High performance ferrite production technology discusstion

Y33H-2 permanent magnetic ferrite have been listed in one of key products in 2003 according to the project No.2003ED810043, which is also put into the project “guideline of high-tech industry for development priority in some important area during 2001-2005” complied by China planned committees and information department and the project” main hortative products and industry and technical directory currently” by china planned committees and china foreign trade committee.(edition of 2000). Therefore, it is fully according with industry police, which is also a key project of development in the tenth “ five-years program”. Successful development and mass production will efficiently push to advancing technical level of West China and prompt the development for west China. Technical data of this kind of material have been equivalent same as FB6B of TDK Inc from Japan internationally, which is also on top in country. That directly represent for the whole permanent magnetic ferrite.

Prompt technical development widens the application area for high grade permanent magnetic ferrite. To follow up the development trend of world, the center of manufacture magnet material is steadily shift to developing country like china. Especially for these years, this trend is more and more obvious, which is not only a chance but also a challenge for further development in permanent ferrite industry. As well as know, labor force of our country is overmuch( the cost of worker to be low), and material and energy is sufficient(mile reserve rank top in the world), but the low lever product take up a great share for product makeup。The higher grades product including FB6 is nearly monopolized by Japan and other several developed countries for production. To improve the technical level of magnetic material as well magnetic application especially to the level of permanent magnet ferrite and artwork, shorten the gap with developed country, acquire the economic and social utility, our company bear the new project Y33H-2 of 2003 (R&D and application to permanent magnet ferrite).

key technical index for project:

  • Br=(420+/-10)Mt
  • Hcb=(300+/-15)ka/m
  • Hcj=(320+/-15)KA/m
  • (BH)max=(33.4+/-1.6)kj/m3

Main topics to realize the project

  1. Improve the artwork of sinter and make higher saturation magnetization strength of pre-sintered material
  2. Milling technical of powder(balling manufacture technical),which is possible to make distribution of particle size up to normal school, secondary mixing to be helpful to advance Br and Hcj
  3. To improve compact of product and balance the product structure by some proper additive
  4. To optimize molding technical and improve magnetization orientation and density of raw product
  5. To optimize sinter technical and control the temperature of sinter, keep particle growth equally with fine microstructure

By continuous testing, it gets the mixture of material up to final upbreak and achieve great improvement in artwork (such as powdering in balling artwork, especially in keeping compound of slurry equal, the magnetization orientation during product molding, as well as secondary sinter artwork).

Key technology to finalize project

  1. Solidifying physical is much enough to mold a M shape hexangular crystal structure.
  2. Improve Hcj though magnetic compound isotropic and anisotropic
  3. Lessen comparison to fine magnetic compound
  4. Optimize mould and product tropism

Testing and technical analysis during R&D of project

  1. Sufficient solidifying physical, shaping fine M shape of hexangular crystal structure
  2. Firstly, it is necessary to choose active Fe2O3. It is better if microstructure of Fe2O3 is ball shape of compound, best for virgulate shape. Secondary, there are moderate Ca2+ and SO42- in the Strontium carbonate, of course, it is as better as lower. Thirdly, saturation magnetic strength of presinter material is related to presinter temperature and heat preservation. Presinter temperature should be matched for heat preservation and material, which depended on activity and compound of material.

  3. Milling
  4. Time of milling has a great influence to Hcj of permanent ferrite material, so it should reach the requested particle size shortly.

    Cycle of milling can be shortened by adjust the ration of material, ball and water, which distribution achieve further improvement, magnet of material take a great advancing. Shape meliorate will be help to low the rate of average compound further, reduce the flaw of crystal and push the property of magnet property advancing further.

    Secondary mixing, that is to say, mix through mix moderate impurity such as CaCO3, SrCO3, SiO2, Cr2O3 and by hydronium alternative of rare earth.

    CaCO3: mix minim CaCO3, which is helpful to melt and increase magnet density and Hc and lead to solidify physical with low melt point.

