High-performance magnetic coded disc AlNiCo composite film material and preparation method thereof

Abstract

The invention provides a high-performance magnetic code disc AlNiCo composite film material and a preparation method thereof, and relates to the technical field of magnetic materials, the high-performance magnetic code disc AlNiCo composite film material comprises a substrate layer and a non-magnetic / ferromagnetic composite multilayer film deposited on the substrate layer; wherein the thin film at least comprises a plurality of layers of AlNiCo films, an intercalation metal film and a protective layer metal film. According to the invention, the AlNiCo film respectively meets the performance requirements of a high-magnetism film and a non-magnetic buffer layer, the preparation method of the film material is simple, the performance is high, the cost is low, and a scientific basis and an innovative idea are provided for the preparation and application of the film type magnetic code disc material.

Description

Technical Field

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

[0002] The magnetic rotary encoder is a non-contact displacement sensor that uses magnetic sensitive elements to sense the magnetic field changes generated by the movement of magnetic poles, and converts physical quantities such as angular displacement and speed in the rotary motion into digital electrical signal output. It has the advantages of anti-vibration, pollution resistance, corrosion resistance, reliable performance and simple structure. Combining the encoder with digital signal processing and control technology can achieve fast and accurate angular displacement detection and position control, so it is widely used in high-precision control fields such as aerospace, industrial production, automobiles, robot joint control and CNC machine tool turntables. The magnetic code disk is the core component of the magnetic encoder, and the magnetic signal is provided by the tiny magnetic poles written on the code disk. For high-precision magnetic encoders, the magnetic code disk is required to provide a uniform and consistent multi-pole magnetic signal. Therefore, the magnetic properties of the magnetic code disk material are required. In order to ensure: 1) The magnetic signal is easy to write and the written magnetic signal has a certain anti-interference ability; 2) The sensor can easily detect the written magnetic signal, thereby outputting a uniform and consistent sine wave signal. Therefore, this requires that the magnetic film material must have relatively excellent magnetic properties, that is, moderate coercivity and high remanence. As a magnetic code disk material, 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 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 easy preparation, 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 film has a high Curie temperature and good magnetic properties, and is a very promising candidate material for magnetic code disks. At present, there are many studies on AlNiCo alloys, but few studies on AlNiCo films. Obtaining AlNiCo 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 studies on AlNiCo magnetic films have focused on obtaining higher coercivity by optimizing the annealing process and introducing non-magnetic atomic diffusion, but 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 make the AlNiCo film 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 film material and a preparation method thereof, so that the AlNiCo film meets the performance requirements of 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 at least includes a multilayer AlNiCo film, 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 100 W, 70 W, 50 W and 80 W respectively. The background vacuum 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 of each layer of AlNiCo was about 330 seconds; the deposition time of W target was 250 seconds; the deposition time of Cr target was 215 seconds; and the deposition time of 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 a clever 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 the W element in the AlNiCo thin film, the magnetic properties of the AlNiCo thin film can be effectively regulated, while the remanence remains at a high level. The introduction of the W intercalation layer forms a pinning synergy 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 with AlNiCo (50 nm) / Ti (5 nm) film). (2) A non-magnetic bottom layer is constructed by the introduction of the Cr intercalation layer, and the bottom layer AlNiCo / Cr / AlNiCo is non-magnetic, providing a non-magnetic buffer layer material with as much lattice matching as possible for the construction of a new non-magnetic substrate.

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

[0021] The novel structural design provided by the present invention - the non-magnetic / ferromagnetic composite AlNiCo film with composite intercalation layer meets the application requirements of high-precision magnetic encoder code disk materials for high coercivity while maintaining high remanence. In addition, the preparation method of the AlNiCo film material of the present invention 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 min, wherein a is the thin film material of comparative example 1, b is the thin film material of embodiment 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 "example" in the present invention should not be interpreted as being more preferred or more advantageous than other embodiments or designs. Specifically, the use of the word "example" is intended to present the concept in a specific way. In addition, in the embodiments of the present invention, the meaning expressed by "and / or" can be both, or it can be either of the two.

[0027] In the embodiments of the present invention, "image" and "picture" can sometimes be used interchangeably. It should be noted that when the difference between them is not emphasized, the meanings they want to express are the same. "of", "corresponding" and "corresponding" can sometimes be used interchangeably. It should be noted that when the difference between them is not emphasized, the meanings they want to express 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 such as W1. When the difference is not emphasized, the meanings to be expressed are consistent.

