What are nanocrystals
The first thing to know is what is amorphous. In the process of preparation, if the metal is cooled with a super-fast cooling rate during its solidification process, the atoms are in a disorderly state and will be frozen instantly without time to rearrange, and the structure formed at this time is amorphous. Nanocrystalline is on the basis of amorphous, through special heat treatment, so that it forms a crystal nucleus and grow, but to control the grain size at the nanometer level, do not form a complete crystal, then the structure formed is nanocrystalline.
How is amorphous prepared?
The principle of the preparation process of amorphous is very simple, that is, the parent alloy is melted and sprayed on a high-speed rotating cooling roller through a nozzle package, which is instantly cooled to form a thin band like paper.
It has several features:
High temperature, the temperature of the liquid alloy is basically 1400 ° C ~1500 ° C, and the instant solidification is close to room temperature, which requires a very high cooling speed, and the cooling speed has reached the level of millions of degrees per second.
High speed, that is, the speed of the spray belt is also very fast, 30m/s, high precision, the thickness of the spray strip 20-30μm, very thin, such precision control is achieved through the design of the slit under the nozzle package and the spacing of the roller nozzle.
Preparation method of nanocrystalline alloy
Nanocrystalline soft magnetic alloy is made of amorphous strip by special heat treatment process. First, the amorphous strip with a specific composition is put into the heat treatment furnace to generate grains within 100 nm through directional control, and in fact, a mixed structure of amorphous and nanocrystalline is formed.
Advantages of nanocrystalline alloys
Compared with cobalt-based amorphous and ferrite, nanocrystals have high saturation magnetic induction and can reduce the size of magnetic devices. High permeability, small loss, coercivity, can reduce the loss of magnetic devices, therefore, nanocrystalline alloys are the best soft magnetic materials in high-frequency power electronics applications.
Properties of nanocrystalline alloys
The current frequency of the wireless charging Qi standard is between 100-200k, at this frequency, the permeability of nanocrystals and the permeability of cobalt-based amorphous is very close, significantly higher than that of iron based amorphous and ferrite, and the loss is on the contrary, significantly lower than that of iron based amorphous and ferrite.
Nanocrystals also have advantages in temperature application, nanocrystals are not only wider than cobalt based amorphous and ferrite in the application temperature, in the range of -40℃-120℃, the stability of nanocrystals is also significantly better than ferrite.
Nanocrystals also have obvious advantages in the design of magnetic materials, and nanocrystals can directional control the permeability and anti-saturation magnetic field. The permeability of nanocrystals can be adjusted at will within 1000-30000. The design of magnetic materials requires that at a specific working current, do not reach magnetic saturation, once magnetic saturation is reached, it will stop working, and the nanocrystal adjustable anti-saturation magnetic field can reach 30~350A/m, making the application range of wireless charging wider.
The saturation magnetic flux density of several kinds of iron based nanocrystals and iron based amorphous, cobalt based amorphous, ferrite: iron based nanocrystals are significantly better than cobalt based amorphous and ferrite except that they are slightly lower than iron based amorphous;
Nanocrystals are superior to other materials in coercivity, initial permeability, saturation magnetostriction coefficient, Curie temperature and performance change rate. Therefore, nanocrystals are the best soft magnetic materials.
With the development of electronic products in the direction of high frequency, energy saving, small size and integration, the application frequency is also constantly improving, and the strip is updated from generation to generation. From the original traditional belt making process (domestic existing production level) thickness of 22-30μm, to the present strip development to three generations, four generations, with advanced belt making process (international advanced production level) can achieve 14-22μm. And mastered the technique of making thinner tape. The development trend of nanocrystalline strip is ultra-thin strip. Ultrathin nanocrystalline strip characteristics: the thinner the strip, the lower the loss.
Since the mass production of magnetic sheets in 2015, the process has continued to change, gradually transitioning from sheet to coil, greatly improving production efficiency and meeting the growing demand.
Wireless charging in the mobile phone has a popular trend, there are also many products in the field of wear, the future in the home, office, public places, travel tools, transportation will have the popularity of wireless charging, the future will also have the popularity of electric vehicles.
