CN114836800B - Preparation method of Co-Ni-Zn ternary nanocrystalline magnetic alloy and product obtained by preparation method - Google Patents

Abstract

The invention discloses a preparation method of a Co-Ni-Zn ternary nanocrystalline magnetic alloy, which comprises the following steps: the activated honeycomb porous Ti substrate is immersed in Co-Ni mixed plating solution in an electrified manner, and high-frequency pulse electrodeposition is adopted to prepare Co-Ni binary alloy, so as to generate a bar-grain phase embedded microstructure; adopting a rapid titration method to make the concentration of ZnSO containing ascorbic acid be 0.5-0.7 mol/L ₄ Adding concentrated liquid into the product obtained in the first step, and promoting abnormal codeposition of ternary alloy of Zn and Ni-Co under the action of an ascorbic acid complexing agent to form a cauliflower-like sphere texture characteristic; drying the product obtained in the second step, and performing heat treatment at 450-480 ℃ to realize that Zn is oxidized into network-like ZnO and is pinned and dispersed along GBs, thereby being beneficial to preventing nucleation and expansion of a domain in a magnetic field and improving coercive force. The method is simple and convenient to operate, and the Co-Ni-Zn ternary nanocrystalline magnetic alloy with compact structure and high magnetic coercivity is obtained by adopting a high-frequency pulse electrodeposition process in combination with complexing agent conditions such as ascorbic acid.

Description

Preparation method of Co-Ni-Zn ternary nanocrystalline magnetic alloy and product obtained by preparation method

Technical Field

The invention belongs to a magnetic alloy and a preparation method thereof, in particular to a preparation method of a Co-Ni-Zn ternary nanocrystalline magnetic alloy and a product obtained by the preparation method.

Background

Ni and Co belong to the category of 3d transition metals, magnetism is provided at room temperature, nickel-cobalt alloy is used as room temperature ferromagnetic material to prepare a magneto-resistance effect element, and the magneto-resistance effect element is widely used in the fields of magnetic memory devices, 5G quantum communication and the like. Moreover, due to the high hardness and the excellent properties such as corrosion resistance, abrasion resistance, high temperature resistance, and the like, the Ni-Co alloy has become a main stream material of surface plating layers of parts and equipment. Ni and Co belong to VIII groups, the electrode potential is similar, co ²⁺ Standard reduction potential of/Co (-0.27V) with Ni ²⁺ The standard reduction potential (-0.25V) of Ni is quite close so that two metal ions can co-deposit on the cathode to form a coating. Co is reduced and deposited preferentially over Ni, and the Co content in the coating is far higher than the Co concentration in the plating solution, so that the nickel-cobalt alloy belongs to abnormal Co-deposition. Meanwhile, ni and Co belong to face-centered cubic crystal systems, the compatibility is good, alloy compounds are easy to form in the Co-deposition process, and the structure is compact and the strength and toughness are good.

As a II-VI wide band gap semiconductor material with photoelectric characteristics, znO has wide application prospect in the aspects of electricity, magnetism and the like. Recent studies have shown that: the Li doped ZnO material may have ferroelectricity and ferromagnetism at the same time, and many researchers in China have studied it in a large amount. Ni and Li co-doped ZnO films are prepared on Song coast of Nanjing university, and the like, and the fact that the ferromagnetism is weakened due to the fact that holes are introduced by Li doping is found. The Co Co-doped ZnO nano-particles are prepared by Li Jianjun of Beijing aviation aerospace university, and experiments show that when the doping concentration is lower than 9%, ferromagnetism is enhanced, and the reason is that interstitial atoms are formed after doping, the electron concentration is obviously increased, so that the concentration of bound magnetic poles is increased, and the magnetic poles are easily overlapped, so that the ferromagnetic coupling effect is enhanced. The ZnO film co-doped with Mn and Li is prepared by Wang Qing of the university of Wuhan and the like, znO samples with different Mn doping concentrations are studied, and the results show that: as the concentration of doped Mn increases, the magnetization increases; however, more interstitial ions are formed with the increase of the doping concentration of Li, so that the hole concentration is reduced, and the room-temperature ferromagnetism is not favored.

Therefore, there is a need to improve the magnetic properties of Co-Ni-based ternary alloys to compensate for the defects of low magnetic coercivity and poor structural properties of AlNi-Co permanent magnet alloys. Generally, co-Ni-based ternary magnetic alloys include Co-Ni-W, co-Ni-Fe, co-Ni-Mn, etc., which exhibit high saturation magnetization and low magnetic coercivity, and common preparation methods are powder metallurgy, vacuum evaporation, ion sputtering, electrodeposition. However, due to poor compatibility between dissimilar metal atoms and not deposition growth under steady-state conditions, defects such as preferential growth of texture, large growth stress or dendrite segregation occur, and the synergistic development of microstructure densification and excellent magnetic properties cannot be achieved.

Disclosure of Invention

The invention aims to: in order to overcome the defects in the prior art, the invention aims to provide a preparation method of the Co-Ni-Zn ternary nanocrystalline magnetic alloy capable of realizing component and magnetic strength regulation and control, and the invention also aims to provide the Co-Ni-Zn ternary nanocrystalline magnetic alloy with high temperature stability and high coercivity.

The technical scheme is as follows: the preparation method of the Co-Ni-Zn ternary nanocrystalline magnetic alloy comprises the following steps:

step one, the activated honeycomb porous Ti substrate is immersed into Co-Ni mixed plating solution in an electrified manner, and high-frequency pulse electrodeposition is adopted to prepare Co-Ni binary alloy to generate a bar-grain phase embedded microstructure;

step two, adopting a rapid titration method to make the concentration of ZnSO containing ascorbic acid be 0.5-0.7 mol/L ₄ Adding concentrated liquid into the product obtained in the first step, and promoting abnormal codeposition of ternary alloy of Zn and Ni-Co under the action of an ascorbic acid complexing agent to form a cauliflower-like sphere texture characteristic;

and thirdly, drying the product obtained in the second step, and performing heat treatment at 450-480 ℃ to realize that Zn is oxidized into network-like ZnO and is pinned and dispersed along GBs, thereby being beneficial to preventing nucleation and expansion of a domain in a magnetic field and improving coercive force.

