At present, only a few countries have developed silicon carbide ceramic membrane products in the world, and only one domestic company has achieved mass production. As the most high-end product in the field of ceramic membranes, all the silicon carbide membrane materials required in the domestic water treatment field need to be imported. The price and supply of materials are monopolized by foreign companies, and the products are expensive, which restricts the speed and scope of the promotion of silicon carbide ceramic membranes. This project implements the industrialization of silicon carbide film series products, breaking foreign monopolies and filling domestic gaps. Therefore, there are not many patent applications and publications for silicon carbide film in the world, but it is in a stage of rapid growth. There is an urgent need to invest quickly to consolidate the patent layout in this field. The global ceramic membrane industry patents are mainly concentrated in developed countries such as the United States and Japan, and the Chinese market has great potential. From the perspective of the existing patented technical fields, they are mainly distributed in the technical fields of filtration, packaging, batteries, and heat insulation, with filtration as the mainstay. From the perspective of important patent applicants, Kurita Industry, Kubota, Hitachi, Nippon Electric, Japan Electric, Toray, JSR, Praxair Technology Co., Ltd., Nanjing University of Technology, Membrane Technology and Research Institute, Asahi Kasei, and Tsinghua University are all related Frequently cited patents. Combining the different application fields and technologies, the focus of research and development is different, there is the possibility of competition and strategic cooperation, and the opportunities and challenges of industry development coexist. In term

Ceramic filter is a widely used filter, which uses rigid microporous materials as filter elements. It includes a series of filters such as ceramic, corundum, silicon carbide, sand chip, etc., as shown in the figure. The excessive airflow can cause dust to stick to the filter and cause blockage. In order to prevent the excessive airflow from directly blowing the ceramic cup, a protective cover is added to the outside of the ceramic cup to make the airflow bypass the lower part of the filter. Then enter the filter. In order to reduce the ineffective volume, the bottom of the filter is tapered and a branch joint is added. On the one hand, the dust can be blown away; on the other hand, the gas exchange is accelerated due to the continuous flow of gas and the lag time is reduced. In order to facilitate the replacement and cleaning of the filter, a ceramic filter system is designed. When one filter is clogged, the two four-way reversing valves can be turned to pass the sample gas into the other filter. The clogged filter can be blown back by high-pressure air to make the dust adhering to the ceramic filter cup Get rid of. In this way, the two filters work alternately. It is suitable for more important analysis systems and sampling systems with higher dust content that are prone to clogging. At present, ceramic filters are more and more widely used in many industrial fields, such as catalytic precious metal recovery, fluidized bed combustion, calcination, organic waste gasification power generation, building materials, chemicals, and high temperature in industrial processes such as various industrial kilns and furnaces. Flue gas purification. The application of high temperature flue gas purification will also appear in smelting, material production and glass manufacturing. These high-temperature soot purifications are often carried out under conditions close to atmospheric pressure. The most prominen

Ceramics is an ancient traditional industry, and the sanitary ware industry has a history of less than 100 years in our country. The traditional ceramic production areas such as Jingdezhen, Chaozhou, Dehua, Yuzhou (junci), Dapu, etc. are all spontaneously formed by relying on local raw materials and have their own characteristics. In recent years, when attracting investment, local governments will do everything possible to find their own advantages. Naturally, there are advantages in raw materials, which is necessary. If a ceramic production area does not have the advantages of raw materials, companies will be very hard. Some companies invest in traditional production areas, but due to unrealistic prejudices, resources are exhausted, and they suffer a lot. The path to the formation and development of sanitary ware production areas is quite different. In addition to sanitary ceramics, hardware sanitary wares, shower rooms, bathroom cabinets, emerging clothes racks, smart toilet covers, etc., have nothing to do with the advantages of raw materials, even sanitary ceramics. , You can also ignore the advantages of raw materials, such as the emerging southern Fujian production area. The author once seriously investigated why Kaiping Shuikou, Nan'an Luncang and even Wenzhou developed into China's most important hardware and plumbing bases. The advantages of these places are still there. I have not dared to draw conclusions for a long time. Some people in Shuikou and Luncang said that this place was developed from the iron shop. It turned out to be very poor and closed. Some people said that it developed from repairing locks and repairing pots. After thinking about it for a long time, the author investigated the case of Hubei Huanggang's development into China's premier kiln base, and finally understood the reasons for the development of these industries in the local area, and discovered that th

