表面涂层技术对镍铬合金耐蚀性能的影响

目的在模拟口腔环境中,研究镍铬合金表面涂钛前后,对抗酸腐蚀能力的变化。方法采用溶胶-凝胶沉积金属钛的表面涂层法,应用ZF-3恒电位仪,测定镍铬合金表面涂钛前后,在不同pH值条件下的极化曲线。结果镍铬合金表面涂钛处理前,pH=7.0时,电极电位为-160mV,自腐蚀电流密度为0.262μA·cm-2;pH=5.6时,分别为-182mV及0.352μA·cm-2。随着pH值降低,电位和电流密度下降,材料容易被腐蚀。涂钛处理后,pH=7.0时,电极电位为-71mV,自腐蚀电流密度为0.152μA·cm-2;pH=5.6时,分别为-89mV及0.174μA·cm-2,表明涂钛后,材料的腐蚀速度降低。结论不论涂钛前或涂钛后,酸性环境同样使镍铬合金耐腐蚀能力下降;而在酸性环境,涂钛后镍铬合金耐蚀性能优于涂钛前,中性环境也如此。说明镍铬合金表面涂钛能提高金属的耐酸性能。

The Effect on Anti-acid Corrosion Resistance of Ni-Cr Alloy Coating Titanium

OBJECTIVE: The aim of this study was to investigate the variation of the corrosion resistance of Ni-Cr alloy in acid environment before and after coating titanium in vitro. METHODS: 1. Surface treatment using sol-gel technique of coating titanium. The steps were as follows: (1) Pre-treatment: sanding, washing and activation in order to remove the oxidative product; (2) The preparation of sol: some small charged particles produced by the hydrolytic reaction, and formed sol. These particles would congeal into extremely small ones (diameter usually is 5 microns); (3) Coating; (4) Heat treatment: The organism was resolved and volatilizeed at high temperature, and the atoms of Ti were left. These atoms of Ti were very active and could combine firmly with the atoms on the surface awaiting of treatment. 2. Conditions: artificial saliva; pH = 7.0 and pH = 5.6; temperature: 36.5 degrees C 3. Electrochemical test: polarization curve; instrument: ZF-3 poteniostat. RESULTS: Before coating titanium, when pH was 7.0, the electrode potential of Ni-Cr alloy was -160 mV, and the self-corrosion current density was 0.262 microA cm-2; when pH = 5.6, the data were -182 mV and 0.352 microA cm-2, respectively. This result showed that when pH value reduced, the potential and current density descended, too. This indicated that the material was easy to be corroded. After coating titanium, when pH value was 7.0, the potential was -71 mV, the self-corrosion current density was 0.152 microA cm-2; when pH = 5.6, the data were -89 mV and 0.174 microA cm-2. This indicated that the corrosion rate of material descended evidently after coating titanium in acid environment. CONCLUSION: (1) Not only before coating Ti but also after coating, the corrosion resistance of Ni-Cr alloy would descend in acid environment;(2) In acid environment, the corrosion resistance of Ni-Cr alloy after coating titanium was superior to that of the material before coating. So was in neutral environment.