JP2882408B2 - In-plane magnetic recording medium for magnetic disk drive - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an in-plane magnetic recording medium for a magnetic disk drive, and is particularly suitable for high recording density and excellent in corrosion resistance and sliding resistance. Media. 2. Description of the Related Art Hitherto, as a magnetic recording medium for high recording density, a medium using a metal magnetic thin film has been proposed as shown in JP-B-54-33523. Here, as a film forming method of the medium, there are a vapor deposition method, a sputtering method, a plating method, an ion beam sputtering method and the like. [0003] Recently, increasing the recording density,
Demands for higher reliability are increasing. In particular, in the case of a metal magnetic thin film, improvement of corrosion resistance is the biggest problem, and in order to improve corrosion resistance, JP-A-57-15406, 57-1965
As described in 08, proposals have been made to add a third element such as Cr or Nb to a magnetic metal. However, these inventions mostly relate to tapes for magnetic recording, and do not satisfy stricter specifications in terms of reliability, such as hard disks for computers. An object of the present invention is to provide an in-plane magnetic recording medium for a magnetic disk drive comprising a Co-Cr-based magnetic thin film having improved corrosion resistance while substantially maintaining the excellent magnetic properties of a metal magnetic thin film. To give. [0005] Means for Solving the Problems] Periodic Table I _b, IIIa, IV _a,
Va, and elements of the fourth, fifth, and sixth periods of the VIII group, etc.
According to the study of the present inventors, which added to Cr and studied the magnetic properties, corrosion resistance, etc. of the magnetic thin film formed by a sputtering method or the like, according to the study of the present inventors, to achieve such an object, Zr
It has been found that its inclusion in a Co-Cr-based magnetic alloy thin film is extremely effective. The in-plane magnetic recording medium according to the present invention is based on such knowledge, and the above object is mainly composed of Co, Cr, Zr on a non-magnetic substrate, and
The Zr content is 6 wt% or more and 30 wt% or less with respect to Co and Cr, and more preferably, the Cr content is 1 at% or more and 17 at% with respect to Co in order to improve in-plane magnetic recording / reproducing characteristics. Or less, more preferably, the content of Cr is 5a relative to Co.
t% or more and 12 at% or less and the Zr content is Co and Cr
At least 10 wt% and not more than 22 wt%. Further, a Cr intermediate layer of 100 mm or more and 5000 mm or less is formed between the magnetic layer and the nonmagnetic substrate, or in the case of a medium using a metal-like substrate, the surface is oxidized by 10 to 400 mm, and directly or By forming the magnetic layer via the Cr intermediate layer, it is possible to provide a recording medium which is particularly excellent for longitudinal magnetic recording. 100Å to 1000 on the media surface
By forming the non-magnetic coating film of Å, a medium having further improved corrosion resistance and excellent sliding resistance can be provided. The present invention is based on the following functions of the above invention. Ar pressure 5mTor
r, input power 5W / cm ² , substrate temperature 200 ° C, film thickness formed on glass substrate by DC magnetron sputtering at 600Å, 30
wt% Zr-Co _0.95 Cr _0.05 , 20 wt% Zr-Co _0.9 Cr _0.1 , 10 wt% Zr-C
o _0.85 Cr _0.15 , 6wt% Zr-Co _0.80 Cr _0.20 , 3wt% Zr-Co _0.82 Cr
The magnetic thin film of _0.18 composition was evaluated by Auger spectroscopy, anodic polarization curve method, etc.
