Experimental Study On Effect Of Particles On Friction And Wear Of Brake Pad Based On "abrasive Wear" Principle

Automobile brake system plays a very important and key role in automobile driving safety.When the brake is exposed to the environment,the invasion of particles of different sizes and shapes in the air will cause unstable abrasive wear,resulting in the increase or decrease of the average friction force and instantaneous peak value of the brake interface.This effect is particularly obvious in the process of braking for a long time in the downhill road with poor road conditions.In order to study the influence of the geometric parameters of three-body particles on the friction characteristics of brake block and the friction and wear mechanism,based on the principle of abrasive wear,the friction and wear experimental platform was used to measure the friction mechanical parameters of the friction interface in real time,taking the geometric parameters of alumina particles and whether "wading" as variables.The influence of particles with different geometric parameters on the friction characteristics and wear rate of brake block in the process of long-term wet friction braking was studied.Combined with the time domain diagram of dynamic friction coefficient,the friction and wear mechanism was analyzed by scanning electron microscopy:(1)In the process of simulating the braking friction for a long period of time,the wear state at different stages was observed and analyzed by electron microscope.The friction and wear presented a mechanism of "running-stably-aggravation-damage",which provided a theoretical basis for the long-term friction of the brake block.(2)In the process of "braking",particles with different geometric parameters were added to simulate the invasion of outer edge particles.By time domain diagram and electron microscope diagram,it was analyzed that particle addition and its geometric parameters had a great influence on the friction properties and wear conditions.During the friction process,the oxide film formed plate-block contact,and the change of stress failure and wear state went through the whole process of the establishment and destruction of the primary platform and the secondary platform,and then produced different friction and wear mechanisms.(3)Under the condition of wading environment,water is added in the middle of the friction pair to simulate wading braking and observe the friction and wear state;Then the particles with different geometric parameters were classified and mixed with water in equal amount,and the friction surface was added respectively to explore the production of oxide film and the new mechanism of platform establishment,and the wear mechanism was further studied.