JP2662904B2 - Cobalt-nickel-phosphorus alloy magnetic film, magnetic recording medium therefor, and method of manufacturing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic film for a magnetic recording medium, and more particularly to a magnetic thin film for a cobalt-nickel-phosphorus alloy having a high coercive force. The present invention relates to a metal thin-film magnetic recording medium, and more particularly to a magnetic recording medium suitable for applications such as a magnetic disk, a magnetic tape, and a magnetic encoder.

[0002]

2. Description of the Related Art As a magnetic recording medium, a so-called coating type magnetic recording medium in which a magnetic material powder such as a metal or a metal oxide is coated on a substrate with an organic binder has been widely used. With the demand for improvement, the use of so-called metal thin film type magnetic recording media, in which a thin film of a magnetic metal is formed on a non-magnetic substrate by a method such as vacuum evaporation, sputtering and electroless plating, has been increasing. I have. At present, thin films are formed mainly by vacuum evaporation and sputtering on this metal thin film type recording medium, but each method requires expensive equipment, and the utilization efficiency of the base material used for forming the thin film is extremely high. The problem is low. Compared to these methods, electroless plating can be manufactured with relatively simple equipment, but has a problem in that reproducibility of magnetic characteristics is difficult and productivity is low.

[0003]

Problems to be Solved by the Invention Magnetic films of cobalt phosphorus alloy (Co-P) and cobalt nickel phosphorus alloy (Co-Ni-P) are known as magnetic recording media by plating. However, it is very difficult to manufacture these alloy films by electroplating while controlling the composition within a certain range. In particular, a cobalt nickel phosphorus (Co-Ni-P) alloy is said to easily obtain good magnetic properties such as a high coercive force as compared with a cobalt phosphorus alloy. The composition range in which the magnetic properties can be obtained has not yet been determined, and a method of controlling the composition so as to obtain a composition having a constant composition has not been established. Therefore, Co-Ni- having good magnetic properties
The P alloy film has not been produced with good reproducibility. by the way,
The plating film of the cobalt-phosphorus alloy is used by being formed on a non-magnetic metal of copper (Cu) or aluminum (Al) or an organic film, but is used for applications requiring mechanical strength or thermal expansion. In the case of, since a nonmagnetic metal substrate of Cu or Al is not suitable, in such a case,
An Fe-Cr-Ni-based non-magnetic stainless steel is often used. However, it is more difficult and problematic to stably form a cobalt-nickel-phosphorus alloy film having a constant composition on the stainless steel substrate by electroplating. An object of the present invention is to solve the problems associated with the composition of a conventional magnetic thin film of a cobalt-nickel-phosphorus alloy and its manufacturing method.

[0004]

SUMMARY OF THE INVENTION According to the present invention, a Co-Ni-P alloy film having good magnetic properties can be obtained because a Co-Ni-P alloy film is formed by electroplating as a magnetic recording medium.
The composition range of the alloy film is established, and the Co—Ni—P alloy film within the composition range is replaced with a nonmagnetic material, in particular, Fe—Cr.
Co-Ni-P having good magnetic properties by establishing plating conditions for forming on Ni-based non-magnetic stainless steel substrate
It is an object of the present invention to provide a method for forming an alloy film on a non-magnetic stainless steel substrate. The present invention relates to a Co-Ni-P alloy by forming a Co-Ni-P alloy thin film by changing the composition of an electrolytic solution and electrolytic plating conditions, and measuring the film composition and magnetic properties of the formed thin film. Research on composition and plating conditions for obtaining good magnetic properties, and base for forming Co-Ni-P alloy thin film of suitable composition on Fe-Cr-Ni-based non-magnetic stainless steel substrate Research was conducted on the processing conditions to arrive at the present invention.

