電沉積Ni-W 合金之耐蝕性研究

Corrosion Resistance of Ni-W Alloy Electroplating Coating

本研究使用田口實驗計劃法及脈衝電流來探討Ni-W 合金之電沉積，並採用腐蝕電流來量測Ni-W 合金鍍層之耐蝕性，且以XRD 繞射和電子微探儀（EPMA）來分析Ni-W 合金鍍層之W含量與微結構的影響，研究結果得到耐蝕性最佳之操作條件為pH 9、尖峰電流密度12.5 A/dm2、鎢酸鈉濃度0.4 M、檸檬酸鈉濃度0.4 M、氯化胺濃度0.5M、糖精添加量0 g/l、負載循環0.2、脈衝頻率1000，而其腐蝕電流(Icorr)為0.106 μA/cm2，且影響耐蝕性最大的因子為鎢酸鈉濃度，同時發現當鍍層中鎢含量增加時，Ni-W 合金鍍層之耐蝕性隨之增加。

This study focused on corrosion resistance related to processing parametersof the Ni-W deposited coatings produced by using pulse currentelectrodeposition. It used the Taguchi experimental design. The corrosionresistance of coatings was measured by corrosion current and the content oftungsten in coatings was detected using an electro probe X-ray micro-analyzer (EPMA). The phase structure of the Ni-W coatings was decidedby the X-ray diffraction pattern. Results indicate the optimal conditionsfor corrosion resistance in this research were pH 9, peak current den- sity 12.5 A/dm2, concentration of Na2WO4‧2 H2O 0.4 M, concentration ofNa3 Cit 0.4 M, concentration of NH4 Cl 0.5 M, concentration of saccharin0 g/l, duty cycle 0.2 and frequency 1000 Hz. Also optimum coating corrosioncurrent (Icorr) is obtained at 0.106 μA/cm2. The result also shows thathigher content of W in Ni-W coatings leads to better corrosion resistance.