铜导线表面热浸镀PbSn合金镀层的组织与性能

为了改善铜导线的可焊性和耐蚀性,采用热浸镀技术在铜导线表面制备Pb40Sn60和Pb37Sn63两种成分的低熔点合金镀层,利用扫描电镜(SEM)、能谱分析(EDS)、X射线衍射(XRD)等分析手段和电阻率检测实验、拉伸实验、中性盐雾实验等方法,系统研究其微观组织、相成分、电阻率、力学性能及耐蚀性。结果表明:Pb40Sn60和Pb37Sn63两种成分的合金镀层均由α相和β相两相组成,镀层的电阻率分别约为2.6832×10^-3,2.5929×10^-3Ω·m,均高于铜基体。铜导线热浸镀Pb40Sn60和Pb37Sn63两种成分合金镀层后的表面硬度分别为13.4,12.6HV0.2;抗拉强度分别为193,180 MPa;伸长率分别为35%和37%,与铜基体相比均降低。铜导线表面热浸镀PbSn合金镀层具有良好的导电性、力学性能及耐腐蚀性等综合性能。随着Pb含量的降低或Sn含量的增加,PbSn合金镀层中α相的相对量减少、β相的相对量增大,其电阻率、硬度和强度降低,塑性略有增大,耐蚀性增强。Pb40Sn60比Pb37Sn63合金镀层的腐蚀速率较高,分别为2.44×10^-2,3.65×10^-3 g·cm^-2·a^-1,耐腐蚀性较差。PbSn合金镀层中α相比β相的腐蚀程度更为严重,α相比β相的耐蚀性要差。

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

Hot dip plating was used to prepare Pb40 Sn60 and Pb37 Sn63 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 Pb40 Sn60 and Pb37 Sn63 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 Pb40 Sn60 alloy coating is 2.6832×10^-3Ω·m and Pb37 Sn63 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 Pb40 Sn60 and Pb37 Sn63 alloy coatings is respectively 13.4 HV0.2 and 12.6 HV0.2, 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 Pb40 Sn60 alloy coatings is higher than that of Pb37 Sn63 alloy coatings, the corrosion rate of Pb40 Sn60 alloy coating is 2.44×10^-2 g·cm^-2·a^-1 and Pb37 Sn63 alloy coatings is 3.65×10^-3 g·cm^-2·a^-1, and the corrosion resistance of Pb40 Sn60 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.