This archaeological discovery is closely related to Qin Shi Huang in history.
Bronze swords were widely used during the Pre-Qin period. During the Spring and Autumn and Warring States periods, ancient sword casting techniques reached their peak. The sword of King Goujian, excavated in Hubei, China in December 1965, is the clearest evidence of the “short weapons” of that time.
In the technique of casting bronze swords, the most crucial step is the mixing of copper and tin. If there is too little tin, the product’s structure will be weak. However, if there is too much tin, the structure of the sword will be too hard, brittle, and prone to breaking.
Therefore, to ensure the durability of the sword, ancient artisans had to elaborate on its design. For example, they shortened the length of the blade and then widened and thickened it. However, this also made ancient bronze swords generally quite “bulky.” To date, most of the ancient bronze swords excavated have three characteristics: “short, wide, and heavy.”
Over time, the weapons production process improved. During the Spring and Autumn – Warring States periods, a sword had a length of about 20 to 60 cm. By the Qin Dynasty, the design of swords had changed.
The transition from bronze swords to steel swords in ancient China occurred during the Qin and Han dynasties. Before the Han Dynasty, a large number of bronze swords were still being cast, but some shortcomings of bronze swords did not meet human needs. Soon after, steel swords emerged.
Qin sword. (Photo: Wudan Academy).
In the 1990s, while the archaeological team was clearing pit number 1 of the terracotta warriors and horses of Qin Shi Huang, they accidentally discovered a strange sword that was 91 cm long. At that time, the excavation of this sword shocked experts “deeply.” Because this was the first time such a long ancient sword had been found.
Subsequently, in 1994, archaeologists discovered a series of bronze swords in Pit Number 2. The shortest was about 80 cm, and the longest was 95 cm. This led people to believe that the Qin had made a breakthrough in casting long swords. To balance between the ductility and hardness of the sword, craftsmen found an almost perfect ratio of copper to tin.
On these Qin swords appeared a technique known as “black technology.” The secret lies in the chrome layer on their surfaces. This coating is only 10 micrometers thick, which is just 1/10 the thickness of a newspaper.
The function of this chrome layer is to protect the blade and prevent rust. When comparing the Qin sword with the sword of King Goujian, the results are surprising. The Qin sword, although delicate, remained as shiny as new upon excavation, capable of cutting through 18 layers of paper, and its durability was higher than that of the remaining sword.
However, the chrome plating technique was only revealed in the previous century, in 1937, by German scientists. In 1950, the United States applied for a patent for this technology. Therefore, the excavation of the Qin sword shocked the world. The answer to the emergence of technology 2000 years ahead of humanity still requires time to seek a solution.
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