It was found that the Zr concentration was high up to about 30 ° and a dense passive oxide film was formed. That is, Zr
Was found to preferentially gather on the surface of the magnetic thin film to form a dense protective film, so that the corrosion resistance of the magnetic thin film was significantly improved. This effect was recognized when the Zr concentration was 6 wt% or more. On the other hand, the saturation magnetic flux density of the magnetic thin film is decreased by the addition of Zr, but it has been found that the content of Zr is practically sufficient if the content of Zr is 30 wt% or less with respect to the total amount of Co and Cr. Further, when the Cr content exceeds 18 at%, the Co-Cr magnetic film becomes a perpendicular magnetization film, and a recording / reproducing waveform reproduced by a ring head is distorted, which is not preferable as a conventional magnetic medium for a longitudinal magnetic recording apparatus. On the other hand, when the amount of Cr was smaller than 1 at%, a high recording density could not be obtained. Therefore, in order to provide a medium having both excellent corrosion resistance and magnetic properties, it is necessary to make the concentration of Cr with respect to Co 1 at% or more and 17 at% or less. In order to further improve the recording / reproducing characteristics of the medium, it is necessary to increase the coercive force and the saturation magnetic flux density of the medium. For this purpose, the content of Cr with respect to Co is set to 5 at% or more and 12 at% or less, and Zr Is desirably 3 at% or more and 200 at% or less with respect to the total amount of Co and Cr. In order to maintain the coercive force in the in-plane direction at a high value with good reproducibility, a distance of 100 mm is required between the magnetic layer and the non-magnetic substrate.
As described above, when a Cr intermediate layer of 5000 ° or less is interposed or a metal-like substrate is used, it is desirable to form the substrate directly or via the Cr intermediate layer on a substrate whose surface is oxidized by 10 ° to 400 °. Further, by forming a non-magnetic coating film having a thickness of not less than 100 ° and not more than 1000 ° on the surface of the magnetic layer,
Not only can the sliding resistance characteristics be significantly improved, but also the corrosion resistance can be improved. An embodiment of the present invention will be described below with reference to FIG. 11 is a substrate made of Al alloy, etc., 12 and 12 'are Ni-P, Ni
Non-magnetic plating layers made of -WP, etc., 13 and 13 'are magnetic control layers made of Cr and the like, and 14 and 14' are magnetic layers made of a Co-Cr-Zr alloy, as shown below. Be composed. [0010] 11 as outer diameter 130mmφ, inner diameter 40mmφ, thickness
1.9mm Al alloy, 15μm non-magnetic as 12,12 'on it
On a substrate with a 11.5wt% P-Ni plating layer formed, a substrate temperature of 2
2000 ° C Cr film at 00 ℃, Ar pressure 5mTorr, RF input power 8W / cm ²
Formed. Further, as a third element, Ti, Zr, V, Nb, Ta, Ni, M
o, W, Ru, Rh, Pd, Pt 0.05wt%, 0.1wt%, 1wt%, 3wt%, 5wt
%, 10wt%, 20wt%, 30wt%, 40wt%, 50wt% Co
_{Using a 0.92} Cr _0.08 alloy target, place the magnetic layer on top of Cr
0 ° formed. FIG. 2 shows the relative concentration of the third element with respect to CoCr by a salt spray test using 1 mol of NaCl at 40 ° C.
The state in which the saturation magnetic flux density of the magnetic disk at 17 wt% changes with time is shown. 21 shows a similar result for a magnetic disk using an alloy thin film having a composition of Co _0.9 Cr _0.1 . The highest corrosion resistance when Zr is added, followed by V, Ti, R
The order is u, Ni, Rh, Ta, Pd, W, Pt, Nb, and Mo. In each case, the corrosion resistance is improved as compared with the Co _0.9 Cr 0.1 master alloy thin film. This effect was substantially the same as long as the added amount was 6 wt% or more. [0011] Next, as 11, the outer diameter 220mmφ, thickness 1.9mm
Al alloy substrate, 20μm non-magnetic 11wt% P as 12,12 '
-A substrate temperature of 180 ° C and an Ar pressure of 7
mTorr, Cr film is 2500Å formed by DC input power 10W / cm ^2, Co