In order to make ceramics resistant to high temperatures and not easy to break, people add some metal powder to the clay used to make ceramics, thus making cermets. A composite material composed of one or several ceramic phases and metal phases or alloys. In a broad sense, cermets also include refractory compound alloys, hard alloys, and metal-bonded diamond tool materials. The ceramic phase in cermet is an oxide or refractory compound with high melting point and high hardness, and the metal phase is mainly transition elements (iron, cobalt, nickel, chromium, tungsten, molybdenum, etc.) and their alloys. Cermet not only has the toughness, high thermal conductivity and good thermal stability of metal, but also has the characteristics of high temperature resistance, corrosion resistance and wear resistance of ceramics. According to the different percentages of the constituent phases, cermets are divided into two types: ceramic-based and metal-based. Ceramic-based cermets mainly include: ①Oxide-based cermets. It is made of aluminum oxide, zirconium oxide, magnesium oxide, beryllium oxide, etc. as the matrix, compounded with metal tungsten, chromium or cobalt. It has the characteristics of high temperature resistance, chemical corrosion resistance, good thermal conductivity, and high mechanical strength. It can be used as a missile nozzle Bushes, crucibles for melting metals and metal cutting tools. ②Carbide-based cermet. It is made of titanium carbide, silicon carbide, tungsten carbide, etc. as the matrix, compounded with metal cobalt, nickel, chromium, tungsten, molybdenum and other metals. It has the characteristics of high hardness, high wear resistance, high temperature resistance, etc., used to make cutting tools, High temperature bearings, sealing rings, wire picking die sets and turbine blades. ③Nitride-based cermet. With titanium nitride,

Industrial ceramics, that is, ceramics for industrial production and industrial products. It is a type of fine ceramics, which can perform mechanical, thermal, chemical and other functions in applications. It has very broad application prospects in the fields of energy, aerospace, machinery, automobiles, electronics, and chemicals. So how high is the high temperature resistance of ceramics? Use ceramics that are resistant to corrosion and chemically stable in contact with biological enzymes to produce crucibles for smelting metals, heat exchangers, biological materials such as artificial dental lacquer joints, etc., and use unique ceramics that capture and absorb neutrons to produce various nuclei Anti-stack structure materials, etc. How much is the high temperature resistance of industrial ceramics? How much is the high temperature resistance of industrial ceramics? Industrial ceramics mainly include zirconia ceramics, alumina ceramics, silicon carbide ceramics, etc. The highest temperature they can tolerate is 1350℃ for zirconia ceramics, 1700℃ for alumina ceramics, and 1650℃ for silicon carbide ceramics. These ceramics can be processed into various high-temperature-resistant ceramic parts, and the finished products also have high-temperature resistance. Control the interface of the drying tower as required, and operate stably to prevent fluctuations in the interface of the drying tower to prevent alkali; control the concentration of the K2CO3 solution in the drying tower between 1.3g/L-1.4g/L, which requires us to prepare alkali or distill alkali It is necessary to control the concentration of alkali preparation and steaming alkali, and replace the dilute alkali solution used for a long time to reduce the phosphate content in the K2CO3 solution and reduce

1. Factors affecting the thermal conductivity of ceramic materials 1. Chemical composition The thermal conductivity of ordinary ceramics is (0.02~1.5) W/(m·K). In practical applications, ceramic materials with low thermal conductivity are far from meeting the requirements for energy saving, high efficiency and special performance. Component doping is an important method to improve the thermal conductivity of ceramic materials. This method can be divided into two types according to the nature of doping components: adding non-metallic materials or adding metallic materials. In the application field of electronic packaging materials, aluminum nitride (AlN)-based special ceramics are prepared from aluminum nitride ceramic composite powders, with a thermal conductivity of 210W/(mk), which is 5-8 times the thermal conductivity of alumina ceramics. High temperature above 2200℃. With high thermal conductivity, stable mechanical properties and excellent electrical insulation properties, with extremely high insulation resistance and low dielectric loss, it is an ideal thermally conductive ceramic material for a new generation of large-scale integrated circuits and power electronic products. 2. Raw material powder particle size The particle size, purity and phase of the raw material powder will have an important impact on the thermal conductivity and mechanical properties of the ceramic material. The larger the particle size, the more obvious the delay in the densification process of the ceramic. During the preparation of the ceramic, pores will inevitably appear in the ceramic. Generally, the more pores, the higher the thermal conductivity of the material. When the ceramic powder particle size drops to nanometer level, its ther