Further, in the first step, the honeycomb porous Ti substrate is activated with dilute hydrochloric acid having a concentration of 5 to 7wt.%, preferably, the honeycomb porous Ti substrate is activated with dilute HCl having a concentration of 5wt.% for 10s. 150-160V DC voltage-stabilizing on H for honeycomb porous Ti substrate ₃ PO ₄ 、H ₂ O ₂ The anode oxidation is carried out in the mixed solution, the temperature of the electrolyte is 5-10 ℃, the honeycomb porous Ti substrate is wide pore mouth, and the pore diameter is 300-350 nm. H ₃ PO ₄ 、H ₂ O ₂ The mixed liquor is preferably 15wt.% H ₃ PO ₄ +20wt.％H ₂ O ₂ The dc voltage regulation is preferably 150V. The honeycomb porous Ti substrate has hydrophilicity, and the contact angle is 40-50 degrees. The pulse frequency of the high-frequency pulse power is 2.0-4.0 kHz, the duty ratio of positive and negative current is 1:5-1:7, and the peak current density is 0.3-0.7 mA/cm ² The electrodeposition time was 30min and the deposition rate was about 10 μm/min. Charged Co-Ni binary mixed solution is put into the mixture for electrodeposition, because of Co ²⁺ Co and Ni ^{2 +} The standard reduction potential of Ni is close. In view of this, co-Zn crystals are preferentially grown on the porous surface, which is advantageous in improving the interfacial bonding force of the alloy plating layer with the Ti base.

The phosphoric acid system anodic oxide film is selected because the porous titanium-based surface of the film contains an active phosphoric acid film component, and the surface of the obtained porous titanium substrate with the phosphoric acid film component has hydrophilicity (contact angle is about 45 degrees) unlike the traditional porous structure hydrophobic property, so that the subsequent crystal growth is facilitated.

Further, in the first step, the Co-Ni mixed plating solution comprises: 110-120 g/L CoSO ₄ ·6H ₂ O，40～50g/L Ni(SO ₃ NH ₂ ) ₂ ·4H ₂ O，12～15g/L CH ₃ COOH，45～50g/L H ₃ BO ₃ 2.0-3.5 g/L ascorbic acid, 0.4-0.5 g/L surfactant and pH 3.8-4.5. The temperature of the Co-Ni mixed plating solution is 35-40 ℃.

Further, the Co-Ni mixed plating solution is preferably: 120g/L CoSO ₄ ·6H ₂ O，45g/L Ni(SO ₃ NH ₂ ) ₂ ·4H ₂ O，12g/L CH ₃ COOH，50g/L H ₃ BO ₃ 3.0g/L ascorbic acid, 0.5g/L surfactant (e.g. EDTA).

Further, in the second step, the dropping speed of the rapid titration method is 5-15 mL/min, and the mechanical stirring speed is 150-200 rpm. Realizing Zn in electrolyte by controlling titration rate ²⁺ A change in concentration; under the action of complexing agents such as ascorbic acid, ni or Co crystal grains which grow preferentially serve as heterogeneous nucleation growth points or autocatalysis centers of subsequent Zn, and abnormal Co-deposition of ternary alloy of Zn and Ni-Co is promoted. ZnSO containing ascorbic acid ₄ The concentrated solution comprises the following components: 45-60g/L zinc sulfate, 2.0-3.5 g/L ascorbic acid, pH value of solution is 3.5-4.0, and titration rate is kept at 3.0-15.0 ml/min.

Further, in the third step, the temperature rising rate is 5 ℃/min, the initial temperature is 150 ℃, the end temperature is set at 450-480 ℃, the heat preservation time is 3h, and the furnace is cooled.

The Co-Ni-Zn ternary nanocrystalline magnetic alloy obtained by the preparation method of the Co-Ni-Zn ternary nanocrystalline magnetic alloy is cauliflower-shaped, precipitated phase ZnO is filled along grain boundary segregation, and the network ZnO whisker wraps the ternary nanocrystalline alloy of Ni and Co, so that a magnetic domain wall pinning effect is formed.

Further, the Co and Ni sizes are 300-500 nm.

Instead of using sulfamic acid systemsBy ZnCl ₂ The system performs the subsequent titration operation, and mainly has two aspects of consideration: firstly, the zinc sulfamate system is sensitive to the pH value and the temperature of the solution, is not beneficial to the continuous addition of the subsequent concentrated solution, and is easy to generate precipitation and slightly-soluble floccules, so that the dispersibility and the stability of the Co-Ni-Zn ternary mixed plating solution are reduced; second, due to Cl ^- The zinc ions can be partially changed into magnesium chloride ions, the magnesium chloride ions are easy to be reduced under the action of complexing agent ascorbic acid, and the magnesium chloride ions are more uniformly dispersed at defect positions indicated by the characteristic Co-Zn alloy of the 'cauliflower', and the dispersing effect is good because of Cl ^- The diffusion and permeation effects along the gaps are achieved, the transportation and diffusion channels are actively opened, alloy ion deposition is facilitated, and chemical reaction is promoted.

The aging heat treatment is carried out at 450 ℃ for 3 hours, and mainly has two purposes: on one hand, the structure of the Co-Ni-Zn alloy is promoted to be stable, and the growth stress in the abnormal Co-deposition process is relieved; on the other hand, the long-time aging heat treatment for 3 hours can realize the diffusion process of low-melting-point atoms Zn along gaps of Co-Zn 'cauliflower' textures, promote nanocrystalline Zn particles to be oxidized into ZnO dispersion phases, and meanwhile, the dispersion phases are pricked along GBs defect positions, and the ZnO dispersion phases are filled as magnetic isolation, and provide 'pinning' positions for domain wall movement, so that the magnetic performance is improved.

