Relationships between microstructures and properties of chinese ancient bronzes
The typical morphology of alloy lead (Pb) in ancient bronzes made in the Spring-Autumn Warring States Period (770 B.C. -221 B.C.), China, was examined by using electron microscopic techniques. We propose that the main purposes for adding metallic Pb in a large quantity into ancient bronzes, such as arrows and ritual vessel—Ding, were for increasing weight and economical reasons. In order to promote adding efficiency and improve casting quality for getting homogenously distributed Pb particles in the bronzes, a process through inserting Pb rod into the mold is supposed to be used during casting, which provided a process for preventing Pb sinkage. Scanning electron microscope (SEM) observations from the fracture surface of the bronzes revealed that the Pb particle possessed a “hollow-cored bubble” structure, which was formed due to absorbing casting gases during solidification and therefore indirectly eliminated the casting porosity and loosen.
Formation of black patina on an ancient Chinese bronze sword of the Warring States Period
Abstract In general, black patina is formed upon the surface of the ancient bronze mirrors. Recently, a kind of black patina is found on an ancient bronze sword, which was made 2500 years ago during the Warring States Period of China. In this paper, chemical compositions and microstructures of the black patina were characterized by using instruments including optical microscope (OM), scanning electron microscope (SEM), energy dispersive spectrometer (EDS), X-ray diffraction (XRD) and Raman spectrometer (Raman). The results revealed that the formation of the black patina on the bronze sword is due to two reasons: (1) high tin (Sn) content reaches to 22.92 wt%; (2) damp, wet and acid burial environment. Therefore, it conforms to the natural corrosion formation mechanism, i.e., after selective dissolution of elements Cu and Pb from the matrix, element Sn was oxidized and then, the gel-like SnO2·xH2O filled the vacancies left by the selective corrosion of Cu and Pb. This work will be helpful for better restoration and preservation of the bronze cultural relics.
The bronze bowls from Ban Don Ta Phet, Thailand: An enigma of prehistoric metallurgy
Remains of 3rd-2nd century B.C. Iron Age bronze bowls from Ban Don Ta Phet, Thailand, are examined. Metallographic analysis indicates a manufacturing technique involving casting mechanical hot-working, heat treatment and quenching, followed by polishing on a wheel or lathe. X-ray fluorescence found a very high tin bronze (23%). Comparison to bowls from other comparable sites are made. -- AATA