That is, according to the present invention, cobalt is 75 to 87% by weight, nickel is 8.5 to 22% by weight, phosphorus is 2.5 to 4.5% by weight, and the thickness is 0.05 μm.
To 50 μm in the cobalt-nickel-phosphorus alloy magnetic film for a magnetic recording medium,
An underlayer is formed on a non-magnetic iron-chromium-nickel alloy base material. On the underlayer, 75 to 87% by weight of cobalt, 8.5 to 22% by weight of nickel, and P A magnetic recording medium comprising a cobalt-nickel-phosphorus alloy magnetic film having a thickness of 0.05 to 50 μm and a thickness of 2.5 to 4.5% by weight.
Further, in the present invention, the pH of the solution is 2.0 to 4.5, the cobalt salt concentration is 0.1 to 0.72 mol / l, and the nickel salt concentration is 0.04 to 0.31 mol / l. And a plating electrolyte having a phosphate concentration of 0.09 to 0.5 mol / l at a temperature of 40 to 60 ° C.
By repeating the electrolysis current with a current density of 30 to 150 A / dm ² and the energization time of 0.5 to 10 milliseconds in a pulsed manner, cobalt is reduced to 7 on the non-magnetic substrate.
5 to 87% by weight, 8.5 to 22% by weight of nickel and 2.5 to 4.5% by weight of phosphorus,
A method for manufacturing a magnetic recording medium, comprising forming a cobalt-nickel-phosphorus alloy film having a thickness of 5 to 50 μm.

A magnetic recording medium requires a coercive force of 400 (Oe: Oersted) or more. The magnetic film of the present invention has a coercive force of 600 Oe or more, and is used for high-density recording or external recording. Demagnetization due to a magnetic field or the like can be reduced. To obtain this high coercivity, cobalt must be
The content is 5 to 87% by weight. 75% cobalt content
In the following, the coercive force drops sharply, and when it exceeds 86%,
A coercive force of 00 oe or more cannot be obtained. Nickel is contained in an amount of 8 to 22% by weight. 7. Nickel content is 8.
Outside the range of 5 to 22% by weight, a high coercive force of 600 Oe cannot be obtained. P is contained in the range of 2.5 to 4.5% by weight. Outside this range, the coercive force is 600
Oe or less, it is necessary to control within this narrow range. Further, when the cobalt content is 84 to 87% by weight, the nickel content is 9 to 12% by weight, and the phosphorus content is 3 to 4.5% by weight, Co- having a higher coercive force of 800 to 900 Oe or more is obtained. This is preferable because a Ni-P alloy magnetic film can be obtained.

In the present invention, the Co—Ni—P alloy magnetic film is obtained by electrolytic plating. The electrolyte has a pH of 2.0 to 4.5, a cobalt salt concentration of 0.1 to 0.72 mol / l, and a nickel salt concentration of 0.04 to 0.31 mol / l. And a plating electrolyte containing a phosphate concentration of 0.09 to 0.5 mol / l. Such an electrolyte is
For example, it can be obtained by preparing the following composition. _{That, CoSO 4 · 7H 2 O 30~200g} / l NiSO 4 · 6H 2 O 12~80g / l NH 4 Cl 40~100g / l NaH 2 PO 2 · H 2 O 10~50g / l wetting agent 4g / l Brightener 1 g / l or less The pH of this electrolytic solution is 2.0 to 4.5, and 40 to 6
By performing electrolytic plating at a temperature of 0 ° C., good magnetic properties can be obtained.

However, in the present invention, it has been found that the film composition is greatly affected by the current density and the current supply time. That is, when the current density is low, the plating time increases and the Co amount of the plating film decreases,
Conversely, since the amounts of Ni and P increase, Co, Ni and P cannot be simultaneously controlled to a suitable composition range. On the other hand, when the current density is increased, the Co and Ni contents of the plating film approach the target composition within a very short time and stabilize at a substantially constant value.
The P component stabilizes at high concentration in a short time. Therefore, when plating is continued for a long time, it is impossible to control the film composition.

