Diamond micro-powders refer to diamond particles with a particle size finer than 60 micrometers, which come in two types: single-crystal diamond micro-powders and polycrystalline diamond micro-powders. Single-crystal diamond micro-powders are produced by grinding artificial diamond single crystals, followed by crushing and shaping treatments, using special manufacturing techniques. Polycrystalline diamond micro-powders are obtained through a unique directional blasting method from graphite, where the shock wave from high-explosive定向爆破 accelerates metal flechettes, colliding with graphite sheets and converting them into polycrystalline diamond. Diamond micro-powders are known for their high hardness and excellent wear resistance, and are widely used in cutting, grinding, and drilling applications. They are the ideal raw material for polishing and finishing hard alloys, ceramics, gems, optical glass, and other high-hardness materials. Products made from diamond micro-powders are tools and components manufactured using these micro-powders.
Diamond micro-powders, in terms of particle size, belong to micrometer, sub-micrometer, and nanometer powders. Compared to coarse particle powders, they exhibit significantly larger specific surface area and specific surface functional groups, leading to a substantial increase in the interaction forces between particles during the production process. Additionally, as the particle size becomes finer, the inherent defects of the particles decrease, necessitating an increase in strength. Therefore, the production process of diamond micro-powders presents considerable difficulty, as it is not only a process of particle refinement but also involves changes in crystal structure and surface physical and chemical properties. Thus, the production technology of diamond micro-powders is an engineering problem involving multiple disciplines such as mechanics, powder engineering, mechanics, physical chemistry, modern instruments, and testing technology.
Diamond Micro Powder Production Equipment
Diamond micro-powder is obtained by crushing and grading coarse-grained single crystal diamond. The use of ball mills for the crushing process to produce diamond micro-powder is a common method, and the ball milling technique has been utilized in China's diamond micro-powder production for many years, achieving relatively satisfactory results. However, due to its low production efficiency, it has been replaced by jet mills, which use compressed air as the working medium. The compressed air passes through special supersonic nozzles to the crushing chamber, where it is喷射 at high speeds. This air flow carries the material at high velocity, causing intense collisions, friction, and shearing between particles to achieve the desired粉碎. The advantage of jet mills is that they are not limited by mechanical linear speed and can generate very high air velocities, especially supersonic jet mills that can produce flow speeds several times the speed of sound, thus generating enormous kinetic energy. This makes it easier to obtain ultra-fine powders in the micrometer and sub-micrometer sizes. From the perspective of the粉碎 principle, this type of mill is highly promising for the production of diamond micro-powder.
Diamond Powder Granularity Grading Technology
Grain size classification is a crucial process in the production of diamond micro-powder. It directly impacts the efficiency and quality of diamond micro-powder production. A widely used grain size classification method in China for diamond micro-powder involves a combination of natural sedimentation and centrifugal methods in the production of micro-powder. Natural sedimentation is a separation method directly applying Stokes' Law, where particles of the same specific gravity settle at different speeds in water due to their varying sizes. It classifies grain sizes by controlling the settling height and time. Although the equipment is simple, operation is easy, and quality is stable, the production cycle is long and labor efficiency is low. As a result, many manufacturers at home and abroad have developed automated classification equipment. These utilize computer technology and variable frequency control, featuring automatic stirring, automatic material extraction, automatic water circulation, and computer control systems. The fully digital design offers precise control, energy saving, and unparalleled efficiency, reliability, and operability compared to manual sorting. The efficiency of manual sorting can be improved by 10 to 20 times, offering significant advantages such as high automation, fast sorting speed, accurate sorting precision, no contamination, no human interference, strong product quality stability, good reproducibility, reduced labor intensity, lower labor costs, and large one-time feed quantity. It aligns with the future development direction of the micro-powder industry.
Introduction to Applications of Several Types of Diamond Micro Powders
Traditional diamond micro-powders can be divided into two main categories: polycrystalline diamond micro-powders and monocrystalline diamond micro-powders. With the rapid development of nanotechnology, a new type of diamond micro-powder has emerged independently among the original two categories: nanodiamond micro-powders. Their main applications are detailed below.
Polycrystalline Diamond Micro Powder
Polycrystalline diamond is synthesized under the action of transient strong shock waves formed by explosions. Composed of micrometer and submicrometer-sized polycrystals made of nanocrystals, these polycrystals, due to their isotropy and lack of cleavage planes, are highly shock-resistant and possess high bending strength. This combination endows them with the hardness of superhard materials while also exhibiting ultra-high strength and toughness typical of nanomaterials. These dual advantages form their physical properties, making them crucial in applications across high-tech industries and traditional pillar industries.
Application: Primarily used in the fields of optical crystal for chips, ultra-fine processing, large silicon wafer ultra-polishing, and surface modification. The spherical polycrystalline diamond micropowder has a gray-black appearance with a slight metallic luster.
Monocrystalline Diamond Micro-Powder
Monocrystalline diamond micro-powder features a regular, complete hexahedral to octahedral shape, offering high strength, toughness, and excellent thermal stability, as well as strong impact resistance. Its primary applications include the manufacturing of electroplated products, sand and grinding wheels, and is used for polishing, carving stone, automotive glass, furniture, ceramics, hard alloy processing, and magnetic material processing.
Nano diamond powder
Nano diamond powder not only retains the inherent properties of diamond but also exhibits the characteristics of nanomaterials, such as small size effects, large specific surface area effects, and quantum size effects. The diamond synthesized in shock waves has a cubic crystal structure with a lattice constant of (0.3562 ± 0.0003) nm, a crystal density of 3.1 g/cm³, and a specific surface area of 300 m²/g to 390 m²/g. After various chemical treatments, the diamond surface can form a variety of different functional groups, endowing this diamond crystal with a high adsorption capacity.
Applications of Nanodiamonds:
Manufacturing high-grade abrasive pastes and polishing liquids for ultra-fine processing of quartz, optical glass, semiconductors, alloys, and metal surfaces.
B. Catalyst Preparation: Nanoscale diamond and amorphous carbon possess a high specific surface area and contain a variety of surface functional groups, demonstrating strong activity. Utilizing these materials to prepare catalysts can enhance activity data and promote the interaction of organic compounds.
Composite Nanocomposite Structural Materials: By combining nanoscale diamond with nanosilicon powder, nanoceramics, and various nanometals, new types of nanocomposite materials can be created. Due to their unique properties, these materials are suitable for manufacturing semiconductor devices, integrated circuit components, and microcomputer parts.
With the maturation of the diamond tool manufacturing industry and the rapid economic growth in China, the domestic demand for diamond micro-powder is also growing at a high pace. The advancement in tool manufacturing technology also poses higher requirements for the upstream diamond micro-powder industry. Due to the unique characteristics of diamond micro-powder with different crystalline states and particle sizes, a few domestic manufacturers have already been able to produce different types of diamond micro-powder based on their specific applications. For instance: PCD cutting blades, resin-bonded abrasive tools, metal-bonded products, and diamond micro-powder for grinding pastes, etc. This represents a significant step for the upgrade and adjustment of the product structure in China's diamond micro-powder industry, aiming to move towards high-end development and catch up with the world's advanced level.
