A magnetic code disk material, a preparation method thereof, and a magnetic encoder

Abstract

This application belongs to the technical field of metal magnetic thin film materials, and specifically discloses a magnetic code disk material, a preparation method thereof, and a magnetic encoder. The magnetic code disk material includes a double-Au catalytic magnetic layer and a Ta layer, wherein the double-Au catalytic FeCrCoMoTi magnetic layer includes a first Au layer, a FeCrCoMoTi layer, and a second Au layer; the FeCrCoMoTi magnetic code disk material also undergoes vacuum annealing at 645°C - 655°C. This application also provides a specific preparation method of the above magnetic code disk material, as well as a magnetic encoder including the above magnetic code disk material. The magnetic code disk material provided by this application, which includes a double-Au catalytic FeCrCoMoTi magnetic layer, has a simple preparation process. Compared with traditional FeCrCoMoTi thin films, its coercivity has a significant increase, and at the same time, the preparation process is simple, efficient, and has a lower cost.

Description

Technical Field

[0001] This application belongs to the technical field of metal magnetic thin films, and particularly relates to a magnetic code disk material, a preparation method thereof, and a magnetic encoder. Background Art

[0002] As a new type of position detection element, the magnetic encoder exhibits great application potential in the fields of industrial automation, robotics, new energy vehicles, etc. due to its significant advantages such as non-contact measurement, strong anti-pollution ability, and good environmental adaptability. The magnetic code disk, as the core component of the magnetic encoder, directly affects the accuracy, resolution, and stability of the encoder.

[0003] In recent years, with the continuous progress of material science and manufacturing technology, significant progress has been made in the research of magnetic code disk materials. The FeCrCo thin film (in some cases including a small amount of other elements such as Mo and Ti, generally collectively referred to as the FeCoCr thin film or FeCrCo thin film) is an important magnetic material and is widely used in the fields of magnetic storage, sensors, etc. However, the magnetic properties of the FeCrCo thin film, especially the coercivity, often fail to meet the requirements of high-performance applications. In the prior art, the magnetic properties of the thin film are usually improved by means of hierarchical heat treatment, doping, or interface engineering, but these methods often have problems such as complex processes, high costs, or limited effects. Therefore, how to improve the coercivity of the FeCrCo magnetic thin film is one of the key issues in the field of magnetic thin film research. Summary of the Invention

[0004] The purpose of this application is to solve the deficiencies of the prior art and provide a magnetic code disk material, a preparation method thereof, and a magnetic encoder, and specifically adopt the following technical solutions:

[0005] First, this application provides a magnetic code disk material, including a double-Au catalytic magnetic layer and a Ta layer; the double-Au catalytic magnetic layer is obtained by vacuum annealing a first Au layer, an FeCrCoMoTi layer, and a second Au layer from bottom to top; the temperature of the vacuum annealing is 645°C - 655°C.

[0006] In this application, in order to be able to improve the coercivity of the FeCrCoMoTi magnetic code disk material as much as possible under the premise of maintaining a relatively simple preparation method, the applicant has determined a technical solution of using a double-Au layer to catalyze FeCrCoMoTi through unremitting scientific research and exploration.

[0007] The applicant found that by tightly sandwiching FeCrCoMoTi with Au layers on both sides of the FeCrCoMoTi thin film, using the surface-active element Au as a catalyst attached to both sides of the FeCrCoMoTi layer, a fine and thin "sandwich structure" was formed, which could exert a unique catalytic effect on FeCrCoMoTi. During the heat treatment process (i.e., the vacuum annealing process), Au atoms in the Au layers on both sides of FeCrCoMoTi in the "sandwich structure" diffused into the boundaries of the FeCrCoMoTi layer, reducing the surface free energy of the FeCrCoMoTi layer. During this process, the α-phase inside the FeCrCoMoTi thin film was catalyzed by the Au layers sandwiched on both sides during the Spinodal decomposition process. The Au layers provided an additional driving force for the Spinodal decomposition of FeCrCoMoTi, so that during the Spinodal decomposition process, the α-phase inside the FeCrCoMoTi layer decomposed into a strongly magnetic phase rich in Fe and Co (α1 phase) and a weakly magnetic phase rich in Cr (α2 phase), greatly improving the magnetic properties of the material.

