Pigment powder ultrafine crushing equipment

Particle size is one of the important indicators of pigments. Generally, pigment particles are required to have stable physical form, uniform particle size, and good dispersion, without agglomeration or precipitation.

​Iron oxide pigment is a pigment with good dispersion, excellent light resistance and weather resistance. It mainly refers to the four types of iron oxide red, iron yellow, iron black and iron brown coloring pigments based on iron oxides. Among them, iron oxide red is the main one.
Precipitated (wet) iron oxide pigments are very fine, but during the filtration and drying processes, due to factors such as van der Waals forces, hydrogen bonds, charges, etc., the micro-aggregates aggregate into large aggregates and cannot be directly used in high-end coatings. For coloring, ultrafine crushing is necessary. Jet milling uses the energy of high-speed airflow or superheated steam to ultrafinely grind solid materials. It is one of the most commonly used ultrafine grinding methods.

At present, in the pigment production industry, the application range of airflow crushing is becoming more and more extensive, which mainly comes from the following two factors:

First, the safety of mechanical crushing is poor, because if hard metal falls on the high-speed rotating mechanical teeth, it is easy to produce an open flame, which is very dangerous in a dusty pigment production workshop, but airflow crushing does not have this question;

Second, airflow crushing belongs to ultra-fine crushing. In the production of some special pigments, the fineness of the pigments is required to be higher.

1. Iron oxide pigment

During the filtration and drying process of iron oxide pigments, due to van der Waals forces, hydrogen bonds, charges and other factors, micro-aggregates aggregate into large aggregates, which cannot be deaggregated through general mechanical action. Using a fluidized bed or disc-type jet mill to process iron oxide pigments, the Hagermann fineness can reach: iron oxide red 5.5 to 7.0, the darker the color, the better the fineness; iron oxide yellow 7.5; iron oxide black 7.0 .

After ultra-fine crushing, the iron oxide pigment is depolymerized from large aggregates into small aggregates. When producing paint, it only takes a short time of high-speed stirring process to achieve the required fineness, thereby saving costs and the small size of the pigment. The aggregates are difficult to coarsen into large aggregates, thus ensuring the quality of the paint.

2. Black high temperature resistant manganese ferrite pigment

The fine particles of manganese ferrite pigment that have been surface-coated, surface-modified, dried, and pulverized are flocculated again into coarse particles of varying degrees, and cannot effectively exert the pigment properties of manganese ferrite.

After deep processing and grinding using a fluidized bed or disc-type jet mill, the Hagermann fineness of the manganese ferrite pigment is approximately 7 to 7.5. It has good dispersion and can give full play to its optical and pigment properties.

3. Brown ceramic pigment

The brown ceramic pigment is ultrafinely pulverized using a flat jet mill. When the air pressure is 7.5×105Pa and the feeding speed is 100kg/h, the product d50 is 4.55μm and the maximum particle size is 9.64μm.

At present, common ultra-fine grinding equipment includes jet mill, mechanical impact ultra-fine grinder, stirring ball mill, sand mill, vibration mill, colloid mill, high-pressure jet grinder, planetary ball mill, pressure roller mill, and ring roller mill. etc.

by ALPA

Production technology of high-quality calcium hydroxide

Calcium hydroxide, commonly known as hydrated lime, has a chemical formula of Ca(OH)2. Generally in powder form, it will lose water and become calcium oxide (quicklime) at 580°C under normal pressure. Calcium hydroxide is slightly soluble in water, and its solubility decreases as the temperature increases. The colorless and transparent solution obtained by dissolving in water is commonly known as clear lime water. A milky suspension composed of calcium hydroxide and water is called milk of lime.

