热处理温度对Ni-W-P脉冲电沉积层耐蚀性的影响

Effect of Heat Treatment Temperature on Microstructure and Corrosion Resistance of Pulse Electrodeposited Ni-W-P Alloy Coating

为了进一步提高电沉积Ni-W-P合金层的耐蚀性,将其在不同的温度下热处理1h,利用XRD谱研究了热处理温度对合金层微观组织的影响,采用Tafel曲线、EIS技术研究了热处理温度对其在3.5%NaCl溶液中耐蚀性的影响。结果表明:随着热处理温度的升高,Ni-W-P合金镀层由非晶态结构逐渐转变为晶态结构,400℃时晶化析出了Ni及Ni3P相,其晶粒尺寸随温度升高逐渐增大;镀层的耐蚀性随热处理温度的升高先增强后降低,400℃时镀层的耐蚀性最好。

Pulse electrodeposited Ni-W-P alloy coating was heat treated at various temperatures for 1 h so as to improve its corrosion resistance. The effect of heat treatment temperature on the microstructure of the alloy coating was investigated by means of X-ray diffraction, while Tafel curves and electrochemical impedance spectra were measured to reveal the effect of heat treatment temperature on the corrosion resistance of the alloy coating in 3.5%NaCl solution. Results show that, with the increase of heat-treatment temperature, the alloy coating experiences gradual microstructure transformation from amorphous phase to crystalline. When the alloy coating is heat treated at 400 ℃, Ni and Ni3P phases are crystallized and precipitated, and their grain sizes rise with increasing heat-treatment temperature. In the meantime, the corrosion resistance of the alloy coating tends to be improved but later worsened with rising heat-treatment temperature, and the coating heat-treated at 400 ℃ has the best corrosion resistance in 3.5% NaCl solution.