Cause Analysis on Inlaid Bubbles Generation of Al/BN Abradable Seal Coatings

The Al/BN abradable seal coatings were cut by wet grinding wheel, and a large number of abnormal bubbles produced when pouring epoxy resin inlay. The causes for bubbles were analyzed by methods of micro analysis, hardness test, verifying test and so on. The results show that the Al/BN abradable seal coatings were porous structure. Water-based cutting fluids were easily adsorbed by the pores and cracks of the coatings, which resulted in electrochemical reactions with the metal aluminum phase. Finally, aluminum oxide was precipitated in high viscosity epoxy resin and produced visible bubbles.