JPS5939809B2 - magnetic memory - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a magnetic storage body used in magnetic storage devices (magnetic disk devices, magnetic drum devices, etc.).

In general, there are two types of recording/reproducing methods for a magnetic storage device that includes a recording/reproducing magnetic head (hereinafter referred to as a head) and a magnetic storage body, as follows.

The first method is to set the head and the magnetic storage surface in contact at the start of operation, and then apply a required rotation to the magnetic storage to create an air space between the head and the magnetic storage surface. This is a method for recording and playing in this state. In this method, the magnetic storage body stops rotating at the end of the operation, and at this time the head and the magnetic storage body surface are in the same frictional state as at the start of the operation. The second method is to apply a required rotation to the magnetic storage body in advance, and then suddenly press the head onto the magnetic storage body surface to create a space equivalent to an air layer between the head and the storage body surface. This is a method of recording and playing back. As described above, in the first method, the head and the magnetic storage surface are in a frictional contact state at the start and end of the operation, and in the second method, the head and the magnetic storage surface are in a frictional contact state when the head is pressed against the magnetic storage surface. The frictional force generated between the head and the magnetic storage body in these contact friction states causes wear on the head and the magnetic storage body, and may eventually cause scratches on the head and the metal magnetic thin film medium. Further, in the contact friction state, a slight change in the posture of the head may cause the load applied to the head to become uneven, causing scratches on the surface of the head and the magnetic storage body. Furthermore, during recording and reproducing, the head suddenly comes into contact with the magnetic storage body, and a large frictional force acts between the head and the magnetic storage body, which often causes the head and the magnetic storage body to be destroyed. In order to protect the head and the magnetic storage body from such contact friction, contact wear and contact breakage between the head and the magnetic storage body, it is necessary to coat the surface of the magnetic storage body with a protective film. Traditionally, metal plating films (e.g. Cr, Rh, N) have been used as protective films.
There are two methods: coating the surface of a metal magnetic thin film medium (i-P, etc.), or oxidizing the surface of a metal magnetic thin film medium to form an oxide to form a protective film. Must not be. The present inventors have already proposed a protective coating made of polysilicic acid that eliminates these drawbacks (Japanese Patent Application No. 81201/1982). This protective film made of polysilicic acid can sufficiently withstand the contact friction between the head and the magnetic memory, and can withstand sudden contact of the head with the magnetic memory, and can also protect the metal magnetic thin film even under high temperature and high humidity conditions. It has sufficient performance as a protective film, providing sufficient protection and not impairing the magnetic properties of the underlying metal body containing the magnetic storage body. However, depending on the head, it is easy to draw dust between the head and the magnetic memory, and this dust acts as an abrasive and wears down the head and the magnetic memory, and the abrasion powder generated by that abrasion can further damage the head. and some that wear out the magnetic memory.

This phenomenon is more pronounced in heads with a tapered front. SUMMARY OF THE INVENTION An object of the present invention is to provide a magnetic storage body having a protective coating that sufficiently protects a metal magnetic thin film medium even from the above-mentioned heads that tend to attract dust.

In the magnetic storage body of the present invention, a metal magnetic thin film medium is coated on a mirror-polished non-magnetic disc-shaped substrate, an amorphous inorganic oxide is coated on the metal magnetic thin film medium, and if necessary, pretreatment is performed on the metal magnetic thin film medium. A layer is coated, and a polysilicic acid film containing or not containing a silane coupling agent is further coated thereon.

Next, the present invention will be explained in detail with reference to the drawings.

FIGS. 1 and 2 are cross-sectional views showing embodiments of the magnetic storage body of the present invention. In FIG. 1, a magnetic storage body 7 of the present invention includes a nonmagnetic disc-shaped re-body composed of an alloy disc 1 and a non-magnetic alloy layer 2 coated thereon, and a polished surface of the non-magnetic alloy layer 2. a protective coating consisting of a metal magnetic thin film medium 3 coated with a metal magnetic thin film medium 3, an amorphous inorganic oxide 4 on the metal magnetic thin film medium 3, and a polysilicic acid coated thereon with or without a silane coupling agent. It consists of 5. The magnetic memory of the present invention shown in FIG. 2 has a pretreatment layer 6 between the amorphous inorganic oxide 4 shown in FIG. It is set up and configured. The alloy disk 1 must be finished with a surface with sufficiently small waviness (50 μm or less in the circumferential direction and 100 μm or less in the radial direction).
.

