表面镀金技术对镍铬合金电化学腐蚀性能的影响

目的研究表面镀金技术对镍铬合金电化学腐蚀性能的影响。方法采用动电位极化曲线法，测定镀金镍铬合金试件在人工唾液中的自腐蚀电位、自腐蚀电流密度、极化电阻，并与镍铬合金、金合金试件进行比较。应用场发射扫描电子显微镜（field scanning electromicroscopy，FSEM）观察实验前后试件形貌变化，x射线能量色散谱仪（energy diffraction X-ray，EDX）分析镀金镍铬合金试件和镍铬合金试件表面元素的变化。结果镀金镍铬合金试件的自腐蚀电流密度为（0．70±0．20）×10^-6 A／cm^2，明显低于镍铬合金（P〈0．05），高于金合金（P〈0．05）。极化电阻为（34．77±12．61）KΩ·cm^2，明显高于镍铬合金（P〈0．05），低于金合金（P〈0．05）。FSEM显示镀金镍铬合金试件表面腐蚀较轻微，镍铬合金试件以晶间腐蚀为特点。EDX结果显示镀金镍铬合金试件实验后镍和铬的减少量明显低于镍铬合金试件（P〈0．05）。结论镍铬合金镀金后耐腐蚀性能明显提高。

Effect of aurum coating on corrosion resistance of Ni-Cr alloy

OBJECTIVE: To evaluate the effect of aurum coating on corrosion resistance of Ni-Cr alloy in artificial saliva environment. METHODS: The corrosion potential (E(corr)), self-corrosion current density (I(corr)), and polarization resistance (R(p)) of three alloys were measured using electrochemical methods to compare the difference of corrosion resistance between aurum-coated Ni-Cr alloy and Ni-Cr alloy or Au alloy. Meanwhile, microstructural and phase diffraction was examined with field scanning electromicroscopy (FSEM) and surface chemical analysis was performed by energy diffraction X-ray (EDX). RESULTS: The I(corr) of aurum-coated Ni-Cr alloy was (0.70 +/- 0.20) x 10(-6) A/cm2, which was significantly higher than that of Au alloy (P < 0.05) and lower than that of Ni-Cr alloy (P < 0.05). R(p) of aurum-coated Ni-Cr alloy was (34.77 +/- 12.61) KOmega.cm2, which was higher than that of Ni-Cr alloy (P < 0.05) and lower than that of Au alloy (P < 0.05). The results of FSEM showed that the corrosion resistance of Ni-Cr alloy coated with aurum was better than that of Ni-Cr alloy. The results of EDX indicated that released Ni and Cr of Ni-Cr alloy coated with aurum after test were less than those of Ni-Cr alloy (P < 0.05). CONCLUSIONS: The corrosion resistance of aurum-coated Ni-Cr alloy is higher than that of Ni-Cr alloy.