Working principle: abnormal Co-deposition of binary Co-Ni and ternary Co-Ni-Zn nanocrystalline alloys was performed in two steps. Firstly, adopting a high-frequency pulse process to perform Co-Ni electrodeposition growth in an sulfamic acid electrolyte system, wherein the texture growth has the characteristic of nanocrystalline 'cauliflower' balls; then, znCl containing ascorbic acid is added by adopting a rapid titration method ₂ And (3) dropwise adding the concentrated solution into the Co-Ni mixed solution to promote Co-deposition of ternary Co-Ni-Zn nanocrystalline alloy, and filling defects along gaps of Co-Ni 'rape flower' spheres with follow-up fine-grain Zn, and carrying out pinning growth. In the abnormal electrodeposition process, co is considered ²⁺ 、Ni ²⁺ The potential difference is small, the co-deposition is convenient, and according to Nernst equation and c-v curve, ni in electrolyte ²⁺ And Co ²⁺ The atomic molar ratio of the components is 1:7, and the Co-Ni texture has typical dish flower ball characteristics. In addition, based on the control variable method, by controlling ZnCl ₂ Drops of concentrateRealizes the constant rate of Zn in the mixed electrolyte ²⁺ Content control, according to EDS multiple determination, calculating ternary alloy compound as Ni _0.12 Co _0.88-x Zn _x Wherein x is Zn ²⁺ The titration rate of the concentrated solution is controlled, and x ranges from 0 to 0.36 and ZnSO ₄ The titration rate corresponds approximately to: 5mL/min (x-0.12), 10mL/min (x-0.24) and 15mL/min (x-0.36).

The beneficial effects are that: compared with the prior art, the invention has the following remarkable characteristics:

1. the method is simple and convenient to operate, and the Co-Ni-Zn ternary nanocrystalline magnetic alloy with compact structure and high magnetic coercivity is obtained by adopting a high-frequency pulse electrodeposition process in combination with complexing agent conditions such as ascorbic acid;

2. the Co-Ni mixed solution adopts an sulfamic acid system, so that the stability of the mixed solution is improved, and the texture growth stress in the Co-Ni abnormal codeposition process is relieved;

3. by ZnSO ₄ The concentrated solution is dripped into Co-Ni-Zn mixed electrolyte to lead ZnSO ₄ With CoSO ₄ The plating solution is in the same type of sulfate system, so that the stability of the plating solution is improved; at the same time, relative to ZnCl ₂ The invention adopts ZnSO ₄ The interfacial bonding force between the coating and the matrix can be obviously improved;

4. the nano-crystalline Co-Ni texture growth has the characteristic of a vegetable flower nano sphere, and fine-crystalline Zn is filled along the gaps of the vegetable flower nano sphere and mutually nested, and as Ni and Co have good high-temperature oxidation resistance and thermal stability, only a small part of Ni and Co are oxidized; the medium-temperature aging treatment at 450-480 ℃ promotes the tissue to be stable, relieves the growth stress in the abnormal codeposition process, promotes the nanocrystalline Zn to be almost 100 percent oxidized into ZnO dispersion phase, and simultaneously diffuses along GBs defect positions, the dispersion phase ZnO is filled as magnetic isolation, and provides pinning positions for domain wall movement, thereby forming the ternary alloy magnetic alloy with network ZnO wrapping nanocrystalline Ni and Co particles, being beneficial to the improvement of magnetic performance, and leading the ternary nanocrystalline alloy coating to have high magnetic saturation strength and magnetic coercive force;

5. ternary nanocrystalline alloy Ni _0.12 Co _0.84-x Zn _x When x=0.24, i.e. Ni _0.12 Co _0.60 Zn _0.24 The alloy coating has the highest coercivity and high saturation magnetization, wherein: ms-saturation magnetization of 127.2emu/g, hc-coercivity as high as 0.51kOe, T _c -curie temperature up to 460.4 ℃;

6. the chemical components and the magnetic strength of Co-Ni-Zn can be regulated and controlled by a rapid titration method.

Drawings

FIG. 1 is an SEM image of a honeycomb porous Ti substrate of the invention, where a has a scale of 5 μm, b has a scale of 1 μm, and c has a scale of 500nm;

FIG. 2 is an SEM image of the original ingot of the Co-Ni-Zn ternary alloy in step (3) of the present invention;

FIG. 3 is a schematic illustration of the apparatus of the present invention;

FIG. 4 is a surface SEM image of binary Co-Ni nanocrystals prior to aging heat treatment;

FIG. 5 is a surface SEM image of the ternary Co-Ni-Zn nanocrystalline coating of the present invention prior to aging heat treatment;

FIG. 6 is a graph of the surface topography of an alloy plating specimen before aging of example 1, wherein a is 5 μm on the scale of a and b is 1 μm on the scale of b;

FIG. 7 is a graph showing the surface morphology of an alloy plating sample after aging treatment of example 1, wherein a is 5 μm on the scale of a and b is 1 μm on the scale of b;

FIG. 8 is an XRD pattern for the surface alloying elements prior to ageing treatment of example 1;

FIG. 9 is an XRD pattern for the surface alloying elements after ageing treatment of example 1;

FIG. 10 is an SEM image of the surface microstructure and an EDS image of a localized micro region after aging treatment of example 1, where a is ternary Ni _0.12 Co _0.84-x Zn _x The surface morphology of the nanocrystalline alloy is shown in SEM after aging treatment, c is an enlarged view of part of Zn or ZnO, and d is an enlarged view of a partial region in fig. 10 c.

FIG. 11 is an XPS diagram of the surface alloy element of example 1, where a is the XPS spectrogram before aging, b is the XPS spectrogram after aging, c is the XPS diagram before Co2p aging, and d is the XPS diagram after Co2p aging; e is an XPS graph before Ni2p aging treatment; f is an XPS graph before Ni2p aging treatment; g is an XPS graph before Zn2p aging treatment; h is an XPS graph before Zn2p aging treatment; i is an XPS graph before O1s aging treatment; j is an XPS graph before O1s aging treatment;

FIG. 12 is a cyclic voltammogram (c-v) plot of the present invention;

FIG. 13 is a cyclic voltammogram (c-v) of comparative example 2 of the present invention;

FIG. 14 shows Ni in various atomic molar ratios according to the invention _0.12 Co _0.84-x Zn _x (x=0 to 0.36) surface SEM images of ternary alloy, where a is comparative example 4, b is example 2, c is example 1, d is example 3;

FIG. 15 is a graph showing statistical comparisons of magnetic properties before and after aging heat treatment according to the present invention;

fig. 16 is a graph of hysteresis loop (M-H) of the present invention.

