Reasons for the detachment of babbitt alloy for sealing pads used in power plant generators

The babbitt alloy on the surface of the sealing pad of a certain nuclear power plant generator was damaged and detached during operation. The reasons for the detachment of Babbitt alloy in sealing pads were analyzed using methods such as macroscopic observation, chemical composition analysis, metallographic examination, hardness testing, scanning electron microscopy and energy spectrum analysis. The results show that improper installation of the sealing pad caused friction between the sealing pad and the sealing seat cover, resulting in surface wear of the sealing pad. The chemical composition of the babbitt alloy material was not qualified, β phase uneven distribution led to a decrease in its load－bearing capacity, and under periodic loads, the babbitt alloy experienced fatigue detachment.