Research Of Contact Fatigue And Tribology Performance Of B₄C/Ni Composite Coating Reinforced By Surface Texture

Thermal spray technology as an important technology, is very promising in the field of damage repairing and surface strengthening of rotating components. Its performance significantly differs from the homogeneous material because of the porosity, multi-interfacial properties and the complicated combination problem at the interface in the coating system.The B4C/Ni composite coating was prepared by plasma spraying equipment in the article, and the surface texture (pattern) was prepared on the coating and substrate respectively, to study the impact of surface texture on the bond strength of coating, tribological properties, and rolling contact fatigue performance.As the spraying power increases, the extent of chemical reactions within Ni and B4C in the coating deepens more and more, leading to the reduction of content of residual B4C in the coating. The content of B4C particle is higher, the overall performance of the coating is not superior. Only ensure the B4C particles dispersed in the coating, control the extent of chemical reactions within Ni and B4C appropriately, can the coating achieve the best overall performance.The density of texture is too small to improve the bonding strength of the substrate and coating significantly because the chimeric effect of texture is limited. The texture density is too large, resulting to roughened surface of the substrate, unfavorable to the mechanical interlocking between coating and substrate. The bonding strength of textured coating of 400?m spacing is the highest. The B4C/Ni composite coatings mainly have two kinds of breaking form in the tensile test: the internal fracture in the coating, the junction fracture in the coating and substrate.With the depth of texture increasing, stable friction coefficient of the coating decreases and then increases. The friction coefficient of coating of lighter texture reaches the minimum stable value. As the friction and wear progresses, the friction coefficient of the coating of different Texture orientation decreases. With the friction and wear continuing, the friction coefficient of surface texture of 30° orientation coating showed a decreasing trend. The wear of textured coating is relatively minor, having superior wear resistance.Under different conditions of surface states, the rolling contact fatigue faiure modes of plasma spraying B4C/Ni composite coating include three kinds, pitting, spalling and wear.Among them, the rolling contact fatigue failure mode of untextured coating is mainly the surface wear failure,the rolling contact fatigue failure mode of textured coating is mainly the pitting and spalling failure. With the depth of texture on the surface increasing, the rolling contact fatigue life of the coating is gradually reduced,the coating of lighter texture shows a superior rolling contact fatigue performance. And the rolling contact fatigue life of the textured coating of 30° orientation is higher, its fatigue resistance is better.