This is because if the waviness is large, the head floating above the magnetic storage body cannot follow the vertical movement of the magnetic storage surface during recording and playback, and the distance between the head and the magnetic storage body changes, causing changes in recording and playback. Because it is from. The nonmagnetic alloy layer coated on the alloy disk 1 by plating is mirror-finished to a surface roughness of 0.04 μm or less by mechanical polishing. Note that if the alloy disk 1 is made of a metal that can be mirror-polished, the non-magnetic alloy layer 2 becomes unnecessary. A metal magnetic thin film medium 3 for high-density recording is coated on the nonmagnetic alloy layer 2 by plating. The protective coating that sufficiently protects the metal magnetic thin film medium 3 from head contact or changes due to humidity and temperature is made of an amorphous inorganic oxide 4 that guarantees hardness and adhesion to the metal magnetic thin film medium, and has crush resistance. and a silane coupling agent to ensure lubricity and environmental resistance.
or a polysilicate film 5 containing no polysilicate, and, in some cases, a pretreatment layer 6 that guarantees adhesion between the amorphous inorganic oxide and the polysilicate film. Next, the present invention will be explained in detail by giving Examples and Comparative Examples.

Comparative Example Alloy Disk 1 had sufficiently small waviness (50μ in each of the circumferential and radial directions) by lathe machining and thermal straightening.
A nickel-phosphorus (Ni-P) alloy is plated to a thickness of about 50 Itm as a non-magnetic alloy layer 2 on a disk-shaped aluminum alloy substrate finished with a surface having a surface area of 100 m and 1001 tm or less. The plating film is mechanically polished to a surface roughness of 0.04μm or less and a thickness of approximately 30mm! ,m
After mirror-finishing the metal magnetic thin film medium 3
Cobalt-nickel-phosphorus (CO--Ni--P) alloy was plated to a thickness of about 0.05 μm.

Furthermore, this cobalt nickel monophosphorus (CO-Ni-P
) After thoroughly mixing the solution with the composition shown below on the alloy film, apply it by spin coating method (500A at 200rpm).
A disc-shaped disc coated with a film thickness of
A magnetic disk was made by firing in an electric furnace for an hour. Tetrahydroxysilane 11% ethyl alcohol solution 10% by weight n-butyl alcohol 90% by weight Example 1 A nickel-monophosphorus coating was coated on an aluminum alloy disc in the same manner as in Comparative Example, and a cobalt-nickel-monophosphorous coating was coated on top of that. Borosilicate glass was deposited on the prepared disk-shaped disk by a sputtering method.
After thoroughly mixing a solution having the composition shown below on it, a disc-shaped disc coated with a film thickness of 0.05 μm using a spin coating method (rotation speed of 200 rpm) was coated with a film of 20 cm. A magnetic disk was obtained by firing the disk in an electric furnace at a high temperature for 3 hours.

Tetrahydroxysilane 1101) Ethyl alcohol solution 10% by weight n-butyl alcohol 90% by weight Example 2
Using the same method as in Example 1, except that amorphous SiO2 was applied to a thickness of 0.05 μm by sputtering on the soil of the cobalt-nickel-phosphorus (CO-Ni-P) alloy film, and then A magnetic disk was prepared by applying and baking a solution having the composition shown in the same manner as in Example 1.

Tetrahydroxysilane 110/) Ethyl alcohol solution 10% by weight Polyaminosilane (silane coupling agent) 0.03% by weight n-butyl alcohol Balance Example 3 In the same manner as in Example 1, except that cobalt nickel monophosphorus ( CO-N
i-P) Borosilicate glass is provided on the alloy film to a thickness of 0.05 μm by sputtering, and 0.1f of gamma-aminopropyltriethoxysilane is applied as a pretreatment liquid on top of it.
) Spin coat the n-butyl alcohol solution and apply it as it is 1
Continue spinning for 0 minutes to evaporate the solvent and dry to form a very thin pretreatment layer of gamma-aminophyltriethoxysilane.