Dry calcium hydroxide production process: qualified quicklime is crushed by a jaw crusher. It is sent into the lime silo via bucket elevator and bin-type vibrating conveyor. The lime in the silo is quantitatively added to the hydrated lime pre-digester through star-shaped feeding, and is initially digested under strong stirring by the stirring rod, and then enters the digester to complete the digestion process. The digested lime is input into the slaked lime silo by the slaked lime elevator and the inlet screw conveyor, and then the qualified refined slaked lime is obtained by the ash adding spiral air separator. The refined slaked lime is unloaded into the finished slaked lime silo and then packaged according to user needs. During the dry digestion reaction, the organizational structure changes, causing Ca(OH)2 to form a loose powder, with the volume increasing to 1.5 to 2.0 times the original volume. The product and raw materials have better fluidity, so the dry digestion process can be used in water. The high conversion rate reaction of quicklime can be achieved under the condition of low ash ratio (mass ratio of water to lime).

Calcium hydroxide applications

(1) Flame retardant materials

Calcium hydroxide powder is widely used as a filler in polymer materials. Adding calcium hydroxide to polymer materials can improve the thermal stability and flame retardant properties of composite materials; calcium hydroxide is alkaline and can react with hydrogen chloride (HCl) released when PVC is thermally decomposed, eliminating the degradation of PVC by hydrogen chloride. The autocatalytic effect of the process has a certain thermal stabilization effect.

(2) Degradable polymer materials

Calcium hydroxide can be used as an auxiliary agent for environmental absorption of plastics. It has dechlorination, cracking and alkaline degradation effects on the decomposition of plastics.

(3) Wastewater treatment

The role of calcium hydroxide in wastewater can be basically summarized into four aspects: neutralizing free acids in wastewater, neutralizing acid salts in wastewater, reacting with metal ions to produce water-insoluble precipitates, and adjusting the pH of wastewater. value.

(4) Desulfurizer

In the calcium hydroxide-gypsum wet desulfurization process, the flue gas comes into contact with the Ca(OH)2 absorption liquid over a large area, so that the SO2 in the flue gas dissolves in water and reacts with the calcium hydroxide slurry to form calcium sulfite, which is then blown in Under the condition of a large amount of air, calcium sulfite is oxidized to generate CaS (V2H2O), thereby achieving the purpose of reducing SO2 in the flue gas. In the calcium desulfurization process, calcium ions are actually involved in the sulfur fixation. Calcium carbonate, calcium oxide, and calcium hydroxide can all be used as desulfurization agents.

(5) Medical and health care

Calcium hydroxide is used for disinfection in a variety of places, such as scientific research, laboratories, medicine, factories, etc. It has a long history of use in clinical medicine.

(6) Food processing

Adding a certain amount of food-grade calcium hydroxide to milk powder can not only adjust the pH value of the milk powder and promote the rapid dissolution of the milk powder in water, but also supplement calcium.

by ALPA

4 key points for choosing powder surface modifiers

There are many types of powder surface modifiers on the market with various functions and of course different prices. How to choose the most suitable modifier?

Practice has shown that when selecting surface modifier varieties, the main considerations include: the properties of the powder raw materials, the use or application field of the product, as well as technology, price and environmental protection.

1. Properties of powder raw materials

The properties of powder raw materials are mainly acid, alkalinity, surface structure and functional groups, adsorption and chemical reaction characteristics, etc. Surface modifiers that can chemically react or chemically adsorb with the surface of powder particles should be selected as much as possible, because physical adsorption on It is easy to desorb under strong stirring or extrusion during subsequent applications.

For example, the surfaces of acidic silicate minerals such as quartz, feldspar, mica, and kaolin can bond with silane coupling agents to form stronger chemical adsorption; however, silane coupling agents generally cannot bond with alkaline carbonates. Minerals undergo chemical reactions or chemical adsorption, while titanate and aluminate coupling agents can chemically adsorb with carbonate alkaline minerals under certain conditions and to a certain extent.

2. Product use

The purpose of the product is the most important consideration in selecting a surface modifier. Different application fields have different technical requirements for powder application performance, such as surface wettability, dispersion, pH value, hiding power, weather resistance, gloss, antibacterial properties, UV protection, etc. This means that surface modification should be selected according to the purpose. One of the reasons for the variety of sexual agents.

