Tell me about your knowledge of China's ancient scientific and technological creation.

1, bronze smelting and casting technology:

In ancient China, natural copper was first used. In the early Shang dynasty, bronze of copper-tin alloy could be refined by pyrometallurgy. The process of smelting bronze is more complicated. Probably, the selected ore is first added with flux, and then put into a smelting furnace for smelting with charcoal. When the temperature is ripe, the refined copper liquid is taken out and the smelting slag is discarded to obtain primary copper. Primary copper is still coarse, and it needs refining to get pure copper. Copper forms an alloy with tin and lead, which is bronze.

The invention of bronze is a great event in the history of human civilization. Because it overcomes the softness of pure copper and has the advantages of low melting point and good castability, it has gradually become the main variety of ancient bronzes, which has promoted the manufacturing technologies such as automobiles, ships, sculptures and metalworking, as well as the development of agriculture, military affairs and economy and society. The application of bronzes represented the level of science and technology and the level of culture and art at that time, and became a distinctive symbol of this era.

2, the ancient cast iron technology:

The great demand for iron tools led to the invention of iron molds. 1953 The iron model unearthed from the metallurgical site of Yan State in Xinglong, Hebei Province was used to cast iron axes, hoes, sickles and turning tools. These irons are reasonable in structure, uniform in wall thickness and consistent in shape with the outline of castings, and iron cores have been adopted. Some models can cast two objects at a time, which shows that the cast iron technology in this period has reached a higher level.

The heat treatment technology of cast iron has made obvious progress in this period. Because cast iron is made of charcoal, its carbon content is mostly near crystallizing point, and other elements are low, so it belongs to a relatively pure iron-carbon alloy. Many devices are cast by iron mold, and the wall thickness is generally 3 ~ 5 mm, which belongs to thin-walled castings. In practice, reasonable heat treatment specifications were adopted, and better quality ductile iron castings were obtained. Most white-core ductile iron castings have been completely treated, with only a small amount of cementite residue and graphite precipitation. Most black core ductile iron castings are based on ferrite and pearlite, and some are based on ferrite or pearlite. The shape of graphite is similar to that of modern similar materials.

3, the ancient cast steel technology:

The steel casting method is an advanced steelmaking process invented by the working people in ancient China. It is the most outstanding achievement of China's early steelmaking technology. It was invented by Mu Huaiwen, a famous metallurgist in Northern Qi Dynasty. /kloc-before the 0/7th century, the method of smelting wrought iron at low temperature was widely used in western countries. Steel can't be melted, iron and slag can't be separated easily, and carbon can't penetrate quickly. After the development process of "block smelting", "hundred steelmaking" and "steel explosion", China invented the steel casting method, which successfully solved this problem and made an epoch-making contribution to the development of smelting technology in the world.

During the Southern and Northern Dynasties, there was a more advanced casting method, and the weapons made by this method were tough and sharp. As early as the Han dynasty, people began to use coal as fuel and use it to smelt iron. In the Northern Song Dynasty, smelting iron from coal was quite common. Thereby increasing the temperature of the iron smelting furnace, accelerating the smelting process and improving the production efficiency of the iron smelting industry.