Non-destructive corrosion removing on bronze historical artifacts by sodium bicarbonate blasting

Abstract

Sodium bicarbonate blasting was applied to remove the corrosion layer of ancient bronze artifacts. Scanning electron microscopy coupled with energy dispersive spectroscopy (SEM-EDS) was employed to investigate the surface morphology, and element composition of the bronze coin surface before and after blasting. X-ray diffraction (XRD) was used to characterize the mineralogical composition of products in the corrosion layer of the bronze coin. The products are cerussite (PbCO3), lead oxide (PbO2), cassiterite (SnO2), bobkingite Cu2Cl2(OH)8(H2O)12 and malachite Cu2(CO3)(OH)2 which can be effectively removed by employing an impinge angle of 90°, working pressure at 0.3 MPa. These results indicate that sodium bicarbonate blasting can achieve non-destructive removal of the corrosion layer on the bronze coin. This work will be helpful for better restoration and preservation of the bronze cultural relics.