Silicon carbide, chemical formula SiC, is a covalent bond material. C and Si belong to the same family, all have a tetravalent bond, while Si also has metal properties. Its structure has the mesh shape and body shape and has high strength in nature, so the properties of silicon carbide material include high-temperature strength, wear-resistant, corrosion-resistant, high thermal conductivity, and high insulation. The structure determines the performance, and the higher the performance, the finer the microstructure of the silicon carbide material is required, so the preparation method becomes the key to the acquisition of the high-performance silicon carbide material. Silicon Carbide has applications in a variety of sectors.
Two kinds of silicon carbide powders are discussed below.
-Silicon carbide Micron Powder
-Silicon carbide Nano Powder
The detailed discussion about SiC Micron Powder and Nanopowder is given below:
Silicon carbide micron powder
Silicon carbide (SiC) micron powder is widely used as abrasives or fillers in ceramic refining abrasives, resin polishing wheels, and diamond polishing wheels. Due to its excellent properties such as high hardness, high strength, outstanding oxidation resistance and wear resistance, SiC micron powder is also widely used in non-grinding applications such as refractory materials, engineering ceramics, and structural materials. At present, SiC has become the main raw material for the development of modern defense, modern industry, and high-tech. Due to the large surface area and fine agglomeration of fine-grained (10μm fine) SiC micron powder, not only the dispensability and fluidity of the ceramic grinding tool cannot meet the molding process performance requirements, but also in the production of resin polishing wheel, The compatibility of the bonding agent is also poor. Therefore, the strength of the abrasive article is low, the premature sand removal, the polishing quality, and the durability are not satisfactory, which seriously affects the quality.
Characteristics and Structure of Silicon Micron Powder
Silicon carbide micron powder is not the best for different customers. Only the relative stability is good. Different customers have different purity and grain shape requirements for the micron powder raw materials due to different production methods and different formulations. Under the premise of the same formula, if the micronized raw materials are in batches. The difference in purity, strength and grain shape in the second time will directly affect the qualification rate and quality of the customer's products, and if the products after the whole batch are unqualified, it may cause serious losses.
The invention relates to the field of silicon carbide micron powder processing equipment, in particular to a processing device for high-iron silicon carbide micron powder and a using method thereof. The utility model comprises a box body without an end cover, wherein a stirring device and a liquid removing the device is present in the box body, and an electric heating tube is arranged on a lower end surface of the bottom plate of the box body, and a temperature sensor is arranged in the box body.
A normal-pressure sintered ceramic-grade silicon carbide micron powder requires an average particle size of D50<0.8μm. The content of impurities such as iron, carbon, and silicon in the raw materials is strict. The mineral content can be up to standard by mineral processing and chemical treatment. Before the grinding, the free carbon is separated by flotation, and more than 70% of the iron mineral can be removed by the pulsating high gradient magnetic separator.
Production of Silicon Carbide Micron Powder
The airflow mill and classifier system for dry industrial production of silicon carbide fine powder is introduced. The system has advanced technology, well-graded cutting grain sharpness, strong regulation and adaptability, high productivity, low wear, and less environmental pollution, and the products have fully met the requirements of national standards and international standards.
Aiming at the agglomeration phenomenon of SiC micron powder (10μm) in the manufacture of fine grinding and polishing abrasives, this process is based on the principle of dispersion and stability of colloids, using silane coupling agent, hydrophobic pretreatment and acrylamide on its surface graft polymerization to modify SiC. The micro-powder (F1200, d50 μm = 3.0 ± 0.5 μm) was prepared, and the organic coated modified SiC fine powder was prepared.
Applications of Silicon Carbide Micron Powder
Due to the specific chemical and physical properties of silicon carbide, the current industrial silicon carbide micron powder is mainly used for abrasives. Among them, green silicon carbide has high hardness and certain toughness, and is mostly used for grinding and polishing optical glass, high hardness metal, titanium alloy and bearing steel; black silicon carbide is mostly used for cutting and grinding low hardness materials, such as non-ferrous materials, glass, ceramics, stone, and refractory materials. The 14 main applications of silicon carbide micron powder are listed below.
1. Due to its purity, its extraordinary hardness, its particle shape, and its micron particle size distribution, micron silicon carbides produced constitute the abrasive material.
2. Due to its high resistance to thermal shock, low expansion coefficient and high resistance to abrasion and chemical attack, silicon carbide is an irreplaceable component in the ceramic and refractory industry.
3. In a process known as sintering, silicon carbide particles - as well as those of the companions - are heated to a temperature lower than the melting temperature of this mixture. Thus, it increases the strength of the ceramic object, by forming strong bonds between the particles.
