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Amorphous & Nanocrystalline
Metglas® is an amorphous metal, Amorphous metals do not have crystalline structure like other magnetic materials. All the atoms in an amorphous metal are randomly arranged, thus giving it a higher resistivity (about three times) value than that for crystalline counterparts. Amorphous alloys are prepared by cooling the melt at about million degrees per second. This fast cooling does not give the atoms enough time to rearrange into stable crystalline form. As a result one gets metastable amorphous structure. Because of the absence of crystalline structure amorphous alloys are magnetically soft (lower coercivity, lower core loss, higher permeability). High resistivity gives lower loss at higher frequencies. The losses are among the lowest of any known magnetic materials.Get more news about Nanocrystalline core,you can vist our website!
Nanocrystalline or Finemet® Nanocrystalline - The precursor of FINEMET® Nanocrystalline is amorphous ribbon (non-crystalline) obtained by rapid quenching at one million °C/second from the molten metal consisting of Fe, Si, B and small amounts of Cu and Nb. These crystallized alloys have grains which are extremely uniform and small, "about ten nanometers in size". Amorphous metals which contain certain alloy elements show superior soft magnetic properties through crystallization. It was commonly known that the characteristics of soft magnetic materials are "larger crystal grains yield better soft magnetic properties". Contrary to this common belief, soft magnetic material consisting of a small, "nano-order", crystal grains have excellent soft magnetic properties.
It is well known that the higher CT core permeability, the lower measurement error & higher measurement accuracy. The silicon steel CT core can’t meet measurement accuracy under the situation of low Ampere-tums or small turn ratios. And the Fe-Ni Permalloy core’s application are limited because of their low Saturate induction and high cost. Nano-crystalline cores are getting wider usage for the 0.2，0.2s, 0.1 accuracy grade precious current transformers because of its high permeability, high magnetization and lower cost in the field of power supply systems, power energy measurement and controlling systems, dynamical system, relay protection, etc.
Amorphous and nanocrystalline Cores
nanoThe improvement of electromagnetic characteristics of materials used for coils manufacturing is one of important and emerged areas in modern electronics. Among such improvement methods one can note the creation of new composite materials based on soft magnetic alloys. These material are widely applied in matching, high-frequency and power transformers, as well as in current sensors and represent complicated multicomponent system. A chemical composition of soft magnetic alloys with two -phase structure is Fe73,5CuNb3Si13,5B9. Ribbons with amorphous structure characterized by the absence of a long-range order in atoms arrangement are obtained from a material melting by spinning or a flat jet methods. The melt falling from the slot of the nozzle on the rotating drum surface, is being cooled, then it solidifies, thus forming a ribbon with an amorphous structure. The ribbon's thickness is ordinary 25 ± 5 µm. In order to achieve the required magnetic properties at the second technological stage, an amorphous ribbon is thermally being treated at high temperatures. As a result of operation carried out at a temperature of not less than 600 °C, the partial crystallization occurs and nucleating centers of the iron silicide phase (α-Fe-Si) are formed.Get more news about Nanocrystalline core,you can vist our website!
Thus, a distinctive feature of such materials is the presence in their composition of both the amorphous component and a certain fraction of the crystalline phase. The crystallites size in such alloys is 10–20 nm; therefore, these materials are often called nanocrystalline. Depending on the composition of the alloy, the percentage phase ratio may vary. As a rule, the proportion of the crystalline structure prevails.
The introduction of such addings as Si and B into alloys content allows an amorphous structure forming, while niobium ions inhibit the growth of grains at higher operating temperatures. In addition to niobium ions, additives of other metals, such as Zr, Mo, Hf, Ta, W can be used to reduce crystallites size. The introduction of copper ions leads to the formation of a large number of crystallization centers.
nanoThe figure shows a schematic representation of an alloy structure with two phases.
To improve the magnetic characteristics and significantly reduce the magnetostriction, a partial removing of iron atoms with aluminum is being carried out. Moreover, due to the distribution of nanoscale crystalline granules in the amorphous matrix in such alloys: very high values of magnetic permeability, a small values of coercive force , and the saturation induction (Bs) is 0.8 ... 1.2 T (Bs) are achieved.
of metal atoms occurs in a random pattern and is used in lieu of conventional Regular Grain Oriented (RGO) silicon steel. RGO has an organized grain structure with much higher resistance to magnetization cycles, which leads to higher core losses.Get more news about Amorphous core,you can vist our website!
Amorphous metal – A technological advantage Amorphous metal (AM) enables a significant reduction in no-load losses as compared to RGO, up to 70 percent lower as noted in the table for representative liquid-filled transformer designs.
Studies have also shown benefits from AM in the presence of harmonics or integer multiples of the power frequency (50 or 60 Hz). When non-linear loads (eg, rotating machines) are present, they cause the current and voltage waveforms to distort, causing harmonics which increase losses in the transformer and reduce power quality. However, these harmonics losses are reduced in an AMDT. This translates into operating savings across a variety of resistive and inductive loads.
The much lower losses of the AMDT result in significant energy and monetary savings over the lifetime of the transformer.
Amorphous transformer manufacturers in India and other countries make these transformers by applying a special method to create the core. In the conventional transformers, the core is made up of metals. Metals get heated during the magnetization and demagnetization processes. As a result, a portion of the electric energy is wasted as heat energy. An amorphous metal core transformer has the core made up of some alloys. Amorphous transformer core materials are mixed together in molten stage and then are super cooled. The process is very similar to making glasses. So, the amorphous transformer manufacturers call the amorphous metal distribution transformer as the Metallic Glass Transformer as well. When the metals used for the core are crystalline, they produce more heat. With the specially made amorphous alloy distribution transformer, the core is not crystalline. This means, the transformer produces less heat during load. When the loss is super low, this type of transformer is called super low loss amorphous transformer.
The applications and advantages of an amorphous distribution transformer are ample. Amorphous iron transformer core has high magnetic susceptibility and high electrical resistance. Amorphous transformers in India are either imported or manufactured locally by amorphous core transformer manufacturers in India. These are made with a ferromagnetic amorphous metal as the core. The mixture of iron, silicon and boron give the core very low coercivity. The two kinds of losses are heavily reduced with an amorphous core transformer. When there is no load, the loss is called the no load loss. This is mainly due the core of the transformer heating up.
With the non-crystalline metal alloys, the loss is reduced to more than 70%. The other type of loss is called the copper loss; this is when the transformer is under heavy load. A typical amorphous core transformer (AMT) has less copper than the conventional transformers. Due to this fact, an AMT can have less efficiency at full load. To compensate this, more copper and core materials are added to making energy efficient AMTs. This is why they are expensive than the traditional ones. The bigger the size of the transformer, the more the copper windings are needed.These are used mainly in the grid distribution systems. There are some specialized electric motors that operate under high frequencies which would use these transformers as well. Rajasthan Powergen Transformer P. Ltd. is one of the leading amorphous core transformer manufacturers in India.