Study On The Technology And Performance Of Preparation Of Lead / Steel Laminated Composites By Rolling

Lead/steel laminated composite materials combines with the strength and good conductivity of steel, as well as the excellent electrochemical properties, corrosion resistance and good absorbance of x-ray and γ-ray of Pb. It has been widely applied in electrochemistry, nuclear shielding and other fields, and has shown a large market potential and a bright future. But preparation and applications of lead/steel laminated composite materials is restricted because of the nonmiscibility of Pb and Fe. Therefore, how to improve the intersolubility of Pb and Fe is the key of this project.The interlayer was put between Pb and Fe to improve the intersolubility in the research, and the wettability can be calculated by the Y-G-G equation of the liquid-solid interface surface tension. Steel plates coating by medium metal were prepared by the induction method under different powers, then were put together with Pb to composite by hot-rolling, then lead/steel laminated composites have been prepared.The microstructure of interface of steel and medium metal as well as lead and steel, elemental concentration distribution and the surface after tearing can be observed and tested by scanning electron microscope(SEM), energy-dispersive spectrometry (EDS) and optical microscope(OM). In the meanwhile, the phase of lead/steel and the boundary between coat and steel were tested by XRD, and the composite interface formation mechanism of lead/steel can be analyzed. Finally, the conductivity, electrochemical property, interfacial bonding strength and other properties of lead/steel laminated composites can be tested and analyzed by the four probes method, electrochemical workstation and universal material testing machine. Based on the results of this research.The results show that:(1) The wetting angle between the medium mental Pb-63%Sn and the matrix can be calculated using the relationship of surface tension and the melting point and Y-G-G equation. The results shows that the angle between medium mental and lead plate surface less than250, wettability very well, while it is better than the wettability between the medium mental and steel of over1050. So the wettability between Pb-63%Sn and steel can be improved by coating the scaling powder (ZnCl2:NH4Cl=1.5:1) on the surface of the steel plate.(2) In the process of coating Pb-63%Sn onto the steel plate, intermetallic compound FeSn2is created by diffusion reaction of Sn and Fe, and finally metallurgical bonding of steel plate and medium metal can be achieved. And as the power increases, the thickness of intermetallic compound layer becomes wider.(3) With the increase of the rolling temperature and reduction rate, the interface diffusion area broadens gradually and in the end interface transition region is composed of transition layer of Pb(solid solution of a-Pb and β-Sn) and steel (Pb-Sn-Fe transition layer). From the fracture morphology of lead/steel laminated composite it can be seen that some dimples has been found with features of plastic fracture by the Pb side, and is typical ductile fracture. It shows that metallurgical bonding of Pb/steel laminated composite is really realized.(4) From the results of the conductivity and mechanical property of lead/steel laminated composite show that:As the rolling temperature and reduction rate increase, the good conductive layer of Pb-Sn solid solution broader, so that the conductivity of lead/steel laminated composite increase. Compared with the same size of Pb-0.2%Ag alloy, average resistivity decreases35.5%; in the rolling process, the action of heat and friction heat of the plastic deformation cause the atoms of the interface to diffuse and finally achieve the metallurgical bonding, so the interface bonding strength of lead/steel laminated composites are higher than the lead matrix.(5) The test results of polarization curves show that:with the increase of rolling temperature and reduction rate, the polarization potential and the current density of Pb/steel laminated composite samples decrease, it indicates that it has the good catalytic activity and resistance corrosion resistance. After corroded100h, lead/steel laminated composite samples have less weight loss, and the corrosion rate(0.366g/m2·h) is about61.7%of Pb-0.2%Ag alloy(0.593g/m2·h), showing high good corrosion resistance performance.