The common feature of the semiconductor ceramic production process is that it must go through a semiconducting process. The semiconducting process can replace some of the main crystal phase ions by doping unequal ions (for example, Ba2+ in BaTiO3 is replaced by La3+) to cause defects in the crystal lattice and form donor or acceptor energy levels to obtain n-type or p-type Type semiconductor ceramics. Another method is to control the firing atmosphere, sintering temperature and cooling process. For example, an oxidizing atmosphere can cause excess oxygen, and a reducing atmosphere can cause insufficient oxygen, which can make the composition of the compound deviate from the stoichiometry and achieve semiconductivity. The production process of semiconductor ceramic sensitive materials is simple, low in cost, small in size, and widely used. Pressure sensitive ceramics refer to ceramics with non-linear volt-ampere characteristics. Such as silicon carbide, zinc oxide ceramics. Their resistivity is variable with respect to voltage, and the resistance value is very high at a certain critical voltage, and the resistance drops sharply when this critical voltage is exceeded. Typical products are zinc oxide varistor ceramics, which are mainly used for surge absorption, high voltage stabilization, voltage and current limitation, and overvoltage protection. Thermal ceramic Also known as thermistor ceramics, it refers to ceramics whose conductivity changes significantly with temperature. There are three types: ①Negative temperature coefficient thermistor (abbreviated as NTC), such as oxide semiconductor ceramics of some transition metals such as manganese, iron, cobalt, nickel, etc. The characteristic is that as the temperature increases, the resistance decreases exponentially. ②Positive temperature coefficient thermistor (referred to as PTC), suc

Ceramic is the general term for bai of pottery and porcelain. The ceramic materials are mostly oxides, nitrides, borides and carbides. Electronic ceramics can be divided into high-frequency and ultra-high-frequency insulating ceramics, high-frequency high-dielectric ceramics, ferroelectric and antiferroelectric ceramics, piezoelectric ceramics, semiconductor ceramics, optoelectronic ceramics, resistance ceramics, etc. according to their characteristics. According to the application range, it can be divided into fixed ceramics, electric vacuum ceramics, capacitor ceramics and resistance ceramics. According to the microstructure, it can be divided into polycrystalline, single crystal, polycrystalline and glass phase, single crystal and glass phase (no glass phase ceramics belong to solid phase sintering, and some glass phase ceramics belong to wave phase sintering). Many ceramics have semiconductor properties, so-called semiconductor ceramics. The nature of resistance changes with temperature can be used for nonlinear resistance (NTC). Iron-based metal oxide ceramics have a negative temperature coefficient of resistance, have chemical and thermal stability, and can be used for non-linear resistors to control the temperature in a wide range. In contrast, the element called positive temperature coefficient thermistor (PTC thermistor) uses semiconductorized BaTiO3 ceramics. This type of ceramic has a rapid increase in resistance at the phase transition temperature. If it is used as a resistance heating element, it can easily and automatically control the temperature around the phase transition temperature. In addition to single-phase ceramics composed of one compound such as oxide ceramics, nitride ceramics, and carbide ceramics, semiconductor ceramics also include composite ceramics composed of two or more compounds. For example, magnesia-alumina spinel

Mechanical polishing. The mechanism of mechanical polishing is to increase the micro-cutting effect and the micro-dao plastic flow of the processed material to achieve the polishing effect by the wedge du extrusion and the rebound of the polishing liquid. Because the thickness of the back plate of the ceramic mobile phone is small, and the mechanical polishing is in direct contact, friction may cause stress deformation of the workpiece, and excessive temperature may also destroy the lattice structure, so pay attention to temperature control during the polishing process. Mechanical polishing is a polishing method that obtains a smooth surface by cutting or plastically deforming the surface of the material to remove the protruding parts of the workpiece surface. Whetstone strips, wool wheels, sandpaper, etc. are generally used, and manual operation is the main method. If the surface quality is high, the super-precision polishing method can be used. Super-finishing polishing is a special-purpose grinding tool, which is pressed against the processing surface of the workpiece surface in a polishing polishing liquid containing abrasives for high-speed rotational movement. Precautions: 1. Hot water rinsing. After oxidation of ceramics, aluminum parts need to be washed with hot water for the purpose of aging the film. However, the water temperature and time should be strictly controlled. If the water temperature is too high, the film will become thinner and the color will become lighter. If the treatment time is too long, the above-mentioned similar problems will occur. The suitable temperature and time are: temperature 40~50℃, time 0.5~1MIN. 2. Drying: It is better to dry naturally. The

