Enhanced material for magnetic beads, preparation method of enhanced material and preparation method of laminated magnetic beads

[0039] The application also provides a method for preparing the reinforced material for magnetic beads, including the following steps:

[0040] A) ZrO 2 Powder, SiO 2 Powder, Al 2 O 3 Powder, TiO 2 Powder, B 2 O 3 Powder and mica KAl 2 (AlSi 3 O 10 )(OH) 2 The powder is mixed by ball milling to obtain additives;

[0041] B) The core-shell structure FeCoNiCrAl@SiO 2 The high-entropy alloy is mixed with the additives to obtain a reinforced material for magnetic beads.

[0042] In the above-mentioned reinforced material for magnetic beads, the ZrO 2 Powder, SiO 2 Powder, Al 2 O 3 Powder, TiO 2 Powder, B 2 O 3 Powder and mica KAl 2 (AlSi 3 O 10 )(OH) 2 The particle size of the powder is 1-20μm. In the process of ball milling, the ball-to-material ratio of the ball mill is (10-20):1, and the rotation speed is 100-300 r/min.

[0043] The above-mentioned base materials and additives have been described in detail and will not be repeated here.

[0044] This application also provides a method for preparing laminated chip magnetic beads, including the following steps:

[0045] Prepare the magnetic beads into a thin film with a reinforced material, and then perform screen printing to obtain a laminated structure material;

[0046] The laminated structure material is calcined at a high temperature to obtain laminated chip magnetic beads.

[0047] In the above preparation method, the preparation into a thin film, screen printing and high-temperature calcination are technical means well known to those skilled in the art, and there is no particular limitation on this application.

[0048] Although the resistivity of high-entropy alloys is higher than that of typical magnetic metal materials, compared with the current mainstream preparation materials of magnetic beads, ferrites have the disadvantage of lower resistivity. This application uses silica as the shell material. Make full use of the high resistance of silicon dioxide to further improve the resistivity of the high-entropy alloy. In addition, as a powder material, the high-entropy alloy particles have a large contact resistance between themselves, which can meet the high resistance required by the magnetic bead material. Rate indicators; the design of the core-shell structure is also very important: deposit a silica shell layer on the surface of the high-entropy alloy through a chemical reaction method, and control the chemical reaction rate to make the silica uniformly and tightly coated on the high-entropy alloy particles Surrounding, after the base material is mixed and calcined with the additives, a zircon layer can be uniformly formed on the surface of the high-entropy alloy, and the bonding strength between the powders can be improved through the close mechanical bonding between the high-entropy alloy and the zircon. It can be seen that the design of the core-shell structure plays an important role in improving the bonding strength between the powders. In the current conventional magnetic bead preparation method, simple mixing between the powders obviously cannot achieve the effect of the shell-core structure.

[0049] The magnetic bead material involved in this application is finally calcined at a high temperature to be used as a bulk material. Therefore, the improvement of the bonding strength has significant significance for improving the use performance of the bulk material. For example, the magnetic bead must meet the requirements of anti-vibration, Performance indicators such as impact resistance and thermal shock resistance. Therefore, in addition to its high resistance, the choice of silica has a lot to do with the choice of additives, because the two require further chemical reactions.

[0050] This application uses high-entropy alloy FeCoNiCrAl@SiO 2 As the basic material, an enhanced material for magnetic beads and a preparation method are proposed, mainly by forming a uniform layer of SiO on the surface of the high-entropy alloy FeCoNiCrAl 2 Shell formation FeCoNiCrAl@SiO 2 The shell-core structure is used as the base material, and the additive contains a certain proportion of ZrO 2 Powder, SiO during calcination 2 With ZrO 2 In-situ formation of zircon ZrSiO 4 , In order to increase the bonding strength between the base material and between the base material and additives; and because of SiO 2 It is uniformly formed on the surface of high-entropy alloy powder, so it is more SiO 2 The effect of sintering directly mixed with additives is better.

[0051] In addition, the main raw material high-entropy alloy in the base material is prepared by ball milling. It is mainly in the shape of lamellae and has shape anisotropy in terms of magnetic properties. According to the Snoek limit formula Where H k As an anisotropic field, it can be seen that magnetic materials with strong shape anisotropy are easier to obtain good high-frequency magnetic permeability, so magnetic beads made of lamellar high-entropy alloys have excellent magnetic properties.

[0053] Example 1

[0054] (1) Measure Fe powder, Co powder, Ni powder, Cr powder and Al powder in equal atomic proportions, with particle sizes ranging from 1 to 10 μm; put the powders in hydrochloric acid with a diluted concentration of 0.1%. Clean at room temperature for 3 minutes to remove the surface oxide scale. After completion, rinse with deionized water for 3 times and dry ethanol for 3 times, vacuum dry, and mix for later use;

[0055] (2) Put the mixed powder in the above (1) into a ball mill for ball milling, with a ball-to-material ratio of 20:1, a rotation speed: 300r/min, and a milling time: 50h, to prepare a high-entropy alloy FeCoNiCrAl, and collect the powder for use;

[0056] (3) Prepare 500mL solution, of which 400mL absolute ethanol, 95mL deionized water, 5mL ammonia water, stir evenly;

