Diamond micropowder refers to the diamond particles with the particle size smaller than 60 microns. There are two types of single crystal diamond micropowder and polycrystalline diamond micropowder.
A: single crystal diamond powder is made of artificial diamond single crystal grinding grain, which is processed by grinding and shaping and produced by special process.
B: polycrystalline diamond powder is made from graphite by using a unique directional blasting method. The shock wave of directional blasting of high explosive speed accelerates the flight of the metal flying sheet and impinges the graphite sheet, thus leading to the transformation of graphite into polycrystalline diamond.
Diamond powder has high hardness and good wear resistance and can be widely used in cutting, grinding and drilling.It is an ideal raw material for grinding and polishing hard alloy, ceramics, gemstones, optical glass and other high hardness materials.Diamond powder products are tools and components made of diamond powder.
Diamond powder belongs to micron, submicron and nanometer powder in terms of its particle size.Compared with coarse powder, its specific surface area and specific surface functional groups increase obviously, so the force between particles increases greatly in the production process.In addition, with the refinement of particle size, the defect of the particle itself is reduced, and the strength is bound to increase.It can be seen that the production process of diamond powder is quite difficult. It is not only a process of particle refinement, but also accompanied by changes in crystal structure and surface physical and chemical properties.Therefore, the production process of diamond powder is a multidisciplinary engineering and technical problem involving mechanical, powder engineering, mechanics, physical chemistry, modern instruments and testing technology.
Production equipment of diamond powder
Diamond powder is obtained by crushing and grading coarse - grained single - crystal diamond.It is the most commonly used method to produce diamond micropowder by grinding diamond with ball mill. Ball grinding method has been used for many years in the production of diamond micropowder in China, and has achieved satisfactory results.But because of the disadvantage of low efficiency, has now been replaced by jet mill, jet mill is compressed air as working medium, the compressed air through the special supersonic nozzle high-speed jet into the crushing chamber, the high speed air flow to carry material movement, the intense collision between the material and the material, friction and shear so as to achieve the aim of crushing.The biggest advantage of airflow crusher is not limited by the mechanical linear speed, can produce a high airflow speed, especially the supersonic airflow shredder can produce several times the speed of sound velocity, so it can produce huge kinetic energy, it is easier to obtain micron and sub-micron ultrafine powder.From the grinding principle, this kind of machine has a bright future in the production of diamond powder.
Diamond powder strength grading process
Particle size grading is an important process in the production of diamond powder.It relates to the production efficiency and quality of diamond powder. At present, the most widely used diamond particle size grading method in China is the process combining natural sedimentation method and centrifugal method.
Natural sedimentation method is a direct application of the stokes law separation method, according to the same proportion of particle settling velocity is also different because of different particle size in water, the principle of the grading by controlling its height and subsidence time granularity, although simple equipment, easy operation, stable quality, but a longer production cycle, low labor efficiency.For this reason, many manufacturers at home and abroad developed automated grading equipment, USES the computer technology and frequency conversion control technology, set up automatic stirring, automatic extraction material, automatic water cycle and four systems, computer control the whole digital design, control precision, saving energy save electricity, has manual incomparable high efficiency, high reliability and good handling.Compared with manual separation efficiency can improve 10 ~ 20 times, with a high degree of automation, separation speed, separation accuracy, no impurity pollution, no human factors interference, product quality stability, good reproducibility, small labor intensity of workers, low labor cost of enterprises, a large amount of disposable ten significant advantages.In line with the future development direction of micro powder industry.
Brief introduction of USES of several types of diamond micropowders
Traditional diamond powders can be divided into two categories polycrystalline diamond powders and monocrystalline diamond powders.With the rapid development of nano-technology, a new type of nano-diamond powder has emerged in the original two categories: nano-diamond powder.Their main USES are described below.
1. Polycrystalline diamond micropowder
Polycrystalline diamond is synthesized under the action of transient strong shock wave formed by explosion.It is composed of nanocrystals of micron and submicron level polycrystalline, polycrystalline due to isotropic, no cleavage surface, impact resistance, bending strength is high, so it has both the hardness of superhard materials, but also nanometer materials have extraordinary high strength and high toughness.Its dual advantages constitute its unique physical properties, which have important applications in high-tech industries and traditional pillar industries.
Application: it is mainly used in the fields of chip optical crystal \ ultra-fine processing, large-scale silicon wafer ultra-fine polishing, surface modification, etc. The spherical polycrystalline diamond powder has a grey-black appearance and slightly metallic luster.
2. Single crystal diamond powder
Single crystal diamond powder has regular and complete six-octahedron crystal shape, high strength, toughness, good thermal stability and strong impact resistance.The main applications are: suitable for electroplating products, grinding wheel, grinding wheel manufacturing, for the polishing of high-grade stone, carving, automotive glass, high-grade furniture, ceramics, hard alloy, magnetic materials processing.
3. Nano diamond powder
Nano-diamond powder not only has the inherent characteristics of diamond, but also has small size effect, large specific surface area effect, quantum size effect and so on.The diamond synthesized in detonation wave has cubic structure, lattice constant of (0.3562+0.0003)nm, crystal density of 3.1 g/cm3, specific surface area of 300 m2 / g ~ 390 m2 / g.Various functional groups can be formed on the surface of diamond after different chemical treatments.
Other USES of nano-diamond:
A. preparation of advanced grinding paste and polishing fluid for ultra-fine machining of quartz, optical glass, semiconductors, alloys and metal surfaces.
B. preparation of catalysts: nano-level diamond and amorphous carbon have a large specific surface area, contain a variety of surface functional groups, and have a strong activity. The preparation of catalysts using them can improve the activity data and promote the interaction of organic compounds.
C. Preparation of nano-composite structural materials: by combining nano-diamond with nano-silicon powder, nano-ceramics and various nano-metals, a new type of nano-structural materials can be produced. Due to its unique properties, semiconductor devices, integrated circuit components and microcomputer parts can be manufactured.
With the increasing maturity of the diamond tool manufacturing industry and the rapid growth of China's economy, the market demand for diamond powder in China is also growing rapidly.The progress of tool manufacturing technology also puts forward higher requirements for the upstream diamond powder industry.Due to the characteristics of different crystalline diamond powders with different grain sizes, a few domestic manufacturers have been able to produce different types of diamond powders according to their different USES.For example: cutting tools (PCD), resin bond grinding tools, metal bond products, grinding paste special diamond powder and so on.This is an important step for China's diamond powder industry to upgrade and adjust its product structure, develop towards high-end specialization, and catch up with the world's advanced level.