Patent Application
20210198761
This application claims the priority of Chinese Patent Application No. 201710060830.7, filed on Jan. 25, 2017, and titled with “IRON-BASED AMORPHOUS ALLOY AND METHOD FOR PREPARING THE SAME”, and the disclosures of which are hereby incorporated by reference.
The present invention relates to the field of soft magnetic material, specifically to an iron-based amorphous alloy and method for preparing the same.
Iron-based amorphous strip is a new energy-saving material prepared by rapid solidification technology which is used in transformer core. Comparing with conventional silicon steel transformer, it is pretty easy to be magnetized, therefore dramatically decreasing no-load loss of the transformer. If it is used in oil-immersed transformer, emission of harmful gases such as CO, SO, and NOx will be reduced, so it is called “green material of 21st century”.
At present, in the process of preparing amorphous transformer both domestic and abroad, iron-based amorphous strip which has a saturation magnetic induction of about 1.56 T is widely used. Comparing with silicon steel which has a saturation magnetic induction of nearly 2.0 T, transformer made from iron-based amorphous material has disadvantage of large volume. In order to improve competitive power of iron-based amorphous material in transformer manufacturing industry, iron-based amorphous material with saturation magnetic induction above 1.6 T is in need to be developed.
The research and development on amorphous material with high saturation magnetic induction has been carried out for many years. The most representative one is an alloy named Metglas2605Co developed by Allied-Signal in America. The saturation magnetic induction of the alloy reached 1.8 T. But the alloy contains 18% of element Co, giving the alloy an extremely high cost and cannot be used in industry production.
In a Chinese Patent Application (Publication No. CN1721563A), Hitachi Metals. Ltd. disclosed a Fe—Si—B—C alloy named HB1, which has a saturation magnetic induction of 1.64 T. However, the disclosed process conditions includes a process comprising blowing C-contained gases to control the C percentage on the surface of the strip making it difficult to control the process conditions during product production, and hard to ensure the stability of industrial production.
Nippon Steel & Sumitomo Metal disclosed a Fe—Si—B—P—C alloy in patent No. CN1356403A. Although it has a saturation magnetic induction of 1.75 T, the unduly high Fe percentage of it leads to poor glass forming ability, making the formation of amorphous phase in industrial production impossible, and the magnetic property of the strip is bad. In addition, on one hand the patent does not mention the addition of P element; on the other hand, P element is added in a large amount. Considering the fact of ferrophosphorous industry both domestic and abroad, the preparation conditions of ferrophosphorous are not so controlled strictly and the percentage of impurities in the ferrophosphorous is too high, which cannot meet the service requirements of amorphous alloy. In preparation process, using a large amount of ferrophosphorous under normal condition will cause crystallization and embrittlement of strip and the performances after heat treatment is worse. If this kind of alloy is used in industrial production, ferrophosphorous refining must be carried out, which on one hand increases complexity of the process, on the other hand, smelting level should be optimized, increasing the production difficulties.
The technical problem solved by the present disclosure aims to provide an iron-based amorphous alloy and method for preparing the same. The iron-based amorphous alloy provided by the present disclosure has a high saturation magnetic induction, glass forming ability and low loss.
In view of above, the present disclosure provides an iron-based amorphous alloy as shown in formula (I):
FeaSibBcPdMe (I);
wherein a, b, c, d and e are each independently atomic percentages of corresponding components; 80.5≤a≤84.0, 3.0≤b≤9.0, 8.0≤c≤15.0, 0.001≤d≤0.3, e≤0.4, a+b+c+d+e=100; M is impurity element.
Preferably, saturation magnetic induction of the iron-based amorphous alloy is ≥1.62 T.
Preferably, atomic percentage of Si is 5.5≤b≤9.0.
Preferably, atomic percentage of P is 0.001≤d≤0.2.
Preferably, atomic percentage of P is 0.01≤d≤0.1.
Preferably, in the iron-based amorphous alloy, a=80.95, 3.0≤b≤8.0, 11.0≤c≤15.0, d=0.05.
Preferably, in the iron-based amorphous alloy, 81.7≤a≤81.99, 3.0≤b≤8.0, 10.0≤c≤15.0, 0.01≤d≤0.3.
