Studies on material science of ancient bronze objects : focusing on heat treatment and corrosion

点击翻译按钮获取中文摘要

The obtained results of our studies are as follows.(1) Subject 1 : Research on possible use of heat treatment in bronze-mirror manufacture of ancient timesWe investigated the influence of heat-treatment conditions on the microstructure, hardness and compression strength of a hi-tin bronze. Mechanical properties of the heat-treated specimens did not show much improvement compared to the specimen that are not heat-treated. We concluded that bronze mirrors were not heat-treated after casting in ancient times.We had observed about 20 ancient bronze mirrors by optical microscope and found that some have different micro structure from that of the hi-tin bronze cast in this experiment. We are planning to cast hi-tin bronze under various cooling rate and investigate their microstructure and mechanical properties.(2) Subject 2 : Research on corrosion of ancient bronze mirror found in groundIn an early stage of the study, a DNA analysis found the presence of a strain, which is regarded as Xanthomonadaceae of Bacteroidales. Further DNA analysis by cloning found microorganisms which can be presumed to be Acetobacter and Gluconacetobacter. These analyses have shown high possibility of the presence of multiple microorganisms in corroded layers of ancient bronze mirrors. We are planning to cultivate the microorganisms, which live in unusual environment, but we have not found the appropriate medium for cultivating them. We presume that these microorganisms are causing corrosion in bronze objects. In further research, we hope to prove microbiological corrosion of ancient bronze objects.