Degree of orientation to upgrade technology
Improve the degree of orientation in two ways, first, the orientation of increasing molding field, the second is added to slurry dispersant.
¡¡¡¡Rientation field of high technology
Ferrite grains in the magnetic field
can be expressed as the force suffered F¦Ì H2A,H-Oriented field,AForce for the grain surface area. Magnetic particle size are reported in the literature0.95¦Ìm, The orientation field480kA / m (6000 Oe)Orientation can be saturated, while the magnetic particle size0.67¦ÌmWhen needed915kA / m (11500Oe)The magnetic field orientation can be saturated. High-performance, especiallyFB6Performance of the above series of finely ground sintered ferrite grain size required0.7¦ÌmThe following, therefore the market demand-oriented800kA / m (10000Oe)Above. JapanTDKRepresented by foreign enterprises in the production of hard ferrite1990Years ago, on the use of orientation field800kA / m (10000 Oe)Presses the production of more thanFB6Series Hard Ferrite, China about2001By the Group have developed western Sichuan8~1010000 ampere-turn water-cooled magnetic field presses,2002Since ferrite gradually some domestic manufacturers to use,2003There were individual enterprises out of small batch productionFB6Series of permanent magnetic ferrite
¡¡¡¡ Dispersant Technology
Ferrite grains in the concentration of slurry is the ferrite grain orientation in a magnetic field arranged in an important reason for reducing the slurry pool in the ferrite powder, ferrite powder can reduce the coercivity and adding dispersant to achieve.
Literature abroad[4,8]Reported that the use of ethanol, toluene, ethylbenzene, heptane and other organic solvents as the grinding media, the use of carboxylic acids and carboxylic acid salts such as stearic acid, stearic acid, calcium (barium, strontium, magnesium, aluminum, zinc), glycerol 3 oleic acid ester, glycerol 3 olein calcium (barium, strontium, magnesium, aluminum, zinc), etc. as dispersing agent addition can also be used sulfuric acid ester and its salts, phosphoric acid ester and its salts as dispersing agent These dispersion agent in finely ground powder weight ratio, press the0.5~5%To join, can effectively reduce the magnetic cohesion. The use of this technology can produceBr = 0.44T(4400G),Hcj = 318 ~ 335kA / m (4000 ~ 4200Oe), Degree of orientation reached98%High-performance sintered ferrite.
Abroad there are also reported in the literature[5, 9, 10]The use of water for grinding media, containing various sugars, such as carboxyl hydrophilic carboxymethyl cellulose, gluconic acid, calcium gluconate, sorbitol, ascorbic acid, etc., and poly-carboxylic acid and poly-carboxylic acid salt as dispersing agent, Similarly, the orientation degree can be reached98%The sintered ferrite.
¡¡¡¡ Special Technology
¡¡¡¡ TDKCompany produces high-performance(FB9Series)Ferrite process not only includesLa-Co,La-ZnAdd technology, grading grinding technology, dispersing agent technology, the most advanced technology, but also adopt more specific technology, there should be a brief introduction of their production process.
Sintered Permanent Ferrite production of the traditional process of (most of our ferrite production units use this process): mixing¡úPre-sintering¡úCoarse grinding¡úGrind¡úPressed¡úSintering¡úGrinding¡úTest¡úPackaging.
Production of high performance ferrite (FB9Series), a special process for the[5, 11]: Mixture¡úPre-sintering¡úCoarse grinding¡úGrind¡úDrying or dehydration¡úMixing¡úPressed¡úDecarbonization¡úSintering¡úGrinding¡úTest¡úPackaging. Special process and are more traditional process of drying or dehydration, mixing, decarburization three processes. In order to obtain high-performance sintered ferrite, ferrite pre-burning materials to fine grinding to0.4 ~ 0.6¦ÌmIn this granular slurry under the molding difficulties, in order to solve the problem first with the dry molding equipment or equipment will be fine abrasive slurry centrifugal dry or dehydrated, and then dry powder mixing with the kneading machine. First, the purpose of mixing with the kneading machine shearing force will gather the ferrite particles dispersed in order to facilitate orientation; another purpose mixing process by adding water to the wet-forming; there is a purpose of mixing dispersants are added to make dispersants and full access to reduce the magnetic powder to enhance the orientation degree of cohesion. After mixing and add the water and dispersing agent in the magnetic field of magnetic wet-forming and after going to the100~500¡æCarried out under the decarbonization (ie, off dispersing agent) treatment. In addition to special process to increase three processes, the mixing of raw materials used, rough grinding, fine grinding process with the traditional process are also some differences. Special process of iron-containing raw materials used inSiO2 <0.1%, Particle size<1¦Ìm, A narrow particle size distribution of iron red (Fe2O3), The traditional craft of iron-containing raw materials used in iron scales, iron red, concentrate powder. When the mixture by adding a special process La-Co, Traditional process withoutLa-Co. Special process using coarse grinding vibration grinding mill surge Sorter winnowing only guaranteed meal particle size and particle size distribution, and can effectively reduce the coercivity and the meal after the fine grinding powder cohesion, so as to achieve increased orientation degree of purpose. The traditional process of rough grinding no special control. Special process using a continuous graded abrasive fine grinding process, which guarantees the magnetic powder has a narrow particle size distribution.
Production of high performance ferrite need for integration, such asLa-CoAdd, grain control, dispersant of new technologies, meal winnowing classification, dehydration, mixing and other new technology, high-field press, at the bottom of a continuous feed sanding machines and other new equipment.