What tools are used to process ceramics? First we classify according to different processing methods. Turning of ceramic materials: Ceramics are typical hard and brittle materials, with high hardness and wear resistance. In addition to easy-cut ceramics, such as general engineering ceramics, only super-hard tool materials (diamonds) can be competent. For the rough machining process of ceramics, polycrystalline diamond tools are generally selected. Polycrystalline diamond tools are made of artificial diamond particles sintered under high temperature and high pressure. They are not easy to be damaged by impact or vibration, and are suitable for roughing ceramic materials. For the finishing of ceramic materials, natural single crystal diamond tools are used for micro-cutting (with a small cutting depth and feed). Natural single crystal diamond cutting tools have sharp cutting edges, high hardness, and wear resistance 10 times that of alumina ceramics. The thermal wear during cutting is very small, which can ensure high dimensional accuracy and surface finish of ceramic materials. At the same time, it is also used for other difficult-to-machine parts such as slotting and curved surface contouring. Ceramic milling: Good processing surface quality plays an important role in reducing surface defects, improving part strength and assembly accuracy, reducing friction and wear, and prolonging the service life of ceramic parts. At this time, superhard milling cutters have become the best for ceramic parts milling select. Processing ceramic parts: For machining

96 alumina ceramic substrate is a kind of ceramics widely used in structural ceramics. Because it has excellent electrical properties at high frequencies, its dielectric loss is small, volume resistivity is large, strength is high, hardness is large, linear expansion coefficient is small, and wear resistance and heat resistance are also very good. The 96 alumina ceramic substrate is a special ceramic sheet made of Al2O3 as the main raw material, rare metal oxide as a flux, and roasted at a temperature of more than one thousand degrees. The 96 alumina ceramic refers to the oxidation with a content of 96% Aluminum ceramic substrate. 96 alumina ceramic substrate performance characteristics: 1. High hardness As measured by the Shanghai Institute of Ceramics, the Chinese Academy of Sciences, its Rockwell hardness is HRA80-90, second only to diamond in hardness, far exceeding the wear resistance of wear-resistant steel and stainless steel. 2. Excellent wear resistance As measured by the Powder Metallurgy Research Institute of Zhongnan Polytechnic University, its wear resistance is 266 times that of manganese steel and 171.5 times that of high-chromium cast iron. According to our customer tracking survey for more than ten years, under the same working conditions, the service life of the equipment can be extended by at least ten times. 3. Light weight Its density is 3.5g/cm3, which is only half of that of steel, which can greatly reduce the equipment load. 4. Wide application For example, coal, conveying systems,

The preparation technology of Si3N4 ceramics has developed rapidly in the past few years. The preparation processes mainly focus on the types of reaction sintering method, hot pressing sintering method, normal pressure sintering method, and air pressure sintering method. Due to the different preparation processes, various types of silicon nitride ceramics have Different microstructures (such as porosity and pore morphology, grain morphology, intergranular morphology, and intercrystalline second phase content, etc.). Therefore, the performance varies greatly. To obtain Si3N4 ceramic materials with excellent performance, first of all, high-quality Si3N4 powders should be prepared. The quality of Si3N4 powders prepared by different methods is not completely the same, which leads to the difference in their uses. Many ceramic materials have failed to apply, often blamed Because developers do not understand the differences between various ceramic powders, they have insufficient knowledge of their properties. In general, high-quality Si3N4 powder should have the characteristics of high alpha phase content, uniform composition, less impurities and even distribution in ceramics, small particle size and narrow particle size distribution, and good dispersion. The α-phase of good Si3N4 powder should account for at least 90%. This is because during the sintering process of Si3N4, part of the α-phase will be transformed into β-phase, and without sufficient α-phase content, the strength of the ceramic material will be reduced. Reaction Sintering (RS) It is a general molding method, first pressing silicon powder into a green body of the desired shape, and putting it into a nitriding furnace for pre-nitriding (partial nitriding) sintering process. The pre-nitrided green body has a certain strength and can be Carry out various mechanical processes (such as turning