For example, inorganic powders (fillers or pigments) used in various plastics, rubbers, adhesives, oily or solvent-based coatings require good surface lipophilicity, that is, good affinity or compatibility with the organic polymer base material. , which requires the selection of surface modifiers that can make the surface of inorganic powders hydrophobic and oleophilic; for inorganic pigments used in ceramic blanks, they are not only required to have good dispersion in the dry state, but also require affinity with the inorganic blanks. Good compatibility and can be evenly dispersed in the blank; for surface modifiers of inorganic powders (fillers or pigments) used in water-based paints or coatings, the dispersion and sedimentation stability of the modified powder in the water phase are required. Good compatibility.

For inorganic surface modifiers, they are mainly selected based on the functional requirements of powder materials in the application field. For example, to make titanium dioxide have good weather resistance and chemical stability, SiO2 and Al2O3 must be used for surface coating (film) , in order to make the muscovite pigment have a good pearlescent effect, it is necessary to use TiO2 for surface coating (film).

At the same time, different application systems have different components. When selecting a surface modifier, you must also consider the compatibility and compatibility with the application system components to avoid the functional failure of other components in the system due to the surface modifier.

3. Modification process

The modification process is also one of the important considerations in selecting surface modifiers, such as temperature, pressure and environmental factors. All organic surface modifiers will decompose at a certain temperature. For example, the boiling point of silane coupling agents varies between 100 and 310°C depending on the type. Therefore, it is best to select a surface modifier with a decomposition temperature or boiling point that is higher than the processing temperature of the application.

The current surface modification process mainly adopts dry method and wet method. There is no need to consider the water solubility of the dry process, but the water solubility of the surface modifier must be considered for the wet process, because only if it is soluble in water can it fully contact and react with the powder particles in a wet environment.

Therefore, for surface modifiers that are not directly water-soluble and must be used in a wet environment, they must be saponified, ammonized or emulsified in advance so that they can be dissolved and dispersed in aqueous solutions.

4. Price and environmental factors

Finally, when selecting surface modifiers, price and environmental factors must also be considered. On the premise of meeting application performance requirements or optimizing application performance, try to choose cheaper surface modifiers to reduce the cost of surface modification. At the same time, attention should be paid to selecting surface modifiers that do not pollute the environment.

by ALPA

5 Major Types of Surface Modification Methods For Carbon Fiber

Carbon fiber (CF), as a new type of composite reinforced material, has been widely used in various industries and has attracted much attention. However, the surface of CF is relatively smooth and has no active groups. The fiber surface is chemically inert, so the fiber has poor hydrophilicity and poor adhesion to the matrix, and is easy to fall off. Therefore, it is necessary to improve the interface between CF and matrix reinforcement.

So far, the common surface modification methods of carbon fiber mainly include coating modification, surface graft modification, oxidation modification, plasma modification and joint modification, among which oxidation treatment and surface grafting treatment are more popular. Methods. These modification methods improve the fiber's wettability, chemical bonding, and mechanical interlocking with the matrix to form a transition layer, promote uniform stress transmission, and reduce stress concentration.

The surface of carbon fiber is smooth, has few active groups, and does not adhere firmly to the matrix. In normal applications, it is necessary to improve the adhesion rate. One method is to roughen the smooth carbon fiber surface through physical effects, creating grooves or small holes to increase the contact area with the matrix material. Polymers or nanoparticles can be filled in the fiber. In the grooves on the surface, the fiber and polymer can be mechanically locked together through the rough shape of the fiber surface after curing, resulting in an obvious mechanical interlocking effect between the fiber and the matrix, which is beneficial to improving the interface strength.

1. Coating modification

Carbon fiber coating modification can cover a variety of materials, such as metal salts, metal alloys, carbon nanomaterials, etc., through spraying, physical or chemical deposition, polymers, sol-gel methods and coating processes. After coating, the surface of CFs has different properties.

2. Surface grafting

Carbon fiber surface grafting is a bottom-up, extensively studied CFｓs modification method. Compared with surface oxidation and coating methods, surface grafting can give the grafted polymer better adhesion to the CF surface. Through radiation or chemical reaction, the grafting reaction is triggered on the surface of CFs, and polymers with functional groups are introduced on the surface of CFs, which improves the interface strength of the composite material.

