What are the main use of silicon carbide? Emery silicon carbide including black silicon carbide and green silicon carbide, including: black silicon carbide, quartz sand and petroleum coke and high quality silica as the main raw material, through the resistance furnace and. Its hardness between corundum and diamond, mechanical strength higher than corundum, brittle and sharp. Green silicon carbide is made of petroleum coke and high quality silica as the main raw material. The hardness between corundum and diamond, mechanical strength higher than corundum. So what are the main uses of silicon carbide?

　　1, abrasive - mainly because silicon carbide has high hardness, chemical stability and toughness, so can be used in the manufacture of silicon carbide bonded abrasives, coated abrasives and free grinding, to glass, ceramics, stone processing, iron and non-ferrous metal, hard alloy, titanium alloy, high speed steel cutting tool and grinding wheel etc..

　　2, refractory material and corrosion resistant materials, mainly because of silicon carbide with a high melting point (resolution), chemical inertness and heat shock resistance, so can be used for silicon carbide abrasives, ceramics kiln used in slab and sagger, zinc smelting industry vertical distillation furnace cylinder with silicon carbide and aluminum electrolytic, crucible lining small pieces of material such as silicon carbide furnace, ceramic products.

　　3, the use of chemical - because silicon carbide can dissolve in molten steel and molten steel in the oxygen, metal oxide reaction to generate carbon monoxide and silicon containing slag. Therefore, the utility model can be used as a purifying agent for smelting iron and steel, which is used as a deoxidizing agent for steel making and an improvement agent for cast iron. This generally uses low purity silicon carbide to reduce costs. At the same time, it can also be used as raw material for producing four silicon chloride.

　　4, electrical purposes - used as heating elements, nonlinear resistance components and high semiconductor materials. The heating elements such as silicon carbide (1100 to 1500 DEG C for the work of a variety of nonlinear resistance element, the electric stove), all kinds of valve arrester.

　　Silicon carbide graphite crucible, isostatic molding technology, long life, is 4 times the ordinary crucible. Chemical resistance, strong oxidation resistance, thermal conductivity, thermal shock stability! bowl shaped container with a ceramic crucible. When a solid is heated by a fire, it is necessary to use a crucible. Because it is more able to withstand high temperatures than glassware.

　　When the crucible is used, it is usually not too full to prevent the heat from jumping out and allowing the air to move in and out for possible oxidation. Crucible because of its small bottom, generally need to stand on the mud triangle in order to direct heating fire. The crucible is placed on the iron tripod with a positive or oblique position, and the requirements of the experiment can be arranged on the self. The crucible should not be placed immediately on the cold metal table after heating, so as to prevent it from cracking due to sharp cooling. Do not immediately put on the wooden table, in order to avoid burning the desktop or cause a fire. The correct way is to keep the iron triangle on the natural cooling, or put on the asbestos network to make it cool.

　　The crucible can be divided into three categories: graphite crucible, clay crucible and metal crucible. In the graphite crucible, there are three kinds of common graphite crucible, special graphite crucible and high pure graphite crucible. Because of the surface treatment process, can be divided into ordinary graphite crucible, graphite crucible coatings (in graphite crucible with a layer of graphite crucible coating way), graphite crucible of various types, due to performance, and the use of different conditions, the raw material used, production method, technology and product specifications are the difference.

　　The main raw material of the graphite crucible is crystalline natural graphite. So it keeps the original physical and chemical properties of natural graphite.

　　That is, good thermal conductivity and high temperature resistance, high temperature in the use of the process, the coefficient of thermal expansion is small, for the heat, the cold has a certain strain resistance. The acid and alkaline solution has good corrosion resistance and excellent chemical stability.

　　The crucible has many types and specifications, and is not limited by the scale of production, the size of the batch and the variety of the smelting material in application, and the utility model has the advantages of arbitrary selection, strong applicability and high purity.

　　The graphite crucible has been widely used in metallurgy, casting, machinery, chemical industry and so on. It has been widely used in the smelting of alloy tool steel and smelting of nonferrous metals and alloys. And has a good technical and economic effect.