_0.99 Cr _0.01 , Co _0.95 Cr _0.05 , Co _0.9 Cr _0.1 , Co _0.88 Cr _0.12 , Co
_A magnetic layer was formed to a thickness of 500 mm using an alloy target in which Zr was added to _0.85 Cr _0.15 , Co _0.83 Cr _0.17 , and Co _0.8 Cr _0.2 at 10 wt%. Z
As compared with the case where r was not added, the medium having any Cr composition exhibited the same excellent corrosion resistance as the case shown in FIG. 2 when Zr was added. Similar effects were observed for a medium in which Zr was added as an additive element in an amount of 6 wt% or more. But,
If Zr is added in an amount of more than 30 wt%, the saturation magnetic flux density and the coercive force are remarkably deteriorated, which is not practically desirable, and the addition amount is preferably 30 wt% or less. An aluminum alloy substrate having an outer diameter of 90 mmφ and a thickness of 1.9 mm was used as a substrate 11 and a nonmagnetic 11 wt% P-Ni plating layer of 10 μm was used as a substrate 12 and 12 ′. DC
Cr film 13, 13 'is formed 1500 で with input power of 10 W / cm ² , and under the same conditions, 12.5 wt% of Ti, Zr, V, Nb, Ta, Ni, Mo, W, Ru, Rh, Rd, Pt is added. Layer 1 using a Co _0.88 Cr _0.12 alloy target
4,14 'was formed 700mm. FIG. 3 shows the in-plane coercive force of these magnetic disks. Each magnetic disk has an in-plane coercive force of 500 Oe or more and an effective gap length of 0.5
As a result of evaluating the recording / reproducing characteristics using a ring head made of Mn-Zn ferrite having a thickness of μm, it was confirmed that the recording / reproducing characteristics were excellent as an in-plane magnetic recording medium. For corrosion resistance,
Disks added with Zr, Ti, V, Ru, Ni, Rh, Ta, etc. were particularly good, but disks added with W, Pt, Nb, Mo also
Good corrosion resistance was exhibited as compared with the case where no element was added.
At this time, all the magnetic films were predominantly polycrystalline. FIG. 4 shows another embodiment of the present invention. 41 is a substrate made of Al alloy, ceramics, brass, organic material, etc., 42, 42 'is a non-magnetic plating layer made of Ni-P, Ni-WP, etc., 43, 43' is a magnetic control layer made of Cr, etc. , 44,44 'are Co-Cr based magnetic alloy thin films, 45,45' are C, B, B
A non-magnetic coating film made of N, SiC, etc. Outer diameter 130mmφ, inner diameter 40mmφ, thickness as 41
1.9mm Al alloy substrate, 15μm 12wt% PN as 42,42 '
Substrate temperature 220 ° C, Ar pressure
5 mTorr, after 2000Å form Cr thin film 43, 43 'in the DC input power 8W / cm ^2, Co in input power _{^{5W / cm 2, Co 0.99 Cr}} 0.1, Co 0.95 C
r _0.5 , Co _0.9 Cr _0.1 , Co _0.88 Cr _0.12 , Co _0.85 Cr _0.15 , Co _0.83 Cr
_0.17 , Co _0.8 Cr _0.2 , Co _0.78 Cr _0.22 , Co _0.77 Cr _0.23 with Zr, 3
The magnetic layers 44 and 44 'were formed to a thickness of 600 ° using an alloy target to which 6, 10, 15, 20, 25, 30, and 35 wt% was added, and the input power was 10 W /
C thin films 45 and 45 'were formed at 450 ° in cm ² . Fig. 5 shows that Zr
4 shows the relationship between the in-plane holding force of the magnetic disk and the Cr concentration with respect to Co when% is added. When the Cr concentration is 22 at% or less, a coercive force sufficient for in-plane recording can be obtained. However, the Cr concentration
If it is higher than 17 at%, the saturation magnetic flux density is small and the perpendicular anisotropy is large, and the reproduced waveform is distorted when recording and reproducing with a ring head. On the other hand, Cr concentration is 1at%
In the following cases, the corrosion resistance was significantly deteriorated even when the third element was added. These effects were similar when the Zr concentration was changed. From the viewpoint of reproduction output, it is desirable that the saturation magnetic flux density is high. When recording and reproduction are performed with a Mn-Zn ferrite ring head having a gap length of 0.4 μm and a flying height of 3600 revolutions of 0.20 μm, the Cr content is reduced. 5at% or more, 12at% for Co
Below, Zr content is more than 10wt%, 25wt% to Co and Cr
High output of 0.3 mV or more was obtained for the following media.
