The use of artificial diamond The principle of artificial diamond The hardness of artificial diamond The classification of artificial diamond tools How to distinguish the use of artificial diamond The brand of natural diamond 1, the manufacture of resin bonded abrasives or their use in grinding, etc.
2. Manufacturing metal bond abrasives, ceramic bond abrasives or abrasives, etc.
3, manufacturing general geological drill, semiconductor and non-metallic material tools, etc.
4. Manufacturing geological drill bits, calibration tools and processing tools for nonmetallic hard and brittle materials in hard strata.
5, resin, ceramic binder or abrasive, etc.
6. Metal bonded abrasives and electroplated products. Drilling tools or grinding tools, etc.
7, cutting, drilling and calibration tools, etc.
Principle of direct method for synthetic diamond
Synthetic diamond is to directly convert carbonaceous materials such as graphite from solid or molten state into diamond by using instantaneous static ultra-high pressure and high temperature technology, dynamic ultra-high pressure and high temperature technology or their mixed technology. The diamond obtained by this method is micron-sized polycrystalline powder.
Melting medium method
Synthetic diamond is produced by the reaction of carbon-containing substances such as graphite and some metals (alloys) under static ultra-high pressure (50 ~ 100 KB, that is, 5 ~ 100 GPA) and high temperature (1 100 ~ 3000℃), and its typical crystallization state is cubic (. Hydrostatic melting medium method is the main method with important application value in industry. The output of artificial abrasive diamond obtained by this method has exceeded that of natural diamond, and the problems to be further solved are to increase the coarse-particle ratio, improve the conversion rate and improve the crystal quality. At present, the formation of high-quality large-particle single crystal diamond is studied by hydrostatic melting medium method in the laboratory. A large single crystal weighing about 65438 0 carats was obtained by seed crystal epitaxy. After slightly improving the general testing technology, crystals of about 2 ~ 4 mm were obtained. Large-particle polycrystalline diamond was grown and sintered by this method, and it has been applied in industry to some extent. The key problem is to further improve the comprehensive properties of this polycrystalline diamond such as compressive strength, impact strength, wear resistance and heat resistance.
Epitaxial method
Synthetic diamond is formed by epitaxial growth on diamond seed crystal or some substrate materials by using carbon sources separated from pyrolysis and electrolysis of some carbon-containing substances.
Uzi reaction method
Let carbon tetrachloride and sodium react at 700℃ to produce diamond. But at the same time, it will produce a lot of graphite.
Formation mechanism
There are mainly the following theories: solvent theory holds that the metal (alloy) used plays the role of carbon solvent; Catalytic theory is considered as a catalyst; The solid phase transition theory emphasizes that graphite crystals can form diamond crystals through simple deformation without bond breaking and disintegration. However, the models proposed by these three typical theories often contradict some major experimental phenomena and laws. Therefore, the theories of solvent-catalyst, catalyst-solvent and melting agent-catalyst (melting medium for short) have emerged to further explore the role of the metals (alloys) used. Generally speaking, the formation mechanism of synthetic diamond is still a complex problem and is still under discussion.
Correlation thermodynamics
In the third edition of Inorganic Chemistry (fourth edition, page 236, line 9, from the left 16), it is clearly mentioned that:
According to the investigation, the transformation of graphite into diamond under high pressure is exothermic! Low temperature is beneficial to conversion.
3. The hardness of synthetic diamond is 10, the new Mohs hardness is 15, the microhardness is 10000kg/mm2, and the microhardness is 1000 times higher than that of time, and 150 times higher than that of corundum. The hardness of diamond is directional. The hardness of octahedral crystal face is greater than that of rhombohedral crystal face, and the hardness of rhombohedral crystal face is greater than that of hexahedral crystal face.
According to Mohshardnessscale) * * * it is classified as 10, and diamond is the highest grade of 10; For example, the hardness of knives is about 5.5, copper coins are about 3.5 to 4, nails are about 2 to 3, and the hardness of glass is 6.
4 Classification of synthetic diamond tools. According to the cutting material:
1. Building structure cutting: divided into concrete cutting, asphalt cutting and brick cutting. 2. Stone cutting: divided into cutting granite, marble, sandstone and slate. 3. Cutting decorative materials and tiles: cutting tiles and glass.
Second, according to the manufacturing process:
1, welding: laser welding products, high frequency welding products. 2. Sintering: cold pressing and hot pressing.
According to the purpose of the machine: marble machine, angle grinder; Used for road saws and road cutting machines; Table saw; Saw stones; Hand saw; Used for sawing walls; High power plane saw.