However, by using the above-mentioned electrolytic solution, the current density is set in the range of 30 to 150 A / dm ² , and the energizing time is repeated in a short period of time in the range of 0.5 to 10 msec. Can be controlled. The current density is in the range of 30~150A / dm ^2. When the current density is lower than 30 A / dm ² , the Co amount becomes higher than the optimum value, the Ni amount becomes lower than the optimum value, the crystal grains become large, and a high coercive force cannot be obtained. When the current density is 150 A / dm ² or more, the amount of Co is significantly reduced, the amount of Ni is increased, and the coercive force is significantly reduced.

[0010] On the other hand, in order to control the P composition, in addition to the control of the current density, the control by the current supply time is performed. The preferred energizing time for controlling the amount of P varies depending on the current density, but if the current density is in the range of 30 to 150 A / dm ² , the amount of P can be controlled in the range of 0.5 to 10 msec for the energizing time. , A coercive force of 600 Oe or more can be obtained. However, if the energization time is very short, the total plating time for obtaining the required film thickness becomes longer and the productivity is reduced.

In the present invention, since the energization during electrolytic plating is repeated in a pulsed manner, the Co—Ni—P alloy magnetic film formed on a non-magnetic substrate such as stainless steel has an extremely thin Co—Ni— Since it is formed from a plurality of stacked P alloy films, the film composition can be easily adjusted.

When plating is performed on a stainless steel substrate represented by SUS304, a passivation film formed on the surface impairs the plating property.
To apply an o-Ni-P plating film, first, a Ni film is applied on a stainless steel substrate to remove the influence of the passivation film and to improve the adhesion of the plating film. The crystal grains of the Co—Ni—P coating film formed thereon are made constant and are deposited stably. As a result, a Co—Ni—P alloy film having good magnetic properties can be obtained stably.

[0013]

According to the present invention, an underlayer is formed on a nonmagnetic iron / chromium / nickel alloy base material, and 75 to 87% by weight of cobalt and 8.5 to 22% by weight of nickel are formed on the underlayer.
%, P is 2.5 to 4.5% by weight, and a magnetic film made of a cobalt-nickel-phosphorus alloy having a thickness of 0.05 to 50 μm is formed, so that it has a high coercive force of 600 Oe or more. The magnetic film can be manufactured stably and easily.

[0014]

The embodiments of the present invention will be described below with reference to specific examples of the present invention. However, the present invention is not limited by the following description. Example 1 The _{CoSO 4 · 7H 2 O 120g /} l NiSO 4 · 6H 2 O 80g / l NH 4 Cl 60g / l NaH solution 5l blended with ₂ PO ₂ 30g / l as a plating solution, pH 3.0, at a liquid temperature of 53 ° C. Non-magnetic stainless steel with a diameter of 6 mm (SUS3
04), a Co—Ni—P alloy film was formed by electrolytic plating. For SUS304, NiCl
_{2 · 6H 2 O250g / l,} Ni energized electrolytic current of 3A / dm ² in an electrolyte containing HCl100g / l 2 minutes
After applying the coating, a NiP coating was formed by electroless plating.

Table 1 shows the plating conditions, the composition of the plating film and
And coercive force, the samples according to this example (sample numbers 1 to
In the case of 6), good magnetic properties are obtained.
Excellent magnetic properties as compared with the comparative example (sample numbers 7 to 9)
Has been obtained.Table 1 Sample Current density Energization method Film thicknessPlating film composition (wt%) Coercive forceNo (A / dm) Energizing time (μm) Co Ni P (Oe) 140 Intermittent 10 84.0 11.5 4.3 770 1 ms 260 Intermittent 10 85.2 10.4 3.7 860 1 ms 380 Intermittent 10 84.4 11.9 3.3 8505 ms 4 100 Intermittent 10 84.6 11.5 2.8 7805 ms 5 140 Intermittent 10 82.6 12 2.8 6802 ms 6 150 Intermittent 10 75.7 20.4 3.5 6602 ms 7 200 Intermittent 10 22.9 73.2 3.6 2902 ms 8 20 Intermittent 10 87.0 8.3 4.3 4001 ms 9 4 continuous 15 79.9 12.8 7.1 40

