percentage by weight:

Bonding substrate 1 5~30,

Reinforcing fiber 25~50,

Friction performance modifier 1 0~20,

Filler 1 0-30,

The bonding matrix is composed of an inorganic ceramic binder and an organic binder in a weight ratio of (1 - 6 ): 1 ;

The reinforcing fiber is composed of steel fiber and auxiliary reinforcing fiber in a ratio of weight ratio of 1:1;

2. The low cermet-based automotive friction material according to claim 1, wherein: the inorganic ceramic binder is magnesium phosphate; the organic binder is selected from the group consisting of phenolic resin or rubber; The magnesium phosphate has a particle size of 350 to 400 mesh; the phenolic resin has a particle size of 180 to 200 mesh; and the rubber has a particle size of 20 to 40 mesh.

3. The low cermet-based automotive friction material according to claim 2, wherein: the steel fiber has a diameter of 62 to 100 μm; and the auxiliary reinforcing fiber is selected from the group consisting of copper fiber, mineral fiber, and ceramic fiber. At least two of carbon fiber, aramid fiber, and polypropylene fiber; the copper fiber has a diameter of 100 to 150 micrometers; the mineral fiber has a length of 300 to 800 micrometers and a diameter of less than 5 micrometers; The fibers, carbon fibers, aramid fibers, and polypropylene fibers have a length of 300 to 500 μm and a diameter of less than 5 μm.

The low cermet-based automotive friction material according to claim 3, wherein: the friction increasing agent is at least one selected from the group consisting of zirconium silicate, alumina, coltan, and pyrite; The anti-wear agent is selected from at least one of molybdenum disulfide, antimony sulfide, graphite and mica; the raw material of the friction increasing agent and the anti-wear agent has an average particle size of 40 to 74 microns.

5. A low cermet based automotive friction material according to claim 4, wherein: said filler is at least one selected from the group consisting of zinc powder, calcium carbonate, cashew nut shell powder or barium sulfate; said zinc powder , calcium carbonate, cashew nut shell powder or barium sulfate

100 to 1 50 microns.

6. A low cermet based automotive friction material according to claim 5, wherein: said bonding matrix is weighted by an inorganic ceramic binder and an organic binder. The ratio is (2~ 5): 1 composition.

7. A low cermet based automotive friction material according to claim 6, wherein: said bonding matrix is made of an inorganic ceramic binder and an organic binder in a weight ratio of (3 to 5): 1 composition.

8. A method of preparing a low cermet based automotive friction material according to claim 1 comprising the steps of:

Step 1: Ingredients

Step 2: Forming

The mixture material obtained in the first step is placed in a hot stamping die, and the pressing pressure is 200 to 300 kgf/cm ² , the hot pressing temperature is 160 to 200 ° C, the exhaust gas is 4 to 10 times, and the holding time is pressed to calculate the thickness of the blank. The thickness of the millimeter is kept at 55~65s;

The third step: heat treatment

Step 4: Surface treatment

The billet obtained in the third step is heated to 650 to 700 ° C, subjected to high temperature ablation surface treatment, and cooled with the furnace to obtain a low cermet based automotive friction material.