Detailed Description

In the following examples, co is considered ²⁺ 、Ni ²⁺ The difference of reduction potential is small, so that Co-deposition is convenient to realize, but Co is found through experiments at the same time ²⁺ Is superior to Ni ²⁺ First reducing and separating out, and during the deposition, ni is blocked ²⁺ The function of the reduction precipitation, in view of this, according to the Nernst equation, finds: when the mole ratio of Ni to Co is 1:7, the crystal growth shows the characteristic of 'rape flower' texture, and the plating layer is smooth and fine.

Example 1

A preparation method of a Co-Ni-Zn ternary nanocrystalline magnetic alloy comprises the following steps:

(1) Preparing a honeycomb porous Ti substrate: by Al ₂ O ₃ Polishing the pure Ti substrate by using the polishing paste, sequentially adopting 500# abrasive paper, 800# abrasive paper and 1200# abrasive paper to polish until no scratch exists, and then carrying out H treatment ₃ PO ₄ System (15 wt.% H) ₃ PO ₄ +20wt.％H ₂ O ₂ ) And (3) carrying out direct-current voltage-stabilizing anodic oxidation on the honeycomb porous Ti substrate with the aperture of about 300nm, sufficiently carrying out ultrasonic oscillation, then washing with deionized water, and drying for later use.

FIG. 1 is an SEM topography of the anodized porous surface showing the porous honeycomb structure, and as can be seen from the contact angle inset in FIG. 1 (a), the porous structure with the phosphate film component is hydrophilic (contact angle 45.+ -. 5 ℃); FIG. 1 (b) shows a partial enlargement of FIG. 1 (a), which is a porous structure with pore-to-pore communication and wide cell openings. FIG. 1c shows that more holes appear in the inside of the holes to provide adsorption positions for crystal nucleation, which is beneficial to the preferential growth of crystals in the holes, and the realization of the pricking growth.

(2) Placing the honeycomb porous Ti substrate treated in the step (1) in 5wt.% HCl for treatment by adopting an experimental device shown in fig. 3, immersing for 10s, placing the honeycomb porous Ti substrate into Co-Ni binary mixed electrolyte, and performing Co-Ni Co-deposition by adopting a high-frequency pulse electrodeposition technology, wherein: the Co-Ni plating solution comprises 45g/L nickel sulfamate, 120g/L cobalt sulfate, 12g/L glacial acetic acid, 50g/L boric acid and 0.2g/L surfactant SDS, the temperature is controlled at 40 ℃, the pH of the solution is kept between 4.0, and the mechanical stirring speed is 150rpm; the high-frequency pulse electrodeposition process comprises the following steps: pulse frequency 2.0kHz, positive and negative current duty ratio 1:5, peak current density 0.6mA/cm ² The electrodeposition time is 25min, and the deposition rate is about 25 mu m/min; the Co-Ni alloy was electrodeposited for about 10 minutes.

(3) On the basis of binary Co-Ni codeposition, co-Ni-Zn ternary alloy growth is carried out by rapid titration, and ZnSO containing ascorbic acid is dripped by a syringe ₄ Concentrated solution, zn ²⁺ The concentration was 0.5mol/L, the dropping rate was 10ml/min, the mechanical stirring rate during the period was 150rpm, and it was clearly observed that the coating color was changed from a grey brown to an off-white, at which time the peak current density was significantly reduced to 0.3mA/cm ² This is mainly due to Zn ²⁺ Substitution of Co ²⁺ Formation of sparingly soluble flocs (e.g. [ Zn (OH)) ₄ ] ^2- ) Covering the surface of the deposition layer and reducing the ion diffusion rate.

(4) And (3) after the Co-Ni-Zn ternary alloy is electrodeposited for 30min, carrying out aging heat treatment on the thickness of the coating with the thickness of 300 mu m, wherein the initial temperature is 150 ℃, the heating rate is 5 ℃/min, the end temperature is 450 ℃, the heat preservation time is 3h, and cooling along with a furnace. The prepared Co-Ni-Zn ternary alloy is denoted as Ni _0.12 Co _0.84-x Zn _x ，x＝0.24。

FIG. 2 is an original crystal blank of Co-Ni-Zn ternary alloy beginning to grow outwards from the porous Ti-based pore canal, corresponding to the step (3), zn (O) preferentially grows and improves more active sites, so that the growth is fast, the nucleation center is evolved, the nucleation rate is improved, the thinning growth is improved, the subsequent crystal is induced to grow outwards from the pore canal together, and the interface binding force between the electrodeposited coating and the titanium-based is favorably improved.

And 4, comparing the surface morphology SEM images of the binary Co-Ni and ternary Co-Ni-Zn nanocrystalline coatings before aging heat treatment. When Zn is not added, the nanocrystalline Ni is inlaid in the strip Co; when Zn is added, the carbon nano tube Zn preferentially grows, so that Co growth is pressed, particles appear integrally, and the compactness is obviously improved.

FIG. 6 is a graph showing the surface morphology of an alloy coating sample before aging, wherein part of Zn grows along the defects such as grain boundaries or holes, active Zn is oxidized into whisker-shaped ZnO to cover the surface of the coating; FIG. 7 shows that after aging treatment for 3h at 450 ℃, part of Zn is oxidized into a reticular porous ZnO dispersed phase, and the reticular porous ZnO dispersed phase is dispersed and separated out along a GBs texture growth defect area, and finally, a ternary nanocrystalline alloy coating of reticular ZnO coated nanocrystalline Ni and Co particles is formed. Further enlargement can be seen: after 3h of medium-temperature aging heat treatment, part of ZnO is dispersed and separated out, takes a rod shape or a sphere shape, is pinned along a GBs defect area and the like, not only prevents nano-particle Ni and Co from coarsening and growing, but also prevents magnetic domain movement just like an isolation net, and is beneficial to improving magnetic coercivity.

Fig. 8, 9 are XRD patterns of surface alloying elements before and after aging of ternary Co-Ni-Zn alloy (x=0.24) at 450 ℃, as can be seen: after 450 ℃ oxidation, only a small portion of the Ni or Co is converted to NiO (101), coO (111) or forms other alloying compounds such as: gamma-Ni ₅ Zn ₂₁ (330)(600)，γ’-Co ₅ Zn ₂₁ (444) (600) mainly due to diffusion metallurgical reaction with part of active Ni and Co in GBs high-energy defect area when low-melting Zn is dispersed, and the alloy compound possibly exists in the net-shaped ZnO-rich texture.