Preferably, in the iron-based amorphous alloy, a=82.95, 3.0≤b≤8.0, 8.0≤c≤14.0, d=0.05.
Preferably, in the iron-based amorphous alloy, a=83.95, 3.0≤b≤8.0, 8.0≤c≤13.0, d=0.05.
The present disclosure also provides method for preparing the iron-based amorphous alloy, comprising:
calculating and preparing raw materials according to the atomic percentage indicated in the iron-based amorphous alloy formula FeaSibBcPd; melting the raw materials; heating and insulating the molten materials; performing single roller rapid quenching to give an iron-based amorphous alloy strip.
Preferably, after the single roller rapid quenching, the method further comprises: performing heat treatment on the iron-based amorphous alloy strip.
Preferably, temperature for the heat treatment is from 300 to 360° C., insulation duration of the heat treatment is from 60 to 120 min, and magnetic field strength is from 800 to 1400 A/m.
Preferably, coercive force of the heat treated iron-based amorphous alloy strip is ≤4 A/m; under condition of 50 Hz and 1.35 T, excitation power of the heat treated iron-based amorphous alloy strip is less than or equals to 0.2200 VA/kg, and core loss is ≤0.1800 W/kg.
Preferably, the iron-based amorphous alloy strip is in completely amorphous phase with a critical thickness of at least 45 μm.
Preferably, thickness of the iron-based amorphous alloy strip is from 23 to 32 μm and width is from 100 to 300 mm.
The present application provides an iron-based amorphous alloy as shown in formula FeaSibBcPdMe, comprising Fe, Si, B and P. Therein, Fe element, which functions as ferromagnetic element, is the main magnetism source of iron-based amorphous alloy, ensuring high saturation magnetic induction of amorphous alloy. Si and B are amorphous forming elements and an appropriate amount of which ensures good glass forming ability of the iron-based amorphous alloy. P element is also amorphous forming element and an appropriate amount of P element gives amorphous alloy good glass forming ability, ensuring the magnetic properties of amorphous alloy. P element can also improve the fluidity of molten alloy and reduce the pouring temperature in the preparation process, therefore reduce the difficulty of preparation. Further, in the process of iron-based amorphous alloy preparation, the present application further improves comprehensive magnetic properties of iron-based amorphous alloy by defining heating temperature and insulation duration of heat treatment and magnetic field strength.
In order to understand the present disclosure better, the preferred embodiments of the present disclosure is described hereinafter in conjunction with the examples of the present disclosure. It is to be understood that the description is merely illustrating the characters and advantages of the present disclosure, and is not intended to limit the claims of the present application.
The present disclosure provides an iron-based amorphous alloy as shown in formula (I):
FeaSibBcPdMe (I);
wherein a, b, c, d, and e are each independently atomic percentages of corresponding components; 80.5≤a≤84.0, 3.0≤b≤9.0, 8.0≤c≤15.0, 0.001≤d≤0.3, e≤0.4, and a+b+c+d+e=100; M is impurity element.
In the present application, the chemical formula of the iron-based amorphous alloy is FeaSibBcPdMe by atomic percentage, wherein M is the unavoidable impurity element; atomic percentages of a, b, c, and d are: 80.5≤a≤84.0, 3.0≤b≤9.0, 8.0≤c≤15.0, 0.001≤d≤0.3; the rest is e: e≤0.4. By adding the above elements and defining the atomic percentage of the same, the iron-based amorphous alloy obtains good comprehensive magnetic properties.
Specifically, in the iron-based amorphous alloy, Fe is ferromagnetic element, which is the main magnetism source of the iron-based amorphous alloy. High Fe percentage is important for ensuring high saturation magnetic induction of the iron-based amorphous alloy. In the present application, atomic percentage of Fe is from 80.5 to 84.0. In the examples, the atomic percentage of Fe is from 80.95 to 83.95; more specifically, the atomic percentage of Fe is from 81.5 to 82.5; even more specifically, the atomic percentage of Fe is 81.15, 81.35, 81.5, 81.7, 81.99, 82.05, 82.15, 82.30, 82.45, 82.65, 82.80, 82.95, 83.25, 83.55 or 83.95. If the percentage of Fe is above 83.0, the glass forming ability of alloy will decrease, making it hard to realize the industrial production.