3. Oxidation treatment

Carbon fiber oxidation treatment is a simple modification method that not only increases the pore distribution and pore size on the CF surface, but also introduces different concentrations of oxygen-containing functional groups, which has a significant impact on the material interface adhesion and immobilization efficiency (IE). Influence.

4. Plasma treatment

Plasma treatment is a prominent and successful treatment method for a variety of materials, including carbon materials. High enough energy plasma is used to hit the CF surface, causing the chemical bonds to break and reorganize on the surface, thereby improving the surface structure and performance of the carbon fiber to achieve good adhesion between CF and the matrix material. Plasma treatment has the advantages of simple operation, high efficiency, green and environmental protection.

5. Joint modification

The above-mentioned single modification methods have more or less defects. For example, coating-modified CF has low adhesion between the coating and CF, requires the use of solvents during the manufacturing process, has low preparation efficiency, and is difficult to produce continuously; investment in plasma treatment equipment is expensive; in wet chemical oxidation and electrolysis Some liquid contamination is inevitable during chemical treatment, and the modification conditions should be precisely controlled in gas-phase oxidation to prevent excessive oxidation from destroying the internal structure of CF, and the use of nanomaterials or grafted polymers to modify the surface of carbon fibers is complex.

Therefore, when modifying the surface of carbon fiber, joint modification using multiple modification methods can avoid the shortcomings of using them alone and combine the advantages with each other. This is the main direction of carbon fiber surface modification treatment in the future.

by ALPA

What are the differences between white talc, black talc and hydrotalcite?

At present, the products related to "talc" on the market mainly include white talc, black talc, hydrotalcite, etc. Although they are all called talc, their ingredients, uses, prices, etc. are very different.

1. White talc

Talc is a hydrous magnesium silicate mineral, most commonly found in white, which is white talc. Look at China for the world's talc. The white talc supplied in the international market mainly comes from China. The advantages of Chinese talc are not only reflected in reserves and output, but more importantly, in the extraordinary quality of white talc, especially high-purity white talc.

White talc has high electrical insulation, heat insulation, high melting point and strong adsorption of oil. It is widely used in papermaking, chemical industry, medicine, rubber, ceramics, paint, cosmetics and other industries.

2. Black talc

Black talc is a 2:1 type (T-O-T) magnesium-rich silicate clay mineral. It is soft, has a flaky structure and a slippery feel. It does not contain water between the layers, is odorless and tasteless, has stable chemical properties, small particles, and a large specific surface area. Black talc is gray to black because it contains organic carbon. Its chemical composition, mineral composition and mineral deposit origin are similar to white talc. The main ore components are usually composed of talc, quartz, organic carbon, etc.

At present, most black talc is processed into white talc through whitening technology and then used in the traditional ceramic industry and basic fillers. The research directions are mainly high-efficiency whitening and ultra-fine processing technology.

3. Hydrotalcite

Hydrotalcite is divided into natural hydrotalcite and synthetic hydrotalcite. Since natural hydrotalcite is difficult to mine and its purity is not high, the market supply of hydrotalcite is dominated by synthetic hydrotalcite.

Synthetic hydrotalcites (LDHs) are a class of anionic layered compounds with broad application prospects, mainly composed of hydrotalcite (HT), hydrotalcite-like (HTLC for short) and their intercalation chemical products pillared hydrotalcite (Pillared LDH) constitute.

Synthetic hydrotalcite is a non-toxic dihydroxy compound with a special layered structure. It has physical and chemical properties such as charging properties, anion exchangeability, adsorption properties, catalytic properties, etc. It has a wide range of applications in the field of polymer resin materials. Mainly used as heat stabilizer for polyvinyl chloride (PVC) production and halogen absorber for polyolefin resin production.

The main finished product categories of synthetic hydrotalcite include general synthetic hydrotalcite, highly transparent synthetic hydrotalcite and flame-retardant synthetic hydrotalcite.

by ALPA

6 Types of Modification Methods for Coal Gangue

In order to solve the problem of coal gangue accumulation, find ways to extract the additional utilization value of coal gangue, and "turn waste into treasure" to the maximum extent, many researchers have modified coal gangue to increase its activity, making it a material with various high Value-added environmentally friendly materials solve the problem of coal gangue pollution from the root cause and achieve the purpose of waste resource recycling and environmental protection.

