Papers by Author: Gui Ying Qiao

Abstract: The influences of jet flow rate and temperature on cathodic polarization of nickel deposits have been studied in this paper. The results indicate that increasing jet flow rate and temperature of the electrolyte make the equilibrium electrode potential decrease. When jet flow rate increases from 1.0 L/min to 6.0 L/min, the grain size of nickel deposits decreases from 22.6 nm to 18.9 nm. X-ray diffraction patterns show that increasing jet flow rate results in (111) preferred growth orientation for nickel deposits.

Abstract: The bulk nano-crystalline cobalt-nickel alloys have been prepared by the double refined methods (DRM) combined the high-speed jet electrodeposition (JED) with the additive added in jet electrolyte, and their microstructure and properties, such as the microhardness and magnetic properties, have been evaluated. The results indicate that the DRM is a very effective technique for grain size refinement and property improvement. The concentration of the additive added in the jet electrolyte has little effect on the Co-content in the deposited alloys, but they have a remarkable effect upon the microstructure and properties.

Abstract: Strain-induced precipitation of complex carbonitrides and recrystallization for three high-Nb pipeline steels with different Nb and C content have been studied by using a stress relaxation technique and two-passes interrupted compression test. Sequentially, the PTT diagrams were obtained, and static recrystallization activation energy was calculated. Furthermore, the effects of Nb and C content on strain-induced NbC precipitation and static recrystallization were discussed. The results confirm the faster kinetics of precipitation and its retarded recrystallization in the case of higher Nb pipeline steel, and that the recrystallization is easier in low Nb pipeline steel in comparison to the case of high Nb steel. However, the effects of Nb on strain-induced precipitation and static recrystallization were associated with the Nb/C ratio. The precipitation start time (Ps) of strain-induced NbC is delayed in lower Nb/C ratio pipeline steel. It is suggested that the reduced supersaturation of Nb can result in the delay of precipitation of strain-induced NbC carbides forming in the low Nb/C ratio steel.