牙科用铬合金在不同pH值的人工唾液中耐腐蚀性能的研究

目的在模拟口腔环境下，研究牙科用铬合金（钴铬合金和镍铬合金）在pH值为7和5的人工唾液中的电化学腐蚀行为。方法用动电位极化曲线法，测定铬合金在pH值为7和5的人工唾液中自腐蚀电位、自腐蚀电流密度，与含钛元素镍铬合金进行比较分析；并用电化学阻抗谱研究铬合金的腐蚀机制和耐腐蚀性能。结果钴铬合金的自腐蚀电流密度低于含钛元素镍铬合金和镍铬合金，阻抗值高于含钛元素镍铬合金和镍铬合金；而镍铬合金自腐蚀电流密度高于含钛元素镍铬合金，阻抗值略低于含钛元素镍铬合金。随pH值下降，合金表面自腐蚀电流密度均升高，阻抗值均降低，但钴铬合金的变化幅度最小。结论钴铬合金的耐腐蚀性能优于镍铬合金和含钛元素镍铬合金；随pH值下降，合金耐腐蚀性能均发生不同程度的下降。

Study on the corrosion resistance of Cr alloy in the artificial saliva with different pH value

Objective To study the effect on the corrosion resistance of Cr alloy in the artificial saliva with different pH value in vitro. Methods Compared to Ti alloy, electrochemical technique was used to measure the electric potential of corrosion (E_(corr)), current density of corrosion (I_(corr))Cr alloy in the artificial saliva with different pH value. The corrosion and corrosion resistance mechanism on Cr alloy in the artificial saliva with different pH value had been investigated by the EIS curves. Results The corrosion resistance of Co-Cr alloy was better than Ti alloy. The value of I_(corr) was lower and the value of R_p, was larger than Ti alloy. The corrosion resistance of Ni-Cr alloy was worse than Ti alloy. The value of I_(corr) was larger and the value of R_p was lower than Ti alloy. The pH value in the artificial saliva was decreased, the I_(corr) value of three types of alloy increased, the R_p, value of three types of alloy decreased. But the changes of Co -Cr alloy was smaller than that of Ti alloy or Ni -Cr alloy. Conclusion The corrosion resistance of Co-Cr alloy was superior to that of Ni-Cr alloy and Ti alloy. In the acid artificial saliva, the corrosion resistance of three types of alloy descended evidently.