| At present, the global is facing the increasingly serious problem such as a shortage of energy, environmental pollution. The development and utilization of new energy sources have become an urgent need for countries to solve the energy crisis. However, the wind power as a renewable, clean, environmental protection, new energy, has become a national focus and utilization of the study. The Wind power brakes is a key component of the wind power in the braking system, during the process of braking friction material performance is good or bad determining the braking safety and efficiency of wind power. Therefore, research and development of high-performance Cu-based powder metallurgy friction material for main shaft bake of wind turbine for improving the wind power industry development and braking technology has important practical significance.The Cu-based powder metallurgy friction material on at different sintering temperatures for main shaft bake of wind turbine are prepared by ammonia protection hot pressing sintered method. The effects of different sintering temperatures on physical and mechanical performance, friction and wear performance of the friction material are studid by Systematic study combining with experimental study and theoretical analysis. The worn surface and wear debris are observed by using scanning electron microscopy(SEM), and wear mechanism is discussed. Finally, the friction and wear properties under simulate real braking conditions are tested by the 1: 1 inertia dynamometer for main shaft bake of wind turbine, and verify the results of speed friction tester. The main research work and results are as follows:(1) According to friction material formulation, several friction materials are prepared by mixing, pressing, sintering under pressure in the high-temperature sintering furnace. The physical and mechanical properties of friction materials at differemt sintering temperature have been tested. Realizing that the sintering temperature on physical and mechanical performance of the friction material has a certain influence. With the rising sintering temperature, the material has better physical and mechanical properties of dense, density, hardness, shear strength and compressive strength.When the sintering temperature is more than 945℃, due to sintering adequate reaction, the temperature has little effect on the density and hardness of friction material.(2) The friction and wear properties of friction materials are tested by speed friction tester.Under the same pressure and speed, the friction coefficient of several friction material firstly increases and then decreases with the rising of temperature. The effects of sintering temperature on the friction coefficient are larger. With the increase of sintering temperature, the fading resistance and recovery performance of friction material is not monotone increasing, but showing a trend of first increased and then decreased. Especially,the friction material has best fading resistance and recovery performance when sintering temperature is at 945℃.Friction performance of friction material is worst at 980℃.(3) The wear rate of Cu-based friction material shows firstly increases and then decreases at several sintering temperature, and with the rising sintering temperature, the wear rate of friction material presented decreasing trend at overall. At lower temperature, wear mainly is abrasive wear.with the increase of temperature, wear mainly is oxidation wear and fatigue wear.The wear rate of friction material reach minimal wear rate and wear resistance has become better when sintering temperature is at 945℃.But the wear rate of friction material reach maximumand wear resistance has become worse when sintering temperature is at 880℃.(4) The effects of different sintering temperature on friction and wear properties under simulate real braking conditions are tested by the 1: 1 inertia dynamometer for main shaft bake of wind turbine, and verify the results of speed friction tester. Under the same brake pressure, the friction coefficient of several friction materials is gradually decrease trend and the wear rate is gradually increased with the increase of velocity.At lower speed, wear mainly is abrasive wear.with the increase of speed, wear mainly is oxidation wear and fatigue wear. The friction coefficient of friction material is most stability,the wear rate lower and friction and wear performance is best when sintering temperature is at 945℃.Friction and wear performance of friction material has become worst at 980℃.The results of inertia dynamometer testing are basically identical with the results of speed friction tester. |
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