Example 2 _{CoSO 4 · 7H 2 O 120g /} l NiSO 4 · 6H 2 the _{O 80g / l NH 4 Cl 60g} / l NaH 2 PO 2 30g / l wetting agent 2 g / l solution 5l blended brightener 1 g / l and the plating solution A Co—Ni—P alloy film was formed on SUS304 having a diameter of 6 mm by electroplating at a pH of 3.0 and a liquid temperature of 50 ° C. The underlayer treatment was performed in the same manner as in Example 1. Table 2 shows the plating conditions, the composition of the plating film, and the coercive force.

As in the case of Example 1, good magnetic properties were obtained.
ing.Table 2 Sample Current density Energization method Film thicknessPlating film composition (wt%) Coercive forceNo (A / dm ² ) Energizing time (μm) Co Ni P (Oe) 10 50 intermittent 10 86.3 9.6 3.8 860 1 ms 11 50 Intermittent 20 86.4 9.1 4.4 910 1 ms 12 50 Intermittent 30 86.6 9.2 4.1 850 1 ms The above embodiment is based on a non-magnetic Fe-Cr-Ni alloy base material.
The case where a plating film is formed on
Similar results were obtained for the material. Also, this example
If implemented, protect Co-Ni-P alloy plating film
In many cases, a protective film is required.
A protective film such as NiP plating is formed according to the application.
Has been confirmed to be possible.

[0018]

According to the present invention, an underlayer is formed on a nonmagnetic iron-chromium-nickel alloy base material, and 75 to 87% by weight of cobalt and 8.5% of nickel are formed on the underlayer.
To 22% by weight, P being 2.5 to 4.5% by weight, and a magnetic film made of a cobalt-nickel-phosphorus alloy having a thickness of 0.05 to 50 μm. Compared with the alloy magnetic film, a plated film having a high coercive force can be obtained with high reproducibility, so that the yield of the magnetic film can be improved. Therefore, the present invention
A great effect can be expected when used for magnetic recording media such as magnetic disks, magnetic tapes, and magnetic encoders.

Continuation of the front page (72) Inventor Reiko Fukaya Chisun Mansion Higaoka 1002, Higashijubancho 65-65, Miyagino-ku, Sendai City, Miyagi Prefecture (56) References JP-A-3-199391 (JP, A)

Claims (3)

(57) [Claims] 1. The method according to claim 1, wherein cobalt is 75 to 87% by weight, nickel is 8.5 to 22% by weight, phosphorus is 2.5 to 4.5% by weight, and the thickness is 0.05 μm to 50 μm. Cobalt nickel phosphorus alloy magnetic film for a magnetic recording medium. 2. An underlayer is formed on a nonmagnetic iron / chromium / nickel alloy base material, and 75 to 87% by weight of cobalt and 8.5 to 2% by weight of nickel are formed on the underlayer.
A magnetic recording medium comprising a magnetic film made of a cobalt-nickel-phosphorus alloy having a thickness of 0.05 to 50 .mu.m and a P content of 2.5 to 4.5 wt%. . 3. The pH of the liquid is 2.0 to 4.5,
A cobalt salt concentration of 0.1 to 0.72 mol / l,
A plating electrolyte containing a nickel salt concentration of 0.04 to 0.31 mol / l and a phosphate concentration of 0.09 to 0.5 mol / l at a temperature of 40 to 60 ° C. and a current density of 30 to 150 A / Dm ² of the electrolytic current and the energization time of 0.5 to 10 milliseconds are repeated in a pulsed manner, so that 75 to 87% by weight of cobalt and 8.5% of nickel are deposited on the nonmagnetic substrate. Forming a cobalt-nickel-phosphorus alloy film having a thickness of 0.05 to 50 .mu.m with a thickness of 0.05 to 50 .mu.m. .