　　In an electrolytic cell, the current from a class called graphite anode plate into the electrolyte electrolysis industry, the anode is made of plate shape, so called graphite anode plate, widely used in electroplating, wastewater treatment, industrial anti-corrosion equipment or special materials. In electrolysis industry, using graphite anode plate as the anode has a history of more than and 100 years, the metal anode is in recent decades, the research and application of metal anode in China late last century, only in 70s the technology related to the research and experiment of metal anode, anode on electrolysis industry, mainly through the silver (2%) (0.5%): low silver lead silver alloy, lead and silver tin antimony alloy, lead calcium alloy and lead silver alloy adding nucleating agents and several stages.

　　Compared with other materials of graphite anode plate has high temperature resistance, good electrical and thermal conductivity, easy machining, good chemical stability, acid and alkali resistance, low ash content; for electrolytic solution, preparation of chlorine, caustic soda, salt alkali electrolytic solution preparation; application such as graphite anode plate can be used as conductive anode electrolytic salt solution preparation of caustic soda. The graphite anode plate can be used as the conductive anode in electroplating industry, and it is an ideal material for electroplating. It can make the products with smooth, fine, wear resistance, corrosion resistance, high brightness, not easy to change color and so on.

　　Two, graphite cathode carbon plate

　　Carbon block made of high quality anthracite, coke and graphite. Cathode for aluminum electrolytic cell. The bottom of the electrolytic tank is also called a bottom carbon block. The characteristic cathode carbon block acts as a conductor and forms the dual role of the inner lining of the electrolytic cell. The production of aluminum electrolysis requires high temperature resistance. Corrosion resistance and good conductivity, good thermal conductivity, high mechanical strength, good thermal shock resistance and strong corrosion resistance. According to the quality requirements of the products, the raw materials and the process conditions, the cathode carbon blocks in China are classified into 3 categories: common cathode carbon block, semi graphite carbon block and graphite carbon block. The common cathode carbon block is made from anthracite calcined at 1250 to 1350 DEG C. Semi graphite carbon block is divided into two kinds according to the production process.

　　Which is a kind of high quality high temperature calcined anthracite or graphite fragments more even with all the bits of graphite as aggregate, green products after forming only after calcination (calcination temperature less than 1200 DEG C) is no longer in the graphite furnace heat treatment, the carbon block called semi graphite carbon block.

　　The utility model is characterized in that the coke is prepared by the use of more easily graphitized coke as raw material, and the heat treatment is carried out at the temperature of 1800 to 2000 DEG C after the raw product is calcined into the graphitization furnace.

　　The former has higher strength and hardness, and the latter has better conductivity and integrity. Graphite carbon block, with easy graphitization coke as raw material, its graphitization temperature should reach 2500 degrees celsius. The difference between the semi graphitic carbon block and the graphite carbon block is that the arrangement of the crystal lattice is different. It can be used to indicate the degree of graphitization degree. The lattice of graphite carbon block is basically in the order of the state, the resistivity is less than 15 ohm m, the graphitization degree of the semi graphite carbon block is low or only partial graphitization, the resistivity is from 15 to 45 Omega M. In the process of heat treatment temperature, the heat treatment temperature of the half graphite carbon block is about 2000 DEG C, and the graphitization temperature of Shi Mozhi carbon block is from 2500 to 2800. Common cathode carbon block, resistivity 50 ~ 60 Omega M. The graphitized cathode is the conductive material used in the cathode of aluminum electrolysis cell, which represents the development direction of electrolytic aluminum industry. With the technical progress and development of the electrolytic aluminum industry, the development of the electrolytic cell to the large capacity of 300KVA and above, requires higher cathode materials. The main advantage is to strengthen the graphitized cathode current, improve the current efficiency and yield of energy, and make the electrolysis groove more stable operation, stable operation effect is more obvious, more significantly improve the current efficiency, the use of the graphitized cathode unit of electrolytic aluminum production capacity increased by 10 - 15% tons of aluminum, saving more than 600KWh. Due to the obvious effect of energy saving and consumption reduction, the graphitized cathode aluminum reduction cell is one of the most important materials for the development of the electrolytic aluminum industry in china.