[0008] Moreover, during this process, when Au atoms diffused into the phase boundaries of FeCrCoMoTi, while refining the grains, the particle separation degree was also increased. This was mainly attributed to the synergistic effect of Au during the above-mentioned catalytic Spinodal decomposition process. During the synergistic effect, a grain boundary modification function was also generated. The grain boundary modification promoted defect healing, which enabled the lattice distortion caused by the size difference between Au atoms and matrix atoms in the Au layer in this application to pin dislocations, reduce the lattice defect density, and improve the crystal integrity.

[0009] As a further improvement of the above technical solution, the thickness of the first Au layer is 5 nm - 10 nm. The thickness of the second Au layer is 5 nm - 10 nm.

[0010] Through continuous experimental research and theoretical exploration, the applicant found that choosing an Au layer with an appropriate thickness as the catalytic layer on both sides of the FeCrCoMoTi layer is of great significance: after rapid annealing, Au atoms in the Au layer diffuse into the FeCrCoMoTi layer, not only refining the grains of the FeCrCoMoTi layer, but also increasing the separation degree of the particles in the FeCrCoMoTi layer. Thus, while reducing the grain size of FeCrCoMoTi, the exchange coupling effect between FeCrCoMoTi particles is also reduced, so that the gaps between these grains can serve as channels for rapid atomic diffusion, greatly enhancing the coercivity of the thin film.

[0011] On the other hand, the applicant also found that when the thickness of the Au layer is greater than 10 nm, while the cost increases, the technical effect is not correspondingly improved. Because when the catalytic layer is too thick, there will be too many Au atoms. Too many Au atoms will cause the gap between the grains in the FeCrCoMoTi layer to decrease, which is not conducive to sufficient diffusion and will make it difficult to improve the film coercivity.

[0012] On the other hand, in this application, Au, as a surface-active element, can act as a catalyst to promote the decomposition of the α-phase stripes inside the FeCrCoMoTi film. This is because Au has a lower surface energy (lower than those of Fe, Co, and Cr elements). After rapid annealing, when Au atoms diffuse into the boundaries of the FeCrCoMoTi phase, it will reduce the free energy of the film surface, thereby increasing the coercivity; while when the thickness of the Au layer is less than 5 nm, its catalytic effect is not obvious.

[0013] As a further improvement of the above technical solution, the thickness of the FeCrCoMoTi layer is 90 nm - 110 nm. The thickness of the Ta layer is 5 nm - 10 nm. The mass ratio of Fe, Cr, Co, Mo, and Ti in the FeCrCoMoTi layer is 42:30:25:2:1.

[0014] Secondly, this application also provides a specific preparation method for the above magnetic code disk material, including the following steps:

[0015] Prepare a substrate, perform DC sputtering on the substrate, and then perform vacuum annealing to obtain the magnetic code disk material; the DC sputtering includes the following processes: perform the first DC sputtering on the substrate to prepare the first Au layer, then perform the second DC sputtering to prepare the FeCrCoMoTi layer, then perform the third DC sputtering to prepare the second Au layer, and then perform the fourth DC sputtering to prepare the Ta layer.

[0016] As a further improvement of the above technical solution, the vacuum degree during the DC sputtering process is: 1×10-5Pa -3 ×10 -5 Pa; the time of the first DC sputtering is 46.2 s, the time of the second DC sputtering is 1785.7 s, the time of the third DC sputtering is 46.2 s, and the time of the fourth DC sputtering is 66.7 s.

[0017] As a further improvement of the above technical solution, the conditions for vacuum annealing are 645 °C - 655 °C, and the time is 5 min - 10 min.

[0018] Finally, this application also provides a magnetic encoder using the above magnetic code disk material.

[0019] The beneficial effects of this application are as follows: The magnetic code disk material including a double-Au-catalyzed FeCrCoMoTi magnetic layer provided by this application has a significantly increased coercivity compared with the traditional FeCrCoMoTi thin film, and at the same time, the preparation process is simple and efficient, and the cost is relatively low. Description of the Drawings

[0020] Figure 1 Shown is the M-H curve of Example 1;

[0021] Figure 2 Shown is the M-H curve of Comparative Example 1;

[0022] Figure 3 Shown is the M-H curve of Comparative Example 2. Detailed Embodiments

[0023] The concept and technical effects of this application will be clearly and completely described below in conjunction with the embodiments and the drawings to fully understand the purpose, solution, and effects of this application. It should be noted that, without conflict, the embodiments in this application and the features in the embodiments can be combined with each other.

