A high-performance magnetic code disk AlNiCo composite film material and its preparation method

Abstract

The present invention provides a high-performance AlNiCo composite thin film material for magnetic code disks and its preparation method, relating to the field of magnetic materials technology. The material comprises: a base layer and a non-magnetic / ferromagnetic composite multilayer thin film deposited on the base layer; the thin film comprises at least multiple AlNiCo films, an intercalated metal film, and a protective metal film. The present invention enables the AlNiCo film to meet the performance requirements of both a high-magnetic film and a non-magnetic buffer layer. The preparation method of the thin film material is simple, high-performance, and low-cost, providing a scientific basis and innovative ideas for the preparation and application of thin-film magnetic code disk materials.

Description

Technical Field

[0001] The present invention relates to the technical field of magnetic materials, and in particular to a high-performance magnetic code disk AlNiCo composite thin film material for a magnetic encoder and a preparation method thereof. Background Art

[0002] A magnetic rotary encoder is a non-contact displacement sensor that uses magnetic sensors to sense the magnetic field changes generated by the movement of magnetic poles, converting physical quantities such as angular displacement and velocity during rotational motion into digital electrical signals. These sensors offer advantages such as shock resistance, pollution resistance, corrosion resistance, reliable performance, and a simple structure. Combining encoders with digital signal processing and control technologies enables fast and accurate angular displacement detection and position control, making them widely used in high-precision control applications such as aerospace, industrial production, automotive, robotic joint control, and CNC machine tool turntables. The magnetic code disk is the core component of a magnetic encoder. The magnetic signal is generated by tiny magnetic poles written on the code disk. High-precision magnetic encoders require a uniform, multi-pole magnetic signal. Consequently, requirements are placed on the magnetic properties of the code disk material. To ensure: 1) easy recording of the magnetic signal and a certain degree of anti-interference capability; and 2) easy detection of the written magnetic signal by the sensor, resulting in a uniform, sinusoidal signal output, the magnetic film material must possess excellent magnetic properties, namely, moderate coercivity and high remanence. As magnetic code disk materials, the Hc of SmCo, NdFeB and Fe(Co)Pt magnetic films is too high, which makes it difficult to write magnetic signals. The Hc of chemically plated CoP films and CoCrTa films is moderate, but the Mr is low. The uneven distribution of alloy phases in bulk materials makes it difficult to obtain small magnetic pole moments and uniform output sine wave signals. Magnetic films have the advantages of being easy to prepare, uniform film formation and excellent magnetic properties. Therefore, the use of magnetic film materials to make magnetic code disk materials for high-precision magnetic encoders has aroused great interest. Therefore, it is necessary to prepare magnetic materials that meet the performance requirements of magnetic code disk materials for use in magnetic encoders.

[0003] AlNiCo thin films have a high Curie temperature and good magnetic properties, making them a very promising candidate material for magnetic code disks. Currently, there is more research on AlNiCo alloys, but less on AlNiCo thin films. Obtaining AlNiCo thin films with suitable coercivity and high remanence is one of the key issues in the current research field of magnetic films for magnetic code disks. Previous research on AlNiCo magnetic films has focused on obtaining higher coercivity by optimizing the annealing process and introducing non-magnetic atomic diffusion. However, the introduction of non-magnetic phases by these methods usually dilutes the main magnetic phase, resulting in a significant decrease in the overall remanence of the material. At the same time, in order to ensure that the AlNiCo film is well deposited on the code disk substrate, it is also necessary to solve the problem of preparing a non-magnetic buffer layer material that is as lattice-matched as possible with the AlNiCo film. Summary of the Invention

[0004] The purpose of the present invention is to provide a high-performance AlNiCo magnetic code disk thin film material and a preparation method thereof, so that the AlNiCo film meets the performance requirements of both a high-magnetic film and a non-magnetic buffer layer. Specifically, the technical solution of the present invention is as follows:

[0005] A high-performance magnetic code disk AlNiCo composite film material, comprising:

[0006] A substrate layer and a non-magnetic / ferromagnetic composite multilayer film deposited on the substrate layer; wherein the film comprises at least multiple AlNiCo films, an intercalation metal film, and a protective metal film. Obviously, the non-magnetic / ferromagnetic composite multilayer film in the present invention refers to a composite multilayer film having both a non-magnetic layer and a ferromagnetic layer.

