The Preparation And Characterization Of Ni-B-(RE) And Ni-P/Ni-B-(RE) Alloy Plating On Mg-RE Alloy

In this paper,nickel acetate is used as the main salt,and DMAB is used as the reducing agent to prepare Ni-B and Ni-B-RE alloy plating by electroless plating and explores the influence of the pretreatment conditions,reaction time,reaction temperature,p H of plating solution,DMAB concentration and lactic acid concentration on the corrosion resistance,quality and thickness of Ni-B alloy plating;the effect of rare earth ions(La³⁺,Ce³⁺,Dy³⁺)on the quality and thickness of Ni-B-RE alloy plating;and the effect of cerium nitrate concentration on corrosion resistance of Ni-B-Ce alloy plating.The Ni-P/Ni-B and Ni-P/Ni-B-RE alloy plating were prepared by electroplating with nickel sulfamate as the main salt.The effect of DMAB concentration on the deposition rate,hardness and corrosion resistance of Ni-P/Ni-B alloy plating;the effects of rare earth species,current density,and dysprosium nitrate concentration on the surface resistivity,deposition rate,hardness and corrosion resistance of the plating;the effects of current density and dysprosium nitrate concentration on the surface morphology of Ni-P/Ni-B-Dy alloy platings were explored.The composition of Ni-B,Ni-B-Ce,Ni-P/Ni-B-Dy alloy plating were characterized by EDX;the surface morphology of Ni-B,Ni-B-Ce,Ni-P/Ni-B,Ni-P/Ni-B-Dy alloy plating were characterized by SEM;XRD and XPS were used to characterize the structure of Ni-P/Ni-B-Dy alloy plating and the valence states of Ni,B and Dy elements.The results are as follows:The Ni-B alloy plating was prepared by electroless plating,and better process parameters were obtained:the pretreatment was only alkaline washing,the electroless plating time was20min,the bath temperature was 35?,the bath p H was 7,3g/L DMAB,15g/L lactic acid.The self-corrosion potential of the prepared Ni-B alloy plating is-1.131V,the mass is 5.07mg,and the thickness is 79.9?m.Adding rare earth ions(La³⁺,Ce³⁺,Dy³⁺)to the electroless plating solution can improve the quality and thickness of the electroless plating plating.When the concentration of dysprosium nitrate is 1mmol/L,the maximum mass and thickness are 6.8mg and 96.4?m,respectively.When the concentration of cerium nitrate is 2.5 mmol/L,the maximum self-corrosion potential of the prepared Ni-B-Ce alloy plating is-1.078V.The Ni-P/Ni-B alloy plating is prepared by electroplating.When the DMAB concentration is0.6g/L,the maximum self-corrosion potential of the prepared Ni-P/Ni-B alloy plating is-0.690V,and the deposition rate and hardness are 50.91 mg/cm²·h and 802.86Hv,respectively.The Ni-P/Ni-B-RE alloy plating was prepared by electroplating,and better process parameters were obtained:the current density is 2A/dm²,the DMAB concentration is 0.6g/L,the rare earth element is Dy,the rare earth concentration is 4mmol/L.The resistivity of the prepared Ni-P/Ni-B-Dy alloy plating is at least 1.02×10^-8?·m,and the deposition rate and hardness are19.72 mg/cm²·h and 527.2Hv,respectively.When the current density is 2A/dm² and the concentration of dysprosium nitrate is 3mmol/L,the maximum self-corrosion potential of the Ni-P/Ni-B-Dy alloy plating prepared is-0.537V.EDX results show that Ni-B,Ni-B-Ce,Ni-P/Ni-B-Dy alloy platings were successfully prepared.SEM results show that Ce can improve the cracks on the plating surface;Dy has the function of leveling the coating,making the surface of the Ni-P/Ni-B-Dy alloy plating smooth,uniform and detailed.XRD results show that the Ni-P/Ni-B-Dy alloy plating is crystalline.XPS results show that Ni and Dy exist in the form of metals;B exists in the form of intermetallic compounds.