模拟服役环境中航空导管连接件耐蚀性能研究

采用自制的航空导管连接件腐蚀试验系统,研究了航空镀镉45^#钢导管连接件在模拟服役环境中的气密性、油压气密性以及应力腐蚀、表面腐蚀等性能.对该导管连接件在高温盐水溶液6%NaCl(90±5)℃浸泡与空气烘烤(60±5)℃循环200次条件下的表面腐蚀及应力腐蚀行为进行了评价;探讨了在模拟服役环境中,45^#钢发生腐蚀的机理.10^＃航空油不对镀镉45^＃钢造成腐蚀.镀镉45^#钢导管连接件在模拟服役环境中只是表面镀镉层发生腐蚀破坏,基体45^#钢只发生轻微腐蚀,表明45^＃钢导管连接件表面的镀镉磷化层可作为阳极性镀层而对基体金属进行保护.在最小屈服强度0.85的弯曲应力水平作用下,无应力腐蚀倾向.导管材料铝合金LF2-M与连接件45^#钢在6％NaCl水溶液中只有很小的电偶腐蚀电流,平均电偶电流密度为0.185μA/cm²,证明该类导管及导管连接件能安全地进行偶接.

Study on corrosion resistance of aircraft conduit connector at simulated service environment

Corrosion resistance, airproof property and oilproof property of aircraft conduit connector of Cd-electroplated 45^# steel were studied by a conduit connector corrosion experiment system at simulated service environment. Cd-electroplated 45^# steel was placed in the solution of 6% NaCl at 90±5℃ for 5 minutes and then in the air at 60±5℃ for 25 minutes. This process was cycled for 200 times. The behaviors of surface corrosion and stress corrosion of the connectors were evaluated and the corrosion mechanism was investigated. It was not found that 45^# steel was corroded in No.10 fuel. Only slight corrosion was found on the surface of 45^# steel at simulated service environment. It was shown that the Cd-electroplated layer as anode plating layer on 45^# steel has excellent protection to the matrix metal. The result of the experiment under the bending stress of 0.85σ_s indicated that the Cd-coated 45^# steel has good corrosion resistance to SCC. Galvanic corrosion of LF2-M coupled with 45^# steel was investigated. It was found that the galvanic current of the couple of LF2-M coupled with 45^# steel is very low. The mean galvanic corrosion current is 0.185μA/cm². It was demonstrated that the conduit of LF2-M and its connector of 45^# steel can be coupled safely.