[0007] Furthermore, in the composite multilayer film, the non-magnetic layer is located at the bottom of the entire film.

[0008] Furthermore, the base layer is a silicon base or a non-magnetic stainless steel base, the intercalated metal film is Cr and W, and the Cr layer is located below the W layer; the protective layer metal film is Ti, and the Ti layer is located on the top of the composite multilayer film and inserted in the middle of the composite multilayer film.

[0009] Furthermore, the structure of the composite multilayer film is:

[0010] AlNiCo / Cr / AlNiCo / Ti / AlNiCo / W / AlNiCo / Ti.

[0011] Furthermore, in the composite multilayer film, the thickness of the AlNiCo layer is 24-26 nm, preferably 25 nm; the thickness of the Cr layer and the W layer is 15-18 nm, preferably 16 nm; and the thickness of the Ti layer is 3-5 nm, preferably 5 nm.

[0012] At the same time, the present invention also provides a method for preparing the aforementioned composite film material, which specifically comprises:

[0013] Step S1, providing a base layer;

[0014] Step S2: Using magnetron sputtering, sequentially DC sputtering AlNiCo target, Cr target, AlNiCo target and Ti target, AlNiCo target, W target, AlNiCo target and Ti target on the substrate layer to obtain a thin film; wherein the sputtering powers of the AlNiCo target, W target, Cr target and Ti target are 100W, 70W, 50W and 80W respectively. The background vacuum degree of the system during the sputtering process does not exceed 4×10 -5Pa, and the Ar gas pressure was maintained at 0.26 Pa. The deposition time for each layer of AlNiCo was approximately 330 seconds; the deposition time for the W target was 250 seconds; the deposition time for the Cr target was 215 seconds; and the deposition time for the Ti target was 20 seconds.

[0015] Step S3: vacuum annealing the film to obtain a composite film material.

[0016] Furthermore, the composition of the AlNiCo target is: Fe:Co:Ni:Al:Ti:Cu=34:35:15:7:5:4, and the above ratio is a mass ratio.

[0017] Furthermore, the vacuum annealing condition in step S3 is vacuum annealing at 750°C for 30 min, wherein the vacuum degree does not exceed 5×10 -5 Pa.

[0018] Furthermore, the composite film material of the present invention is applied in the field of magnetic encoders.

[0019] The AlNiCo thin film material of the present invention adopts an ingenious structural design of introducing a double intercalation of Cr and W, which plays an important regulatory role in two aspects: (1) By controlling the diffusion of W elements in the AlNiCo thin film, the magnetic properties of the AlNiCo thin film can be effectively regulated, while the remanence is still maintained at a high level. The introduction of the W intercalation layer forms a pinning synergistic effect of the Fe-W ferrimagnetic phase and the Ni-Al non-magnetic phase in the film, so that the coercivity of the film is increased from 173 Oe when W is not introduced to more than 500 Oe after the introduction of W / layer, and the coercivity is increased by nearly 300%. At the same time, the remanence is still maintained at more than 9000 Oe (compared to AlNiCo (50 nm) / Ti (5 nm) film). (2) The introduction of the Cr intercalation layer constructs a non-magnetic bottom layer, and the bottom layer AlNiCo / Cr / AlNiCo is non-magnetic, providing a non-magnetic buffer layer material with the best possible lattice matching for the construction of a new non-magnetic substrate.

[0020] The beneficial effects brought about by the technical solution of the present invention include at least:

[0021] The novel structural design provided by this invention—a non-magnetic / ferromagnetic composite AlNiCo thin film with a composite intercalation layer—meets the requirements for high-precision magnetic encoder code disk materials requiring high coercivity while maintaining high remanence. Furthermore, the AlNiCo thin film material preparation method is simple, efficient, and low-cost. It is suitable for the preparation of high-performance magnetic code disk materials and high-precision magnetic encoder technology. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0023] Figure 1 MH curves of different thin film materials after annealing at 750°C for 30 minutes, wherein a is the thin film material of Comparative Example 1, b is the thin film material of Example 1, and c is the thin film material of Comparative Example 2.

