Researches on the Materials Science for the Ancient Bronze Mirrors focused on the Heat Treatment.

为了提高古铜镜的韧性，进一步降低古铜镜在粘土中的腐蚀，对古铜镜进行了热处理工艺研究。我们得到了以下主要结果。国产高锡青铜合金经720℃固溶水淬，保温20分钟后，韧性得到明显提高。从测量密度和计算密度得到的密度降低率与镜面的腐蚀程度相对应。纯铜块在镜面中的外观形状呈现出不同的模式，如层状沉积，大颗粒或细颗粒沉积，或像线或闪电一样沉积，只是在镜面的裂缝中毛刺。在镜子中观察到氧化铜（Cu_2O）层和颗粒的形状与纯铜沉积的形状完全相同。在腐蚀的最外层形成了无定形的SiO_2。在腐蚀的中间层形成了Cu_2O （cuprite）和Cu (OH)_2，它们组成了与腐蚀层相邻的前两层内层。cu - sn - pb络合物氧化物在腐蚀的中间层形成，下一层为内层。微量的PbSO_4和一种sn有机化合物也被检测到。我们观察到，经过机械抛光并放置约一个月后，腐蚀层的抛光表面，特别是第四层，Cu_2S（辉铜矿）形成了霉菌状。假定Cu_2S是硫酸盐还原菌的产物。大量纯铜块以层或颗粒形式出现，并倾向于在中间腐蚀层附近形成。从这些分析中得到的证据表明，微生物可能是从粘土中挖掘出来的古代铜镜被腐蚀的原因。

We carried out researches into the heat treatment technique to ancient bronze mirrors for the aim at improvement of toughness, farther, corrosion of ancient bronze mirrors in clay. We obtained the following principal results.1. Toughness of the home made high tin bronze alloy was improved remarkably when, for example, water quenching from 720℃ of solution treatment and 20 minutes holding was performed.2. The rates of density reduction obtained from the measured and the calculated densities corresponded to the degree of corrosion of the mirrors.3. The shapes of appearances of pure copper lumps in the mirrors show various modes, i.e., depositions like layers, large or fine particles, or depositions like string or flash of lightning just burring the cracks in the mirrors.4. The oxide copper (Cu_2O) layers and particles were observed in the mirrors showing just the same shapes as those of pure copper depositions.5. Amorphous SiO_2 had formed in the outermost corroded layer.6. Cu_2O (cuprite) and Cu (OH)_2 had formed in the middle layer of corrosion, which comprise the first two internal layers adjacent to the layer.7. Cu-Sn-Pb-complex oxide had formed in the middle layer corrosion, the next internal layer. Small amounts of PbSO_4 and an Sn-organic compound were also detected. We observed that Cu_2S (chalcocite) forms like mold on the polished surface of the corroded layers, especially notable on layer IV, after being mechanically polished and left to stand for about one month. Cu_2S is presumed to be the resultant of sulfate reducing bacteria.8. Numerous pure copper lumps appeared in layers or particles and tended to form in the vicinity of the middle corrosion layer.9. The evidence from these analyses suggests that microorganisms could have been the cause of the corrosion found in ancient bronze mirrors excavated from clay.