Custom Soft Magnetic Materials and Transformer Core Manufacturers in China

Comparison of Amorphous and Nanocrystalline Alloys

by:Transmart     2022-07-28

Iron-based amorphous alloys are competing with silicon steel in the power frequency and medium frequency fields. Compared with silicon steel, iron-based amorphous alloys have the following advantages and disadvantages.​​

1) The saturation magnetic flux density Bs of iron-based amorphous alloys is lower than that of silicon steels.
However, under the same Bm, the loss of Fe-based amorphous alloy is smaller than that of 0.23mm thick 3% silicon steel. It is generally believed that the reason for the small loss is that the iron-based amorphous alloy strip has a thin thickness and high resistivity. This is only one aspect. The main reason is that the iron-based amorphous alloy is amorphous, and the atomic arrangement is random. There is no magnetocrystalline anisotropy caused by the atomic orientation, and there is no crystallographic anisotropy that produces local deformation and composition shift. grain boundaries. Therefore, the energy barrier that hinders the movement of the domain wall and the rotation of the magnetic moment is very small, and it has unprecedented soft magnetic properties, so the magnetic permeability is high, the coercive force is small, and the loss is low.​​
2) The filling factor of the iron-based amorphous alloy core is 0.84 to 0.86

3) The working magnetic flux density of the iron-based amorphous alloy core is 1.35T~1.40T, and the silicon steel is 1.6T~1.7T. The weight of iron-based amorphous alloy power frequency transformer is about 130% of that of silicon steel power frequency transformer. However, even if the weight is heavy, for a power frequency transformer of the same capacity, the loss of the iron-based amorphous alloy for the magnetic core is 70% to 80% lower than that of the silicon steel.​​

4) Considering the loss, the total evaluation price is 89%. Assume that the load loss (copper loss) of the power frequency transformer is the same, and the load rate is also 50%. Then, to make the iron loss of the silicon steel power frequency transformer the same as that of the iron-based amorphous alloy power frequency transformer, the weight of the silicon steel transformer is 1 to 8 times that of the iron-based amorphous alloy transformer. Therefore, the weight, cost and price of iron-based amorphous alloy power frequency transformers that are generally recognized by domestic people aside from the loss level of transformers are 130% to 150% of those of silicon steel power frequency transformers, which do not meet market requirements. The principle of cost performance. Two comparison methods have been proposed abroad. One is to find out the weight and price of the copper-iron materials used in the two power frequency transformers under the same loss conditions and compare them. Another method is to reduce the wattage of the loss of the iron-based amorphous alloy power frequency transformer and convert it into currency for compensation. The no-load loss per watt is equivalent to USD 5-11, which is equivalent to RMB 42-92. The load loss per watt is equivalent to US$0.7-1.0, equivalent to RMB 6-8.3. For example, a silicon steel magnetic core for a 50Hz, 5kVA single-phase transformer is quoted at 1700 yuan/unit; no-load loss of 28W, calculated at 60 yuan/W, is 1680 yuan; load loss of 110W, calculated at 8 yuan/W, is 880 yuan; then, the total evaluation price is 4260 yuan / set. Using iron-based amorphous alloy magnetic core, the quotation is 2500 yuan/set; the no-load loss is 6W, which is equivalent to 360 yuan; the load loss is 110W, which is equivalent to 880 yuan. The total evaluation price is 3740 yuan/set. If the loss is not considered, the 5kVA iron-based amorphous alloy power frequency transformer is 147% of the silicon steel power frequency transformer. If the wear and tear is considered, the total assessed value is 89%.​​

5) Iron-based amorphous alloys have stronger ability to resist power waveform distortion than silicon steel. Now the core material loss of power frequency power transformers is tested under the sine wave voltage whose distortion is less than 2%. The actual power frequency grid distortion is 5%. In this case, the iron-based amorphous alloy loss increases to 106% and the silicon steel loss increases to 123%. If the higher harmonics are large and the distortion is 75% (such as power frequency rectifier transformer), the loss of iron-based amorphous alloy increases to 160%, and the loss of silicon steel increases to more than 300%. It shows that the iron-based amorphous alloy has stronger resistance to power waveform distortion than silicon steel.​​

6) The magnetostrictive coefficient of iron-based amorphous alloy is 3 to 5 times that of silicon steel. Therefore, the noise of the iron-based amorphous alloy power frequency transformer is 120% of the noise of the silicon steel power frequency transformer, which is 3 to 5dB larger.​​

7) The price of iron-based amorphous alloy strip is 150% of that of 0.23mm3% oriented silicon steel. In the current market, it is about 40% of that of 0.15mm3% oriented silicon steel (after special treatment).​​

8) The annealing temperature of iron-based amorphous alloy is lower than that of silicon steel The annealing temperature of iron-based amorphous alloy is lower than that of silicon steel, and the energy consumption is small, and the iron-based amorphous alloy magnetic core is generally manufactured by specialized factories. Silicon steel cores are generally manufactured by transformer manufacturers.
According to the above comparison, as long as a certain production scale is reached, iron-based amorphous alloys will replace part of the silicon steel market in electronic transformers within the power frequency range. In the intermediate frequency range of 400Hz to 10kHz, even if new silicon steel varieties appear, iron-based amorphous alloys will still replace most of the silicon steel market with a thickness of less than 0.15mm.
It is worth noting that Japan is vigorously developing FeMB series amorphous alloys and nanocrystalline alloys. Its Bs can reach 1.7-1.8T, and the loss is less than 50% of the existing FeSiB series amorphous alloys. If it is used in power frequency electronic transformers , the working magnetic flux density reaches more than 1.5T, and the loss is only 10% to 15% of the silicon steel power frequency transformer, which will be a more powerful competitor of the silicon steel power frequency transformer. It is estimated that in 2005, Japan will be able to successfully trial-manufacture FeMB series amorphous alloy power frequency transformers and put them into production.​​

Amorphous nanocrystalline alloys are competing with soft ferrites in the medium and high frequency fields. In electronic transformers from 10kHz to 50kHz, the working magnetic flux density of iron-based nanocrystalline alloys can reach 0.5T, and the loss P0.5/20k≤25W/kg. Therefore, it has obvious advantages in high-power electronic transformers. In electronic transformers from 50kHz to 100kHz, the loss P0.2/100k of iron-based nanocrystalline alloys is 30 to 75W/kg
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