TC6钛合金真空感应渗氮层的电化学腐蚀行为研究

Study on Electrochemical Corrosion Behavior of Vacuum Induction Nitrided Layer of TC6 Titanium Alloy

为了评估渗氮强化后TC6钛合金在含氟离子溶液中的耐蚀性,利用间歇式真空感应渗氮技术在合金表面获得渗氮层,研究了渗氮层的组织结构及其在HNO3+HF体系溶液中的电化学腐蚀行为。结果表明:经真空感应渗氮处理后的TC6钛合金表层物相为TiN,氮化层随温度升高而增厚。经开路电位(OCP)、极化曲线及交流阻抗(EIS)测试后发现:随渗氮温度的升高,TC6钛合金的抗腐蚀性能逐渐提高,和原样相比腐蚀电流密度降低了27倍,而薄膜电荷转移电阻R1最高达到1.110×10^14Ω·cm^2。经电化学腐蚀后的试样表面具有明显腐蚀坑,腐蚀形态均为点蚀。

In order to evaluate the corrosion resistance of TC6 titanium alloy after nitriding in fluoride-containing ionic solution,the nitriding layer was obtained on the surface of the alloy by intermittent vacuum induction nitriding,and the microstructure of nitriding layer and electrochemical corrosion performance in HNO3+HF system were studied. Results showed that the surface phase of the TC6 titanium alloy after vacuum induction nitriding treatment was composed of TiN,and the nititride layer thickened with the temperature. By open-circuit potential( OCP),polarization curve,and electrochemical impedance spectroscopy( EIS),it was found that the electrochemical corrosion resistance of TC6 titanium alloy gradually improved with the increase of nitriding temperature. Compared with the original state,the corrosion current density was reduced by 27 times,and the transfer resistance R1 rose to 1. 110 × 10^14Ω · cm^2. Furthermore,the surface of the sample after electrochemical corrosion had obvious corrosion pits,and the corrosion form belonged to pit corrosion.