[0024] Example 1

[0025] First, this embodiment provides a magnetic code disk material, which sequentially includes from bottom to top: a double-Au-catalyzed magnetic layer, and the double-Au-catalyzed magnetic layer is obtained by vacuum annealing a first Au layer with a thickness of 5 nm, a FeCrCoMoTi layer with a thickness of 100 nm, a second Au layer with a thickness of 5 nm, and a Ta layer with a thickness of 5 nm from bottom to top; the temperature of the vacuum annealing is 650 °C.

[0026] The preparation method of the magnetic code disk material provided by this embodiment is as follows:

[0027] (1) Select a 316 non-magnetic stainless steel code disk as the metal substrate material (i.e., the substrate). In a magnetron sputtering device, using the DC sputtering method, at a vacuum degree of 3×10 -5 Pa, deposit the first Au layer on the substrate, with a sputtering power of 30 w, a deposition time of 46.2 s, and a thickness of 5 nm;

[0028] (2) Using the DC sputtering method, with a power of 100 W, at a vacuum degree of 3×10 -5 Pa, select a FeCrCoMoTi target with a mass ratio of Fe, Cr, Co, Mo, and Ti of 42:30:25:2:1, and deposit a FeCrCoMoTi nano-film layer on the first Au layer, with a deposition time of 1785.7 s and a thickness of 100 nm;

[0029] (3) Using the DC sputtering method, at a vacuum degree of 3×10 -5Under a Pa vacuum, a second Au layer is further deposited on the FeCrCoMoTi magnetic layer with a sputtering power of 30 w, a deposition time of 46.2 s, and a thickness of 5 nm;

[0030] (4)Using the DC sputtering method, under a 3×10 -5 Pa vacuum, a Ta protective layer is further deposited on the FeCrCoMoTi layer with a deposition time of 66.7 s, a sputtering power of 50 w, and a thickness of 5 nm;

[0031] (5)After the deposition step is completed, the material obtained in the above step (4) is subjected to vacuum annealing treatment. Among them, the annealing temperature is 650 °C, the annealing time is 5 min, and the vacuum degree of the annealing environment is 5×10 -5 Pa.

[0032] After annealing is completed, the magnetic disk material containing the double Au catalytic magnetic layer film is obtained, and its coercivity is 552 Oe and the remanence is 8434 Oe.

[0033] Appendix Figure 1 is the M-H curve (i.e., the hysteresis loop) of the magnetic disk material provided in this embodiment. Appendix Figure 1 The provided M-H curve details the whole process of the material provided in this embodiment from the initial state (unmagnetized) to saturated magnetization, reflecting the response of the material to the external magnetic field.

[0034] From Appendix Figure 1 it can be learned that the coercivity of the magnetic disk material provided in Example 1 is 552 Oe; the remanence is 8434 Oe; and the saturation magnetic field strength is 10716 Oe.

[0035] Example 2

[0036] First, this embodiment provides a magnetic disk material, which sequentially includes from bottom to top: a double Au catalytic magnetic layer, which is obtained by vacuum annealing a first Au layer with a thickness of 10 nm, a FeCrCoMoTi layer with a thickness of 100 nm, a second Au layer with a thickness of 10 nm, and a Ta layer with a thickness of 10 nm from bottom to top; the temperature of the vacuum annealing is 650 °C.

[0037] The preparation method of the magnetic disk material provided in this embodiment is as follows:

[0038] (1)Select a 316 non-magnetic stainless steel disk as the metal substrate material (i.e., the substrate). In a magnetron sputtering device, using the DC sputtering method, under a 3×10 -5 Pa vacuum, a first Au layer is deposited on the substrate with a sputtering power of 30 w, a deposition time of 92.4 s, and a thickness of 10 nm;

[0039] (2) Using the DC sputtering method with a power of 100 W, at a vacuum of 3×10 -5 Pa, on the first Au layer, deposit an FeCrCoMoTi nanometer thin film layer with a mass ratio of Fe, Cr, Co, Mo, and Ti of 42:30:25:2:1. The deposition time is 1785.7 s and the thickness is 100 nm;