Electric vacuum ceramics include oxide ceramics, silicate ceramics, nitride ceramics, etc. The oxide ceramics include alumina (Al2O3) ceramics, beryllium oxide (BeO) ceramics, magnesium oxide (MgO) ceramics, zirconia (&02) ceramics, and the like. The main component of oxide ceramics is a single oxide crystal, the crystal phase has high purity and less glass phase. The purity of raw materials is high and the sintering temperature is high. Therefore, the electrical, thermal and mechanical properties of oxide ceramics are better. Among the electric vacuum ceramics, the amount of alumina ceramics is the most. According to the difference in Al2O3 content, alumina ceramics can be divided into 75 porcelain with Al2O3 content of 75%, 95 porcelain with Al2O3 content of 92-97%, 99 porcelain with Al2O3 content of 99%, and Al2O3 content of 99.9% Transparent corundum porcelain, etc. Among them, 95 porcelain and 99 porcelain are most widely used. Because ceramics are much superior to glass in mechanical properties, physical and chemical properties, modern electric vacuum devices have increasingly used ceramics to replace glass as insulating materials. The microwave tube is due to its special requirements such as high working frequency and very bad working environment. Now almost no exceptions have adopted metal-ceramic structure. The realization of the metal-ceramic structure first depends on the hermetic connection of the metal material and the ceramic, which is called sealing. Metal-ceramic sealing is developed on the basis of metal brazing technology, but unlike metal and metal brazing, solder cannot infiltrate the ceramic surface, and therefore cannot directly connect ceramic and metal. In order to solve the problem of solder and ceramic wetting, after years of research, people have summarized two methods: ceramic metallization and active metal method. The former is to coat a ceramic layer on the surface of the ceramic with a strong metal lay

With the continuous advancement of processing technology and the increasing level of technology, the cost of ceramic bearings has been declining. It has been applied in a small range of high, fine, and sharp fields from the past, and has been gradually extended to various industrial sectors of the national economy. It is also gradually approaching practicality, reaching a level acceptable to users, and the wave of large-scale application of ceramic bearings has come! Ceramic bearing use classification 1. High-speed bearings: It has the advantages of cold resistance, low stress elasticity, high pressure resistance, poor thermal conductivity, light weight, low friction coefficient, etc. It can be applied to high-speed spindles of 12,000 rpm-75,000 rpm and other high-precision Equipment. 2. High temperature bearing: The material itself has a high temperature resistance of 1200 ℃, and has good self-lubrication. The use temperature does not produce expansion due to temperature difference between 100 ℃ and 800 ℃. It can be used in high-temperature equipment such as furnaces, plastics, steel, etc. 3. Corrosion-resistant bearings: The material itself has corrosion-resistant characteristics, and can be used in the fields of strong acids, strong alkalis, inorganics, organic salts, seawater, and other fields, such as: electroplating equipment, electronic equipment, chemical machinery, shipbuilding, medical equipment, etc. 4. Anti-magnetic bearing: Because it is non-magnetic, it does not absorb dust, which can reduce the peeling of the bearing surface, thereby reducing the operating noise. Can be used in demagnetizing equipment. Precision instruments and other fields. 5. Electrically

Heat treatment of brass Brass is a copper-zinc alloy, with a bright golden yellow luster on the surface, high corrosion resistance in the atmosphere, fresh water and sea water, good strength, wear resistance, heat resistance, electrical conductivity, thermal conductivity It has high plasticity, good cold and hot pressure processing performance, can be welded, brazed and cold cut, and can be strengthened by heat treatment. There are 11 varieties of ordinary brass, the main purpose: H59, H62, H63 aluminum alloy quenching furnace agent, H65 brass is used to manufacture hardware daily necessities, screws, nuts, pins, anchors, cushion rolls, springs, screens, Radiator, various deep extension force parts, welding parts, hot punching and hot rolling parts, etc.; H68, H68A, H70 brass are used to manufacture complex cold drawn parts and deep drawn parts, such as radiator shell, duct, bellows , Bullet casings, detonators, etc.; H80, H85 brass are used to make paper nets, thin-walled tubes, and house building supplies; H90, H96 brass are used to manufacture conduits, condensation tubes, radiator tubes, automobile water tanks, drain pipes, conductive Parts, medals, artworks, etc. Brass plays an increasingly important role in the rapidly developing machinery manufacturing industry. Selected representative H59, H62, H68, H96 four kinds of brass for analysis, test and research, and the H box-type resistance furnace price of 62 brass for cryogenic treatment strengthening test, and achieved practical results. The chemical composition, organization and performance of brass Brass is Cu-zN alloy, and its structure is (a+8) two-phase structure. Zn can dissolve into Cu to form a solid solution. Above 456 ℃, its solubility increases with the temperature drop; at 456 ℃, the s