The application of synthetic diamond is 1. Turn slowly when you open your eyes. When the hole depth reaches 10- 15mm, it gradually turns to full load operation. During drilling, the drill pipe should advance in a straight line according to the hole position design and be located in the center of the hole.
2. Propeller shaft thrust should be tested reasonably when drilling. If the axial thrust is too small, the machine will rebound, the vibration will increase and the drilling efficiency will decrease; The thrust of the shaft is too large, and the drill bit presses on the fundus, which makes the machine overload, easy to wear parts prematurely and slow down the drilling speed.
3. When sticking, the axial thrust should be reduced and gradually become normal. If it is ineffective, stop the machine immediately. Turn the drill pipe slowly with a wrench, and then turn on the air pressure to turn the drill pipe slowly. It is forbidden to deal with it by tapping the drill pipe.
4, often observe the powder discharge. When the powder is discharged normally, the mud slowly flows out along the orifice; On the contrary, blow the hole hard. If it still doesn't work, check the drill tail state of the water hole, then check the water needle and replace the damaged parts.
5. Observe the fuel injection quantity and adjust the fuel injection quantity. When working without oil, it is easy to make parts wear prematurely. When there is too much lubricating oil, the working face will be polluted.
6. Pay attention to the sound of the machine during operation, observe its operation, and handle it in time when problems are found.
7. Pay attention to the working state of the drilling rig, and replace it in time if it is abnormal.
8. Pay attention to the air supply of the air leg when operating the upward rock drill to prevent the rock drill from swinging up and down and causing accidents. The air leg support point should be reliable. Don't hold the machine too tightly, and don't ride on the air leg to prevent personal injury and machine damage.
9, pay attention to the rock, avoid perforation along the bedding, joints and cracks, it is forbidden to play residual eye, and observe the danger of roof caving and spalling at any time.
10 to effectively use the hole function. In the process of drilling, there is an important link, which is completed by reducing the impact pressure and fixing the propulsion pressure. The propulsion pressure should be as low as possible to facilitate drilling on the rock surface with very large dip angle and avoid bending of the drill pipe.
6 The difference between natural diamond and synthetic diamond (1) Different solvents, natural diamond grows in silicate solution, in which the solubility of carbon is very low, while synthetic diamond grows in metal melt, in which the solubility of carbon is much higher than that of silicate. As shown in the equation: α=ε( 1-X2s)-(lnXs+c), "The higher the solubility, the smaller the α value", so the solid-liquid interface is rough, so for synthetic diamonds, the facet growth is less than expected.
α-Jackson factor in the above formula
ε—— Orientation factor
Xs- density of solute in solution
The c constant is 1-2.5.
(2) The growth temperature of natural diamond (estimated as1000-1300 C) is lower than that of synthetic diamond (above1400 C), and the lower the growth temperature, the smaller the α value. Therefore, for synthetic diamonds, a rough interface can be expected.
(3) The supersaturation of synthetic diamond is greater than that of natural diamond, so it can be predicted that the surface of synthetic diamond is rough, but the observed synthetic diamond presents a smooth interface.
The difference in morphology between natural diamond and synthetic diamond, and the difference in crystal morphology predicted by theory and observed in practice are all caused by the different sizes of growth elements.
The morphological differences between natural diamonds and synthetic diamonds can be summarized as follows:
7 How to Distinguish between Artificial Diamonds and Natural Diamonds Bian Xiao summed up six tips to distinguish between natural diamonds and artificial diamonds (Su Diamond and Mo Xing Stone), hoping to help everyone.
The first measure: hardness distinction. The Mohs hardness of natural diamonds is 10, that of Soviet diamonds is 8.5, and that of Mohs stone is 9.25.
The second measure: chemical composition. The chemical composition of natural diamonds is carbon, the chemical composition of Soviet diamonds is carbon dioxide, and the chemical composition of Moxingshi is silicon carbide.
The third measure: thermal probe reaction. Natural diamonds make a sound, Soviet diamonds don't make a sound, and Moxingshi makes a sound, which is easy to confuse true and false.
The fourth measure: conductivity. Natural diamonds and Soviet diamonds do not conduct electricity, while Moxingshi occasionally reacts.
The fifth measure: optical characteristics. Natural diamonds have a single refractive index, Soviet diamonds have a single refractive index, and Moxingshi has a double refractive index.
The sixth measure: 10 times magnifying glass observation. Natural diamonds are not only polished smoothly, but also have sharp edges; Soviet diamonds are poorly polished and the edges are often dull; Mo Xingshi is not only not sharp, but also has weight.
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