Some industrial applications of amorphous and nanocrystalline alloys

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Some industrial applications of amorphous and nanocrystalline alloys
V K Nosenko, V V Maslov, V V Kirilchuk, A P Kochkubey G.V. Kurdymov Institute for Metal Physics of National Academy of Sciences of Ukraine, 36 Vernadsky Str., 03142, Kyiv, Ukraine
E-mail: [email protected]
Abstract. The example of successful realization of developments of Institute for Metal Physics of National Academy of Sciences of Ukraine in the field of nanotechnology is organization and successful, during 14 years, functioning of production of modern precision amorphous and nanocrystalline magnetic cores in the frames of the small research-and-production enterprise MELTA Ltd. The most important, from the practical standpoint, high heat-time stability of initial magnetic permeability of cores is provided by using new methods of final treatment of cores, minimization of their package influence on characteristics of the process using liquid impregnation heat-resistant materials and new polymeric coatings. The most effective fields of industrial use of MELTAâ magnetic cores are ground leakage current sensors, current measuring transformers (converters), power medium frequency, broadband and pulse small- size transformers, filter chokes, reactors, storage transformers and ferroprobes.
Instrument-making, electro- and radio engineering enterprises occupy important place in the economic complex of Ukraine. It is known that manufacture of corresponding products by these enterprises is connected today with import of absolute majority of necessary soft magnetic materials such as transformer steel, various marks of permalloys, permendures as well as amorphous alloys not produced till recently in Ukraine. Its development at metallurgical giants of the country can not be considered as expedient taking into account large capital investments for their technical re-equipment as well as necessity to arrange a precision rolling technology for production of sheet steel and special alloys. At the same time Ukraine possesses considerable resources and production of iron, silicon and ferroalloys - feed stock for possible production of precision amorphous and nanocrystalline alloys with development of corresponding technological complexes at relatively small special-purpose enterprises. The example of successful realization (commercialization) of developments of Institute for Metal Physics of National Academy of Sciences of Ukraine in the field of nanotechnology is organization and successful (more than 14 years) production of modern precision amorphous and nanocrystalline magnetic cores in the frames of the small research-and-production enterprise MELTA Ltd.
Manufacturing application of developments of IMP of NAS of Ukraine and production of new precision rapid quenched alloys and products on their basis considerably decreased need of the country for import of semi-finished products and valuable raw, allowed to raise competitive capacity of goods on foreign markets and ensured employment at organization of manufacture of absolutely new products for industry of Ukraine.
13th International Conference on Liquid and Amorphous Metals IOP Publishing Journal of Physics: Conference Series 98 (2008) 072016 doi:10.1088/1742-6596/98/7/072016
c© 2008 IOP Publishing Ltd 1
Figure 1. Amorphous ribbon production process.
MELTAâ toroidal, U-shaped and rod magnetic cores (figure 2) are used in electronic and electrical equipment in frequency range from 10 Hz up to 1-3 MHz at ambient temperature from -60 up to +1300 and in separate cases up to +1500 at relative humidity up to 98% at 350.
Figure 2. Amorphous and nanocrystalline tape wound cores.
Special advantages of magnetic cores made of MM alloys are magnetostriction close to zero, high initial (1500 - 160000) magnetic permeability and extraordinarily low level of core losses. Various special treatments of finished cores allow obtaining both linear (flat) and nearly square remagnetization loops depending on use. In that case field of BS achievement can vary from 5 up to 2500 A/m. Main characteristics of the produced alloys (and, respectively, magnetic cores) are presented in Tables 1, 2. High-permeability magnetic cores allowed a number of enterprises to develop
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production of new competitive kinds of products such as electronic single- and three-phase electricity meters, compact welding apparatuses, precision measuring transformers and sensors, protective circuit breakers (PCB) at earth leakage current appearance, converters for electric transport and others.