Thereafter, a solution having the same composition as in Example 2 was coated on the gamma-aminopropyltriethoxysilane pretreatment layer and baked to obtain a magnetic disk.

In the recording and reproducing method using each of the magnetic disks shown in Comparative Example and Examples 1 to 3, in which the head and the magnetic disk surface are always in a state of contact at the start and end of the operation, this operation start and end are repeated. The test was carried out using a tapered front head that easily pulled in dirt.
After 00 repetitions, about 35% of the friction marks on the head of the magnetic disk of the comparative example were peeled off, but in Example 1
There was no peeling in each of the magnetic disks No. 3 to 3. Furthermore, the magnetic disk of Example 2 showed no peeling even after 30,000 repetitions, and the magnetic disk of Example 3 showed no peeling even after 40,000 repetitions. As shown in Comparative Examples and Examples 1 to 3 above, a magnetic disk having a protective film made of polysilicic acid on which an amorphous inorganic oxide is coated on a metal magnetic thin film medium is made of an amorphous inorganic oxide. It can be seen that the wear resistance of the head is improved compared to a magnetic disk having a protective film of polysilicate alone that does not cover any material. It can also be seen that a magnetic disk having a protective film made of polysilicic acid containing a silane coupling agent on an amorphous inorganic oxide has even better wear resistance. Additionally, magnetic disks that have a pretreatment layer coated on an amorphous inorganic oxide and a protective film made of polysilicic acid containing a silane coupling agent have further improved wear resistance. I understand. Note that a silane coupling agent is included on the amorphous inorganic oxide according to the present invention.
Or a protective coating made of polysilicic acid that does not contain it, or a protective coating made of polysilicic acid that contains or does not contain a silane coupling agent on top of a pretreatment layer coated on an amorphous inorganic oxide, is only polysilicic acid. Although the abrasion resistance was improved compared to the protective coating made of the above, other properties such as head crushing resistance, lubricity, environmental resistance, and magnetic properties of the underlying metal body remained unchanged.

Further, in the comparative examples and examples of the present invention, metal was used as the non-magnetic disc-shaped substrate, but it is clear that plastic or the like can also be used, and the type of the substrate is not limited.

In addition, in the present invention, a silane coupling agent was used as a pretreatment agent and an additive in polysilicic acid, but it may enhance the adhesion between the amorphous inorganic oxide and polysilicic acid, or Obviously, stress-relieving substances such as chromium-based silane coupling agents (Werna type 1 chromium complexes) may also be used.

[Brief explanation of the drawing]

FIGS. 1 and 2 are cross-sectional views showing embodiments of the magnetic storage body of the present invention. In the figure, 1 is an alloy disk, 2 is a mirror-finished nonmagnetic alloy layer, 3 is a metal magnetic thin film medium, 4 is an amorphous inorganic oxide layer, and 5 is a polysilicon with or without a silane coupling agent. Acid film 6 is a pretreatment layer.

Claims (1)

[Claims] 1. A metal magnetic thin film medium is coated on a mirror-polished nonmagnetic disk-shaped substrate, an amorphous inorganic oxide is coated on the metal magnetic thin film medium, and polysilicate is further applied on top of the metal magnetic thin film medium. A magnetic memory body characterized by being coated with a film or a polysilicate film containing a silane coupling agent. 2. The magnetic memory according to claim 1, wherein the polysilicic acid coating or the polysilicic acid coating containing a silane coupling agent is coated on the amorphous inorganic oxide via a pretreatment layer. 3. The magnetic memory according to claim 2, wherein the amorphous inorganic oxide is amorphous alumina, quartz galane silicate glass, or borosilicate glass. 4. The magnetic memory according to claim 2, wherein the pretreatment layer is a silane coupling agent layer.