At present, the modification methods of coal gangue mainly include traditional acid or alkali treatment, mechanochemical method, surface organic modification method, calcination modification method, hydrothermal modification method and composite modification method.

1. Mechanical modification method

Mechanical grinding is a common physical method for modifying materials. Grinding coal gangue will increase its specific surface area and thereby improve the adsorption activity of solid particles. It will also change the crystal structure and crystal particle size of coal gangue, and the raw materials are in When the particles are refined, micro-homogenization is obtained, and the reactivity will be greatly improved.

2. Acid or alkali modification method

Acid modification is to dissolve acid-soluble metal ions such as Al, Fe, and Ca in the coal gangue through acid leaching, improve the pore size distribution, number of holes, and specific surface area inside the coal gangue, and change the crystal structure and surface properties of the coal gangue; in addition In addition, acid modification can also increase the active sites of coal gangue to make its adsorption performance stronger.

3. Surface organic modification method

Surface modification of coal gangue refers to grafting a layer of organic modifiers on the surface of coal gangue through chemical or physical methods to change the surface charge, hydrophilicity, dispersion and other properties of coal gangue, and perform modification and activation to give coal gangue its unique properties. Adsorption characteristics, enhance the repair and activation ability of coal gangue, and broaden the application scope of coal gangue.

4. Calcination modification method

Calcination modification refers to the process of transforming low surface activity kaolinite in coal gangue into highly active metakaolinite through high-temperature roasting. The porosity and crystal structure of coal gangue can be changed through calcination. The degree of calcination modification of coal gangue is mainly affected by the calcination temperature and calcination time. The difference between these two main factors will cause different phases of kaolin in coal gangue. Changes will lead to performance differences in the calcined modified coal gangue.

5. Hydrothermal modification method

Hydrothermal modified coal gangue refers to a certain degree of physical or chemical modification of coal gangue under a certain temperature and pressure to obtain a more complete material. In particular, the supercritical hydrothermal method has many unique properties. It can not only improve the reactivity of coal gangue, but also change the internal structure of coal gangue to a certain extent. When used to prepare zeolite molecular sieves, it can obtain high cleanliness and complete crystal form. New Materials.

6. Compound modification method

Composite modification is generally based on thermal modification, using mechanical modification or chemical modification to stimulate the activity of coal gangue. Composite modification can integrate the advantages of a single modification method to a certain extent, make up for its inherent defects, and produce synergistic effects. The comprehensive performance of composite modified coal gangue is obviously better than that of coal gangue modified by a single process, and it can also meet various needs. Industrial needs. Moreover, the composite process can greatly improve the activation efficiency of coal gangue, obtain coal gangue composite materials with better performance, and promote the efficient utilization of mineral resources in coal gangue, so it is widely used.

by ALPA

Stirring mill, jet mill, sand mill, how to choose?

Ultra-fine grinding equipment uses mechanical force to grind materials to the micron level and classify them. Due to its good processing performance, it is widely used in high-end coatings, food, medicine, chemicals, building materials, medicinal materials, mining and other industries. With the rapid development of the global economy, my country's powder industry is booming, and powder equipment, especially ultra-fine crushing equipment, plays a key role in this.

Mixing mill

A stirrer grinder (stirrer mill) refers to a type of ultra-fine grinding equipment consisting of a stationary cylinder filled with grinding media and a rotating agitator. The cylinder of the mixing grinder is generally made with a cooling jacket. When grinding materials, cooling water or other cooling media can be passed into the cooling jacket to control the temperature rise during grinding. The inner wall of the grinding barrel can be lined with different materials according to different grinding requirements, or a fixed short shaft (rod) can be installed and made into different shapes to enhance the grinding effect. The agitator is the most important part of the mixing mill, and there are types such as shaft-rod type, disc type, perforated disc type, cylindrical type, ring type, spiral type, etc. Among them, spiral and rod stirrer mills are mainly vertical, while disc stirrer mills come in two types: vertical and horizontal.