FIG. 10 shows the ternary Co-Ni-Zn alloy (Ni _0.12 Co _0.84-x Zn _x X=0.24) in the surface microtopography SEM image and the local micro-area EDS analysis results. Fig. 10 (a) shows that x=0.24, ternary Ni _0.12 Co _0.84-x Zn _x The surface topography of the nanocrystalline alloy is shown in an elliptic characteristic of the particle shape, but the particle shapes are different in size. As can be seen from fig. 10 (b) which is a partial enlargement: after the aging treatment is performed for 3h at 450 ℃, the nano-particles Zn are oxidized into long strip tubes (ZnO phase), and the long strip tubes are filled in the defects such as grain boundaries or holes, thereby being beneficial to improving the compactness of the coating. FIG. 10 (c) shows an enlarged view of Zn or ZnO as a selected portion, and the grain shape is elliptical, and the grain size is mainly concentrated in the range of 250-400nm according to statistics. Further EDS analysis, as shown in fig. 10 (d), shows that the spherical particles are alloy compounds, mainly Zn phase, in amounts up to 58.16wt.%. From the analysis result of EDS on the coating element, the white area is ZnO enriched nanospheres, the characteristic of typical cauliflower spheres is that the O content is 3 times higher than that of other areas, the whole grains do not obviously coarsen before and after aging, and the size is concentrated in the range of 250-400 nm.

FIG. 11 is an XPS spectrum of surface alloying elements before and after aging of ternary Co-Ni-Zn alloy (x=0.24) at 450℃with no excessive oxidation of Ni and Co by external O, ni _2p And Co _2p Satellite peaks (sat.) were found to be present at high scan, indicating that Ni and Co moieties were in an atomic state and were not oxidized; however, zn with high activity is oxidized to ZnO (Zn _2p1/2 )、ZnO ₂ (Zn _2p3/2 ) Or a mixture of the two, validating the formation of dispersed phase ZnO. The element valence analysis result is basically consistent with the XRD phase analysis result.

Example 2

This comparative example is identical to the rest of example 1, except that: aging at 450 deg.C to obtain concentrated solution ZnSO ₄ When the dropping rate of the alloy is reduced from 10mL/min to 5mL/min in example 1, the chemical component measurement of the ternary alloy coating by EDS finds that: the mole ratio of Ni to Co to Zn is about 1:6:1, converted to Ni _0.12 Co _0.84-x Zn _x When x=0.12, corresponding to Ni _0.12 Co _0.72 Zn _0.12 At this time, the Co content in the alloy coating is up to 70 wt%, and the texture growth of the prepared ternary alloy coating is similar to that of a Co-Ni binary structure, and the typical characteristic of "rape flower" texture growth appears. However, the amount of Zn deposited in the ternary alloy is smaller than in example 1, and only a small amount of ZnO is precipitated along the GBs region after aging at 450℃and cannot be obtainedContinuously dispersed and pinned. In the magnetic performance measurement, it was found that: example 2 has substantially similar magnetic properties as the sample of example 1.

Example 3

This comparative example is identical to the rest of example 1, except that: aging at 450 deg.C to obtain concentrated solution ZnSO ₄ When the dropping rate is increased to 15ml/min, the chemical components of the ternary alloy coating are measured by EDS, and the following results are found: the mole ratio of Ni to Co to Zn is about 1:6:1, converted to Ni _0.12 Co _0.84-x Zn _x When x=0.36, corresponding to Ni _0.12 Co _0.48 Zn _0.36 At the moment, zn grows preferentially in the texture growth of the alloy coating, and gamma-Ni is formed in the aging process at 450 DEG C ₅ Zn ₂₁ And gamma' -Co ₅ ZnNi ₂₁ Phase and appearance of ZnO nanowire structural characteristics, the structure is unstable, broken and easily forms powder, severely degrading magnetic properties, as compared to example 1.

By ZnCl ₂ In the rapid titration process of concentrated solution, the c-v curve is adopted to measure Ni ²⁺ 、Co ²⁺ And Zn ²⁺ Reduction peak potential by controlling ZnCl ₂ The dripping rate (5-15 ml/min) of the concentrated solution realizes the regulation and control of the ion concentration of each alloy in the Co-Ni-Zn ternary mixed solution, and finally realizes the ternary alloy Ni _0.12 Co _0.84-x Zn _x The chemical composition of (2) is controllable, and the EDS is used for multiple measurement, which shows that: titration rate and x show a linear relationship, specifically 5mL/min (x.apprxeq.0.12), 10mL/min (x.apprxeq.0.24) and 15mL/min (x.apprxeq.0.36).

Comparative example 1

This comparative example is identical to the rest of example 1, except that: after aging at 450 ℃, the subsequently added concentrated solution is not ZnSO ₄ The system adopts Zn (SO) ₃ NH ₂ ) ₂ (zinc sulfamate) substituted ZnCl ₂ Other electrodeposition processes and plating solution components are consistent with those of the embodiment 1, and the aging temperature is 450 ℃ and the temperature is kept for 3 hours. Titrating by adopting a concentrated solution of a zinc sulfamate system, wherein the sulfamate has the complexing agent function and Zn ²⁺ Slow release rate, and can be produced in the mixed electrolyte with pH value of 3.8-4.5Precipitate and slightly-soluble floccules are generated, compared with the embodiment 1, the plating solution has poorer dispersibility and stability under the process condition, and the Co-Ni-Zn alloy with the scorched black is deposited, and the Co-Ni-Zn alloy is partially floccule powder, so that the electromagnetic performance is obviously reduced.

Comparative example 2

This comparative example is identical to the rest of example 1, except that: aging at 450 ℃, and dripping ZnSO ₄ When the concentrated solution is not provided with an ascorbic acid complexing agent, other electrodeposition processes and plating solution components are consistent with those of the embodiment 1, and the heat aging is carried out to 450 ℃ and the temperature is kept for 3 hours.