4. Silicon carbide structural ceramics have had a wide range of uses. They are used in disc brakes and clutches of motor vehicles, in particulate filters present in diesel and as an additive in oils to reduce friction.
5. The uses of silicon carbide structural ceramics have become widespread in parts exposed to high temperatures. For example, this is the case of the throat of rocket injectors and furnace rollers.
6. The combination of high thermal conductivity, hardness, and high-temperature stability makes the components of the heat exchanger tubes manufactured with silicon carbide.
7. Structural ceramics are used in sandblasting injectors, automotive water pump seals, bearings and extrusion dies. It also constitutes the material of the crucibles, used in the smelting of metals.
8. It is part of the heating elements used in the melting of glass and non-ferrous metals, as well as in the heat treatment of metals.
10. When added in the iron and steel smelting process, the silicon carbide micron powder results in significant cost savings due to its properties as a slag reducer, energy supply and improved characteristics of the metal obtained.
11. New technologies (such as the electronics and aeronautics industry, or high-temperature applications) require new products and processes in which silicon carbide finds application due to its high purity and special properties.
12. Moreover, it can be used in gas temperature measurement. In a technique known as pyrometry, a silicon carbide filament is heated and emits radiation that correlates with temperature in a range of 800-2500 K.
13. It is also used in nuclear plants to prevent the leakage of fission material.
14. In steel production, it is used as fuel.
Silicon Carbide Nano-powder
The organic-inorganic hybrid precursors were synthesized from industrial silica sol and water-soluble phenolic resin to produce Silicon Carbide Nano-powder. After high-temperature heat treatment, silicon carbide Nano-powder was prepared by a carbothermal reduction reaction. The thermal decomposition process of the precursor and the preparation process were analyzed. Silicon Carbide Nanopowder has more applications due to its smaller size.
Studies show that the preparation process of this product is simple, and the product is a mixture of high purity Nano silicon carbide powder and silicon carbide whiskers. In a study by researchers from Northwestern Polytechnical University of China, NANO-SiC powder was synthesized by the CARBO-THERMAL reduction method and its dielectric parameters in the frequency range of 8.2 to 12.4 GHz were measured. The β, 12H, and 21R type silicon carbide powders were obtained by changing the aluminum content and reaction atmosphere. The SiC powder has a much higher relative dielectric constant ε'r=30-50 than the α-SiC powder and a dielectric loss tangent (tgδ=~0.7) although the solid solution of Al and N will resist the resistance of the SiC powder. Polyacrylate/ Nano-SiO2 composite material has excellent film-forming properties, weather resistance, adhesion and high hardness, abrasion resistance and UV resistance of inorganic Nano-powder.
Applications of Silicon Carbide Nanopowder
Silicon carbide nanopowder has been the most commonly used material for structural ceramic applications. Features such as relatively low thermal expansion, high strength-to-weight radius, high thermal conductivity, hardness, resistance to abrasion and corrosion, and most importantly, the maintenance of elastic resistance at temperatures up to 1650 °C, have led to a wide range of uses.
1. They are used more for operation with low-temperature wear than for high-temperature behavior. The uses of SiC are such as sandblast injectors, automotive water pump seals, bearings, pump components, and extrusion dies that use high hardness, abrasion resistance, and carbide corrosion resistance of silicon.
2. The structural uses at high temperature extend from the throats of the rocket injector to the furnace rollers and the combination of high thermal conductivity, hardness, and high-temperature stability causes the components of the exchanger tubes to be manufactured by silicon carbide.
3. This thermal ceramic is resistant and strong against heat shock and provides great thermal conductivity, ideal for the manufacture of furnace linings and accessories.
4. It is used in the making of pencils, sandpaper, ceramics and as an abrasive for cutting or polishing.
5. Silicon carbide nanopowder is also used to produce aerospace mirrors. The material was used because it is very rigid and resistant to thermal shock. Silicon carbide also prevents mechanical fatigue, moisture absorption and deterioration caused by space radiation.
6. Silicon carbide is well known as an effective material in armor protection. This is because it is mechanically strong and lightweight. It limits the impact of armor weight on user performance (mobility and fuel consumption).
7. Silicon carbide nanopowder is an attractive material for a wide range of electronic applications thanks to its specific properties, including chemical inertia at all temperatures, resistance to thermal shock and hardness and sintering of abrasion. Its main application in this industry is in the manufacture of furnace furniture and process components for the semiconductor industry, as well as in the electric field classification and surge protection.