[0029] In order to make the technical problems, technical solutions and advantages to be solved by the present invention more clear, 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, DC sputtering AlNiCo target, Cr target, AlNiCo target and Ti target, AlNiCo target, W target, AlNiCo target and Ti target on the substrate layer in sequence 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 brackets represent the thickness of each layer (nm); wherein the sputtering powers of the AlNiCo target, W target, Cr target and Ti target are 100 W, 70 W, 50 W and 80 W respectively. During the sputtering process, the background vacuum of the system does not exceed 4×10 -5 Pa, and the Ar gas pressure was maintained at 0.26 Pa. The deposition time of each layer of AlNiCo was about 330 seconds; the deposition time of W target was 250 seconds; the deposition time of Cr target was 215 seconds; and the deposition time of 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, vacuum annealing the composite film at 750° C. for 30 min 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 AlNiCo target and the Ti target were sputtered on the substrate layer in sequence by magnetron sputtering to obtain the thin film. The sputtering powers of the AlNiCo target and the 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 about 660 seconds; 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 by 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 of each layer of AlNiCo was about 330 seconds; the deposition time of Cr target was 215; and the deposition time of 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 respectively. 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 greatly increased the coercive force increase 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 before and after the introduction of the intercalation layer still maintains a high remanence of more than 9000 Oe. 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 the melting points of W and Fe, a trace amount of W will still diffuse into the AlNiCo layer, which will not only promote the precipitation of the non-magnetic phase, but also the pinning effect of the domain wall of the film magnetic domain, resulting in a significant increase in the coercive force of the film; it will also combine with Fe to form Fe-W intermetallic compounds, which have ferrimagnetism, thus causing a slight decrease in the remanence of the film, and the material can still maintain a high remanence. After annealing, the AlNiCo / Cr / AlNiCo film structure sample will have Cr that dissolves in the AlNiCo layer and combines with Fe to form a large amount of non-magnetic FeCr alloy, which leads to a significant decrease in the magnetic properties of the film, and a non-magnetic film is obtained through actual magnetic testing. For the introduction of Cr / W double intercalation, the AlNiCo / Cr / AlNiCo / Ti / AlNiCo / W / AlNiCo / Ti non-magnetic / ferromagnetic composite multilayer film is constructed. Compared with the AlNiCo(50) / Ti(5) (nm) film, the coercivity increase is greatly increased. At the same time, the remanence of the film remains high above 9000Oe before and after the introduction of the intercalation layer. The magnetism comes from the AlNiCo / W / AlNiCo structure on the top. This composite film takes into account the performance requirements of both high magnetic film and non-magnetic buffer layer.

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

Claims

1. A high-performance magnetic code disk AlNiCo composite film material, characterized in that: include: A substrate layer, and a non-magnetic / ferromagnetic composite multilayer film deposited on the substrate layer; The thin film at least includes multiple layers of AlNiCo films, intercalated metal films and protective metal films.

2. The composite film material according to claim 1, characterized in that: The non-magnetic phase is located below the ferromagnetic phase in the composite multilayer film.

3. The composite film material according to claim 1, characterized in that: 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.

4. The composite film material according to claim 1, characterized in that: The structure of the composite multilayer film is: AlNiCo / Cr / AlNiCo / Ti / AlNiCo / W / AlNiCo / Ti.

5. The composite film material according to claim 4, characterized in that: In the composite multilayer film, the thickness of the AlNiCo layer is 24-26 nm, the thickness of the Cr layer and the W layer is 15-18 nm, and the thickness of the Ti layer is 3-5 nm.

6. The method for preparing the composite film material according to any one of claims 1 to 5, characterized in that: include: Step S1, providing a base layer; Step S2, using magnetron sputtering to sequentially direct current sputter 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; Step S3: vacuum annealing the film to obtain a composite film material.

7. The method according to claim 6, characterized in that In step S2, the sputtering powers of the AlNiCo 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 AlNiCo 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.

8. The method according to claim 6, characterized in that The composition mass ratio of the AlNiCo target is: Fe:Co:Ni:Al:Ti:Cu=34:35:15:7:5:

4.

9. The method according to claim 6, characterized in that The vacuum annealing condition in step S3 is vacuum annealing at 750° C. for 30 minutes.

10. Use of the composite film material according to any one of claims 1 to 5, or the composite film material prepared by the method according to any one of claims 6 to 9, in the field of magnetic encoders.

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