The Si element and B element are amorphous forming element, which are necessary conditions for the formation of amorphous alloy system under industrial production condition. In the present application, the percentage of Si is from 3.0 to 9.0. In the examples, the percentage of Si is from 5.5 to 9.0; more specifically, the percentage of Si is 5.5, 6.0, 6.5, 6.8, 7, 7.2, 7.8, 8.0, 8.5 or 9.0. When the atomic percentage of Si is above 9.0, eutectic point is deviated and the glass forming ability also decreases. When the percentage of Si is less than 3.0, the glass forming ability of the alloy is decreased and the magnetic properties of strip are influenced. In the present application, the percentage of B is from 8.0 to 15.0; in specific examples, the percentage of B is 13.7≤c≤14.7; in specific examples, the percentage of B is 8.0, 8.5, 9.0, 9.5, 10.0, 10.8, 11.0, 11.2, 11.8, 12.0, 12.7, 13.0, 13.6 or 14.0. When the atomic percentage of B is above 16.0, the alloy components deviate from the eutectic point, causing the decrease of glass forming ability of the alloy.
P is also an amorphous forming element. But in the present application, adding a trace amount of P element mainly aims to improve the fluidity of molten alloy, decreasing the pouring temperature in the preparation process and reducing the preparation difficulty. In actual industrial production process, addition of P element is realized by adding ferrophosphorus. However, the quality of domestic ferrophosphorus production is not high, adding it in a large amount will introduce mass amount of impurities into the molten steel, dramatically decreasing the quality of the molten steel. This not only influences the preparation success rate of the iron-based amorphous alloy strip, making it hard for the strip to form amorphous phase, but also influences the magnetic properties of the amorphous alloy strip. Large amount of impurities are included and solidified in the strip, forming extreme point of internal defect in the strip, which has pinning effect on magnetic domain in heat treatment process, leading to deterioration of magnetic properties. Therefore, in the present disclosure, atomic percentage of P is from 0.001 to 0.3; in specific examples, the percentage of P is from 0.001 to 0.2; further, the percentage of P is from 0.01 to 0.1.
M represents impurity element and the content of M is preferred as low as possible. Therefore, the present application does not limit the content of M, as long as it is ≤0.4.
In some specific examples, the iron-based amorphous alloy has a component of a=80.95, 3.0≤b≤8.0, 11.0≤c≤15.0, d=0.05; in some specific examples, the iron-based amorphous alloy has a component of 81.7≤a≤81.99, 3.0≤b≤8.0, 1, 0.0≤c≤15.0, 0.01≤d≤0.3; in some specific examples, the iron-based amorphous alloy has a component of a=82.95, 3.0≤b≤8.0, 8.0≤c≤14.0, d=0.05; in some specific examples, the iron-based amorphous alloy has a component of a=83.95, 3.0≤b≤8.0, 8.0≤c≤13.0, d=0.05.
Thus, considering the requirements of improving magnetic induction, improving glass forming ability and reducing preparation difficulty, the present disclosure provides a reasonable combination of component and content of the iron-based amorphous alloy to form an iron-based amorphous alloy with high saturation magnetic induction.
The present disclosure also provides a method for preparing the iron-based amorphous alloy, comprising the following steps:
calculating and preparing raw materials according to the atomic percentage indicated in the iron-based amorphous alloy formula FeaSibBcPd; smelting the raw materials; heating and insulating the molten materials; performing single roller rapid quenching to give an iron-based amorphous alloy strip.
