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The effects of MCMB ultrafine powder and its forming process on the properties of sinter

This work adopts the thermal analysis and scanning electron microscope (sem) analysis method to study the powder characteristics and moulding technology affect the performance of blank forming and sintering body, and the material defects are briefly analyzed.

2. The preparation of the MCMB ultrafine powder was put into the 2L stainless steel reaction caldron, and in the closed state, the thermal condensation reaction was carried out and stirred continuously. After the reaction, the natural cooling to room temperature, and the product containing MCMB. Then thermal polycondensation reaction the products in the soxhlet extractor using toluene isotropic matrix components, was isolated by acetone washing, drying mesophase carbon microspheres, then through sieving to obtain ultrafine powder of MCMB, observed under scanning electron microscopy (sem), its size is about 0.1 Mm ~ said take a suitable amount of MCMB superfine powder into the steel mold, vanda QY10 type hydraulic press in Shanghai from 80 mpa to 240 mpa pressure forming is 60 mmx10mmx3mm cattle billet.

Will die after the density of the body into the tubular coking furnace, under N2 protection to 1 ° C/min ~ 5 C/min heating rate of the heat off 1 item by zhejiang green or aromatic fused ring compounds by liquid phase carbonization of mesophase carbon microspheres (MCMB) itself has cohesiveness, after can be directly moulded or isostatic pressing molding, since I became a high density sintered isotropic carbon materials (HDIC), eliminating the traditional kneading, repeatedly impregnated graphite products for production and roasting process, is the excellent raw material preparation HDIC. The fine structure density, high strength carbon materials with good mechanical properties, thermal conductivity, conductive and isotropic characteristics and application in the hot-pressing mold, metal continuous casting crystallizer and semiconductor production using crucible container, fuel cell, double plate and nuclear reactor core structure materials, and other areas of the modern advanced technology.

This experiment is based on the particle size far smaller than the ultrafine powder of MCMB (5 b 111 ~ 50 p 111), which is based on its special properties. Due to the physical and chemical structure of the powder, the defect formation and mechanical properties of the material are directly determined. M1-28 repair back to date: the 2004-04-10 fund project: the national natural science fund project (50172034 ° c), constant temperature for 1 h ~ 3 h, appropriate cooling rate to control 1 ° Qmin ~ 3 ° Qmin, until after cooling, sintered products. 2.4 samples test powder thermal analysis: use island ferry TA - 50 type thermal analyzer, under 20 ml/minN2 protection atmosphere, with 15 ° C/min speed, within the scope of the room temperature to 1000 ° C, the powder thermo-gravimetric analysis (TGA) and differential thermal analysis (DTA). Universal testing machine, with three point bending method (GB 1994-80) determination of its flexural strength, the speed is 0.1 mm/min. The flexural strength according to the following formula: (3) body for microstructure analysis: the raw materials and specimen section after spraying gold, in Philip XL - 30 type of scanning electron microscope (SEM) on the morphology and structure was observed.

3 results and discussion 3.1 MCMB ultrafine powder thermal analysis for MCMB superfine powder heat loss and differential thermal analysis curve. Sample at 100 ° C to 200 ° C or so of weightlessness is smaller due to the adsorption of water, small molecules in MCMB powder impurities such as volatile; Corresponds to the DTA curve of 400 ° C before samples slightly endothermic phenomenon is the MCMB powders, including what - resin on the surface of the particles, melting and light component part of volatile evolution and molecular rearrangement, etc. TGA curves showed that the powder of weightlessness significantly began in about 550 ° C, liquid phase disappearing solid-phase carbonization, thermal decomposition of MCMB surface molecules and thermal polycondensation reaction, a large number of small molecules such as hydrogen, such as paraffin removal, breaking and peripheral atoms and groups are excluded, 3.2 reunited powder characteristics influence on sinter strength, approximate spherical or ellipsoidal particles, particle size is about 0.1 m to 0.5 m, is isotropic zhejiang green in mother liquor, the early growth of colloidal particles.

MCMB were adhered on the surface of the ultrafine powder of bonding effect of small molecules, and makes it have good from caking, forming uniform structure can be obtained after firing, the bending strength of up to 134.3 MPa carbonized samples (see table 1).

According to the diffusion theory of powder sintering, the sintering process is a process of transition to low energy, the higher the excess surface of the pre-sintered granule system can be, the more the sintering activity is, and the more densification. Carbon 197 carbon in Japan. Introduction to new carbon materials. Specialized (lv yongen, ling, wu, etc. Using suspension to prepare micron spheres from asphalt and resin. New carbon materials, 2 for 1, li fu tiger shen zengmin, xue acute sheng, etc. Emulsion legal preparation of intermediate carbon microspheres for the study of gao yan, song huaihe, Chen xiaohong. The effect of oxidation treatment on the properties of carbon microspheres in the middle phase of asphalt. New carbon material, 2. Theory of powder sintering.