Table 1. Main characteristics of soft magnetic alloys: Alloy MM-2 MM-4 MM-1N MM-11N MM-3Co MM-5Co
Basic component of the alloy Fe Fe Fe Fe Co Co Density, g, g/cm3 7.3 7.6 7.4 7.35 7.7 7.7 Electrical resistivity, r, Wmm2/m 1.25 1.30 1.15 1.20 1.30 1.35 TC of resistivity (20-200 OC), 10-4/K 1.8 2.0 1.1 1.0 1.1 0.8 Crystallization temperature (heating rate 20 K/s), OC
510 480 500 510 510 540
Continuous service temperature, OC 120 100 130 130 90 105
Table 2. Magnetic properties (Typical values)
Nr Alloy MM-2 MM-4 MM-
1N MM- 11N
MM- 3Co
MM- 5Co
1 Saturation induction, BS, T ³1.45 ³1.28 ³1.25 ³1.2 ³0.52 ³0.46 2 Curie temperature, TC, 0C 390 300 600 600 180 160 3 Magnetostriction, ´ 106 <24 <20 <1.5 <1.0 <1 <0.5 4 Static coercive force, HC,
mA/cm £30 £20 £6 £5 £4 £2
5 Initial magnetic permeability at f=1kHz, (H=1mA/cm) ³
7000 12000 30000 - 80000
6 Initial magnetic permeability at f=40 kHz, (H=1mA/cm)
5000 7000 20000 - 40000
£10 £8 £5 £4 £6 £3
8 Core losses, PFe , W/kg, (0.3T / 100 kHz)
£180 £130 £110 £100 £110 £90
Extreme operating conditions of control systems, information transfer (telecommunication) systems as well as control and measuring systems are high and low temperatures, abrupt temperature drops, large mechanical load and radiation as well as, especially, their possible combined action. For reliable and stable operation of abovementioned systems the necessary condition is high heat-time stability of characteristics of their inductive components. Precision alloys conventionally used for their manufacture have both advantages and disadvantages. Tape wound permalloy and supermalloy cores are characterized by high values of magnetic permeability, but they are very sensitive to mechanical load. Typical frequency range of their use does not exceed 20 kHz because of small electrical resistance. Specific remagnetization loss PFe in permalloy cores increases by 50% at high and low temperatures.
Magnetodielectrics (composite powder permalloys and sendust) have high heat-time stability of properties, but very low initial magnetic permeability that doesn’t allow their use in high-frequency, pulse and broadband high class transformers, particularly at manufacture of high-inductive components of minimum dimensions
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Ferrites have low values of magnetic permeability and Curie temperature as well as are characterized by essentially nonlinear temperature dependence of magnetic characteristics. So, their magnetic permeability change typically by 3-4 times in temperature range of use and moreover values of PFe considerably vary.
New nanocrystalline magnetic cores made of MM-1N and MM-11N alloys have evident advantages over conventional crystalline analogues (Figure 3). Magnetic properties of these alloys developed in IMP of NAS of Ukraine are determined by their nanocrystalline (5-12 nm) structure obtained by controlled heat-time treatment crystallization of amorphous ribbons of Fe-Nb-Cu-Si-B alloys with possible other additions. So called single domain nanocrystalline ribbon structure possesses:
· high heat stability (high Curie temperature 6000, high crystallization temperature 5000);
· high heat stability PFe; PFe exhibits even slight negative temperature coefficient in wide temperature range;
· high saturation induction – 1.25 , which also slightly changes (£ 15%) in temperature range -60 - +1300;
· low (typical for amorphous Co based alloys) coercive force and saturation magnetostriction £0,5 ppm
Figure 3. Saturation flux density as a function of temperature.
The most important, from the practical viewpoint, high heat-time stability of initial magnetic permeability of cores (figure 4) is ensured by
· careful optimization of alloy chemical composition; · use of modern (new) methods of final treatment of cores (HMT, rapid quenching etc.); · minimization of core packing (incapsulation) influence (use of liquid impregnation
heat-resistant materials and new polymeric coatings);
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Figure 4. Temperature stability of initial permeability m of cores made of nanocrystalline MM-11N alloy.
The most prevalent fields of use of MELTAâ magnetic cores: 1. Current measuring transformers (converters), industrial current transformers, earth leakage
current sensors (MM-1N, MM-11N, MM-5Co alloys). 2. Magnetic amplifiers, magnetic keys, saturation chokes (MM-11N, MM-3Co, MM-5Co alloys). 3. Power transformers, broadband transformers, pulse small-size transformers (MM-1N, MM-
11N, MM-2, MM-4 alloys). 4. Filter chokes, reactors, storage transformers (MM-11N, MM-2, MM-4 alloys). 5. Magnetic shields (MM-4, MM-3Co, MM-5Co alloys). 6. Induction sensors and ferroprobes (MM-1N, MM-11N, MM-5Co alloys).
Characteristics of MELTAâ magnetic cores and examples of their use are presented in 12 Technical Bulletins and separate brochures of MELTA Ltd.
Main consumers of tape wound amorphous and nanocrystalline magnetic cores today are: NPO “Kiev-Pribor”, OAO “ENERGOTERM” (Vinnitsa), Chmelnitsk high-voltage network (OAO “Energy supplying company “CHMELNITSK-OBLENERGO”), Lviv Center of Space Research Institute of NKAU-NASU, Petrovsky Kiev automatic plant, GP “Plant “Burevestnik” (Kiev), GP “Dniepropetrovsk research-and-production complex “Electrovozostroenie”, NPO “CHARTRON” (Charkov), OAO “Zaporozhtransformator”, OAO “Electroizmeritel”.
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Some industrial applications of amorphous and nanocrystalline alloys