Ceramic coatings have developed rapidly in recent years. Due to their excellent fire resistance, good scratch resistance, durability, stain resistance, high decorativeness, and green environmental protection, they are gradually recognized by the metal curtain wall industry. Especially in crowded public places, underground works, and places with high fire rating requirements, ceramic coatings have their unique advantages. At present, the application of ceramic coatings in the decoration of aluminum veneer mainly has three major areas: first, rail transit locomotive interior panels; second, subway stations, high-speed rail stations, airports, tunnel projects and other public transportation areas; third, high-end business buildings, shopping malls, Hospitals and other architectural fields. At present, in the curtain wall ceramic coating market, the amount of ceramic coatings for locomotive interior panels accounts for about 20%; the amount of aluminum veneer ceramic coatings for subway stations, high-speed rail stations, airports, and tunnel engineering accounts for about 50%-60%, of which tunnel engineering is nearly There have been cases of applying ceramic metal plates for two years. Although the proportion is not large, the market prospect of ceramic coatings in tunnel engineering is very broad. In the field of locomotive interior panels, high-speed rail and Harmony trains, due to their high driving speed, are considered to be lightweight composite panels and do not use metal aluminum plates because of their own weight. Therefore, the focus of ceramic coatings on locomotive interior panels is For subway locomotives, at present, about 20% of the newly-built subway locomotives are coated with metal aluminum plates coated with ceramic coatings. Considering that the application of ceramic coatings on locomotive interior panels has on

Silicon nitride (Si3N4) is a compound of nitrogen and silicon. In nature, nitrogen and silicon are extremely common elements, and they are ubiquitous in the world we live in. However, no compound of these two elements has yet been found in nature. At present, all silicon nitrides are synthesized under artificial conditions. Silicon nitride ceramics are prepared by sintering inorganic powder, and the research process is very difficult. As early as 140 years ago, people directly synthesized silicon nitride, but it was not until the mid-1970s that they really produced high-quality, low-cost, widely used silicon nitride ceramic products. In the preparation of silicon nitride ceramics, the preparation, sintering of silicon nitride ceramic powders and the toughening and strengthening of ceramic bodies are the key technical points in the preparation of silicon nitride ceramics. Due to different preparation processes, various types of silicon nitride ceramics have different microstructures (such as porosity and pore morphology, grain morphology, intergranular morphology, and intercrystalline second phase content, etc.). Therefore, the performance varies greatly. To obtain silicon nitride ceramic materials with excellent performance, first of all, high-quality silicon nitride powder should be prepared. The quality of silicon nitride powder prepared by different methods is not exactly the same, which leads to the difference in its use. Many properties of silicon nitride are due to its structure. The crystal structure of silicon nitride has three kinds of crystal structures: α, β and γ. The α phase will undergo a phase change at high temperature. This phase change is irreversible and is beneficial to sintering. Therefore, high-quality silicon nitride powder should have the characteristics of high alpha phase content, uniform composition, less impurities and

1. Dry press molding Figure the dry press molding machine. Dry compression molding (axial compression molding) is to add AlN powder pre-treated with surfactant modification to the metal mold, and slowly apply pressure to make it into a compact green body molding process. The essence is to rely on the external pressure to rely on the interaction force between the AlN powder particles to keep the green body in a certain shape and high density. The green body is conducive to ceramic sintering, which can reduce the sintering temperature and increase the ceramic density. Because AlN powder is easily hydrolyzed, the water-polyvinyl alcohol (PVA) commonly used in dry press molding cannot be used for the compression of AlN powder. Paraffin and organic solvents can be used instead. Advantages: The dry press molding method is easy to operate, has few process links and high efficiency. Disadvantages: It is not possible to suppress the blanks of complex geometry; it is necessary to strictly control the pressure, too large or too small are not conducive to obtaining high-density AlN ceramic sintered parts. 2. Isostatic Pressing Isostatic pressing is an improved method of traditional dry pressing method. The AlN powder is placed in a high-pressure container, and the powder is placed in an elastic material using the incompressibility of the liquid and the characteristics of liquid to pressure transmission. In the manufactured molding die, the method is to uniformly press the powder to be pressed from different directions, and pressurize the die with a liquid to form the green body. Advantages: The compact has high density, uniform density distribution, and can be molded near the net size. Disadvantages: The molding equipment is expensive and there are mold release problems, which limits its application to large-scale industrial production. 3. Casting m