Study on Production Technology of 40 Million Ton of Water - atomized Iron and Steel Powder Production Line

High-pressure water atomization method is an important production method for the production of iron powder. Because of the advantages of uniform composition, compactness and good moldability, the powder metallurgy structure parts produced by water atomization method are widely used in automobile , Motorcycle, home appliances and other industries. Water atomization milling technology is the key to high-performance nozzle design, atomization process parameters selected, dehydration drying process equipment and product variety system perfect.

Powder metallurgy parts in the application of each car China's powder metallurgy parts in the car on the application of the United States, Europe, Japan, as shown in the comparison. It can be seen that in 2002, the United States each car on the use of powder metallurgy parts have reached more than 18kg, while China is only about 5kg.

60% ~ 70% of the output of powder metallurgy parts in developed countries is used in the automobile industry, while China only 30% 40% .2001 world steel powder sales amounted to 860,000 1, which water atomization production of powder accounted for 40% ~ 50%. At present, the world's major steel powder production lines have large-scale water atomization production line, and production capacity are at an annual output of 60,000 t or more. Sweden's Hingner uses a 55t EBT furnace steel refining and furnace refining, plate V-type nozzle atomization, the annual output of about 150,000 t; Canada Quebec company using pure high-carbon hot metal as raw material, in 56t In the converter smelting into steel, part of the low-carbon steel into the ladle refining furnace, adding alloy to adjust the chemical composition after the atomization, the water atomization of pure powder and steel powder production of 200,000 t / a. Japan Kobe Corporation Is the largest steel powder production enterprises in Asia, the use of 30t tapping steel arc furnace smelting, tapping directly after the atomization, the annual output of about 72,000 t, Japan's Kawasaki companies rely on the parent company's steelmaking advantages, Kawasaki iron 300t converter in the extraction of 100t molten steel for ladle refining furnace, after the completion of refining pressure water atomization, with an annual output of 40,000 tons of water fog powder (its production capacity is not fully play).

China's water atomized steel powder production started late, and foreign advanced level difference between the larger, as of the end of 2002, China's water atomized steel powder production total of 25,000 t or so, built by the water atomized steel powder production line mostly foreign The company invests in the construction or introduction of the line. Due to the small scale of production, the level of technical equipment and foreign companies have a certain gap, resulting in high production costs, small profit margins, poor quality and stability. Therefore, the use of independent technology to build large-scale steel powder production line, the efficiency of the production quality and stability of the water atomized steel powder has become China's iron and steel powder industry development priorities.

2 Laiwu Steel Group Powder Metallurgy Co., Ltd. Annual production of 40,000 tons of water atomized steel powder production line Overview 000t / a water atomized steel powder production line on the basis of Laiwu Steel Group Powder Metallurgy Co., Ltd. in early 2002 began to invest in an annual output of 40,000 T water atomized steel powder production line, the entire production line overall planning, ancillary equipment and steelmaking, atomization, raw powder processing system by an annual output of 80,000 t design, sequencing processing line with an annual output of 40,000 t design. After 14 months of construction, in February 2003 gradually put into normal production.

3 production process and technical equipment with an annual output of more than 10,000 tons of water atomization powder production line construction in the country for the first time, no mature experience available in the production line construction process, the design and construction personnel to Japan Kobe, Kawasaki, Sweden Hagnas company field trips, drawing on the experience of foreign advanced manufacturers, breaking the original ideas, in the process to determine the equipment selection, process parameters, such as the adjustment of a number of innovations.

3.1 Process Flow Laiwu Steel Group Powder Metallurgy Co., Ltd. can produce five kinds of iron and alloy steel powder, the process flow are: water atomization of pure iron powder production process pressure water scrap - smelting - atomization - dehydration drying - grading life Powder Treatment - Magnetic Separate Treatment Crushing - Grading - Combination - Packaging - Pure Iron Powder Water Atomized Alloy Steel Powder Production Process High Pressure Water I Smelting Atomization - Dehydration - Drying - Classification - Reduction Processing - Crushing - Grading Batch Powder Alloy Diffusion Alloy Steel Powder Production Process Water Fog Pure Iron Powder 丨 Mixing One Diffusion Treatment - Crushing - Classification One Batch One Package - Diffused Alloy Steel Powder Alloy Element 1 No Segregation Mixed Powder Production Process Bonding Ingredients Water atomization Pure iron powder 丨 I Mixing - Anti-segregation treatment - Packaging No segregation Mixed powder Trace element Free cutting steel powder Production process Binder Water atomization Pure iron powder 丨 1 Micro-element mixture A anti-segregation treatment - Packaging - Easy-to-cut steel powder easy cutting additive I 3.2 Steelmaking The steelmaking system uses a 20t EBT electric furnace with a tapping capacity to match the 20t steel ladle refining furnace. The advantages of using the above process equipment are as follows.