FIGS. 12 and 13 are graphs showing cyclic voltammetry (c-v) of ternary Co-Ni-Zn alloys with or without ascorbic acid, respectively, and can be seen from the graph: c-v testing in Pt-Pt and Standard calomel electrode System, adding ascorbic acid as complexing agent to promote Ni ²⁺ And Co ²⁺ Reduction potential difference is shortened, abnormal codeposition is realized, and Zn is not observed ²⁺ Reduction peak (or with Ni) ²⁺ Or Co ²⁺ Reduction peaks overlap), further illustrating Co-deposition of ternary alloy Co-Ni-Zn. No apparent Zn was found ²⁺ Reduction peaks, considered to be with Ni ²⁺ 、Co ²⁺ The reduction peaks overlap. Although Zn ²⁺ Standard reduction precipitation potential of Zn is higher than Co ²⁺ /Co、Ni ²⁺ The Ni reduction potential is much negative but combines thermodynamic and kinetic effects, zn in an acidic solution at 30 DEG C ²⁺ +2e ^- →Zn，ΔG _ibbs The negative free energy triggers the reaction to spontaneously proceed, thereby realizing Co-Ni-Zn ternary alloy codeposition. Compared with the example 1, after no ascorbic acid (complexing agent) is added, the oxidation peak potential of Zn or Co is negatively shifted by about 0.2mV, which is unfavorable for the reduction precipitation of Co and Zn; however, the addition of the complexing agent has little influence on the oxidation peak potential of Ni, and is kept at about-0.29 mV. In addition, the SEM image of the surface morphology revealed that: under the condition of no ascorbic acid addition, zn is in flaky growth and unevenly distributed, a small amount of ZnO is dispersed and strengthened along a defect area, the pinning effect of GBs is limited, the movement of magnetic domains cannot be effectively blocked, and the influence on magnetic properties is small.

Comparative example 3

This comparative example is identical to the rest of example 1, except that: znCl containing ascorbic acid without syringe ₂ The concentrate was directly subjected to aging heat treatment of example 1 by Co-deposition of binary Co-Ni to obtain ternary alloy Ni _0.12 Co _0.84-x Zn _x ，x＝0.0。

Ni with different atomic mole ratios _0.12 Co _0.84-x Zn _x (x=0 to 0.36) ternary alloy surface topography as shown in fig. 14. As can be seen from fig. 14: when x=0.0, i.e. Ni _0.12 Co _0.84 Binary alloy, hydrogen is separated from partial areas under the acidic condition, so that local hole defects are generated; when x=0.12, a small amount of Zn (O) is Co-deposited with the Ni, co textures, and microcracks are generated due to high growth stress caused by compatibility differences; when x=0.24, the ternary alloy surface is elliptically dense; when x=0.36, the ternary alloy surface structure is loose, which is mainly due to preferential coarsening growth of Zn during abnormal Co-deposition, inhibiting Ni and Co growth, while too low a content of Ni is detrimental to fine grain growth.

For systematic research of ageing heat treatment on ternary Ni _0.12 Co _0.84-x Zn _x (x=0 to 0.36) magnetic properties effects fig. 15 is a graph showing a statistical comparison of magnetic properties (saturation magnetization and coercivity) of four groups of samples, x=0.0 (comparative example 3), 0.12 (example 2), 0.24 (example 1) and 0.36 (example 3), before and after aging heat treatment at 450 ℃. It can be seen that: overall, the aging at 450 ℃ is helpful for remarkably improving the magnetic coercivity, and has little influence on the saturation magnetization, which is mainly due to the fact that the dispersed phase ZnO whiskers are as magnetic isolation, and a domain wall moving pinning mechanism is formed; the aging at the medium temperature of 450 ℃ has little influence on the coarsening growth of crystals, and has limited influence on the magnetic saturation strength; when x=0.0, i.e., ni _0.12 Co _0.84 The sample has high magnetic saturation strength and minimal coercivity, probably due to the intrinsic properties of the Co magnetic material.

However, too high a temperature may change the magnetic domain structure of atoms, resulting in disappearance of the magnetic properties of the substance. Therefore, to determine the Curie point (T _c ) And the actual operating temperature (T _w Half of the magnetic property), experimental samplingMeasuring induced electromotive force and temperature curve (. Epsilon.) from point to point by using Curie point tester (model QS-CT) _eff (B) -T) by tangential method, obtaining T _c ＝460.4℃，T _w = 435.2 ℃. The higher the Curie temperature is, the magnetic property of the material is stable, and the material is favorable for the occasion of high Wen Fuyi.

Comparative example 4

This comparative example is identical to the rest of example 1, except that: the ageing process at 450 ℃ is not carried out, and other processes are the same. Since there is not a sufficient number of ZnO dispersed phases pinned along GBs, the domain movement cannot be effectively impeded; in addition, the stress of texture growth in the abnormal codeposition process can not be relieved, part of impurities are adsorbed at the high-energy defect position, and the magnetic performance stability of the Co-Ni-Zn ternary alloy is seriously reduced. The measurement results and the selected areas of the samples were changed to a larger extent than those of example 1 and comparative examples 1 to 4, and the samples showed unstable magnetism, in which: the average saturation magnetization was 98.9emu/g and the maximum magnetic coercive force was 0.31kOe.

Analysis of the alloy chemical composition by EDS revealed that: x=0.24, i.e. Ni _0.12 Co _0.60 Zn _0.24 The plating layer has good flatness, highest saturation magnetization and high coercivity. According to the VSM test result, each plating sample has an S-shaped M-H curve under different process conditions, does not reach a magnetic saturation state, and shows soft magnetic characteristics with certain characteristics.

FIG. 16 is ternary nanocrystalline alloy Ni _0.12 Co _0.84-x Zn _x M-H curves under different process conditions for example 1, example 2, example 3, comparative example 1, comparative example 5. When x=0.24 after ageing at 450 ℃, i.e. Ni _0.12 Co _0.60 Zn _0.24 The magnetic coercive force of the plating layer is obviously improved to 0.51kOe. This is mainly due to the diffusion of the ZnO dispersed phase along the GBs of the Co-Zn "cauliflower" texture, the dispersed phase ZnO fills as magnetic isolation, and provides "pinning" sites for domain wall movement, facilitating magnetic performance enhancement.

