Effect of CeO2 particles on the high phosphorus electroless Ni layer
Electroless Ni (EN) technology is widely used in electronic package field and the high phosphorus composite EN technology was studied. In this paper, we discussed the influence of nano-CeO2 and micro-CeO2 particles with different amounts when they were added in high phosphorus content Ni-P composite coating. The microstructure and crystal structure of the coating were observed by scanning electron microscope (SEM) and X-ray diffraction analysis (XRD) respectively. The results showed that whether nano-CeO2 or micro-CeO2, both refined the grain, increased the specific surface area, however the micro-CeO2 particles made more obvious effect. As the XRD result showed, the peak gradually become gentle, the coating turned into amorphous which may cause by the CeO2 particles absorbed in the grain boundary and crystal defects. The results indicated the CeO2 deposited with the coating very well. Finally, the corrosion resistance of the coating was tested with the method of electrochemical impedance (EIS) and linear polarization. The results were unified. When the dosage is 5g/L, the corrosion resistance was the best. However, lower corrosion resistance was got when excessive CeO2 particles were added which may affect by the catalytic property.
Thermal conductive properties of Ni–P electroless plated SiCp/Al composite electronic packaging material
Abstract Electroless plated SiC p /Al composites with a high thermal conductivity are required for electronic packaging application. In this paper, in-plane thermal conductive properties of SiC p /Al composites with and without electroless plated Ni–P coatings are compared, and influence of various characteristics of Ni–P coatings are investigated. It is found that in addition to thickness of the coatings, phosphorus concentration and microstructure of the plated layers also influence the thermal conductive properties of plated composites. Based on the results, it is suggested that a low phosphorus concentration and a properly tailored crystalline microstructure of the Ni–P coatings, together with a reasonable choice of coating thickness, may contribute to optimization of thermal conductive properties of the composite material.
Numerical Simulation of Induction Heating Process of Continuous Casting Slab
Compared with traditional blazing furnace, the Continuous Casting-Direct Rolling is an advanced manufacturing steel technology, which can reduce energy waste, decrease pollution and enhance efficiency. The characteristics of steels during induction heating are complex, the change of material properties with temperature makes exact analysis methods very difficult to implement. Therefore, a powerful computer aided numerical tool (i.e., finite difference analysis) is selected to numerically model the induction heating process in this paper. The mathematic model coupling with electromagnetic field and thermal field was established, and it was solved by finite difference method (FDM), thus the slab temperature distribution and its variation with time were obtained, and the characteristics in whole induction heating process were studied. To validate the program feasible, the results were evaluated and compared with experiment results, which showed that the simulation results are reliable and effective. The skin effect in heating process from the two results was studied and demonstrated, the temperature change caused by different parameters such as the induced power intensity and the corner radian were also presented, which indicate that the slab temperature can be heated uniformly through adjusting these parameters, thus the continuous casting slab can meet the rolling requirement.