Jet mill

The particle size of the finished product of airflow mill is in the range of 1~30μm, and the particle size of the processing feed is strictly controlled below 1mm under normal circumstances. It can be widely used in materials such as rare earths, various hard marbles, kaolin, talc and other medium-hard non-metallic minerals. of ultra-fine processing.

Flat airflow pulverizer: Flat airflow pulverizer is also called horizontal disc airflow mill. When the equipment is working, high-pressure airflow is ejected from the nozzle at ultra-high speed, and the material is accelerated by the Manchuri nozzle and then sent to the crushing chamber for high-speed circular motion, where it is crushed through impact, collision, and friction. Under the action of centrifugal force, coarse particles are thrown towards the wall of the crushing chamber for circular crushing, and fine particles overflow with the airflow and are collected. The advantages of this equipment are simple structure and easy operation.

Fluidized bed air jet mill: commonly used for ultra-fine crushing, breaking up and shaping of materials in ceramics, chemical raw materials, refractory materials, battery materials, pharmaceuticals and other industries. When the equipment is working, high-pressure air is sprayed into the crushing chamber at high speed through several nozzles. The fed materials are accelerated by the high-pressure airflow in the crushing chamber. They are crushed through collision and friction at the intersection of each nozzle, and then enter the classification chamber with the airflow to complete classification. The coarse material settles back to the crushing area to continue crushing, and the overflow of qualified products is collected by the cyclone separator.

Counter-jet airflow pulverizer: Counter-jet airflow pulverizer is also called collision airflow mill and reverse jet mill. When the equipment is working, two accelerated materials and high-speed airflow meet at a certain point on the horizontal straight line and collide to complete the crushing. The solid particles that enter the classification chamber with the airflow are under the action of the classification rotor, and the coarse particles remain on the outer edge and are crushed. Return to the crushing chamber for re-crushing, and the fine particles that meet the particle size requirements continue to rise, and after flowing out, they become products through gas-solid separation.

Sand mill

A sand mill is another form of stirrer or bead mill, so named because it originally used natural sand as the grinding media. Sand mills mainly rely on the high-speed rotation between grinding media and materials to perform grinding work. They can be divided into open and closed types, and each can be divided into vertical and horizontal types.
Generally speaking, the difference between a horizontal sand mill and a vertical sand mill is that the horizontal sand mill has a larger sand capacity, higher grinding efficiency, and is relatively easy to disassemble and clean. In terms of application, sand mills are widely used in coatings, dyes, paints, inks, medical drugs, nanofillers, magnetic powder, ferrite, photosensitive film, pesticides, papermaking, cosmetics and other fields for efficient grinding of nanopowders.

No matter how the powder industry develops, ultrafine impact grinding has always been one of the main means to obtain ultra-fine powder.

by ALPA

Using powder metallurgy to prepare high thermal conductivity copper and diamond composite materials

In fields such as electronic packaging and aerospace, metal-based heat dissipation devices have been developed for decades. As the power density of devices continues to increase, higher requirements are placed on the thermal conductivity of electronic packaging materials. By compounding diamond with high thermal conductivity (2 200 W/(m·K)) and low thermal expansion coefficient ((8.6±1)×10-7/K) with metals such as copper and aluminum, high thermal conductivity can be integrated , a "metal + diamond" composite material with an adjustable thermal expansion coefficient and high mechanical properties and processing properties, thereby meeting the stringent requirements of different electronic packaging, and is regarded as the fourth generation of electronic packaging materials.

Among various metal materials, compared with other metals such as aluminum, copper has a higher thermal conductivity (385~400 W/ (m·K)) and a relatively low thermal expansion coefficient (17×10-6/K). By simply adding a smaller amount of diamond reinforcement, the thermal expansion coefficient can match that of semiconductors and it is easy to obtain higher thermal conductivity. It can not only meet the stringent requirements of today's electronic packaging, but also has good heat resistance, corrosion resistance and chemical stability. It can meet the requirements of extreme service conditions such as high temperature and corrosive environment to a greater extent, such as nuclear power projects, acid-base and dry, wet, cold and hot atmospheric environments.