By forming the non-magnetic coating films 45 and 45 ', corrosion resistance, CSS characteristics, and the like were significantly improved. FIG. 6 shows an embodiment having another configuration. 61 is a substrate made of ceramics, tempered glass, etc., 62, 62 'are Zr,
Magnetic property control layer made of Cr, etc., 63, 63 'is CoCrZr, CoCr
Magnetic layers made of Ta, CoCrTi, etc., 64 and 64 'are non-magnetic coating films, and 65 and 65' are surface lubrication layers. A ceramic substrate having an outer diameter of 130 mmφ, an inner diameter of 40 mmφ, and a thickness of 1.9 mm was used as 61, and a Cr thin film was formed at 62 ° and 62 ′ at a substrate temperature of 180 ° C., an Ar pressure of 5 mTorr, and a DC input power of 10 W / cm ^2. , 100Å, 1000Å, 2500Å, 3000Å, 5000Å, 1
and μm formed, Co in input power 8W / cm ² as further 63, 63 '
After forming a magnetic film of 650 mm using a target in which 18 wt% of Zr is added to _0.9 Cr _0.1 , the applied power is 12 W / cm ² as 64,64 ′.
C was formed to a thickness of 400 °, and polyhexafluoropropylene oxide having a film thickness of 50 ° was applied to form 65 and 65 ′. With a Cr thin film of 100 mm or more, practically sufficient recording / reproducing characteristics were obtained using a MnZn ferrite head. Even if the Cr film thickness is 5000 mm or more, no improvement in characteristics is observed, and conversely, there is a drawback such as poor smoothness of the disk surface
It is desirable that the film thickness be 5000 ° or less, more preferably 3000 ° or less. This effect is due to Ni-P alumite, Ni-W
-P, when Cr was formed thereon, the same was true. FIG. 7 shows still another embodiment. 71 is Al
Substrates made of alloys, etc., 72, 72 'are non-magnetic plating layers made of Ni-P, Ni-WP, etc., 73, 73' are surface oxidized layers, 74, 74 'are CoCrZr, CoCrTa, CoCrTi, etc. A magnetic layer composed of C, B, BN, SiC, etc .;
6,76 'is a surface lubricating layer made of a liquid lubricant or the like. [0019] 71 as the external diameter of 130mmφ, Al alloy substrate having a thickness of 1.9mm, 10μm 13wt% P-Ni plated layer and the Ar gas the surface of the disk containing O ₂ 10% of the 72, 72 '(total gas Pressure 5m
Torr, 0.5 W / cm ² , substrate temperature 150 ° C.) After reverse sputtering, the surface oxide layers 73, 73 ′ were formed 40 °, and then the Ar gas pressure was 1
0mTorr, 7W / cm ^2, the Zr at a substrate temperature of 150 ℃ 6,10,15,20,25wt
%, Using Co _0.87 Cr _0.13 target
At an Ar pressure of 10 mTorr, 9 W / cm ^{2 at} 100 ° C.
Films 75 and 75 'were formed at 450 °. Finally, polyhexafluoropropylene oxide 76, 76 'was applied to a film thickness of 60 °. The coercive force of this disk showed an excellent value equivalent to that shown in FIG. 3, and the recording / reproducing characteristics of the ring head were also good. On the other hand, when the reverse sputtering was not performed and the surface oxide layer was not provided, the coercive force in the in-plane direction of the disk was only about 50 Oe and could not be used as an in-plane medium. Although the corrosion resistance was slightly deteriorated as compared with the disk shown in FIG. 6, there was no practical problem. The effect of the surface oxide layer was recognized when the film thickness was 10 ° or more. However, if the thickness is more than 400 °, the surface properties are poor and the flying characteristics are deteriorated, and the process time is prolonged. In the structure shown in FIG.