[0040] (3) Using the DC sputtering method, at a vacuum of 3×10 -5 Pa, further deposit a second Au layer on the FeCrCoMoTi magnetic layer. The sputtering power is 30 w, the deposition time is 92.4 s, and the thickness is 10 nm;

[0041] (4) Using the DC sputtering method, at a vacuum of 3×10 -5 Pa, further deposit a Ta protective layer on the FeCrCoMoTi layer. The deposition time is 133.4 s, the sputtering power is 50 w, and the thickness is 10 nm;

[0042] (5) After the deposition steps are completed, perform vacuum annealing on the material obtained in the above step (4). Among them, the annealing temperature is 650 °C, the annealing time is 5 min, and the vacuum of the annealing environment is 5×10 -5 Pa.

[0043] Comparative Example 1

[0044] First, this embodiment provides a magnetic code disk material, which sequentially includes from bottom to top: an FeCrCoMoTi layer with a thickness of 100 nm and a Ta layer with a thickness of 5 nm obtained by vacuum annealing; the temperature of the vacuum annealing is 650 °C.

[0045] First, this comparative example provides a magnetic code disk material, which sequentially includes from bottom to top: an FeCrCoMoTi layer with a thickness of 100 nm and a Ta layer with a thickness of 5 nm, and the magnetic code disk material also undergoes vacuum annealing at 650 °C.

[0046] The preparation method of the magnetic code disk material provided by this embodiment is:

[0047] (1) Select a 316 non-magnetic stainless steel code disk as the metal substrate material (i.e., the substrate). In the magnetron sputtering device, using the DC sputtering method with a power of 100 W, at a vacuum of 3×10 -5 Pa, select an FeCrCoMoTi target with a mass ratio of Fe, Cr, Co, Mo, and Ti of 42:30:25:2:1, and deposit an FeCrCoMoTi nanometer thin film layer on the substrate. The deposition time is 1785.7 s and the thickness is 100 nm;

[0048] (2) Using the DC sputtering method, at a vacuum of 3×10 -5Under a Pa vacuum, a Ta protective layer is further deposited on the FeCrCoMoTi layer for 66.7 s with a sputtering power of 50 w and a thickness of 5 nm;

[0049] (3) After the deposition step is completed, the material obtained in the above step (2) is subjected to vacuum annealing. Among them, the annealing temperature is 650 °C, the annealing time is 30 min, and the vacuum degree of the annealing environment is 5×10 -5 Pa.

[0050] After annealing is completed, the magnetic disk material containing the FeCrCoMoTi magnetic layer film is obtained, with a coercivity of 380 Oe and a remanence of 6423 Oe.

[0051] Attached Figure 2 is the M-H curve (i.e., the hysteresis loop) of the magnetic disk material provided in this comparative example. Attached Figure 2 The provided M-H curve details the whole process of the material provided in this example from the initial state (unmagnetized) to saturation magnetization, reflecting the response of the material to the external magnetic field.

[0052] From the attached Figure 2 it can be learned that the magnetic disk material provided in Comparative Example 1 has a coercivity of 380 Oe; a remanence of 6423 Oe; and a saturation magnetic field intensity of 7787 Oe.

[0053] Comparative Example 2

[0054] First, this example provides a magnetic disk material, which is obtained by vacuum annealing in sequence from bottom to top: a 100-nm FeCrCoMoTi layer and a 5-nm Ta layer; the specific method of vacuum annealing is: vacuum annealing at 700 °C for 15 min, and then vacuum annealing at 630 °C for 15 min.

[0055] The preparation method of the magnetic disk material provided in this example is:

[0056] (1) Select a 316 non-magnetic stainless steel disk as the metal substrate material (i.e., the substrate). In a magnetron sputtering device, using the DC sputtering method with a power of 100 W, under a 3×10 -5 Pa vacuum, select an FeCrCoMoTi target with a mass ratio of Fe, Cr, Co, Mo, and Ti of 42:30:25:2:1, and deposit an FeCrCoMoTi nanometer thin film layer on the substrate for 1785.7 s with a thickness of 100 nm;

[0057] (2) Using the DC sputtering method, under a 3×10 -5 Pa vacuum, further deposit a Ta protective layer on the FeCrCoMoTi layer for 66.7 s with a sputtering power of 50 w and a thickness of 5 nm;

[0058] (3) After the deposition step is completed, the material obtained in the above step (2) is subjected to vacuum annealing. Among them, the specific method of vacuum annealing is: vacuum annealing at 700 °C for 15 min, and then vacuum annealing at 630 °C for 15 min. The vacuum degree of the annealing environment is 5×10 -5 Pa.

