Friction and wear properties of the hottest calciu

Friction and wear properties of calcium carbonate reinforced resin matrix composites

calcium carbonate products must appear in recent years. A new kind of needle like material, because its crystalline form is a single product, with almost no defects inside the crystal, has excellent characteristics such as high strength, high modulus, good heat resistance and heat insulation, and has good compatibility with the matrix resin when compounding with plastic, which can improve the processability and mechanical properties of products. Calcium carbonate must be a kind of green environmental protection material with high quality and low price, which has strong market competitiveness, so it is widely used in the fields of automobile, plastic, electrical component manufacturing, high finish structural component manufacturing and so on. However, due to a considerable proportion of the surface of calcium carbonate can be hydrolyzed, the particle surface becomes hydrophilic and oil repellent due to the existence of a large number of hydroxyl groups, which is difficult to be evenly dispersed in the organic medium, and there is no binding force with the base material, which is easy to cause interface defects. According to the theory of hydrogen bonding, when CaC03 particles are dry, the surface hydroxyl groups interact to form hydrogen bonds, and the particles gather with each other by hydrogen bonding, thus forming hard agglomeration. Therefore, the surface of CaC03 whiskers must be modified to reduce the surface energy, reduce the cohesion of CaC03 particles, improve the dispersion and dispersion stability in the matrix, reduce the interfacial tension between the two phases, adjust the hydrophobicity, and improve the wettability and adhesion with the organic matrix, so as to improve the properties of the composites. When calcium carbonate is mixed with various plastics, it can obtain excellent reinforcement effect. Especially when used as a composite of plastics, the bending strength is inch. In terms of stability, the residual concave deformation after the experiment should not be greater than: class a 3.00mm has excellent performance and good thermal stability, so it has a broad application prospect in engineering plastics. In addition, various plastics have silver gray streak defects due to the influence of moisture, etc. during injection molding, while the above problems will not occur when using calcium carbonate whisker because of crystal water. At the same time, it can overcome the use of long fibers on its surface and finally develop aluminum alloy for electrical purposes. 4. Force magnification: × 1. Exposed, which affects its smoothness and poor aesthetics

the application of calcium carbonate in friction materials was developed earlier in Japan and the United States, and a large number of application patents were published. The application of calcium carbonate in composites in China has entered the pre planning research for industrial development. The domestic development of calcium carbonate whisker, a new material with high development potential and high cost performance, is still in its infancy, and most of it is still at the laboratory level. Although some products can be seen, it can not meet the requirements of industrialized mass production

in this paper, calcium carbonate is used to prepare various. The effects of resin content and coupling treatment on the friction and wear properties of composites were studied, which provided an experimental basis for the application of calcium carbonate in composite friction materials

1 experiment

1.1 experimental material

composites are mainly composed of reinforcing phase, matrix and filler. In this paper, the reinforcing phase is calcium carbonate whisker, with an average length diameter ratio of 50 ~ 80mm and a length of 50 ~ 200 μ m. Diameter is 1 ~ 4 μ m. Density 2.9 ~ 3.0g/cm ³， The tensile strength is 20.5gpa and the elastic modulus is l78 GPA; The matrix is phenolic resin modified by pomace oil; Fillers include copper powder, alumina, carbon, zinc stearate, etc

1.2 sample preparation

before molding, fully mix the resin, reinforcing materials, fillers and other raw materials, and make the resin melt under high turbulence and high pressure through hot pressing, so as to further increase its fluidity and permeability, so that the fillers and reinforcing fibers are closely combined under the action of resin. After treatment: put the semi-finished products into the heat treatment box and pass through at a certain temperature. Duan Shiwen, so that the resin that has not been completely indolated in the hot press molding can be completely cured, so that the performance of the brake pad tends to be stable

l.3 performance test

jfl50d-ii constant speed friction tester is used for experiment, which is designed in full accordance with the standard of gb5763-l998. The friction test method is to smooth the surface of the test piece first, and then run in the test piece at room temperature until the contact between the test piece and the disc reaches more than 95%. Measure the thickness of the run in test piece with a micrometer. Measure five points of each test piece (i.e. the four corners and central position of the test piece) and calculate its arithmetic mean. Record the friction force during 5000 R/rain test when the disc temperature is L50 ℃, and measure the thickness after friction when the test piece is cooled to channeling temperature

2 experimental results and discussion

2.1 effect of calcium carbonate whisker content on the friction properties of composites

calcium carbonate products must have significant strengthening and toughening effects, and have a wide range of sources. Therefore, it can reduce the manufacturing cost of products and improve the performance of products at the same time, so as to improve the cost performance of products. Calcium carbonate must be micron level, with less condensation and easy dispersion, which can play a more effective role in strengthening and toughening. This experiment analyzes the influence of different contents of calcium carbonate on the friction and wear properties of composites according to the following formula, as shown in table L. The friction and wear properties of each sample tested at 150 ℃ are shown in Table 2

it can be seen from table 2 that the friction coefficient of the composite increases first and then decreases with the increase of calcium carbonate whisker content, and reaches the maximum when the calcium carbonate whisker content is 20 phr; The wear rate of the composite decreased first and then increased with the increase of the content of calcium carbonate whisker, and reached the minimum value when the content of calcium carbonate whisker was 20 phr. That is, when the content of calcium carbonate is 20 phr, the friction coefficient of the sample is the largest and the wear rate is the lowest, which has excellent friction and wear properties. Compared with 10 parts of whiskers, the friction coefficient increases by 32% and the wear loss decreases by 42%, indicating that when the amount of whiskers is less than 30 parts, the change of a small amount of whisker content has a greater impact on the friction performance

2.2 effect of coupling treatment on the friction properties of composites

the surface of calcium carbonate whiskers was treated with silane coupling agents KH-550 and KH-570. The experimental arrangement is shown in Table 3. Because the alcohol solution instrument KH-550 or KH-570 of KH-550 or KH-570 is easier to react with the hydroxyl group on the surface of whiskers, the force between the coupling agent and whiskers is strengthened, so as to further improve the interface properties of composites. Conduct friction on the samples with different treatments. 2. It is necessary to carry out clearing and protection wear performance test on the equipped ball screw every half a year. The experimental results are shown in Figure L. the abscissa in the figure represents the sample number and the ordinate μ Represents the friction coefficient, and V is the wear rate

it can be seen from figure L that the friction coefficient of the samples after coupling treatment is higher than that of the samples after surgical treatment, while the wear rate of the samples after treatment is reduced. In particular, the wear rate of the samples added with 30 parts of calcium carbonate whiskers is 0.82 after coupling treatment, but after coupling treatment, the wear rate is reduced to 0.50 and 0.57. This is because the surface properties of the materials are improved after the treatment of calcium carbonate with coupling agent, and the interfacial adhesion between calcium carbonate whiskers and cashew nut shell oil modified phenolic resin matrix is improved, thus effectively improving the friction and wear properties of the composites

3 conclusion

1) when the content of calcium carbonate is 20 parts, the friction coefficient of the sample is the largest and the wear rate is the lowest, which has excellent friction and wear properties

2) the friction coefficient of calcium carbonate samples after coupling treatment is higher than that of untreated samples, and the wear rate of treated samples is reduced