Microstructure and properties of hot-dip PbSn alloy coating on copper wires

• Main Authors: YAO Xiao-fei, TIAN Wei, LI Nan, WANG Ping, LYU Yu-kun
• Format: Article
• Language: zho
• Published: Journal of Materials Engineering 2019-03-01
• Series: Journal of Materials Engineering
• Subjects: copper wire; hot dipping; pbsn alloy; electrical resistivity; mechanical property; corrosion resistance
• Online Access: http://html.rhhz.net/CHXB/html/2020-3-148.htm
• ISSN: 1001-4381; 1001-4381

Hot dip plating was used to prepare Pb40Sn60 and Pb37Sn63 low melting point alloy coatings on copper wires to improve the properties of weldability and corrosion resistance, and the microstructure and phase composition were examined by scanning electron microscopy (SEM), energy dispersive spectrometry (EDS) and X-ray diffraction (XRD). Resistivity, mechanical properties and corrosion resistance of the alloy were investigated by the tests of electrical resistivity, tensile and neutral salt spray. The results show that the Pb40Sn60 and Pb37Sn63 alloy coatings are all composed of α phase and β phase, the resistivity of PbSn alloy coatings are all higher than that of copper substrate, the resistivity of Pb40Sn60 alloy coating is 2.6832×10^-3Ω·m and Pb37Sn63 alloy coating is 2.5929×10^-3 Ω·m. Hardness, strength and plasticity of copper after hot dipped PbSn alloy coatings all decrease, surface hardness of Pb40Sn60 and Pb37Sn63 alloy coatings is respectively 13.4HV_0.2 and 12.6HV_0.2, tensile strength is respectively 193 MPa and 180 MPa, elongation is respectively 35% and 37%. PbSn alloy coatings on copper wire have good properties of conductivity, mechanical and corrosion resistance. With the decrease of Pb content or the increase of Sn content, the relative amount of α phase is reduced and relative amount of β phase increases in the PbSn alloy coating, resistivity, hardness and strength are all reduced, plasticity increases slightly, its corrosion resistance is enhanced. The corrosion rate of Pb40Sn60 alloy coatings is higher than that of Pb37Sn63 alloy coatings, the corrosion rate of Pb40Sn60 alloy coating is 2.44×10^-2 g·cm^-2·a^-1 and Pb37Sn63 alloy coatings is 3.65×10^-3 g·cm^-2·a^-1, and the corrosion resistance of Pb40Sn60 alloy coatings is relatively poor. The corrosion resistance of α phase is poor than that of β phase, the corrosion degree of α phase is more serious than that of β phase in PbSn alloy coating.