[0059] After the annealing is completed, the magnetic code disk material containing the FeCrCoMoTi magnetic layer thin film is obtained, and its coercivity is 455 Oe and the remanence is 7244 Oe.

[0060] Attached Figure 3 is the M-H curve (i.e., the hysteresis loop) of the magnetic code disk material provided by this comparative example. Attached Figure 3 The provided M-H curve details the whole process of the material provided by this embodiment from the initial state (unmagnetized) to saturation magnetization, reflecting the response of the material to the external magnetic field.

[0061] From the attached Figure 3 it can be learned that the coercivity of the magnetic code disk material provided by Comparative Example 2 is 455 Oe; the remanence is 7244 Oe; and the saturation magnetic field strength is 9021 Oe.

[0062] In summary, combining Example 1, Comparative Example 1 and Comparative Example 2, and attached Figure 1 - attached Figure 3 it is not difficult to see that compared with the FeCrCoMoTi magnetic code disk material, the magnetic code disk material provided by this application has excellent performance and simple processing. The coercivity of the FeCrCoMoTi thin film prepared by this method can reach 552 Oe, making the code disk material prepared by using this structure have higher performance in the future. At the same time, after the code disk signal is written, it has higher stability and anti-external interference ability.

[0063] Although the description of this application has been quite detailed and several of the described embodiments have been described in particular, it is not intended to be limited to any of these details or embodiments or any particular embodiment, but rather should be regarded as providing a broad interpretation of these claims in light of the prior art by reference to the appended claims, thereby effectively covering the intended scope of this application. In addition, the above description of this application with embodiments foreseeable by the applicant is for the purpose of providing a useful description, and those non-substantive changes to this application that are not currently foreseeable may still represent equivalent changes to this application.

Claims

1. A magnetic code disk material, characterized in that: It comprises a double Au catalytic magnetic layer and a Ta layer; the double Au catalytic magnetic layer is obtained by vacuum annealing a first Au layer, a FeCrCoMoTi layer and a second Au layer from bottom to top; the vacuum annealing temperature is 645°C-655°C.

2. A magnetic code disk material according to claim 1, characterized in that: The thickness of the first Au layer is 5nm-10nm.

3. A magnetic code disk material according to claim 1, characterized in that: The thickness of the second Au layer is 5nm-10nm.

4. A magnetic code disk material according to claim 1, characterized in that: The thickness of the FeCrCoMoTi layer is 90nm-110nm.

5. The magnetic code disk material according to claim 1, characterized in that: The thickness of the Ta layer is 5nm-10nm.

6. The magnetic code disk material according to claim 1, characterized in that: The mass ratio of Fe, Cr, Co, Mo and Ti in the FeCrCoMoTi layer is 42:30:25:2:

1.

7. A method for preparing a magnetic code disk material according to any one of claims 1 to 6, characterized in that: The steps include: Prepare a substrate, perform DC sputtering on the substrate, and then perform vacuum annealing to obtain the magnetic code disk material; the DC sputtering includes the following processes: perform a first DC sputtering on the substrate to prepare the first Au layer, then perform a second DC sputtering to prepare the FeCrCoMoTi layer, then perform a third DC sputtering to prepare the second Au layer, and then perform a fourth DC sputtering to prepare the Ta layer.

8. The method for preparing a magnetic code disk material according to claim 7, characterized in that: The vacuum degree during the DC sputtering process is: 1×10 -5 Pa-3×10 -5 Pa; the first DC sputtering time is 46.2s, the second DC sputtering time is 1785.7s, the third DC sputtering time is 46.2s, and the fourth DC sputtering time is 66.7s.

9. The method for preparing a magnetic code disk material according to claim 7, characterized in that: The vacuum annealing conditions are 645° C.-655° C. and the time is 5 min-10 min.

10. A magnetic encoder, characterized in that: The magnetic code disk material comprises any one of claims 1-6.

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