[0024] Figure 2 Schematic diagram of atomic diffusion of different thin film materials, where a is AlNiCo film, b is AlNiCo / W / AlNiCo film, and c is AlNiCo / Cr / AlNiCo film. DETAILED DESCRIPTION

[0025] The technical solution of the present invention is described below in conjunction with the accompanying drawings.

[0026] In the embodiments of the present invention, words such as "exemplarily" and "for example" are used to indicate examples, illustrations, or explanations. Any embodiment or design described as an "exemplary" in the present invention should not be interpreted as being preferred or advantageous over other embodiments or designs. Rather, the use of the word "exemplary" is intended to present concepts in a concrete manner. Furthermore, in the embodiments of the present invention, "and / or" can mean both or either of the two.

[0027] In the embodiments of the present invention, "image" and "picture" may sometimes be used interchangeably. It should be noted that, when the distinction between them is not emphasized, the meanings they convey are the same. "of," "corresponding," and "corresponding" may sometimes be used interchangeably. It should be noted that, when the distinction between them is not emphasized, the meanings they convey are the same.

[0028] In the embodiments of the present invention, sometimes a subscript such as W1 may be mistakenly written as a non-subscript form such as W1. When the difference is not emphasized, the meanings to be expressed are the same.

[0029] In order to make the technical problems, technical solutions and advantages to be solved by the present invention clearer, a detailed description will be given below with reference to the accompanying drawings and specific embodiments.

[0030] Example 1

[0031] Step S1, providing a silicon base layer;

[0032] Step S2: Using magnetron sputtering, AlNiCo target, Cr target, AlNiCo target and Ti target, AlNiCo target, W target, AlNiCo target and Ti target are sequentially DC sputtered on the substrate to obtain a composite film of AlNiCo(25) / Cr(16) / AlNiCo(25) / Ti(5) / AlNiCo(25) / W(16) / AlNiCo(25) / Ti(5) structure, where the numbers in the brackets represent the thickness of each layer (nm); wherein the sputtering powers of the AlNiCo target, W target, Cr target and Ti target are 100W, 70W, 50W and 80W, respectively. The background vacuum degree of the system during the sputtering process does not exceed 4×10 -5 Pa, and the Ar gas pressure was maintained at 0.26 Pa. The deposition time for each layer of AlNiCo was approximately 330 seconds; the deposition time for the W target was 250 seconds; the deposition time for the Cr target was 215 seconds; and the deposition time for the Ti target was 20 seconds.

[0033] The composition of the AlNiCo target is: Fe:Co:Ni:Al:Ti:Cu=34:35:15:7:5:4 (mass ratio).

[0034] Step S3: annealing the composite film in vacuum at 750° C. for 30 minutes to obtain a composite film material.

[0035] Comparative Example 1

[0036] The difference from Example 1 is that the composite film structure obtained in step S2 is AlNiCo(50) / Ti(5).

[0037] The thin film was obtained by sequentially sputtering AlNiCo target and Ti target on the substrate using magnetron sputtering. The sputtering powers of AlNiCo target and Ti target were 100W and 80W respectively. The background vacuum of the system during the sputtering process did not exceed 4×10 -5 Pa, and the Ar gas pressure was maintained at 0.26 Pa. The AlNiCo deposition time was approximately 660 seconds, and the Ti target deposition time was 20 seconds.

[0038] Comparative Example 2

[0039] The difference from Example 1 is that the composite film structure obtained in step S2 is AlNiCo(25) / Cr(16) / AlNiCo(25) / Ti(5).

[0040] The multilayer film was obtained by sequentially sputtering AlNiCo target, Cr target, AlNiCo target and Ti target on the substrate using magnetron sputtering. The sputtering powers of AlNiCo target, Cr target and Ti target were 100W, 50W and 80W respectively. The background vacuum of the system during the sputtering process did not exceed 4×10-5 Pa, and the Ar gas pressure was maintained at 0.26 Pa. The deposition time for each AlNiCo layer was approximately 330 seconds; the deposition time for the Cr target was 215 seconds; and the deposition time for the Ti target was 20 seconds.