　　The refractory material , graphite and graphite products have the properties of high temperature resistance and high strength. They are mainly used to make graphite crucible in metallurgical industry. Commonly it’s used as a protective agent for steel ingot in steel making.

　　Graphite is often used as lubricant in mechanical industry. The lubricating oil often can not be used under the condition of high speed, high temperature and high pressure, but the graphite wear resistant material can be operated at a temperature of 200~2000 DEG C at a high sliding speed without lubricating oil. The piston cup, sealing ring and bearing which are made of graphite material are used in a lot of equipment conveying corrosive medium widely, they do not need to add lubricating oil. Graphite grease is the good lubricant in many metal processing.

　　The conductive material , graphite is used for manufacturing the electrode, carbon nanotubes, carbon brush, and the positive electrode of the mercury rectifier,graphite gasket, telephone parts, TV tube coating etc.in the electrical industry .

　　Graphite has good chemical stability, the graphite products after special processing with corrosion resistance, good thermal conductivity, low permeability, it is widely used in the manufacturing of the heat exchanger, the reaction tank, condenser, combustion tower, absorption tower, cooler, heater, filter and pump equipment in petrochemical industry, hydrometallurgy, acid and alkali production, synthetic fiber, paper and other industrial sectors, it can save a lot of metal materials.

　　Casting, molding and high-temperature metallurgical materials because the graphite thermal expansion coefficient is small, and the capability of cold and hot change, it can be used as a mold of the glass, the use of graphite after black metal castings get precise size, smooth surface, high rate of finished products, it can be used without processing or minor processing, thus saving a lot metal.

　　Graphite rupture disk is the rupture disk which is impregnated by resin After a lot of molding and can withstand the high corrosion.The graphite rupture disk is a special type of safety device, it is mainly used in high corrosion condition and can bear any invasion from the strong corrosive chemicals.

　　The rupture disk utility model is a non closed pressure relief device composed of a blasting piece (or a bursting sheet component) and a clamping device (or a support ring). When it is under the given blasting temperature and the pressure difference between the two sides of the bursting disc reaches the preset value, the rupture disk instantly moves (breaks or falls off) and releases the fluid medium. There are two kinds of common graphite type rupture disk: flat-type and concave-type.

　　The graphite rupture disk size: conventional size 25mm--1000mm,bursting disc pressure: 0.001MPa--2MPa, applicable medium: gas, liquid and mixed medium, no insulation layer maximum temperature 200℃,80% operation rate, the highest manufacturing standards.

　　The graphite rupture disk is a safety device when we use acid, alkali and organic solvents and other corrosive fluids.It ruptures rapidly when the pressure is too large so as to ensure the safe. Our graphite rupture disk was produced with homogeneous graphite as the basic material, the machining setting pressure,its precision is high when the working pressure below 75% of the preset failure pressure .

　　The features of graphite rupture disk: corrosion resistance and excellent chemical weathering sleep, most media outside of the strong oxygen gasification has corrosion resistance, the probation period (1 years) no material degradation phenomenon; no plastic deformation phenomenon, the special properties of graphite is different from the metal materials, it almost has no plasticity until rupturing . That is to say, it damages facing the over pressure immediately, opening out the pressure of 100% ; a wide range of uses:it also be used in low pressure and the failure pressure characteristics of long-term stability.

　　Pistons for internal combustion engines have been made of such materials as cast iron, steel and aluminum. Most pistons manufactured today are made of aluminum. However, aluminum has low strength and stiffness at elevated temperatures, and aluminum has a large coefficient of thermal expansion. A new piston concept, made of carboncarbon refractory-composite material, has been developed that overcomes a number of the shortcomings of aluminum pistons. Carbon-carbon

　　material, developed in the early 1960's, is lighter weight than aluminum, has higher strength and stiffness than aluminum and maintains these properties at temperatures over 2500°F. In addition, a low coefficient of thermal expansion and a high thermal conductivity give carbon-carbon material excellent resistance to thermal shock. An effort, called the Advanced Carbon-Carbon Piston Program was started in 1986 to develop and test carboncarbon pistons for use in two-stroke-cycle and fourstroke-cycle engines. The carbon-carbon pistons developed under this program were designed to be replacements for existing aluminum pistons, use standard piston pin assemblies and use standard ring sets. The purpose of the engine tests was to show that pistons made of carbon-carbon material could be successfully operated in a two-stroke-cycle engine and a four-stroke-cycle engine.

