Due to extremely high temperature

arc may cause the local temperature of electric contact surface to exceed the melting point of a material and change the material phase so as to facilitate the formation of a molten pool on the surface and ablation crater. Arc ablation will seriously affect the electrical contact properties and shorten the material life.Consequently

we established an MHD model of arc. Based on heat conduction theory

the temperature distribution of electrical contact pair（copper-immersed carbon material and copper-tin material） was obtained. The variation of the ablation process of contact materials under different arc currents and arc gaps was analyzed. After the evaporation and sublimation of the copper-impregnated carbon material are taken into account

the temperature distribution on the surface of the material

the formation of the molten pool

and the velocity distribution inside the molten pool were solved. The simulation results show that the temperature of the copper-tin material increases slowly

while the temperature of the copper-impregnated carbon material rises rapidly. The maximum temperature of the surface of copper-impregnated carbon material rises to the melting point of copper

which lead to material melting and gradually forming the molten pool. When the arc current rises

the molten pool on the surface of copper-impregnated carbon material increases. The radius of the molten pool on the surface of the copper-impregnated carbon material increases with the increase of the arc gap. After melting

evaporation and sublimation

an ablation crater is formed on the surface of the copper-impregnated carbon material. The maximum temperature of the surface fluctuates around sublimation temperature of carbon. The liquid inside the molten pool flows which eventually roughens the surface of the material.