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Is it true that "flying" diamonds in graphite powder?

Issuing time:2018-12-14 Popularity:831

When you mention a diamond, people will think of a dazzling, dazzling scene that shines with the owner's activities. But because of its expensive price, most people can only be discouraged. Despite this, people still have a longing for diamonds.

Do you know what a diamond is? Its chemical composition is carbon (C), and natural diamonds are honed by diamonds to be called "diamonds". Natural diamonds are very rare. There are only 2 diamonds in the world weighing more than 1000 carats (1 g = 5 carats), and there are only more than 400 carats. The largest diamond we have found so far weighs 158.786 carats. "Changlin Diamond". Things are rare, just because natural diamonds that can be used as "diamonds" are rare, people want to "artificial" diamonds instead of it, which naturally comes to mind the diamond "twin" brother - graphite.


The chemical composition of diamond and graphite is carbon (C), which scientists call "homogeneous multi-image variants", and some people call "allotropes." From this name, we can know that they have the same "quality", but "shape" or "sex" is different, and there is a world of difference, diamond is the hardest substance at present, and graphite is one of the softest substances. Everyone knows that the pencil lead is made of graphite powder and clay. The graphite powder is soft, and it is represented by "B". If the clay is mixed, it is hard, and it is represented by "H". Mineralogists use Mohs hardness to indicate relative hardness, diamond is 10, and graphite has a Mohs hardness of 1. The difference in their hardness is so great that their internal structure is very different.

The carbon atoms inside the graphite are arranged in layers, and only one carbon atom is connected to one carbon atom. Carbon and carbon form a hexagonal ring shape, and an infinite number of hexagons form a layer. The connection between the layers is very weak, and the three carbon atoms in the layer are very tightly connected, so the layers are easily slipped after the force is applied, which is why graphite is very soft to write.

The carbon atoms inside the diamond are arranged in a three-dimensional space of "skeleton" shape. Four carbon atoms are connected around one carbon atom, so a skeleton is formed in three-dimensional space. This structure has a uniform contact force in all directions, and the coupling force is strong. Therefore, the diamond has a high hardness characteristic.

The difference in hardness between graphite and diamond is so great, but it is still hoped that synthetic diamonds can be used to obtain diamonds because the amount of graphite (carbon) in nature is very rich. However, it is not so easy to make the carbon in the graphite into carbon arranged like diamond. In the late eighteenth century, people began to search for synthetic pathways until the middle of this century. In 1938, scholar Rossini established the theoretical basis of synthetic diamond through thermodynamic calculations. It was calculated that it was necessary to convert graphite into diamond, at least under the high temperature of 15,000 atmospheres and 1500 degrees Celsius. It was built in the 50s and 60s. An instrument device that can achieve the above conditions. Graphite can be converted into diamond by using metal iron, cobalt, nickel or the like as a catalyst at a temperature of 5 to 60,000 atmospheres ((5-6) x 103 MPa) and a temperature of 1000 to 2000 degrees Celsius.

At present, more than a dozen countries (including China) in the world have synthesized diamonds. However, this kind of diamond is mainly used for cutting and drilling bits for geology and petroleum drilling because the particles are very fine. At present, 80% of the world's diamond consumption is mainly used in industry, and its output far exceeds the output of natural diamond.

The initially synthesized diamond particles are black, 0.5 mm in size and weigh approximately 0.1 carats (the diamond used for gemstones is generally at least 0.1 carats minimum). At present, the large-grain diamond developed in China has reached more than 3mm, and the United States, Japan, etc. have made more than 6.1 carats of diamond. We say that diamonds have "flyed" out of graphite, and gem-quality synthetic diamonds will be available in the market in the near future.


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