　　Carbon-carbon pistons can potentially enable engines to be more reliable, to be more efficient (lower hydrocarbon emissions, greater fuel efficiency), and to have greater power output. By utilizing the unique characteristics of carbon-carbon material -- very low expansion rate, low weight, high strength and stiffness at elevated temperatures, and high thermal conductivity -- a carbon-carbon piston can (1) have greater resistance to structural damage caused by overheating, lean air-fuel mixture conditions and detonation, (2) be designed to be lighter-weight than an aluminum piston thus, reducing the reciprocating mass of an engine, and (3) be operated in a higher combustion temperature environment without failure.

　　Pyrolytic graphite is a new type of carbon material, is the high pure hydrocarbon gas in the furnace pressure in pyrolytic carbon of 1800 DEG C to 2000 C high crystallinity graphite matrix on the chemical vapor deposited, it has a high density (2.20g/cm), and the content of impurities (heat, electricity and magnetism and the anisotropy of mechanical properties. The vacuum degree of 10mmHg can still be maintained at about 1800℃

　　The process of decomposition of matter. Many inorganic substances and organic matter are heated to a certain degree of decomposition reactions will occur. The pyrolysis process does not involve the reaction of the catalyst, as well as other energy, such as UV radiation.

　　High temperature strength increases with the temperature increasing, the strength reached the highest value at 2750 C 3600 C sublimation. low elastic modulus, high thermal conductivity, low thermal expansion coefficient, good thermal shock resistance. good chemical stability, acid, alkali, salt and organic reagent of molten metal, slag and other corrosive media have no effect, in the atmosphere at a temperature below 400 DEG C oxidation is not obvious, the oxidation rate increased significantly at 800 C. do not put any gas at high temperature, at 1800 degrees Celsius or so to maintain the vacuum of 10-7mmhg.

　　Heat transfer process requires a large amount of heat absorption process. The heating method can be divided into self heating process and external heating process. For example, limestone pyrolysis to produce lime, temperature above 800 degrees Celsius, or even in the presence of oxygen does not affect the reaction process, so you can use the direct calcination of the industrial furnace for heating process. For the cracking of petroleum fractions, the reaction temperature is over 750 DEG C, and the lowest possible hydrocarbon partial pressure, is the product of combustible gas, so commonly used partition heat transfer mode (such as pyrolysis tube furnace) or by the carrier (such as direct heating regenerative furnace pyrolysis, sand furnacecracking, high temperature water vapor cracking). External thermal process. But can also be used to burn some of the raw materials for the self heating process, such as natural gas or heavy oil combustion pyrolysis of acetylene, carbon black, etc..

　　Mold in the home appliance, automobile, mechanical and electrical, aerospace and other industrial fields are increasingly becoming the main production process of industrial mass production equipment, undertake the processing of these products in the industry 60%-90% production. In recent years, the high speed milling has broken through the limitation of the traditional milling, which is difficult to process the material with high hardness, high strength and high toughness. But the EDM has high machining accuracy and surface quality, machining range, especially in the complex and precise, thin-walled, narrow, mold processing high hard materials in the advantage of high speed milling cannot be compared, so the electric discharge machining will be the main means of mould cavity machining. The graphite electrode (compared with copper) electrode consumption, discharge machining speed, good machining performance, light weight, small thermal expansion coefficient and other advantages.Compared with copper, graphite electrode has the advantages of less consumption, high discharge rate, light weight and low thermal expansion coefficient.