Before being sintered, the ceramic green body is composed of many single solid particles. There are a lot of pores in the green body, and the porosity is generally 35%~60% (that is, the relative density of the green body is 40%~65%). The value depends on the characteristics of the powder itself and the molding method and technology used. When the solid green body is heated at a high temperature, the particles in the green body migrate, and the body shrinks after reaching a certain temperature, and the grain grows, accompanied by the elimination of pores, and finally at a temperature below the melting point (generally at (0.5 to 0.7 times the melting point) The green body becomes a dense polycrystalline ceramic material. This process is called sintering. Conventional sintering The conventional heating method is generally used, which is carried out in a traditional electric furnace, and it is currently the most commonly used sintering method in the production of ceramic materials. Because pure ceramic materials are sometimes difficult to sinter, some sintering aids are usually introduced under the conditions that allow performance, in order to form part of a low-melting solid solution, glass phase or other liquid phase to promote the rearrangement of particles and viscous flow to obtain Dense products can also reduce the sintering temperature. Hot press sintering Hot pressing sintering adopts a special hot pressing machine, which is completed by single-phase or two-phase pressing at high temperature. The interaction of temperature and pressure strengthens the viscosity and plastic flow of the particles, which is conducive to the compaction of the blank, and products with almost no pores can be obtai

The grinding performance of cubic boron nitride abrasive tools is very good, not only can be used to process difficult-to-grind materials, improve productivity, but also help to strictly control the shape and dimensional accuracy of the workpiece, but also effectively improve the grinding quality of the workpiece and significantly improve The surface integrity of the workpiece after grinding improves the fatigue strength of the parts, extends the service life, and increases the reliability. In addition, the cubic boron nitride abrasive production process is better than ordinary abrasive production in terms of energy consumption and environmental pollution. Therefore, expanding the production and application of cubic boron nitride abrasive tools is mechanical application and an inevitable trend in the development of the machinery industry. 1. Sharpening and rough grinding of tungsten, tungsten and molybdenum and other high speed steels, especially vanadium alloy steel, cobalt alloy steel, special high speed steel cutters. 2. Precision grinding and final grinding of precision parts made of heat-resistant steel, stainless steel and high-hardness alloy structural steel. When these parts are used with ordinary abrasive tools, the abrasive tools are consumed or blunt too quickly, and high accuracy cannot be obtained. 3. Grinding of various material parts sensitive to local thermal stress and thermal shock. 4. Fine grinding and final grinding of large precision workpieces (machine tool guide rails, high-precision machine screws). These workpieces often cause large thermal deformation due to the high grinding temperature, which fails to achieve high accuracy. 5. Fine grinding and final grinding of workpieces (parts of instrument

1. Creep is the first. The structural parts of alumina ceramics under high temperature, when subjected to external force, will continuously and slowly appear plastic deformation due to the increase of time, so we can call it creep . However, when the creep of alumina ceramic structural parts is related to stress or temperature, when the stress increases or the temperature continues to increase, the creep rate will continue to increase. 2. Graphitization and spheroidization, under the action of high temperature, the cementite contained in the structural parts of alumina ceramics will gather or migrate due to the large energy obtained, and will be transformed into coarse grains Cementite is intercalated in ferrite, and cementite will also gradually change from flaky to spherical, we can call it spheroidization. Because graphite is very low in strength, and it is mainly in the form of flakes, resulting in a great reduction in the strength of the material, and the brittleness will also increase, so it can be called graphitization. 3. The performance of thermal fatigue. If the structural parts of alumina ceramics are alternated between cold and hot for a long time, the changes in the internal temperature difference of the material will appear due to the effect of thermal stress. Rupture phenomenon. Therefore, when working under the condition of fluctuating temperature, the fatigue performance of its structural parts should be considered.