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钛合金材料与不同材料相互连接,并处于富含氯离子的电解质溶液中,有可能使得材料发生电偶腐蚀而遭到破坏。采用极化曲线的方法分别研究了NiAl涂层、TA15的电化学行为。结果表明NiAl涂层的腐蚀电位较TA15的低,二者相差约30 mV,NiAl涂层腐蚀电流为1.718×10-4A,TA15腐蚀电流为1.170×10-5A。研究了NiAl封严涂层和TA15钛合金之间在5%NaCl水溶液中的电偶腐蚀行为。测试了NiAl-TA15电偶对的电偶电流-时间曲线,并通过计算出的平均电偶电流密度,评价了钛合金和NiAl封严涂层的电偶腐蚀敏感性。结果表明,TA15钛合金和NiAl封严涂层之间的电位差很小,电偶腐蚀倾向很小,电偶电流密度为0.0253μA.cm-2。电偶腐蚀过程中,腐蚀电位较低的NiAl涂层作为电偶对的阳极发生腐蚀,钛合金作为阴极得到保护。电偶腐蚀后电偶对的阳极、阴极的自腐蚀电位均升高,阳极电位从-347 mV正移到-242 mV,阴极电位从-323 mV正移到-210 mV;电偶电位为-300 mV。NiAl涂层含有较多孔洞,可以作为腐蚀介质的渗透通道,在含有Cl-并且有溶解氧存在的腐蚀性介质中,容易导致腐蚀的发生与发展。
Titanium materials and materials connected to each other, and is rich in chloride ion electrolyte solution, may make the material galvanic corrosion and destruction. The polarization curves were used to study the electrochemical behavior of NiAl coating and TA15 respectively. The results show that the corrosion potential of NiAl coating is lower than that of TA15, the difference is about 30 mV, the corrosion current of NiAl coating is 1.718 × 10-4A, and the corrosion current of TA15 is 1.170 × 10-5A. The galvanic corrosion behavior between NiAl sealing coating and TA15 titanium alloy in 5% NaCl aqueous solution was studied. The galvanic current-time curve of the NiAl-TA15 galvanic couple was tested. The galvanic corrosion susceptibility of the titanium alloy and the NiAl seal coating was evaluated by the calculated average galvanic current density. The results show that the potential difference between the TA15 titanium alloy and the NiAl sealing coating is very small, the galvanic corrosion tendency is small, and the galvanic current density is 0.0253μA.cm-2. In the galvanic corrosion process, the NiAl coating with lower corrosion potential corrodes as the anode of the galvanic couple, and the titanium alloy is protected as the cathode. After the galvanic corrosion, the self-corrosion potentials of the anode and the cathode increased, the anode potential moved from -347 mV to -242 mV, and the cathode potential moved from -323 mV to -210 mV. The galvanic potential was - 300 mV. NiAl coating contains more pores, which can be used as the corrosive medium for the permeation channel. In the corrosive media containing Cl- and dissolved oxygen, the occurrence and development of corrosion easily occur.