8. It is also useful in the construction of diodes, transistors, suppressors and high energy microwave devices. Light-emitting diodes (LED) and the first radius detectors (1907) were manufactured with the compound. Currently, silicon carbide has been replaced in the manufacturing of LED bulbs with gallium nitride that emits a light 10 to 100 times brighter. In electrical systems, silicon carbide is used as a lightning rod in electrical energy systems since they can regulate their resistance by regulating the voltage across it.
Research on Silicon Carbide Nanopowder
Application of mini emulsion polymerization and SiC Nano Powder in a Waterproof Coating
The silicone-acrylic emulsion was selected as the main film-forming material for waterproof coatings. The effects of different dispersants on the dispersion properties of Nano-powders in aqueous solutions were investigated. The results showed that composite dispersant [m(R-30A):m(STPP) was used. The dispersion performance is best when =1:11; the effect of ultrasonic dispersion on the particle size of the fine emulsion droplets and the stability of the Nano suspension dispersion is studied.
It is also showed that the ultrasonic dispersion can be reduced to 90 nm. At 20 min, the cracking r-degree and sedimentation volume of the Nano-suspended dispersion have a minimum value; the tensile strength and elongation of the Nano-composite waterproof coating show a maximum when the content of Nano-powder ZnO and TiO2 is about 3%; The photo-aging properties of Nano-powder and water-repellent coatings with 3% Nano-ZnO and 3% Nano-TiO2 show that the mechanical properties of the non- Nano-doped waterproof coatings are significantly reduced before and after UV irradiation, while the Nano-powder-coated waterproof coatings . The mechanical properties did not change much.
The rapid development of portable electronic devices and electric vehicles has spurred the development of a new generation of high energy density lithium-ion battery anode materials. Silicon carbide Nano-materials are considered to be promising alternatives, but there are still many problems in practical applications. Therefore, novel spiral silicon and silicon carbide Nano-materials are rationally designed and prepared by the sol-gel method. The performance of the anode material as a lithium-ion battery was studied. In the first part of the thesis, a pair of double-headed amphiphilic proline derivatives were designed and synthesized, and their self-assembly behavior was studied. The self-assembly was used as a template and tetraethoxysilane (TEOS) was used as the precursor. One-handed spiral silica Nanotubes were prepared by the sol-gel method and then mixed with magnesium powder. The silicon Nanomaterial is prepared by the magnesium thermal reduction method and used as negative electrode materials for lithium-ion batteries. Its application in done energy storage
Production of SiC nanopowder by Self-propagating high-temperature synthesis (SHS)
The method is to ignite the reactant body by an external heating source using the material.
The heat of the chemical reaction released during the synthesis process is maintained by the synthesis Cheng. No external heat source other than ignition, less energy consumption, equipment process simple, and high production efficiency is exhibited. Its shortcoming is that the spontaneous reaction is difficult to control the system. Besides, the reaction between silicon and carbon is a weak exothermic reaction in the chamber. The temperature reaction is difficult to ignite and maintain, and chemical furnaces are often used for this purpose.
Direct current through the reaction body, preheating the reaction body and supplementing the power field and other methods are used to supplement energy. Such as the SHS reduction synthesis method using SiO2.An exothermic reaction with Mg to compensate for the lack of heat, such as
SiO2 + C + 2Mg SiC + 2MgO
The SiC powder obtained by this method has high purity and small particle size but needs pickling. The subsequent steps remove the Mg from the product.
Production of Silicon Carbide Nanopowder by resin pyrolysis carbon
The application of ceramic materials in the high-temperature field makes it have great attraction and is also widely used in electronics and glass. Glass, insulation, semiconducting, superconducting bodies, and other industrial fields are of prime significance. NAMI ceramics is one of the main means of solving the brittleness of ceramics. The physicochemical properties are determined by particle sizes which are different from those of conventional polymers, to caused more and more interest. The research on rice materials has become a hot topic in the research of materials science. When the SiC is prepared by the carbothermal reduction method, the main reaction mechanism is a gas-solid reaction. The particle size of the carbon determines the SiC powder degree while how to prepare ultra-fine carbon powder is the key to preparing ultra-fine SiC powder.
The raw materials used in the laboratory are SiC Nano-powder and phenolic resin, and its pyrolytic carbon, phenolic resin is self-made providing high activity. According to the different raw materials used, the test samples are prepared according to two different processes the good resin will be synthesized. Dissolved in the alcohol, calculated according to the carbon yield, the amount of SiO2 added, so that the carbon in the mixture is 4% 5%, and then loaded into the ball mill after mixing and drying, the product was thermally decomposed under N2 protection. The heating rate is not greater than C/rain, final temperature 600C to on. After pyrolysis, the sample is grinded into a fine powder and then pressed into a certain shape. The furnace will be a good resin at 150C solid and pyrolysis according to the pyrolysis process described above, the obtained pyrolytic carbon and SiO2 are chemically proportioned and mixed as well as simultaneously pyrolyzed. The amount of charcoal is 4% to 5%. It is milled for 2Bh with alcohol as the medium. After drying, it is pressed into a certain shape. Microwave heating is carried out in a multimode harmonic cavity microwave oven. The frequency of the microwave source is 245 GHz and the sample is taken into the furnace.