[0041] like Figure 1 The MH curves of the AlNiCo films obtained in Example 1 and Comparative Examples 1 and 2 are shown. As can be seen from the figure, the coercive force of the AlNiCo(50) / Ti(5) (nm) film is low and the remanence is high; after the introduction of Cr intercalation, the AlNiCo(25) / Cr(16) / AlNiCo(25) / Ti(5) (nm) film loses its magnetism; the introduction of Cr / W double intercalation to construct the AlNiCo / Cr / AlNiCo / Ti / AlNiCo / W / AlNiCo / Ti non-magnetic / ferromagnetic composite multilayer film has a significant increase in coercive force compared to the AlNiCo(50) / Ti(5) (nm) film (Hc=173Oe, Mr=10795 Gs), and the coercive force is increased to more than 500 Oe. At the same time, the remanence of the film remains at a high remanence of more than 9000 Oe before and after the introduction of the intercalation layer. This shows that this composite film takes into account the performance requirements of both high magnetic film and non-magnetic buffer layer.

[0042] And by Figure 2 It can be seen that after annealing, the W layer of the AlNiCo / W / AlNiCo structured film sample exists in the form of a single substance, and the film can maintain a good layered structure. However, due to the difference in melting points between W and Fe, a trace amount of W will still diffuse into the AlNiCo layer, which not only promotes the precipitation of non-magnetic phases and pins the domain walls of the film, resulting in a significant increase in the film's coercivity; it also combines with Fe to form an Fe-W intermetallic compound, which is ferrimagnetic, resulting in a slight decrease in the film's remanence, but the material can still maintain a high remanence. After annealing, the Cr in the AlNiCo / Cr / AlNiCo film structure sample will dissolve in the AlNiCo layer and combine with Fe to form a large amount of non-magnetic FeCr alloy, which leads to a significant decrease in the film's magnetic properties. Actual magnetic testing results in a non-magnetic film. The introduction of Cr / W double intercalation layers to construct an AlNiCo / Cr / AlNiCo / Ti / AlNiCo / W / AlNiCo / Ti non-magnetic / ferromagnetic composite multilayer film significantly increases the coercivity compared to the AlNiCo(50) / Ti(5) (nm) film. At the same time, the film's remanence remains high, exceeding 9000 Oe, both before and after the introduction of the intercalation layers. The magnetism originates from the AlNiCo / W / AlNiCo structure on top. This composite film combines the performance requirements of a highly magnetic film with a non-magnetic buffer layer.

[0043] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any modifications or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in the present invention should be included in the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be based on the scope of protection of the claims.

Claims

1. A method for preparing a high-performance magnetic code disk AlNiCo composite film material, characterized in that: include: Step S1, providing a base layer; Step S2, using magnetron sputtering, sequentially DC sputtering a FeCoNiAlTiCu target, a Cr target, a FeCoNiAlTiCu target and a Ti target, a FeCoNiAlTiCu target, a W target, a FeCoNiAlTiCu target and a Ti target on the substrate layer to obtain a thin film; Step S3, vacuum annealing the film to obtain a composite film material; In the FeCoNiAlTiCu target, Fe:Co:Ni:Al:Ti:Cu=34:35:15:7:5:

4.

2. The method according to claim 1, characterized in that In step S2, the sputtering powers of the FeCoNiAlTiCu target, W target, Cr target, and Ti target are 100 W, 70 W, 50 W, and 80 W, respectively; the background vacuum degree of the system during the sputtering process does not exceed 4×10 -5 Pa, Ar gas pressure is maintained at 0.26 Pa; the deposition time of each layer of FeCoNiAlTiCu target is 330 seconds; the deposition time of W target is 250 seconds; the deposition time of Cr target is 215 seconds; and the deposition time of Ti target is 20 seconds.

3. The method according to claim 1, characterized in that The vacuum annealing condition in step S3 is vacuum annealing at 750° C. for 30 minutes.

4. A composite film material prepared according to the method according to any one of claims 1 to 3.

5. Use of the composite film material prepared by the method according to any one of claims 1 to 3, or the composite film material according to claim 4, in the field of magnetic encoders.

Images