What are black metals? Black gold
The names ferrous and non-ferrous metals often lead people to misunderstand that ferrous metals must be black, but they are not. There are only three types of ferrous metals: iron, manganese, and chromium. And none of them are black! Pure iron is silver white; manganese is silver white; chromium is gray white. Because the surface of iron is often rusted, covered with a layer of black iron oxide and tan iron oxide mixture, it looks black. No wonder people call it "black metal".
First, what is black metal?
Ferrous metals and non-ferrous metals are collectively referred to as metals. Ferrous metals are not black as people imagine, and their classification mainly refers to: iron, chromium, manganese and their alloys, such as steel, pig iron, ferroalloy, cast iron, etc. Like iron, chromium, and manganese are not black, pure iron is silver white, chromium is gray white, and manganese is silver white.
Which are called ferrous metals. In the past, people saw that the surface of iron was covered with a mixture of black ferric oxide and tan ferric oxide, which looked black. Later, manganese and chromium were also counted as "ferrous metals". He is the general term for the classification of iron, chromium and manganese in industry, so it can be said that other single metal elements except iron, chromium and manganese are non-ferrous metals.
Second, what are the classifications of ferrous metals?
Iron, manganese, chromium
Because the surface of iron was often rusty, covered with a layer of black iron oxide and brown iron oxide mixture, it looked black. The "black metallurgy industry" often referred to mainly refers to the iron and steel industry. Because the most common alloy steels are manganese steel and chromium steel, manganese and chromium are also regarded as "black metals".
Metals are materials that have good electrical conductivity, thermal conductivity and mechanical properties, and have a positive temperature resistance coefficient. Metals are a big family. There are 86 kinds of metals in the world now. Usually people divide metals into two categories, ferrous metals and non-ferrous metals.
The names ferrous metals and non-ferrous metals often make people misunderstand that ferrous metals must be black, but they are not. There are only three types of ferrous metals: iron, manganese, and chromium. And none of them are black! Pure iron is silver-white; manganese is silver-white; chromium is gray-white. Because the surface of iron is often rusted, covered with a layer of black iron oxide and tan iron oxide mixture, it looks black. No wonder people call it "ferrous metal". The "ferrous metallurgy industry" often referred to mainly refers to the iron and steel industry. Because the most common alloy steels are manganese steel and chromium steel, manganese and chromium are also considered "ferrous metals".
Except for iron, manganese, and chromium, other metals are considered non-ferrous metals.
In non-ferrous metals, there are various classification methods. For example, according to the specific gravity, the specific gravity of aluminum, magnesium, lithium, sodium, potassium, etc. is less than 5, which is called "light metal", while the specific gravity of copper, zinc, nickel, mercury, tin, lead, etc. is greater than 5, which is called "heavy metal". Gold, silver, platinum, osmium, iridium, etc. are more expensive and called "precious metals". Radium, uranium, thorium, Polonium, etc. are radioactive and called "radioactive metals". There are also niobium, tantalum, zirconium, lutetium, gold, radium, hafnium, uranium, etc. Because the content in the earth's crust is less or more dispersed, people also call it "rare metals".
In the metallurgical industry, iron, chromium, manganese and their alloys (mainly alloy steel and steel) are called ferrous metals. In fact, pure iron and chromium are silver-white, while manganese is silver-gray. The reason why they are called ferrous metals is that the surface of steel is often covered with a layer of black ferric oxide, and manganese and chromium are mainly used to smelt alloy steel, so people call iron, chromium, manganese and their alloys ferrous metals. In addition, people specifically group these three metals and their alloys into one category, and all other metals and alloys are classified as non-ferrous metals. This is because steel occupies an extremely important position in the national economy and is one of the important symbols to measure a country's national strength. Its production accounts for about 95% of the world's total metal production.
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