EBT electric furnace for the bottom of the tapping, slag operation, steelmaking process of the reduction period in the ladle refining furnace, the smelting time significantly reduced production efficiency further mention. At present, the output of single furnace up to 18 tons of steel up to 8 steel ladle refining furnace argon mixing, can make the chemical composition of molten steel more uniform and pure, powder impurities to further reduce the chemical composition more uniform. The chemical composition shown in Table 1.

Table 1 The chemical composition of raw powder requirements Hydrogen loss due to large-capacity ladle refining furnace temperature drop speed, so that the steel from the original 1700 or so reduced to about 1600, smelting power consumption and refractory consumption significantly reduced.

LF refining furnace equipment (three-phase single arm) Process parameters: 775A; electrode diameter 250mm; polar circle diameter 460mm. 3.3 atomization atomization system part of the introduction of foreign advanced equipment, the use of four-point spray atomization nozzle, atomization speed 400kg / min or more, so that the atomization cycle control within 60min or less, to avoid the atomization process due to lower temperature of molten steel caused by poor atomization, energy consumption is too large and so on. The atomization pressure, water flow and nozzle angle of the atomization system are adjustable. The atomization pressure can be adjusted from 6MPa to 12MPa. After several production tests, the powder company has worked out the powder particle size, loose density And other physical properties and the relationship between atomization water pressure, water flow, nozzle angle, molten steel temperature and other parameters, summed up the different uses of different production processes. 3.4 dehydration after the dewatering system using wet magnetic separator as the first level of dehydration equipment, the use of internal filter vacuum dewatering machine as the second level of dehydration equipment. The use of wet magnetic separator can be removed during the process of steelmaking into the powder of mechanical inclusions and non-metallic impurities, improve the purity of the powder. And the combination of two kinds of dehydration equipment can greatly mention the processing capacity of the dehydration system, so that the water content of dehydrated wet powder reduced to below 8%.

3.S atomization of water treatment of water with softened water treated by the two, and by two filters, the first level of filtration for the 150wn, the main role for the filter out the metal particles in the water, the second filter for the production of Israel 25um filter Device, you can filter out the vast majority of suspended solids and powder, to ensure the purity of water.

Table 2 Analysis of water after treatment test items Conductivity / ((uSim1) total hardness (calcium carbonate V (mg.L, pH test results 3.6 atomization powder processing powder drying system using indirect heating dryer , The powder transport layer and the heating layer isolation, and in which a certain flow of nitrogen, in order to avoid the powder drying process of oxidation. Powder by cooling, magnetic separation, after screening to ensure that each batch of powder Uniformity and consistency.

After the batch of raw powder into the reduction process, the reduction process using German imports of large steel belt reduction furnace to decompose ammonia as a protective atmosphere to ensure that the powder after the reduction of the performance indicators to meet the requirements.

4 powder performance comparison (Table 3) Table 3 Comparison of the product and the international similar products Chemical composition /% Physical - Process performance Variety of grades Hydrogen loss of mobility is small. (In the wide pre-30 powder Germany Mannesmann MSP-2 men's 30 pure iron powder 28 Japan Kobe 300M carry on 30 diffuse carry on 26 gold powder Sweden hegenas foreheadAB 30 5 summary Laiwu Steel 40,000 tons of water atomized steel powder production line The construction of a series of iron and steel powder to solve the technical problems of large-scale production, the formation of a set of advanced, applicable and reliable technology and equipment.The technical information of the project can be used to guide the domestic water atomization of steel powder plant construction, The international competitiveness of China's powder metallurgy enterprises has great potential.

Yangzhou lide company breakthrough powder metallurgy key core technology

Yangzhou lide powder metallurgy co., Ltd. Has been led by Chen baisheng, the managing director of infiniti co., LTD., and has made various cooperation intentions.

Founded in 1997, khalid company, started as a low-end products "workshop" type of small business, after 10 years of unremitting efforts, now has become the international influential specialized is engaged in the automobile shock absorber of powder metallurgy parts development and production of high-tech enterprises, as the first "new three board" for yangzhou listed enterprises.