Wireless energy transmission (WPT) : smart phones, smart wear (small power) wireless charging structure is similar to a transformer, composed of the transmitter and the receiving end, the transmitter and the receiving end are composed of coils and magnetic materials, magnetic materials have different choices, ferrite, amorphous, nanocrystals and so on.
The role of soft magnetic shielding materials in wireless charging
Magnetic shielding: provides a low-impedance path for magnetic flux, reduces the outgoing magnetic field lines, reduces the impact on surrounding metal objects, and prevents eddy currents and signal interference.
Magnetic conductivity resistance reduction: improve the coupling coefficient, improve the magnetoelectric conversion efficiency, use fewer turns to achieve a higher inductance coil, reduce the coil resistance, reduce the efficiency reduction caused by heating (the more turns, the higher the resistance).
Common types of soft magnetic shielding materials:
Comparison of charging efficiency of nanocrystalline magnetic permeator:
The charging efficiency of nanocrystalline magnetic sheets with different thickness and ferrite with different permeability and thickness were compared under the same conditions. With the increase of thickness, the charging efficiency is constantly improving, but the nanocrystalline is not the thicker the better, and it is basically saturated to 0.1mm. Therefore, when designing wireless charging modules, the nanocrystalline magnetic conductive sheet does not need to be too thick, which will increase the material cost. The law of ferrite is similar to that of nanocrystals, the higher the permeability, the higher the charging efficiency, the thicker the thickness, the higher the charging efficiency, but under the same charging efficiency, the thickness of the nanocrystalline magnetic sheet is only half of the ferrite.
History of wireless charging for smart phones
In 2012, Nokia launched a wireless charging mobile phone Lumia 920, the magnetic material used is hard ferrite. In 2013, a mobile phone sold overseas HiKe 868 designed wireless charging and NFC integration, equipped with magnetic materials WPC-ferrite (rigid), NFC-ferrite (flexible). In 2015, mobile phone wireless charging occurred a milestone change, Samsung launched the first wireless charging flagship mobile phone Galaxy S6, not only compatible with two wireless charging standards, WPC and PMA, but also configured with two payment standards NFC and MST, matching with the soft magnetic shielding material in addition to ferrite, the first use of amorphous magnetic conductive sheet. The mobile phone is not only thin and beautiful, but also greatly improves the efficiency of wireless charging. By 2016, Samsung has made improvements, replacing all magnetic materials with more advanced nanocrystalline magnetic conductive sheets, leading the change of wireless charging technology, and always in a leading position. From the development history of the past few years, the function of NFC and MST near field communication has been added from simple wireless charging. Magnetic materials gradually transition from ferrite to nanocrystalline.
Application case
The application of nanocrystals in wireless charging starts with S7, where a single material achieves all functions, replacing the combination of amorphous and ferrite. It is generally believed that ferrite is the best soft magnetic material for NFC, and nanocrystalline is not suitable, because at high frequency, the loss of nanocrystalline is much greater than ferrite, but Samsung precisely made a breakthrough, the successful application of S7 proved that nanocrystalline can be used in NFC, followed by S8/N8/A7/J5/J7 and many other models of products. The application of nanocrystals is extended from WPC to NFC and MST.
The domestic nanocrystalline production representative enterprise Antai technology has also made some attempts at the transmitter end, and has made several wireless charger products with nanocrystalline magnetic conductive sheets, with multi-station, multi-function and other characteristic products, there is no problem in performance, and now the only problem is that the cost of magnetic conductive sheets is higher than ferrite.
Mobile phone wireless charging development trend:
Function: WPC→WPC+NFC→WPC/Airfule+NFC
Wireless charging - Wireless charging + - charge at will
Power: 5W→7.5W→10W→15W
Slow charge - universal charge - Fast charge - flash charge
Development trend of magnetic permeator:
Receiving end: absorbing material → ferrite → amorphous + ferrite → nanocrystals
Nanocrystalline magnetic conductive sheet:
Thin - Ultra-thin :0.14→0.12→0.11 →0.10
High permeability, low loss - high Q
Application and popularization:
n Low power: mobile phones, smart wearables, etc
n Medium power: computers, kitchen appliances, etc
High power: electric vehicles, roads and other infrastructure
In the future, it will be a wireless world, changing lives and changing the world.
