| AgCuO is a new environmental protection electrical contact materials, it gets widely attention because of great chemically stability, low contact resistance and excellent electrical erosion resistance. We have researched the AgCuO composites and the results showed that there are two crystal structures of CuO particles, cubic CuO and monoclinic CuO, in the AgCuO composites prepared by reaction synthesis method. In the process of extrusion, cubic CuO particles could deform into fiber with the increase of deformation, while the monoclinic CuO particles only change the position without large plastic deformation. However, formation conditions and control mechanism of fiber CuO are not clearly. It is not conducive to control the ratio of fiber CuO and particle CuO in the AgCuO composites. In this paper, the FEM simulation and the experiments are employed to illustrate the formation conditions of fiber CuO. It is convenient to control the ratio of fiber CuO and particle CuO in the AgCuO composites under extrusion. Which has an important theoretical guiding for the industrial application of AgCuO composites.In this paper, the FEM software is used to simulate the influence of formation conditions, such as CuO particle sizes, extrusion temperature and die angle, to the microstructure of AgCuO composite. The conclusions are as follows:By studying the effects of CuO particle sizes on the microstructure, we find that: with decreasing of particle size, the degree of radial compression and axial elongation of CuO particle clusters gradually increased, and the dispersion of CuO particles gradually increased. Meanwhile, with the decrease of particle size, the degree of cubic CuO particles deform into fiber are gradually increased, and the ratio of benting fiber CuO gradually decreased. The ratio of linear fiber CuO gradually increased, where the fibers’direction is parallel to the axis.By studying the effects of die angle on the microstructure, we find that:with increasing of die angle, the dispersion of CuO particles near the surface is gradually increased, and the cubic CuO fibers become finer and longer. The phenomenon of fibrosis of cubic CuO particles gradually decreased along the radial direction.In the extrusion process, temperature variation rules of AgCuO composites are found as follows:at the beginning of extrusion, the temperature of the sample in the front is the highest, and the temperature gradually decreased along the outward radial direction. While the horizontal temperature change little, and the lowest temperature is found in the position of the angle between the extrusion stem and the die. Entering the deformation zone, the temperature of the sample in the deformation zone is the highest, and the temperature gradually decreased along the axial direction, while the temperature is the same along the radial direction. The lowest temperature is found in the position of the angle between the extrusion stem and the die. After entering into the sizing zone completely, the temperature of the sample is the highest in the left deformation zone, and the temperature gradually decreased along the axial direction to the edges. The lowest temperature in the surface of the sample.By studying the CuO particle evolution law in the extrusion process, we find that: cubic CuO particles begin to deform after entering the deformation zone, and cubic CuO particles deformation are mainly occurred in the sizing zone. The more die angle, the less particle, the CuO particles more easy to deform. In the extrusion, monoclinic CuO particles only changes the position, and it deforms not obvious. While the less particles sizes of CuO, the state of monoclinic CuO cannot deform more to breaking down easily.Finally, compared the experimental results with the simulation results, it is found that there are four typical microstructure zones in the sample both simulation and experiments, which are due to cubic CuO and monoclinic CuO has influence to each other in the extrusion process. |
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