Powder metallurgy is an important branch in the field of new materials, but high-end powder metallurgy has been monopolized by foreign countries. To this end, lide works with the research team of Beijing university of science and technology to target the key core technologies in the field of powder metallurgy, focusing on the implementation of the powder formula. Khalid company established a special yangzhou engineering technology research center of powder metallurgy products, powder metallurgy experts were hired to the company technical guidance, with the Beijing university of science and technology of powder metallurgy research institute of the united team. After thousands of times of trial and error, finally figured out a set of complete with independent intellectual property rights of iron powder self-lubrication processing preparation technology, successfully developed a set of high density, high precision, high performance, can in a long time to maintain a larger performance, cost-effective advantage of high precision iron-based powder metallurgy parts.

At present, khalid company has formed the car shock absorber 100 million with an annual output of the production capacity of powder metallurgy parts, for the automotive, motorcycle, electric tools, household appliances and other industries, open the steam and 2 of the high-end market, also passed the TS16949 international automotive industry's highest quality management system certification, won the special passes to the international high-end market, the company's sales growth for three consecutive years by more than 30%.

China makes the world's largest CNC machine tool

China makes the world's largest CNC machine tool, break the western blockade! Nc machine tool is the abbreviation of digital control machine tool, which is an automatic machine tool equipped with programmed control system. Nc machine tools is better solved the precision, complex, small batch and many varieties of parts processing, is a kind of flexible, highly efficient automation of machine tools, represents the development direction of modern machine tool control technology, is a typical mechatronics product.

In recent years China's equipment manufacturing industry developing rapidly, beiping machine tool for a new product to get the attention of the world, it is nine shaft five linkage machine tool, in addition to this, wuhan heavy duty machine tool group in China, built the world's largest CNC horizontal machine tools. The machine weighs 1,450 tons and produces the world's largest spiral pulp of 106.3 tons and 9.1 meters in diameter. Shanghai machine tool factory has developed the world's largest CNC roll grinder, which marks the advanced level of China's heavy-duty high-precision CNC machine tools. Tsinghua university and nanjing quarto electronics company teamed up with the development of five-axis linkage laser processing machine tools, precision is equivalent to one over seventy of a human hair, this is only the size of the cash register machine tool, can high machining accuracy requirement of heart stents and other medical equipment.

Now in the high-end machine localization has reached more than 70%, even five axis nc machine tool export success in Germany, dalian machine tool to seventh place in the global machine tool sorting, beiping machine tool overall acquisition of Germany set up for nearly a century of the resistance of the machine tool, marks our no longer subject to other countries in the field of precision machining, multi-axis linkage machine tool technology confidentiality has always been the western countries, the west for the embargo on the Soviet union in the 1980 s and trade restrictions, it is said that the Soviet union from Toshiba company imported a five axis four five linkage machine tool, by decoding machine tool software, enhance the level of the Soviet union multi-axis nc machine tools software, and used in the manufacture of nuclear submarine propeller, the noise is greatly reduced. Even in 1986, when a soviet-american nuclear submarine collided in the straits of Gibraltar, the sudden threat raised alarms in the west, forcing Japan to arrest the responsible person for a trading machine. Our country now develops nine axis five linkage machine tools, compared with the five axis five linkage machine tool in Toshiba incident more advanced. The nine axis refers to the machining of a part from nine directions, such as the horizontal axis and the vertical axis. The five linkage means that the five directions can be carried out simultaneously. Initially create a pentagon common machine tool for processing five times, five and nine axis linkage machine tool at a time, nine shaft five linkage used military-industrial complex, aerospace and aviation, etc, especially suitable for ship and submarine propeller propulsion, such as aircraft engine blade impeller parts processing. It is a microcosm of the level of precision machinery and equipment in a country.

the founding of new China's heavy industry is still a blank, let alone have the capacity of production of machine tools, weapons, relies on to buy and imitation, in order to reverse the passive situation, since the founding of the "key, the machine tool industry development in our country but the western countries have been neck for us, we not only purchasing channel is not smooth, and must accept GuoChanShang outside of the so-called" end user access "harsh conditions, the foreign party to obtain the numerical control machine tool of the end-use, usage, such as intelligence, easy to cause leaks. In order to get rid of its power of control, China has launched a policy to enter the ranks of manufacturing powers by 2025. Today we have the opportunity to compete with Germany on the launch of the nine-to-five linkage machine. , of course, we also there is a big gap with foreign countries in the field of machine tools, some of the features most need to rely on foreign countries, this is mainly related to our late on related technologies, but even so, the gap is also in a little narrow, the machine tool industry in China is like space engineering, construction engineering, hydraulics, give some time we will grow stronger! For China's machine tool industry, we will wait and see, one day, the whole world will be amazed!