Study On Laser Cladding Preparation Of Bionic Surface Of Cast Iron Brake Disc

China's rail transportation is developing towards the direction of high speed and speed,which brings forward higher requirements on the performance of the brake disc.In the process of braking,the traditional gray cast iron brake disc will produce serious friction and wear and thermal fatigue damage,which will affect the braking performance and service life of the brake disc.It has been difficult to meet the development needs of the modern railway train,so it is of great significance to study on the modification of the two aspects of thermal fatigue resistance and wear resistance.In this paper,the method of laser cladding on the surface of gray cast iron was studied by means of laser cladding technology.Long term survival of shellfish on the beach,they have evolved over hundreds of millions of years of nature,so that it has a strong ability to adapt to the environment.The surface morphology,structure and material with excellent wear resistance and anti fatigue properties were studied from the view of bionics.In this paper,based on the bionics theory,the shellfish stripes form design model of the bionic sample,combined with the special shape of the brake disc,bionic surface design,using orthogonal design method to optimize process parameter,and to study the effect of laser parameters on the cladding layer width and height of the prepared samples,bionic coupling of the morphology,structure and material the use of laser cladding technology.The composition,hardness distribution,microstructure and phase of the unit were analyzed by means of microhardness tester,scanning electron microscope(SEM)and XRD.At the same time,do not deal with bionic specimens and gray cast iron sample thermal fatigue properties and friction wear performance test,analysis and Research on bionic samples and the untreated sample hardness,microstructure,wear and wear morphology,this paper draws the following conclusions:(1)the pulse width is the most influential factor of the width and height of the cladding layer in the laser processing parameters.The optimum parameters of the orthogonal design are the current 180 A,the pulse width 10 ms,the frequency 10 Hz,the defocusing amount 8mm.(2)The laser cladding has a compact structure and a metallurgical bond with the substrate.The test results show that the hardness of the unit is 2 times of that of the gray cast iron matrix.(3)The results of thermal fatigue test showed that the hardness of the samples was reduced by thermal fatigue,and the hardness of the samples was smaller than that of untreated gray cast iron samples.(4)Thermal fatigue test results show that the thermal fatigue to coarsening,material crack,compared with untreated gray cast iron specimen,the crack number of bionic specimens increased slowly,and the surface of the maximum crack length is smaller,indicating the bionic laser cladding preparation improves the resistance to thermal fatigue properties of materials.(5)The friction and wear test results show that the wear volume of the untreated sample was 1.4 times that of the bionic sample at the same time,the wear morphology of the bionic sample was better than that of the untreated sample,indicating that the bionic laser cladding preparation can greatly improve the wear resistance of materials.(6)The research results of this paper provide a reference for the preparation and practical application of bionic laser cladding gray cast iron brake disc.