The results of the magnetic properties of examples are shown in Table 1 in comparison with those of comparative examples 1 to 4. High-frequency pulse electrodeposition process is adopted to obtain high-quality sulfamic acid from sulfamic acid systemFirstly, preparing nanocrystalline Co-Zn binary alloy, wherein crystal grains are fine and show the characteristic of 'cauliflower'; subsequently through regulating ZnCl ₂ Titration rate of concentrated solution, ni is realized _0.12 Co _0.84-x Zn _x When x=0.24 (titration rate 10 ml/L), the nano-particle Zn is oxidized into ZnO after aging treatment for 3h at 450 ℃ to form the ternary nanocrystalline alloy with the microstructure characteristics of the network ZnO dispersed phase wrapped nanocrystalline Ni and Co. Wherein: the aging treatment promotes the diffusion of atoms and forms continuous and uniform crystal boundaries, the dispersed phase ZnO is biased near the polycrystalline boundaries, and the pinning domain walls move. The design of the ternary magnetic alloy coating prevents nucleation and expansion of the anti-domain in a magnetic field, is favorable for magnetic performance, particularly improvement of coercive force, and effectively overcomes the defect of low magnetic coercive force of the alnico permanent magnetic alloy.

Table 1 Co-Ni alloys, examples, comparative examples 1 to 4, comparative results of magnetic property test

Example 4

A preparation method of a Co-Ni-Zn ternary nanocrystalline magnetic alloy comprises the following steps:

(1) By Al ₂ O ₃ Polishing the pure Ti substrate by using the polishing paste, sequentially polishing the pure Ti substrate by using 500# abrasive paper, 800# abrasive paper and 1200# abrasive paper until no scratch exists, and then stabilizing the voltage by 150V direct current and H ₃ PO ₄ System (15 wt.% H) ₃ PO ₄ +20wt.％H ₂ O ₂ ) Anodic oxidation, wherein the temperature of electrolyte is 5 ℃, the pore diameter of the obtained porous Ti substrate is 300nm, and the porous Ti substrate is cleaned by deionized water and dried for standby after full ultrasonic oscillation;

(2) Activating the honeycomb porous Ti substrate with dilute hydrochloric acid with the concentration of 5wt.% for 10s, immersing the honeycomb porous Ti substrate in a Co-Ni mixed plating solution in an electrified manner, and preparing a Co-Ni binary alloy by adopting high-frequency pulse electrodeposition to generate a bar-grain phase embedded microstructure; the Co-Ni mixed plating solution comprises: 15g/LZnSO ₄ ，110g/LCoSO ₄ ·6H ₂ O，40g/LNi(SO ₃ NH ₂ ) ₂ ·4H ₂ O，12g/LCH ₃ COOH，45g/LH ₃ BO ₃ 2.0g/L ascorbic acid, 0.4g/L surfactant, pH 3.8. The temperature of the Co-Ni mixed plating solution was 35 ℃. The pulse frequency of the high-frequency pulse electricity is 2.0kHz, the positive and negative current duty ratio is 1:5, and the peak current density is 0.3mA/cm ² The electrodeposition time was 30min and the deposition rate was about 10 μm/min.

(3) Adopting a rapid titration method, wherein the dropping speed is 5mL/min, the mechanical stirring speed is 150rpm, and the concentration of ZnSO containing ascorbic acid is 0.5mol/L ₄ Adding concentrated solution drop by drop to the obtained product of step (2), znSO containing ascorbic acid ₄ The concentrated solution comprises the following components: 45g/L zinc sulfate, 2.0g/L ascorbic acid, 3.5 pH value of the solution, 3.0ml/min titration rate, and promoting abnormal codeposition of ternary alloy of Zn and Ni-Co under the action of an ascorbic acid complexing agent to form a cauliflower-like sphere texture feature;

(4) Drying the product obtained in the step (3), setting the initial temperature at 150 ℃ and the final temperature at 450 ℃, performing heat treatment, heating at a rate of 5 ℃/min, preserving heat for 3 hours, and cooling along with a furnace.

Example 5

A preparation method of a Co-Ni-Zn ternary nanocrystalline magnetic alloy comprises the following steps:

(1) By Al ₂ O ₃ Polishing the pure Ti substrate by using the polishing paste, sequentially polishing the pure Ti substrate by using 500# abrasive paper, 800# abrasive paper and 1200# abrasive paper until no scratch exists, and then stabilizing the voltage by 160V direct current and H ₃ PO ₄ System (15 wt.% H) ₃ PO ₄ +20wt.％H ₂ O ₂ ) Anodic oxidation, wherein the temperature of electrolyte is 10 ℃, the pore diameter of the obtained porous Ti substrate is 350nm, and the porous Ti substrate is cleaned by deionized water and dried for standby after full ultrasonic oscillation;

(2) Activating the honeycomb porous Ti substrate with dilute hydrochloric acid with the concentration of 7wt.% for 10s, immersing the honeycomb porous Ti substrate in a Co-Ni mixed plating solution in an electrified manner, and preparing a Co-Ni binary alloy by adopting high-frequency pulse electrodeposition to generate a bar-grain phase embedded microstructure; the Co-Ni mixed plating solution comprises: 50g/LZnSO ₄ ，120g/LCoSO ₄ ·6H ₂ O，50g/LNi(SO ₃ NH ₂ ) ₂ ·4H ₂ O，15g/LCH ₃ COOH，50g/LH ₃ BO ₃ 3.5g/L ascorbic acid, 0.5g/L surfactant, pH 4.5. The temperature of the Co-Ni mixed plating solution was 40 ℃. The pulse frequency of the high-frequency pulse electricity is 4.0kHz, the positive and negative current duty ratio is 1:7, and the peak current density is 0.7mA/cm ² The electrodeposition time was 30min and the deposition rate was about 10 μm/min.

(3) Adopting a rapid titration method, wherein the dropping speed is 15mL/min, the mechanical stirring speed is 200rpm, and the concentration of the ZnSO containing ascorbic acid is 0.7mol/L ₄ Adding concentrated solution drop by drop to the obtained product of step (2), znSO containing ascorbic acid ₄ The concentrated solution comprises the following components: 60g/L zinc sulfate, 3.5g/L ascorbic acid, pH value of the solution of 4.0, titration rate of 15.0ml/min, under the action of an ascorbic acid complexing agent, promoting abnormal codeposition of ternary alloy of Zn and Ni-Co to form a cauliflower-like sphere texture feature;

(4) Drying the product obtained in the step (3), setting the initial temperature at 150 ℃ and the final temperature at 480 ℃, performing heat treatment, heating at a rate of 5 ℃/min, preserving heat for 3 hours, and cooling along with a furnace.

