Soldering of LD31 aluminum alloys using Sn-Pb solder paste after electric brush plating Ni and Cu coatings was investigated. The technology of electric brush plating Ni and Cu was studied and plating solution was deve...Soldering of LD31 aluminum alloys using Sn-Pb solder paste after electric brush plating Ni and Cu coatings was investigated. The technology of electric brush plating Ni and Cu was studied and plating solution was developed. The microstructure of the coatings, soldered joint and fracture face were analyzed using optic microscopy, SEM and EDX. The shear strength of soldered joint could reach as high as 26.83MPa. The results showed that reliable soldered joint could be obtained at 230℃, the adhesion of coatings and LD31 aluminum alloy substrate was high enough to bear the thermal process in the soldering.展开更多
Cu-coated graphite composites were prepared by an electroless plating method,and the composites were examined by scanning electron microscopy(SEM). The copper content of the composites was measured to reach 73%(mass f...Cu-coated graphite composites were prepared by an electroless plating method,and the composites were examined by scanning electron microscopy(SEM). The copper content of the composites was measured to reach 73%(mass fraction). Brush samples made with composites contents of 10%,15% and 20% and with copper powders content of 11% were obtained. The results show that the resistivity of the brush samples decreases and hardness becomes higher with increasing composites content. Copper is dispersively distributed in the brush samples made with the composites,whereas copper agglomerates in Cu-graphite mechanical mixture. For the same Cu content,Cu-coated graphite composites possess lower resistivity and higher hardness than Cu-graphite mechanical mixture. A new type of electric brush was obtained by using Cu-coated graphite composites,the wear and durability tests carried out on a HGH5435M120 AC motor indicate that its service life reaches 250 h. The electric brushes possess relatively low resistivity(275 μΩ·m) and good wear resistance,so they are very suitable for high-speed micromotors.展开更多
The Ni-Cr-Mo-Cu multi-element surface alloying with the electric brushplating Ni interlayer on the low carbon steel substrate has been investigated. By theelectrochemical method in 3.5 percent (mass fraction) NaCl sol...The Ni-Cr-Mo-Cu multi-element surface alloying with the electric brushplating Ni interlayer on the low carbon steel substrate has been investigated. By theelectrochemical method in 3.5 percent (mass fraction) NaCl solution, the corrosion resistance of thecomposite alloying layer and single alloying layer is determined. The experimental results showthat the corrosion resistance of the composite alloying layer is obviously better than that of thesingle alloying layer. The structure and composition of passive films formed on the two kinds ofalloyed layers after electrochemical tests in 3.5 percent NaCl solution have been studied usingX-ray photoelectron spectroscopy (XPS). It is concluded that the double glow plasma surface alloyingof low carbon steel with the electric brush plating Ni interlayer is an appropriate technique toenhance the corrosion resistance compared with the single double glow surface alloying.展开更多
文摘Soldering of LD31 aluminum alloys using Sn-Pb solder paste after electric brush plating Ni and Cu coatings was investigated. The technology of electric brush plating Ni and Cu was studied and plating solution was developed. The microstructure of the coatings, soldered joint and fracture face were analyzed using optic microscopy, SEM and EDX. The shear strength of soldered joint could reach as high as 26.83MPa. The results showed that reliable soldered joint could be obtained at 230℃, the adhesion of coatings and LD31 aluminum alloy substrate was high enough to bear the thermal process in the soldering.
基金Project (59972009) supported by the National Natural Science Foundation of China
文摘Cu-coated graphite composites were prepared by an electroless plating method,and the composites were examined by scanning electron microscopy(SEM). The copper content of the composites was measured to reach 73%(mass fraction). Brush samples made with composites contents of 10%,15% and 20% and with copper powders content of 11% were obtained. The results show that the resistivity of the brush samples decreases and hardness becomes higher with increasing composites content. Copper is dispersively distributed in the brush samples made with the composites,whereas copper agglomerates in Cu-graphite mechanical mixture. For the same Cu content,Cu-coated graphite composites possess lower resistivity and higher hardness than Cu-graphite mechanical mixture. A new type of electric brush was obtained by using Cu-coated graphite composites,the wear and durability tests carried out on a HGH5435M120 AC motor indicate that its service life reaches 250 h. The electric brushes possess relatively low resistivity(275 μΩ·m) and good wear resistance,so they are very suitable for high-speed micromotors.
文摘The Ni-Cr-Mo-Cu multi-element surface alloying with the electric brushplating Ni interlayer on the low carbon steel substrate has been investigated. By theelectrochemical method in 3.5 percent (mass fraction) NaCl solution, the corrosion resistance of thecomposite alloying layer and single alloying layer is determined. The experimental results showthat the corrosion resistance of the composite alloying layer is obviously better than that of thesingle alloying layer. The structure and composition of passive films formed on the two kinds ofalloyed layers after electrochemical tests in 3.5 percent NaCl solution have been studied usingX-ray photoelectron spectroscopy (XPS). It is concluded that the double glow plasma surface alloyingof low carbon steel with the electric brush plating Ni interlayer is an appropriate technique toenhance the corrosion resistance compared with the single double glow surface alloying.