Post time: 09-19-2024
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The first thing to know is what is amorphous. In the process of preparation, if the metal is cooled with a super-fast cooling rate during its solidification process, the atoms are in a disorderly state and will be frozen instantly without time to rearrange, and the structure formed at this time is amorphous. Nanocrystalline is on the basis of amorphous, through special heat treatment, so that it forms a crystal nucleus and grow, but to control the grain size at the nanometer level, do not form a complete crystal, then the structure formed is nanocrystalline.
How is amorphous prepared?
The principle of the preparation process of amorphous is very simple, that is, the parent alloy is melted and sprayed on a high-speed rotating cooling roller through a nozzle package, which is instantly cooled to form a thin band like paper.
It has several features:
High temperature, the temperature of the liquid alloy is basically 1400 ° C ~1500 ° C, and the instant solidification is close to room temperature, which requires a very high cooling speed, and the cooling speed has reached the level of millions of degrees per second.
High speed, that is, the speed of the spray belt is also very fast, 30m/s, high precision, the thickness of the spray strip 20-30μm, very thin, such precision control is achieved through the design of the slit under the nozzle package and the spacing of the roller nozzle.
Preparation method of nanocrystalline alloy
Nanocrystalline soft magnetic alloy is made of amorphous strip by special heat treatment process. First, the amorphous strip with a specific composition is put into the heat treatment furnace to generate grains within 100 nm through directional control, and in fact, a mixed structure of amorphous and nanocrystalline is formed.
Advantages of nanocrystalline alloys
Compared with cobalt-based amorphous and ferrite, nanocrystals have high saturation magnetic induction and can reduce the size of magnetic devices. High permeability, small loss, coercivity, can reduce the loss of magnetic devices, therefore, nanocrystalline alloys are the best soft magnetic materials in high-frequency power electronics applications.
Properties of nanocrystalline alloys
The current frequency of the wireless charging Qi standard is between 100-200k, at this frequency, the permeability of nanocrystals and the permeability of cobalt-based amorphous is very close, significantly higher than that of iron based amorphous and ferrite, and the loss is on the contrary, significantly lower than that of iron based amorphous and ferrite.
Nanocrystals also have advantages in temperature application, nanocrystals are not only wider than cobalt based amorphous and ferrite in the application temperature, in the range of -40℃-120℃, the stability of nanocrystals is also significantly better than ferrite.
Nanocrystals also have obvious advantages in the design of magnetic materials, and nanocrystals can directional control the permeability and anti-saturation magnetic field. The permeability of nanocrystals can be adjusted at will within 1000-30000. The design of magnetic materials requires that at a specific working current, do not reach magnetic saturation, once magnetic saturation is reached, it will stop working, and the nanocrystal adjustable anti-saturation magnetic field can reach 30~350A/m, making the application range of wireless charging wider.
The saturation magnetic flux density of several kinds of iron based nanocrystals and iron based amorphous, cobalt based amorphous, ferrite: iron based nanocrystals are significantly better than cobalt based amorphous and ferrite except that they are slightly lower than iron based amorphous;
Nanocrystals are superior to other materials in coercivity, initial permeability, saturation magnetostriction coefficient, Curie temperature and performance change rate. Therefore, nanocrystals are the best soft magnetic materials.
With the development of electronic products in the direction of high frequency, energy saving, small size and integration, the application frequency is also constantly improving, and the strip is updated from generation to generation. From the original traditional belt making process (domestic existing production level) thickness of 22-30μm, to the present strip development to three generations, four generations, with advanced belt making process (international advanced production level) can achieve 14-22μm. And mastered the technique of making thinner tape. The development trend of nanocrystalline strip is ultra-thin strip. Ultrathin nanocrystalline strip characteristics: the thinner the strip, the lower the loss.
Since the mass production of magnetic sheets in 2015, the process has continued to change, gradually transitioning from sheet to coil, greatly improving production efficiency and meeting the growing demand.
Wireless charging in the mobile phone has a popular trend, there are also many products in the field of wear, the future in the home, office, public places, travel tools, transportation will have the popularity of wireless charging, the future will also have the popularity of electric vehicles.
