Performance test Friction and wear performance according to the fourth category test in GB5763-1998, the test temperature is 100,150,200,250,300,350, respectively. The friction disc used is made of HT250 gray cast iron (metallurgical structure is pearlite with a hardness of 180220HBS) and the test speed is 500r/min.

The effect of potassium titanate whiskers on the friction coefficient of the braided brake band shows the friction coefficient of the samples A, B, and C at different temperatures during the heating process. The coefficient of friction of sample C with non-dip-coated potassium titanate whiskers was higher than that of samples A, B at lower temperatures, began to decay at about 270, and dropped to less than 0.3 at 300 hours. This is due to the hardness of GF (Mohs hardness of 6) is higher than the hardness of potassium titanate whiskers (Mohs hardness of 4), the scoring effect of friction on the mating parts is obvious, so that the friction coefficient is higher, apparently also makes the duality The wear of the parts increases; at high temperatures above about 270, the strength and hardness of the GF begin to decrease, and it is easy to peel and pull, plus the decomposition of the adhesive (the temperature of the actual frictional contact surface is higher than the test temperature), flow The formation of interfacial film and carbonized layer led to a decrease in friction coefficient.

Friction coefficients of samples A, B, and C at different temperatures during cooling. As can be seen, the friction coefficients of Samples A and B have better recovery performance. Among them, the friction coefficient at a lower temperature rises slowly with increasing temperature, which can be seen as the result of wear and decomposition of the adhesive on the frictional contact surface and exposure of the fiber-rich layer.

The effect of potassium titanate whiskers on the high temperature strength of the braided brake band When the GF braided brake band is generally subjected to a friction test of about 250 or more, the sample undergoes shear deformation due to the decomposition of the adhesive and the decrease in the strength of the GF. And edge crushing (the most obvious at the frictional contact surface), wear rate increased significantly. The higher the temperature, the more pronounced the deformation and breaking, and the higher the wear rate.

The test found that the brake band sample C of the unpoured potassium titanate whisker had a small amount of shear deformation at 250 hours, and there was a significant shear deformation and edge breakage at 300 hours, and the wear rate increased significantly; At this point, the sample must be ground before being placed in the tester. The accuracy of the test has been reduced. The samples A and B impregnated with potassium titanate whiskers did not show obvious shear deformation and edge breakage at 300 o'clock. After 350 friction tests, only a small amount of deformation and breakage occurred. The deformation and fragmentation of whisker sample B are slightly more obvious). This is because the high temperature performance of potassium titanate whisker is more stable than that of GF, and its strength and wear resistance are much higher than GF. The slow increase of temperature and the filling of the whiskers increase the density and strength of the braid, thereby reducing the deformation and wear rate of the sample. The adhesion of the bar-like potassium titanate whisker to the carbonized matrix is ​​better than that of GF, which is one of the reasons for its reduced wear rate.

Conclusion (1) After GI composite braided brake band is surface dip coated with potassium titanate whisker, it helps to improve the stability of high and low temperature coefficient of friction and thermal decay resistance of the braid, resulting in lower wear rate and significantly improved weaving. With high temperature resistance to deformation and edge damage resistance, can adapt to more severe working conditions.

(2) Because the hardness of potassium titanate whisker is lower than that of GF, the wear resistance is better. Therefore, after the GI composite weaving brake belt is dip-coated with potassium titanate whisker on the surface, it helps to reduce the wear rate of the mating parts. .

Fiber Laser Cutting Machine

Laser Cutting Machine,CNC Cutting Machinery,Fiber Laser Cutting Machine,Laser Cutting Machine Metal

Tengzhou Borui CNC Machine Tool Co,.Ltd , https://www.br-cnc.com