Hongru Wang

Corrosion behaviour of electrodeposited Ni–Sn–P alloys

Abstract Ni–Sn–P alloys with a stannous content of 2·91–4·05 wt-% and a phosphorous content of 13·54–14·56 wt-% produced as a coating on copper by constant current electrodeposition were studied, with regard to their corrosion behaviour upon immersion in 10 wt-% H2SO4 solutions. The corrosion resistance of Ni–Sn–P alloy improved with increasing stannous content. X-ray photoelectron spectroscopy and energy dispersive X-ray spectroscopy confirmed the formation of Sn and P enriched layers at the alloy surface. After corrosion, a layer of passive film composed of SnO2, Ni(OH)2 and Ni3(PO4)2 was formed on the surface, which could prevent the contact between metal surface and corrosive liquid.

Influence of Bi2O3 addition on structure and dielectric properties of Ag(Nb0.8Ta0.2)O3 ceramics

The structure and dielectric properties of perovskite Ag(Nb0.8Ta0.2)O3 ceramics were explored. A small amount of Bi2O3 was used to modify the dielectric properties of the ceramics. The addition of Bi2O3 led the ceramics to a high densification and optimal dielectric properties. With the addition of 4.5 wt% Bi2O3, the permittivity of Ag(Nb0.8Ta0.2)O3 ceramics increased from 470 to 733, the dielectric loss decreased from 62×10−4 to 6.7×10−4, and the temperature coefficient of capacitance, TCC, decreased from 2004 ppm/°C to −50 ppm/°C. The high permittivity obtained was due to the high densification and weak Ta-O or Nb-O bond strength in the oxygen octahedron that results from the addition of Bi2O3.