In the process of preparing iron-based amorphous alloy, conventional techniques in the art are used in the present application to produce the iron-based amorphous alloy with specific components. The present application will not particularly describe the detailed operations which relates to material preparation and smelting process. During smelting process, the smelting temperature is from 1300 to 1600° C., and the duration is from 80 to 1.30 min. In the present application, after smelting, the smelted molten alloy is heated, insulated, and then subjected to single roller rapid quenching to give iron-based amorphous alloy strip. The heating temperature is preferably from 1350 to 1550° C., and the insulation duration is preferably from 90 to 120 min. The spraying temperature of single roller rapid quenching is from 1300 to 1450° C., and the linear velocity of cooling roller is from 20 to 30 m/s. After the single roller rapid quenching, the iron-based amorphous alloy strip is obtained, which is completely amorphous, having a critical thickness of at least 45 μm and relative good toughness, which will not crack after 180 degree folding. The glass forming ability (GFA) of alloy is the size of amorphous alloy that can be obtained under certain preparation conditions, the larger the size is, the heater the glass forming ability will be. For amorphous strip, critical thickness is an important index to evaluate the glass forming ability. The thicker the critical thickness is, the better the glass forming ability will be. For the present disclosure, the critical thickness is at least 45 μm, which gives considerable margin for industrial production of the present product and reduces the requirement for cooling devices in industrialization process. Ductile-brittle is an important index in the application of amorphous strip. In the application process, the strip will be subjected to shearing. If the fragility of the strip is high, more fragments will be generated during shearing process, which will influence the modifying of iron core and the assembling of transformer. The strip of the present disclosure has a good ductile-brittle, which will not crack after 180 degree folding, and will not generate fragments in the following shearing process.
The thickness of the iron-based amorphous alloy strip in the present application is from 23 to 32 μm, and the width of which is from 100 to 300 mm. For amorphous strip, thickness of strip is one of the important factors that influence the core loss and also a main factor that determines the superiority of amorphous strip over silicon steel in respect of no-load loss. The core loss of soft magnetic material is mainly from three aspects: hysteresis loss, eddy current loss and residual loss. The thickness influences the eddy current loss directly. For magnetic material, eddy current appears on magnetic domain wall, With the flow of eddy current, magnetic influx opposite to that of the external magnetic field is generated at every moment. This kind of opposite effect becomes stronger in the direction from the external to the inner part, causing unevenness of the magnetic induction intensity and magnetic field strength along the cross section of a sample. This is why soft magnetic materials are made into thin strips—reducing the influences of eddy current. However, the amorphous strip is not the thinner, the better. Unduly thin strip will increase abrasion of cutters in the follow-up shearing process of the core, increase group number of strip, therefore increasing cost of the core. Considering the two aspects above comprehensively, an iron-based amorphous alloy strip with a thickness of 23 to 32 μm is prepared by choosing preparation processes. At present, the width of the strips on the market is usually 142 mm, 170 mm and 213 mm. The wider the strip is, the harder it is to be prepared.
In the present application, heat treatment is carried out after the iron-based amorphous alloy strip is prepared. The temperature for the heat treatment is from 300 to 360° C., the insulation duration is from 60 to 120 min, and the magnetic field strength is from 800 to 1400 A/m. Except for the components of the alloy itself, heat treatment process is also a key factor that influences the magnetic property of amorphous, nano-crystalline soft magnetic material. Generally, annealing treatment can eliminate the stress of amorphous magnetic material is eliminated, reduce the coercive force and improve the magnetic permeability, therefore obtaining good magnetic property. For iron-based amorphous strip, the heat treatment process mainly includes three parameters: insulation temperature, insulation duration and magnetic field strength. Firstly, the insulation temperature needs to be less than crystallization temperature. Once the temperature is above the crystallization temperature, crystallization occurs in amorphous strip, causing a dramatic decrease of the magnetic. The crystallization temperatures of all the alloys in the present disclosure are less than 500° C. in the premise of below crystallization temperature, suitable insulation temperature range is the guarantee of the excellent magnetic property of amorphous strip. Research of the present disclosure shows that core loss of the strip, excitation power and insulation temperature of heat treatment have relationship as follows: with the increase of temperature, the two parameters tend to decrease firstly and then increase, That is, for the present disclosure, the properties are adverse when the insulation temperature is lower than 300° C. or above 360° C.; qualified magnetic property can be obtained between 300 and 360° C. Secondly, the insulation duration has a similar influence as the insulation temperature, i.e., there is a suitable duration range. Neither unduly short insulation duration nor unduly long insulation duration can obtain optimized properties. Finally, suitable magnetic field strength is a necessary guarantee for the magnetization of materials. The main reason for carrying out magnetic field annealing on amorphous material is that magnetic field with fixed direction and fixed strength promotes the magnetic domain of material to turn toward the field direction, reducing magnetic anisotropy of material and optimizing soft magnetic property. For the present disclosure, when the magnetic field strength is less than 800 A/m, the material is not completely magnetized, so that the optimal effect cannot be reached. When the magnetic field strength is >1400 A/m, the material is completely magnetized. The magnetic property will not be better optimized with the increase of magnetic field strength; on the contrary, extremely high magnetic field strength will increase the difficulty and cost of heat treatment.