    The melting point of SiO2 up to 1728 degree C, which enable conduct reaction with Fe2O3 under special conditions and create Fe Siliceous adhered to crystal—tended to be antiblastic and improve Hcj. However, redundant Fe Siliceous will be bad to the property of magnet on the contrary as non-magnet substance.

    SrCO3 tends to break down for SrO, moderation of which will create much of liquid substance and surround the crystal under secondary sinter, which is enable accelerate the compacted reaction of liquid substance. The Br of material is higher as good as the compact of product is higher.

  5. Optimize the molding artwork and improve the tropism of product
  6. Hydrous rate of Slurry at 50% is ideal, If the rate is higher, then it is hard to molding and without avail to property of material. The density of raw products not only directly effect surface quality of product, also it tends to be effected for the property of material much more at a range, especially for Br. It is necessary that take magnetic distribution into consider fully while making mould. Besides, the initial permeability should be min 3000Oe, and final permeability over 8000Oe, which can hit the excellent tropism of crystal. It is very useful at assistance of pulse to magnetic field during molding.

  7. In fact, Secondary sinter is a solidifying physical reaction, its reaction extent presents inverse rate with the size of compound reactant—r2; which just need to reach the range of molding and would be good as small as possible. Besides this, the solidify reaction is relating to sinter temperature and attemptation and shape of product
  8. Testing result
  9. The following property of productions is available through testing by quality controls & inspection center of information industry department under 20 °C working temperature.

    Parameter
    Number
    Br(Mt)
    Hcb(kA/m)
    Hcj(kA/m)
    (BH)max(kj/m3)
    Y33H-2
    1
    416
    292.9
    318.5
    32.8
    2
    413
    293.8
    319.4
    32.4
    3
    414
    295.5
    324.3
    32.5
    4
    415
    298.6
    325.4
    33.1
    5
    418
    301.2
    328.1
    33.8

Project fruit and application

The basic target of setting up project is to bring the fruit of technical development into productivity, finalizing mass production to obtain the great economy utility. Therefore, the core of job is to put project into industrializing.

It brings up the sales return 5.96 million and foreign exchange USD0.18 million and direct profit 1.2 million by project industrializing. It was widely applied on the motor of electric information, automobile and motorcar. The mass production not only improves the level of the whole industry but also further advance manufacture technical innovation and upgraded in these area. It plays an important role to prompt development of these industries with great range.

It shows that the growing speed is soaring for main area where high grade permanent ferrite Y33H-2 apply on, which leads to greatly widening the application range and profit space according the information from anywhere. In our country, the sales return of information industry has broken up 1800 billions on 2003 with up 30% comparison with last year. Export value of electronic products part broke up 100 billion dollars and come to 140 billon dollar. Sales of automobiles reach to 4.39 million sets with up 30% (total cars sales turnover account to 1.97 million, which take up 44.87% on the whole), the turnout reach 4.22 million sets with up 34%, both turnout and turnover for automobile broke up 4 million sets. GDP of our country reach 11,669.4 billion with up 9.1%in this year, equivalent to USD1,400 billion. Per capita income broke up USD1000 firstly and come up to USD1090. Such promising situation like this is undoubtedly establish an excellent fundament for industrious development of our country, and take a good chance to permanent ferrite industry especially for high grade material like Y33H-2. As authorized professional estimation, the demands of electrical components will be about USD300 billion in 2005. About 150-180 billion are contributed by new fashioned items. Products values of domestic demands will be around 300 billion RMB, it takes up about 160 billion for new fashioned items. The sales revenue of electric industry will finish near 1350 billion estimated with up to 30%, accordingly total profit up to 35 billion with upto 30%.

Magnetic material will have a further development for high grade material, whose demands will become larger. It is estimated that the demand of permanent magnetic ferrite will reach 2.21 million tons in 2005, only the products used for automobile and loudspeakers area will increase from 0.15 million tons to 0.25 million tons. Besides, the price of magnetic material will higher, which will be raised up by 10%-20%. Undoubtedly, the spring of high grade magnetic ferrite Y33H-2 and application are coming for us.