Example 6

A preparation method of a Co-Ni-Zn ternary nanocrystalline magnetic alloy comprises the following steps:

(1) By Al ₂ O ₃ Polishing the pure Ti substrate by using the polishing paste, sequentially polishing the pure Ti substrate by using 500# abrasive paper, 800# abrasive paper and 1200# abrasive paper until no scratch exists, and then stabilizing the voltage by 155V direct current and H ₃ PO ₄ System (15 wt.% H) ₃ PO ₄ +20wt.％H ₂ O ₂ ) Anodic oxidation, wherein the temperature of electrolyte is 7 ℃, the pore diameter of the obtained porous Ti substrate is 325nm, and the porous Ti substrate is cleaned by deionized water and dried for standby after full ultrasonic oscillation;

(2) Activating the honeycomb porous Ti substrate with dilute hydrochloric acid with the concentration of 6wt.% for 10s, immersing the honeycomb porous Ti substrate in a Co-Ni mixed plating solution in an electrified manner, and preparing a Co-Ni binary alloy by adopting high-frequency pulse electrodeposition to generate a bar-grain phase embedded microstructure; the Co-Ni mixed plating solution comprises: 35g/LZnCl ₂ ，115g/LCoSO ₄ ·6H ₂ O，45g/LNi(SO ₃ NH ₂ ) ₂ ·4H ₂ O，14g/LCH ₃ COOH，48g/LH ₃ BO ₃ 2.8g/L ascorbic acid, 0.4g/L surfactantThe pH was 4.0. The temperature of the Co-Ni mixed plating solution was 37 ℃. The pulse frequency of the high-frequency pulse electricity is 3.0kHz, the positive and negative current duty ratio is 1:6, and the peak current density is 0.5mA/cm ² The electrodeposition time was 30min and the deposition rate was about 10 μm/min.

(3) Adopting a rapid titration method, wherein the dropping speed is 10mL/min, the mechanical stirring speed is 175rpm, and the concentration of the ascorbic acid-containing ZnSO is 0.6mol/L ₄ Adding concentrated solution drop by drop to the obtained product of step (2), znSO containing ascorbic acid ₄ The concentrated solution comprises the following components: 52g/L zinc sulfate, 2.8g/L ascorbic acid, 3.8 pH value of the solution, and 9.0ml/min titration rate, under the action of an ascorbic acid complexing agent, promoting abnormal codeposition of ternary alloy of Zn and Ni-Co to form a cauliflower-like sphere texture feature;

(4) Drying the product obtained in the step (3), setting the initial temperature at 150 ℃ and the final temperature at 465 ℃, performing heat treatment, heating at a rate of 5 ℃/min, preserving heat for 3 hours, and cooling along with a furnace.

Claims (6)

1. The preparation method of the Co-Ni-Zn ternary nanocrystalline magnetic alloy is characterized by comprising the following steps:

step one, the activated honeycomb porous Ti substrate is immersed into Co-Ni mixed plating solution in an electrified manner, and high-frequency pulse electrodeposition is adopted to prepare Co-Ni binary alloy to generate a bar-grain phase embedded microstructure; the pulse frequency of the high-frequency pulse power is 2.0-4.0 kHz, the positive and negative current duty ratio is 1:5-1:7, and the peak current density is 0.3-0.7 mA/cm ² The method comprises the steps of carrying out a first treatment on the surface of the The Co-Ni mixed plating solution comprises: 110-120 g/L CoSO ₄ ·6H ₂ O，40~50 g/L Ni(SO ₃ NH ₂ ) ₂ ·4H ₂ O，12~15 g/L CH ₃ COOH，45~50 g/L H ₃ BO ₃ 2.0-3.5 g/L ascorbic acid, 0.4-0.5 g/L surfactant, pH 3.8-4.5; the temperature of the Co-Ni mixed plating solution is 35-40 ℃;

step two, adopting a rapid titration method to obtain the ZnSO containing ascorbic acid with the concentration of 0.5-0.7 mol/L ₄ Adding concentrated liquid into the product obtained in the first step, and promoting abnormal codeposition of ternary alloy of Zn and Ni-Co under the action of an ascorbic acid complexing agent to form a cauliflower-like sphere texture characteristic; dripping by rapid titrationThe speed is 5-10 mL/min, and the mechanical stirring speed is 150-200 rpm;

and thirdly, drying the product obtained in the step two, and performing heat treatment at 450-480 ℃.

2. The method for preparing the Co-Ni-Zn ternary nanocrystalline magnetic alloy according to claim 1, wherein the method comprises the following steps: in the first step, the honeycomb porous Ti substrate is activated by dilute hydrochloric acid with the concentration of 5-7wt%.

3. The method for preparing the Co-Ni-Zn ternary nanocrystalline magnetic alloy according to claim 1, wherein the method comprises the following steps: in the first step, the honeycomb porous Ti substrate is stabilized at H by 150-160V direct current ₃ PO ₄ 、H ₂ O ₂ And (3) carrying out anodic oxidation in the mixed solution, wherein the temperature of the electrolyte is 5-10 ℃, the honeycomb porous Ti substrate is wide-pore mouth, and the pore diameter is 300-350 nm.

4. The method for preparing the Co-Ni-Zn ternary nanocrystalline magnetic alloy according to claim 3, wherein the method comprises the following steps: the honeycomb porous Ti substrate has hydrophilicity, and the contact angle is 40-50 degrees.

5. The Co-Ni-Zn ternary nanocrystalline magnetic alloy obtained by the preparation method of the Co-Ni-Zn ternary nanocrystalline magnetic alloy according to any one of claims 1 to 4, which is characterized in that: the crystal grain boundary is formed by filling precipitated phase ZnO along the crystal grain boundary in a segregation way, and the network ZnO whisker wraps ternary nanocrystalline alloy of Ni and Co to form a magnetic domain wall pinning effect.

6. The Co-Ni-Zn ternary nanocrystalline magnetic alloy according to claim 5, wherein: the sizes of Co and Ni are 300-500 nm.