After annealing, the iron-based amorphous strip in the present disclosure has a core loss P of ≤0.1800 W/kg, excitation power Pe of ≤0.2200 VA/kg and coercive force He of ≤4 A/m. Coercive force is an important index to evaluate the property of soft magnetic materials. The smaller coercive force is, the better the soft magnetic property will be. For amorphous strip used in distribution transformer industry, the indexes used to evaluate the magnetic property mainly include two indexes: core loss and excitation power. The smaller the two indexes are, the better the property of the follow-up core and transformer will be. Therefore, the iron-based amorphous alloy prepared in the present disclosure can be used as core material of transformer, engine and genera tor.
In order to understand the present disclosure better, the iron-based amorphous alloy provided by the present disclosure and the preparation method thereof will be illustrated clearly in combination with examples. The protection scope of the present disclosure is not limited by the examples hereinafter.
Metal raw materials were prepared in proportion to alloy formula FeaSibBcPdMf and smelted in medium frequency furnace (the smelting temperature was from 1300 to 1600° C. and the insulation duration was from 80 to 130 min). After smelting, steel liquid was output to intermediate frequency furnace, heated, insulated, and stood (heated to 1350 to 1550° C. and the insulation duration was 90 to 120 min). Thereafter, single roller rapid quenching method (spray temperature was from 1300 to 1450° C. and the linear velocity of cooling roller is from 20 to 30 m/s) was used to prepare an iron-based amorphous wide strip with width of 142 mm and thickness of 23 to 28 μm. Table 1 showed alloy components, pouring temperature and critical thickness of the examples and comparative examples of the present disclosure. Therein, examples 1 to 29 were the examples of the present disclosure and examples 30 to 35 were comparative examples.
In view of the examples above, all the alloys with the components of the present disclosure obtained completely amorphous strip, and the largest critical thickness of which was 45 μm. In view of examples 7 to 11 and comparative example 31, pouring temperature significantly decreased when a trace amount of P was added to the alloy. Therefore, the preparation difficulty of the iron-based amorphous strip is reduced, making the manufacture of the product easier.
Table 2 showed saturation magnetic induction (Bs), excitation power (Pe) and core loss (P) of heat treated examples and comparative examples of the present disclosure. In the present application, the temperature for heat treatment was from 300 to 360° C., the duration was from 60 to 120 min, and the magnetic field strength was from 800 to 1400 A/m.
Remark: annular samples were used in heat treatment process: the inner diameter was 50.5 mm, the outer diameter was from 52.5 to 54.5 mm, and the testing condition was 1.35 T/50 Hz.
In view of the examples above, the iron-based amorphous alloy of the present disclosure have a good saturation magnetic induction, the value of which is not less than 1.62 T, higher than the conventional iron-based amorphous material used in power transformer at present, which has a saturation magnetic induction of 1.56 T (comparative example 30). Improving of saturation magnetic induction of core material makes the design of core of transformer optimized, reducing volume of the transformer and decreasing the cost. Table 2 also indicates that alloy with a components conforming to the present disclosure has good magnetic properties. Under condition of 50 Hz and 1.35 T, heat treated core has excitation power of ≤0.2200 VA/kg and core loss of ≤0.1800 W/kg, which meets operational requirements compared with conventional amorphous material (comparative example 31).
The embodiments above are illustrated to help understand the methods and core ideas of the present disclosure. It should be noted that without departing from the principles thereof, the improvements and modifications of the present disclosure made by the one of ordinary skill in the art, fall into the protection scope of the present application.
The descriptions of the disclosed embodiments above enable one of ordinary skill in the art to realize or use the invention. Various modifications to these examples will be apparent to one of ordinary skill in the art, and the generic principles defined herein may be embodied in other embodiments without departing from the spirit or scope of the present disclosure. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.
| Number | Date | Country | Kind |
|---|---|---|---|
| 201710060830.7 | Jan 2017 | CN | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/CN2017/075138 | 2/28/2017 | WO | 00 |