Wireless energy transmission (WPT) : smart phones, smart wear (small power) wireless charging structure is similar to a transformer, composed of the transmitter and the receiving end, the transmitter and the receiving end are composed of coils and magnetic materials, magnetic materials have different choices, ferrite, amorphous, nanocrystals and so on.
The role of soft magnetic shielding materials in wireless charging
Magnetic shielding: provides a low-impedance path for magnetic flux, reduces the outgoing magnetic field lines, reduces the impact on surrounding metal objects, and prevents eddy currents and signal interference.
Magnetic conductivity resistance reduction: improve the coupling coefficient, improve the magnetoelectric conversion efficiency, use fewer turns to achieve a higher inductance coil, reduce the coil resistance, reduce the efficiency reduction caused by heating (the more turns, the higher the resistance).
Common types of soft magnetic shielding materials:
Comparison of charging efficiency of nanocrystalline magnetic permeator:
The charging efficiency of nanocrystalline magnetic sheets with different thickness and ferrite with different permeability and thickness were compared under the same conditions. With the increase of thickness, the charging efficiency is constantly improving, but the nanocrystalline is not the thicker the better, and it is basically saturated to 0.1mm. Therefore, when designing wireless charging modules, the nanocrystalline magnetic conductive sheet does not need to be too thick, which will increase the material cost. The law of ferrite is similar to that of nanocrystals, the higher the permeability, the higher the charging efficiency, the thicker the thickness, the higher the charging efficiency, but under the same charging efficiency, the thickness of the nanocrystalline magnetic sheet is only half of the ferrite.
History of wireless charging for smart phones
In 2012, Nokia launched a wireless charging mobile phone Lumia 920, the magnetic material used is hard ferrite. In 2013, a mobile phone sold overseas HiKe 868 designed wireless charging and NFC integration, equipped with magnetic materials WPC-ferrite (rigid), NFC-ferrite (flexible). In 2015, mobile phone wireless charging occurred a milestone change, Samsung launched the first wireless charging flagship mobile phone Galaxy S6, not only compatible with two wireless charging standards, WPC and PMA, but also configured with two payment standards NFC and MST, matching with the soft magnetic shielding material in addition to ferrite, the first use of amorphous magnetic conductive sheet. The mobile phone is not only thin and beautiful, but also greatly improves the efficiency of wireless charging. By 2016, Samsung has made improvements, replacing all magnetic materials with more advanced nanocrystalline magnetic conductive sheets, leading the change of wireless charging technology, and always in a leading position. From the development history of the past few years, the function of NFC and MST near field communication has been added from simple wireless charging. Magnetic materials gradually transition from ferrite to nanocrystalline.
Application case
The application of nanocrystals in wireless charging starts with S7, where a single material achieves all functions, replacing the combination of amorphous and ferrite. It is generally believed that ferrite is the best soft magnetic material for NFC, and nanocrystalline is not suitable, because at high frequency, the loss of nanocrystalline is much greater than ferrite, but Samsung precisely made a breakthrough, the successful application of S7 proved that nanocrystalline can be used in NFC, followed by S8/N8/A7/J5/J7 and many other models of products. The application of nanocrystals is extended from WPC to NFC and MST.
The domestic nanocrystalline production representative enterprise Antai technology has also made some attempts at the transmitter end, and has made several wireless charger products with nanocrystalline magnetic conductive sheets, with multi-station, multi-function and other characteristic products, there is no problem in performance, and now the only problem is that the cost of magnetic conductive sheets is higher than ferrite.
Mobile phone wireless charging development trend:
Function: WPC→WPC+NFC→WPC/Airfule+NFC
Wireless charging - Wireless charging + - charge at will
Power: 5W→7.5W→10W→15W
Slow charge - universal charge - Fast charge - flash charge
Development trend of magnetic permeator:
Receiving end: absorbing material → ferrite → amorphous + ferrite → nanocrystals
Nanocrystalline magnetic conductive sheet:
Thin - Ultra-thin :0.14→0.12→0.11 →0.10
High permeability, low loss - high Q
Application and popularization:
n Low power: mobile phones, smart wearables, etc
n Medium power: computers, kitchen appliances, etc
High power: electric vehicles, roads and other infrastructure
In the future, it will be a wireless world, changing lives and changing the world.
Post time: 09-19-2024