Abstract
In this paper, the solid–liquid composite method is used to prepare the steel–copper bimetal sample through two-stage cooling process (forced air cooling and oil cooling). The relationship between the different microstructures and friction properties of the bimetal copper layer is clarified. The results show that: the friction and wear parameters are 250 N, the speed is 1500 r/min (3.86 m/s), the friction coefficient fluctuates in the range of 0.06–0.1, and the lowest point is 0.06 at 700 °C. The microstructure of the copper layer was α-Cu, δ, Cu3P, and Pb phases, and Pb was free between α-Cu dendrites. When the solidification temperature is 900 °C, the secondary dendrite of α-Cu develops. With the decrease temperature, the growth of primary and secondary dendrites gradually tends to balance at 700 °C. During the wear process, Pb forms a self-lubricating film uniformly distributed on the surface of α-Cu, and the Cu3P and δ phases are distributed in the wear mark to increase α-Cu wear resistance.
Highlights
Two-Stage Cooling on the Bimetallic materials are composed of two or more metals with different properties that are combined in a layered manner to form a metallurgical interface [1,2,3]
The microstructure of the copper layer produced by traditional casting processes show a coarse reticular dendritic structure, which leads to intergranular segregation and negative segregation, and hot-cracking in metal materials [15]; all of these defects severely restrict the tribological performances of materials
0.06–0.1, reaching the lowest point of 0.06 at 700 ◦ C; As the solidification temperature decreases, the growth of primary and secondary dendrites gradually tends to balance at 700 ◦ C, which is lower than this temperature, and the primary dendrite arms gradually grow up
Summary
Two-Stage Cooling on the Bimetallic materials are composed of two or more metals with different properties that are combined in a layered manner to form a metallurgical interface [1,2,3]. Steel–copper bimetallic materials are widely used in the axial piston pump [4,5], and copper-based alloys, as one component of the bimetal, play an unreplaceable role due to their outstanding selflubricating properties [6,7]. In this paper, we select EN CC497K as the research object of the bimetallic copper layer. The microstructure of the copper layer produced by traditional casting processes show a coarse reticular dendritic structure, which leads to intergranular segregation and negative segregation, and hot-cracking in metal materials [15]; all of these defects severely restrict the tribological performances of materials. The structure of the bimetallic copper layer formed at room temperature is still coarse, the hardness of the copper layer is low, and the wear resistance is insufficient
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