C films of 100, 400, 600, 1000, and 1500 mm were formed by sputtering to obtain magnetic disks. (The formation conditions were the same as in FIG. 4, and a magnetic film obtained by adding 15 wt% of Zr to Co _0.9 Cr _0.1 was used as 44, 44 ′.) Mn-Zn having a gap length of 0.35 μm
Using a ferrite ring head with a flying height of 0.25 μm, these recording and reproduction characteristics were evaluated.
When the thickness of the 5 'film is more than 1000 °, the loss of spacing increases and the recording density characteristics are remarkably deteriorated, which is not preferable as a high performance magnetic recording / reproducing magnetic disk. On the other hand, if the thickness of the C film is smaller than 100 mm, the sliding resistance such as CSS characteristics deteriorates, and the thickness of the non-magnetic coating film becomes 100 mm.
It is desirable that: This effect is not limited to C only,
The same was true even if the surface of a non-magnetic material such as B, BN, or SiC, or the surface of the magnetic film was thermally oxidized. According to the present invention, the metal magnetic recording thin film has substantially superior corrosion resistance while substantially maintaining the excellent magnetic properties of the metal magnetic recording thin film, as compared with a medium made of a conventional material. A Co-Cr based in-plane magnetic recording medium having excellent reliability such as sliding resistance can be provided.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a cross-sectional view of a magnetic disk according to an embodiment of the present invention, FIG. 2 is a diagram showing a result of a corrosion resistance test of the magnetic disk of the present invention by salt spray, and FIG. FIG. 4 is a cross-sectional view of another embodiment, FIG. 5 is a cross-sectional view of its magnetic characteristics, and FIGS. 6 and 7 are cross-sectional views of another embodiment. . [Explanation of the symbols] ... magnetic property control layer, 14, 14 ', 44, 44', 63, 63 ', 74, 74' ... magnetic layer, 45,
45 ', 64,64', 75,75 '... non-magnetic coating layer, 65,65', 76,7
6 ': lubricating layer, 73, 73': surface oxide layer.

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Norio Kazuda 1-280 Higashi Koikekubo, Kokubunji-shi, Tokyo Inside the Central Research Laboratory, Hitachi, Ltd. (72) Inventor Yasuo Suganuma 1-280 Higashi Koikekubo Kokubunji-shi, Tokyo (72) Inventor Yoshio Gohara, 2880 Kozu, Kozuhara, Odawara-shi, Kanagawa Prefecture, Ltd.Hitachi Seisakusho Odawara Plant (72) Inventor, Masaaki Hayashi 2880, Kozu, Kozu, Hitachi-Odawara, Kanagawa, Japan 56) References JP-A-57-183004 (JP, A) JP-B-8-16974 (JP, B2) (58) Fields investigated (Int. Cl. ⁶ , DB name) G11B 5/66

Claims (1)

(57) [Claims] The magnetic layer of a magnetic recording medium in which a magnetic layer is formed on a non-magnetic substrate, and an intermediate layer formed of a single metal or alloy containing Cr as a main component is formed between the magnetic layer and the non-magnetic substrate. Alloy in which the content of Cr is 1 at% or more and 22 at% or less with respect to Co, and an alloy containing Co and Cr as main components and Zr added so that the total content of the elements is 6 wt% or more An in-plane magnetic recording medium for a magnetic disk drive, comprising: 2. Between the magnetic layer and the non-magnetic substrate, at least 100 mm
4. The longitudinal magnetic recording medium for a magnetic disk drive according to claim 1, wherein the following Cr intermediate layer is interposed. 3. 2. The in-plane magnetic recording medium for a magnetic disk device according to claim 1, wherein a magnetic layer is formed via an intermediate layer on a substrate obtained by oxidizing the surface of the nonmagnetic metal substrate by 10 to 400 degrees. 4. 2. A non-magnetic coating film having a thickness of not less than 100 [deg.] And not more than 1000 [deg.] Is formed on the surface of the magnetic layer.
Item 14. The longitudinal magnetic recording medium for a magnetic disk device according to item 8.