How to prepare?

There are currently many methods for preparing diamond/copper composite materials, such as powder metallurgy, chemical deposition, mechanical alloying, spray deposition, casting, etc. Among them, powder metallurgy has become one of the most commonly used preparation methods because of its simple preparation process and excellent performance of the prepared composite materials. In this way, Cu powder and diamond particles can be mixed evenly through ball milling, etc., and then sintering and molding can be used to prepare a composite material with a uniform microstructure. As the most critical step in powder metallurgy, sintering molding is related to the final quality of the finished product. Commonly used sintering processes currently used in the preparation of Cu/diamond composite materials include: hot press sintering, high temperature and high pressure sintering, and discharge plasma sintering.

Hot press sintering
The hot pressing sintering method is a diffusion welding forming method. As a traditional method for preparing composite materials, the main process is to mix the reinforcement and copper powder evenly, put them into a mold of a specific shape, and place them in the atmosphere, vacuum or protected environment. In the atmosphere, pressure is applied in the uniaxial direction while heating, so that forming and sintering proceed simultaneously. Since the powder is sintered under pressure, the powder has good fluidity and the material has a high density, which can discharge the residual gas in the powder, thereby forming a stable and strong interface between diamond and copper. , improve the bonding strength and thermophysical properties of composite materials

by ALPA

The 8 most popular ceramic powders currently

Advanced ceramics have excellent mechanical, acoustic, optical, thermal, electrical, biological and other properties, and can be seen everywhere in high-end technology fields such as aerospace, electronic information, biomedicine, and high-end equipment manufacturing. There are many types of ceramics, and ceramics with different compositions have their own characteristics, such as the oxidation resistance of alumina ceramics, the high strength and electrical corrosion resistance of silicon nitride ceramics, the high toughness and biocompatibility of zirconia ceramics, etc.

High purity alumina

High-purity alumina (4N and above) has the advantages of high purity, high hardness, high strength, high temperature resistance, wear resistance, good insulation, stable chemical properties, moderate high temperature shrinkage performance, etc., and has good sintering properties as well as ordinary alumina With unparalleled optical, electrical, magnetic, thermal and mechanical properties, powder is one of the high-end materials with the highest added value and the most widely used in modern chemicals. As a representative category of high-performance alumina products, high-purity alumina is widely used in high-tech and cutting-edge industries such as fluorescent materials, transparent ceramics, electronic devices, new energy, catalytic materials, and aerospace materials.

Boehmite

Boehmite contains a crystal water with the chemical formula γ-Al2O3·H2O or γ-AlOOH, which is a type of aluminum oxide hydrate.

Aluminum Nitride

Based on the current development of electronic chips whose comprehensive performance is getting higher and higher and whose overall size is getting smaller and smaller, the heat flow density displayed during the working process of electronic chips has also increased significantly. Therefore, selecting appropriate packaging materials and processes and improving device heat dissipation capabilities have become technical bottlenecks in the development of power devices. Ceramic materials themselves have properties such as high thermal conductivity, good heat resistance, high insulation, high strength, and thermal matching with chip materials, making them very suitable as power device packaging substrates.

Silicon nitride

Silicon nitride is currently mainly used as a ceramic material, and silicon nitride ceramics are an indispensable key material in industrial technology, especially cutting-edge technology.

Spherical alumina

Among many thermally conductive powder materials, spherical alumina relies on its high thermal conductivity, high filling coefficient, good fluidity, mature technology, rich specifications and relatively reasonable The price has become the most mainstream thermal conductive powder category in the high-end thermal conductivity field in the thermal conductive powder industry.

Barium titanate

Barium titanate (BaTiO3) is an ABO3 type perovskite structure. Since the excellent dielectric properties of barium titanate ceramics were discovered in the first half of the 20th century, it has been used as a dielectric material for capacitors. It is currently the most commonly used dielectric material. One of the most common electronic ceramic powders is also the parent material for manufacturing electronic components, so it is called the "backbone of the electronic ceramic industry."

