Electrochemical grinding of honeycomb seals using sodium dodecylbenzene sulfonate as an eco-friendly inhibitor: machining principle and performance evaluation

Abstract

To enhance the performance of aero-engines, honeycomb seals are commonly used between the stator and rotor to reduce leakage and improve mechanical efficiency. Because of the thin-walled and densely distributed honeycomb holes, machining defects are prone to occur during manufacturing. Electrochemical grinding (ECG) can minimize machining deformation because it is a hybrid process involving electrochemical dissolution and mechanical grinding. However, electrolysis will generate excessive corrosion on the honeycomb surface, which affects the sealing capability and operational performance. In this study, an ECG method using an electrolyte of 10% (mass fraction) NaCl is proposed to machine the inner cylindrical surface of the honeycomb seal, and an eco-friendly inhibitor, sodium dodecylbenzene sulfonate (SDBS), is introduced to the electrolyte to inhibit corrosion of the honeycomb structure. A theoretical relationship between the voltage and feed rate during ECG is proposed, and the excessive corrosion of the honeycomb single-foiled segment is used as a measurement of the impact of electrolysis. The corrosion inhibition efficiency of SDBS on the honeycomb material in 10% (mass fraction) NaCl solution is evaluated through electrochemical tests, and the suitable feed rate and optimal concentration of SDBS are determined through ECG experiments. Additionally, the corrosion inhibition effect of SDBS is validated through four groups of comparative experiments. The results indicate that the inhibition efficiency of SDBS increases with increasing concentration, reaching the maximum of 73.44%. The optimal SDBS mass fraction is determined to be 0.06%. The comparative experiments show that excessive corrosion is reduced by more than 40%. This establishes ECG as an effective and environmentally friendly processing method for honeycomb seals by incorporating SDBS into a 10% (mass fraction) NaCl solution.