[0057] (4) The mixed powder described in (2) above is slowly added to the solution in (3) above, and fully stirred for 5 minutes;

[0058] (5) In the above (4), slowly add 100 mL of ethyl orthosilicate ethanol solution, of which 5 mL of ethyl orthosilicate, 95 mL of absolute ethanol, and finish the operation in 30 minutes;

[0059] (6) Collect the reaction product after 24h, which is the base material high-entropy alloy FeCoNiCrAl@SiO 2 Powder, dried in vacuum for later use;

[0060] (B) Preparation of additives

[0061] (1) Weigh the composition of the additives according to the proportion, and the proportion is based on the total amount of the base material: ZrO 2 : 0.1%, SiO 2 :0.1%; Al 2 O 3 : 0.8%; TiO 2 : 1%; B 2 O 3 : 1%; Mica KAl 2 (AlSi 3 O 10 )(OH) 2 : 0.3%, the particle size is 1-10 microns;

[0062] (2) Mix the additives in (1) above by ball milling, the ball-to-battery ratio is 20:1, the speed is 300r/min, and the ball milling time: 3h;

[0063] (3) Collecting the mixture in (2) above is the additive.

[0064] Mix the base material in (A) and the additives in (B) uniformly to form the powder material that can be used for laminated chip magnetic beads.

[0065] When preparing laminated chip magnetic beads, the powder can be made into a film through a casting process, and a laminated structure is formed after screen printing. After the laminated structure is calcined at a high temperature, terminal electrodes are formed on both sides of the laminated structure. Laminated chip magnetic beads are required; among them, during the high temperature calcination of the laminated structure, the ZrO in the material is added 2 Respectively with SiO in additives 2 , SiO in base material 2 Reaction to form zircon ZrSiO 4 Can improve the bonding strength between the base material and the additive.

[0066] The interaction between the magnetic beads prepared in this embodiment and radio frequency waves mainly includes two processes: one is whether the radio frequency waves can enter the magnetic beads smoothly when they are transmitted from the air to the surface of the magnetic beads, which generally depends on whether the impedance of the magnetic beads matches the impedance of the air. ; The second is whether the attenuation of the radio frequency wave after entering the magnetic bead is large enough, mainly depends on the attenuation constant; figure 1 Is a graph of the impedance value of the laminated chip magnetic beads in the frequency range of 2~18GHz, by figure 1 It can be seen that as the frequency increases, the impedance value of the laminated chip beads gradually decreases in the range of 2-18GHz. figure 2 Is a graph of the attenuation constant of laminated chip beads in the frequency range of 2-18GHz. figure 2 It can be seen that as the frequency increases, the attenuation constant gradually increases.

[0067] Example 2

[0068] (1) Measure Fe powder, Co powder, Ni powder, Cr powder and Al powder in equal atomic proportions. The particle size is between 1 and 10 μm. The powders are respectively placed in hydrochloric acid with a dilution concentration of 0.1%. Wash for 3 minutes at room temperature to remove the surface oxide scale. After completion, wash with deionized water for 3 times and anhydrous ethanol for 3 times, vacuum dry, and mix for later use;

[0069] (2) Put the mixed powder in the above (1) into a ball mill for ball milling, with a ball-to-material ratio of 20:1, a rotation speed: 300r/min, and a milling time: 50h, to prepare a high-entropy alloy FeCoNiCrAl, and collect the powder for use;

[0070] (3) Prepare 500mL solution, of which 400mL absolute ethanol, 95mL deionized water, 5mL ammonia water, stir evenly;

[0071] (4) The mixed powder described in (2) above is slowly added to the solution in (3) above, and fully stirred for 5 minutes;

[0072] (5) In the above (4), slowly add 100 mL of ethyl orthosilicate ethanol solution, of which 5 mL of ethyl orthosilicate, 95 mL of absolute ethanol, and finish the operation in 30 minutes;

[0073] (6) Collect the reaction product after 24 hours, which is the base material high-entropy alloy FeCoNiCrAl@SiO2 powder, which is vacuum dried for later use;

[0074] (B) Preparation of additives

[0075] (1) Weigh the composition of the additives according to the proportion, and the proportion is based on the total amount of the base material: ZrO 2 : 3%, SiO 2 : 0.5%; Al 2 O 3 : 3%; TiO 2 : 1.5%; B 2 O 3 : 2%; Mica KAl 2 (AlSi 3 O 10 )(OH) 2 : 0.5%, particle size is 10-20 microns;

[0076] (2) Mix the additives in (1) above by ball milling, the ball-to-battery ratio is 20:1, the speed is 300r/min, and the ball milling time: 3h;

[0077] (3) Collecting the mixture in (2) above is the additive.

[0078] Mix the base material in (A) and the additives in (B) uniformly to form the powder material that can be used for laminated chip magnetic beads.

[0079] When preparing laminated chip magnetic beads, the powder can be made into a film through a casting process, and a laminated structure is formed after screen printing. After the laminated structure is calcined at a high temperature, terminal electrodes are formed on both sides of the laminated structure. Need laminated chip magnetic beads. Among them, during the high-temperature calcination of the laminated structure, the ZrO in the additive 2 Respectively with SiO in additives 2 And SiO in base 2 Reaction to form zircon ZrSiO 4 Can improve the bonding strength between the base material and the additive.