Nanocomposite zirconia

Nanocomposite zirconia is a type of zirconia that can maintain the tetragonal or cubic phase at room temperature after adding stabilizers. The stabilizers are mainly rare earth oxides (Y2O3, CeO2, etc.) and alkaline earth metal oxides (CaO, MgO, etc.) ).

High purity silicon carbide

Silicon carbide materials can be mainly divided into two categories: ceramic and single crystal. As a ceramic material, its purity requirements are not very strict in general application fields. However, in some special environments, such as photolithography machines and other semiconductor equipment, when used as precision components, its purity needs to be strictly controlled to avoid affecting the quality of silicon wafers Purity.

by ALPA

Applications of diamonds with different crystal structures

A natural diamond requires carbon atoms to be born at a depth of 150-200 kilometers underground and undergo hundreds of millions of years of high temperature and pressure. To appear in front of people, it must continue to be brought to the surface of the earth by geological movements over time. , it can be said to be very scarce. So by simulating the crystallization conditions and growth environment of natural diamonds, people used scientific methods to synthesize artificial diamonds that also have excellent properties such as super hardness, wear resistance, and corrosion resistance, shortening the synthesis time of diamonds to more than ten days or even a few days. Synthetic diamonds are divided into single crystals and polycrystals. They each have unique crystal structures and characteristics, making them different in applications.

1. Single crystal diamond

Single crystal diamond is a crystal bound by covalent bonds with saturation and directionality. It is the most common type of diamond crystal. The particles inside the crystal are regularly and synchronically arranged in three-dimensional space, with few defects. , without grain boundary restrictions, so it has outstanding advantages in thermal conductivity, hardness, light transmittance and electrical properties.

Thermal conduction applications

The thermal conductivity of diamond basically comes from the propagation of carbon atom vibrations (that is, phonons). Impurity elements, dislocations, cracks and other crystal defects in diamond, residual metal catalysts, lattice orientation and other factors will collide with phonons. It scatters, thereby limiting the mean free path of phonons and reducing thermal conductivity. Single crystal diamond has a highly ordered lattice structure, which makes it almost unaffected by grain boundary scattering. Therefore, it has a thermal conductivity of up to 2200 W/(m·K).

Optical applications

High-quality single crystal diamond prepared by the CVD method can be completely colorless and transparent, with almost no impurities. Its highly ordered crystal structure also prevents light from being interfered by structural irregularities when propagating in the crystal, thus showing Produce more excellent optical performance.

Cutting applications

The microhardness of single crystal diamond tools is as high as 10000HV, so it has good wear resistance. Since the cutting edge of single crystal diamond can achieve atomic level straightness and sharpness, the perfect cutting edge can be copied directly onto the workpiece during cutting to produce a mirror surface with extremely smooth finish, ensuring extremely high dimensional accuracy. , and can maintain the tool life and stable performance under high-speed cutting and heavy load. It is suitable for ultra-thin cutting and ultra-precision machining.

Grinding and polishing

Single crystal diamond has good dispersion and higher utilization rate of sharp corners. Therefore, when it is prepared into a grinding liquid, the concentration is much lower than that of polycrystalline diamond, and its cost performance is relatively high.

2. Polycrystalline diamond

The structure of polycrystalline diamond is composed of many tiny nanometer-sized particles bonded through unsaturated bonds, which is very similar to natural black diamond (natural polycrystalline diamond with black or dark gray as the main color).

Semiconductor field

As semiconductor materials, the application directions of diamond polycrystalline and single crystal materials are quite different. The optical and electrical properties of polycrystalline diamond are not as good as those of single crystal diamond. The application of optical grade and electronic grade polycrystalline diamond films is relatively demanding. The preparation requires ideal deposition rate and extremely low or controllable defect density.

Grinding and polishing

Since the polycrystalline diamond grains do not need to be arranged, the micro-fractures produced when subjected to high pressure can be limited to a small range of microcrystals, without large cleavage plane fractures, and have good self-sharpening properties, so they are allowed to be ground during grinding. And use higher unit pressure when polishing.

Cutting tools

Compared with large single crystals of diamond, the disordered crystal structure of polycrystalline diamond gives it more impact resistance and is less likely to crack during cutting.

by ALPA