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Yu Z.X.,University of Sichuan | Yu Z.X.,The Material Corrosion and Protection Key Laboratory of Sichuan Province | Zheng D.T.,University of Sichuan | Guo H.,University of Sichuan | And 3 more authors.
Advanced Materials Research | Year: 2014

To improve the wear resistance and anti-corrosion properties of the aluminum, the electroless plating Ni-W-Mo-P on aluminum is necessary. The influences of heat treatment and additives (stabilizers) on the porosity, deposition rate, corrosion current, corrosion potential, microhardness and wear resistance of electroless plating Ni-W-Mo-P alloy coating, were investigated using electrochemical methods, etc. The results show that the deposition rate and anti-corrosion properties of electroless plating Ni-W-Mo-P are improved when the stabilizers, including KI (1mg/L) and "KIO3 (1mg/L) + Pb(Ac)2 (1mg/L)", are added into bath, respectively. In addition, the maximum hardness (902 HV) and good wear resistance of Ni-W-Mo-P coatings are obtained when heated at 400°C (1h). However, its corrosion resistance is worse. Its microhardness is also obviously improved after heated at 200°Cfor 6 h, and the microhardness reaches to 950 HV. © (2014) Trans Tech Publications, Switzerland.


Yu Z.X.,University of Sichuan | Yu Z.X.,The Material Corrosion and Protection Key Laboratory of Sichuan Province | Sun Y.L.,University of Sichuan | Sun Y.L.,The Material Corrosion and Protection Key Laboratory of Sichuan Province | Huang X.,University of Sichuan
Advanced Materials Research | Year: 2014

To improve the anti-corrosion properties of the AZ91D magnesium alloy, the electroless plating Ni-Co-P on the AZ91D magnesium alloy is necessary. The influences of additives (ammonium fluoride (NH4F) and hexamethylenetetramine (HMTA)) on deposition rate, corrosion rate, acid resistance, corrosion current, corrosion potential and webster hardness of electroless plating Ni-Co-P alloy coating, were investigated using electrochemical methods, etc. The results show that the deposition rate and corrosion resistance properties of electroless plating Ni-Co-P are obviously improved when the additives, including NH4F (2%) and hexamethylenetetramine (HMTA, 1%), are added into plating solution, respectively. In addition, the global particles in the Ni-Co-P coating become smaller with the addition of NH4F by comparison with no additives and coatings are dense, uniform and defect-free. © (2014) Trans Tech Publications, Switzerland.


Yu Z.,University of Sichuan | Yu Z.,The Material Corrosion and Protection Key Laboratory of Sichuan Province | Hao S.,University of Sichuan | Hao S.,The Material Corrosion and Protection Key Laboratory of Sichuan Province | And 2 more authors.
Advanced Materials Research | Year: 2013

Effects of impurity (Fe, Si, Cu), temperature and Na2SnO3 on anodic behaviors of various grades of pure aluminum namely Al-1(99.999%),Al-2(99.99%),Al-3(99.82%) and Al-4(99.5%) in 4mol/L KOH solution have been examined by studying corrosion rate, polarization, open circuit potential (OCP, or Eocp), discharge performance and transfer resistance values (Rt) of EIS. The results indicate that aluminum has higher activation and more severe corrosion with the temperature increase. When impurities (Fe, Si, Cu) content increases, aluminum has higher corrosion and achieving stationary open current potential (OCP) needs longer time. However, Al-3 has lower polarization and higher current density(400mA/cm2,at 1.224V) than others at 50 °C. Meanwhile, for Al-3, the stationary OCP is about 120 mV more negative at 50 °C than at 25 °C. In order to achieve the stationary OCPs and avoid the appearance of tin oxidation peak, 20min is suitable soaking time for Al in 5mmol/LNa2SnO3 +4mol/LKOH solution. The optimal electrochemical behaviors of Al including corrosion-resistance, activation, OCP and shorter delay time of electrode potential, have been achieved by adding 5mmol/L SnO3 2+ into 4mol/LKOH solution. © (2013) Trans Tech Publications, Switzerland.


Yu Z.X.,University of Sichuan | Yu Z.X.,The Material Corrosion and Protection Key Laboratory of Sichuan Province | Hao S.X.,University of Sichuan | Hao S.X.,The Material Corrosion and Protection Key Laboratory of Sichuan Province | And 2 more authors.
Applied Mechanics and Materials | Year: 2013

To increase active property of aluminum anode material and decrease its corrosion rate, the effect of urotropine ((CH2)6N4) and saturated Ca(OH)2 environment-friendly additives on electrochemical behaviors of aluminum anode (99.999%) has been investigated by adding urotropine and saturated Ca(OH) 2 into 4 mol/L KOH solution. The results show that additive urotropine ((CH2)6N4) can decrease the hydrogen-segregation and can increase activation property of aluminum anode greatly. With 1.0% (w) of urotropine ((CH2)6N4) and saturated Ca(OH) 2 addition in 4mol/L KOH solution, the corrosion current of aluminum anode becomes to minimum;its corrosion-inhibition ratio gets high to 87.3%. At the -1.20 V potential the current density of aluminum anode reaches to 37.7 mA.cm-2; the open circuit potential (Eocp) moves negatively and greatly to -1.815 V. © (2013) Trans Tech Publications, Switzerland.

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