Firstly, all the material is taken out and then filled with pure N to atmospheric pressure. Afterward, an average of 40 is taken. The speed of C/min is raised to temperature, and after a predetermined temperature, it is kept for 10~20 minutes. They often stop heating and cool with the stove.
The obtained SiC is subjected to performance testing by x-ray diffraction and electron microscopy analysis. Figure l is x shot According to the results of the line diffraction test, it can be seen that the main composition of SiC is SiC content of 90%~95% and other SiC. About
The conversion of SiC from n-type to n-type has been observed and studied by many researchers. The results of the study show that the reaction is sintered.
Effect of the heating mode
Microwave heating and conventional heating has different heating mechanisms. Thus showing great superiority, in which it can be a large reduction in temperature 1500 under normal heating conditions. C reacts with SiO2 and the SiC synthesis rate is 50% left.
The synthesis rate of SiC is more than 90% at C; secondly, it can greatly reduce the synthesis time, often it takes a few hours or even tens of hours to heat. the heat and the microwave heating only needs L-I-minutes or even a few minutes - because of the temperature is low and the heating time is short, which not only saves time and energy but also prevents the growth of the crystal grains, the transformation of the crystal form and the intergranular, the sintering is beneficial to obtain the ceramic powder with fine crystal grains, uniform grain size, and single crystal form. The traditional heating is mostly heating radiation or heat. Conduction energy is only used on the surface of the sample; the whole temperature must be completed by thermal diffusion, so the heating rate is low when heating. The length of the sic granules obtained from the sic granules is relatively thick.
The effect of the addition of polyamine (PEI) and its concentration on the dispersion of silicon carbide powder in water was studied in the range of pH 2-12. It was found that when dispersant was added to the slurry, the silicon carbide reached an optimum dispersion at pH = 10.4, at which time the slurry exhibited Newtonian fluid characteristics, exhibiting a minimum settling height and a maximum potential. In acidic conditions (pH = 2-7), the slurry produces a large agglomeration, with a large sedimentation height, a large particle size, and a low potential value, exhibiting non-Newtonian fluid characteristics.
Research progress on silicon carbide Nanopowder
With better performances than the traditional SiC powder, the Nano-sized SiC powder can meet the strict demands in the new high tech fields and has more extensive uses. It summarized the preparation methods of Nanosizeded SiC powder developed in the new high - tech fields in recent years and emphasized introducing some new preparation methods. Moreover, the basic principle, characteristics and current research situation of those methods were set forth and comparison was made among different method. For example, CARBO thermal reduction method is characterized by cheap raw material, stable quality, easy to realize industrialization, etc.; the Nano-sized powder made by liquid - phase method is high in purity; the gas-phase method is a relatively advanced method currently, but it is different to realize batch progress.
High-performance SiC materials (such as β-SiC powder, SiC whiskers, and complex Composite material) with high technology and high added value, so SiC Production has become a matter of great concern to people. Covalent bond due to SiC The material has a high sintering temperature and is difficult to be sintered by conventional sintering methods. Dense, Therefore, the use of high purity, high activity ultrafine SiC powder is made An important prerequisite for dense SiC materials.
Thus, both micron and nano Silicon Carbide are of extreme importance due to their specific properties and applications. The applications can be found in Metallurgy, Electronics, Refractory, Ceramics, Aerospace mirrors, etc. Silicon Carbide has high virtue, restricted range molecule size appropriation, and bigger explicit surface region. This item has compound soundness, high warm conductivity, littler warm extension coefficient, and better-scraped spot opposition. Its mechanical quality is higher than the corundum.
Nano-SiC has fantastic warm conductivity. It is a semiconductor and impervious to oxidation in high temperatures while Silicon Carbide (SiC) Micron Powder bristles, Nano-dots or Nano-powder are round high surface territory particles. Nano-scale Silicon Carbide Particles are ordinarily 10 - 150 Nanometers (nm) with the explicit surface zone (SSA) in the 10 - 75 m2/g run. Nano Silicon Carbide Particles are likewise accessible in ultra-high virtue and high immaculateness, covered and scattered structures.