　　Speed: Graphite discharge is 2-3 times faster than copper material, not easy to deformation, obvious advantages in the processing of thin electrodes, copper softening point at about 1000 degrees, easily deformed by heat, graphite sublimation temperature is about 3650 degrees, compared with graphite material thermal expansion coefficient of copper is only 1/30;

　　Light weight: the density of the graphite is only 1/5 of the copper, large electrode discharge processing, can effectively reduce the burden of machine tools (EDM), more suitable for large mold applications;

　　The loss is small: due to the C atom in the spark oil, in the process of discharge, high temperature causes the C atoms in the spark oil to be decomposed, and the protective film is formed on the surface of the graphite electrode

　　Low cost: due to rising copper prices in recent years, today, the price of copper than the isotropic graphite graphite products are lower; the same volume and the price is lower than copper in thirty percent to sixty, the price is relatively stable, short-term price fluctuations are relatively small.

　　The machining quality of the graphite plate influences its service life directly.It must be processed carefully to reach the standard indicators. it must be uniform such as dipping, the resistivity must be consistent, it also can avoid a part is intact and another part is serious corrosion in the production process so that the total body waste down.

　　It is the key to make a good use environment to prolong the service life of graphite anode plate. In the production process, reduce the impact, keep the working environment clean, detect the circuit on time and organizing the production at a fixed temperature, reduce the degree of oxidation of the air.

　　The Matters needing attention for prolonging the service life of graphite plate:

　　The larger the amount of current is, the higher the surface temperature of the graphite plate. Minimum load density (power) is recommended.

　　The graphite plate should be in parallel as far as possible. the resistance of the graphite plate is high when the resistor is connected in series If the resistance value of the graphite plate is different,and it will leads to the rapid increase of the resistance of a graphite plate and the short life

　　The appearance of the graphite plate will form a dense silicon oxide film after it is heated in the air, it’s a anti-oxidation maintenance film and play a life extending effect. In recent years, various kinds of coatings have been developed to avoid the cracking of graphite plates.

　　The shorter of the service lift of graphite plate , the higher the use temperature , so when the furnace temperature over 1400℃, the oxidation rate accelerated ,the life shorten , we shouldn’t let the graphite plate surface temperature is too high when we use it.

　　Carbon / carbon - silicon carbide composite material is carbon fiber reinforced carbon and silicon carbide ceramic matrix composite material , it appears in early 1980s as the thermal structure of materials with low density, good oxidation resistance, corrosion resistance, excellent high temperature mechanical properties and thermal physical properties, good self-lubricating performance and other advantages, it is a new high temperature structural materials and functional materials which can be used in the 1650℃. As the brake disk material , the carbon / carbon - silicon carbide composite material not only has the advantages such as carbon disk density is small, stable brake wear, the rate of weight loss is small and large heat capacity , but also it overcome the high hygroscopicity of the carbon disc, low friction coefficient in wet hygrometric state , low static friction coefficient, lack of adaptability, so it’s taken the lead in the F16 fighter. Silicon carbide ceramic matrix material use a silicon carbide impregnation process based on the carbon / carbon material , it use carbon fiber as reinforcement, silicon carbide as the matrix material, its performance has exceeded the current application of carbon / carbon brake disk material.

　　The carbon / carbon-silicon carbide ceramic brake disks can make the braking response more sensitive and the braking effect is more obvious. At the same time, it also has excellent resistance to power attenuation. The service life of the brake disks is longer than the ordinary brake disks, and it has stronger durability because the maintenance cost is lower. The body weight of the vehicles can be reduced 15 kg after equipping with the carbon / carbon - silicon carbide ceramic matrix brake disk, it reduce the unsprung mass and improve the power weight ratio without increasing engine power so that the overall performance of the vehicles and handling are promoted.

　　The application of carbon - carbon / silicon carbide ceramic matrix material: brake disk materials: including aircraft brakes (military and civil aircraft brakes), helicopter rotor, a new generation brake system of of the tanks, the train brake disk (EMU and fast train), car brakes (in luxury cars, cars, large truck truck etc.).