Magnetic recording medium

[Detailed Description of the Invention]

[Industrial Application] The present invention relates to a magnetic recording medium like a magnetic disk or a floppy disk, and relates to the magnetic recording medium using the diamond-like carbon film as a topcoat film particularly.

[Description of the Prior Art] Now, in OA equipment, such as an electronic meter r1 set and a word processor, etc., various kinds of magnetic recording media are used. Among these, since that a storage capacity is large, excelling in preservability, and the response are good, hard disks, such as a magnetic disk and a floppy disk, are used widely. these magnetic recording media are excellent in mechanical strength, in order that they may obtain good roadability while preventing generating and poor reproduction of a noise resulting from slide contact wear with a magnetic head, damage, etc., form the topcoat film as a wear-resistant lubricous film in the surface, and come out to it. As this topcoat film, various things, such as carbon and a silica dioxide, are used and there are it, and not only a monolayer but the thing formed in two layers (for example, JP,61-204834,A). And since it has the feature that mechanical strength is high at high hardness, and the effect of wear and the prevention from damage is high in recent years, a diamond-like carbon film has come to be used as a topcoat film.

[The problem which should be solved] However, when it acted as 21 Tyng of the diamond-like carbon film directly on the ferromagnetic metal membrane as the topcoat film, since the hardness of a diamond-like carbon film was high, there was a fault of a film having exfoliated by the stress or producing a crack. For this reason, having the feature that it is suitable for the topcoat film with high hardness, the diamond-like carbon film could be put in practical use and had the problem of being nothing. The present invention was made in view of the above-mentioned problem, improves adhesion nature with a ferromagnetic metal membrane, prevents film exfoliation and generating of a crack, and aims at offer of the magnetic recording medium using the diamond-like carbon film practical as a topcoat film.

[The solving means of a problem] The magnetic recording medium of the present invention forms a ferromagnetic metal membrane on a base material in order to achieve the above-mentioned object, on this ferromagnetic metal membrane, it is the magnetic recording medium which formed the diamond-like carbon film as a topcoat film, and the amount of absorbed water matter in the above-mentioned diamond-like carbon film is considered as the composition decreased from the ferromagnetic metal membrane side gradually or continuously to the surface side, and it comes out. Hereinafter, the magnetic recording medium of the present invention is explained with reference to drawings. Drawing 1 shows the partial fault figure of the present invention, and, as for 1, a ferromagnetic money m film and 3 are diamond-like carbon films a base material and 2. As base material l used as the base of a magnetic recording medium, light alloys, such as thermoplastics, such as polyethylene terephthalate and polystyrene +A B S+'I Riphenylene ether, an aluminium alloy, or a titanium alloy, etc. are used. It forms by Metsuki, sputtering, and a vacuum evaporation method, and ferromagnetic metal membrane 2 formed on a base material is an alloy as the material about metal, such as Fe+Co and Ns, or C, -N i alloy, and CO-P. The thing which made these, such as an alloy, a F e-G o alloy, a Fe-Ni alloy, an F @-C6-N i alloy, a F e-Co-B alloy, a Co-N+-F e-B alloy, and a Co-Cr alloy, contain metal, such as Cr and A.I. Artificial Intelligence, for CO-N l-P is used. Diamond-like carbon film 3 is used for the topcoat film formed in the surface of ferromagnetic metal membrane 2 as a protective film. This diamond-like carbon film 3 is formed in the surface of ferromagnetic metal membrane 2 by the thickness more than 100A, preferably more than 400A. This diamond-like degree matter M / 43 are formed with low-pressure gaseous phase synthetic methods, such as RF plasma CVD method, DC plasma CVD method, an ion plating method, or the sputtering method. For example, when diamond-like carbon film 3 is formed with RF (high frequency) plasma CVD method, The reaction interior of a room which has arranged base material l which formed ferromagnetic metal membrane 2 for the mixed gas of the source gas of carbon or the source gas of carbon, and carrier gas is supplied, By exciting the source gas of carbon, or mixed gas, and generating plasma, a diamond-like carbon film is formed in the surface of ferromagnetic metal membrane 2 of base material 1 by impressing high frequency to 1w1 pole, and producing glow discharge between the anodes, heating base material l. In this case, as source gas of carbon, they are Alekan, such as methane, ethane, Flopan, butane, pentane, and hexane, ethylene, and propylene, for example. Flickin, such as Al Ken, such as Butene, a pen ten, and butadiene, and acetylene Cycloolefins, such as cycloparaffins, such as aromatic hydrocarbon, such as benzene, toluene, xylene, indene, naphthalene, and phenanthrene, cyclopropane, and cyclohexane, the Si * Cropen ten, and cyclo Hexane, are used. Nitrogen-containing carbon compounds, such as oxygenated carbon compounds, such as - carbon monoxide, carbon dioxide, methyl alcohol, and ethyl alcohol, methylamine, ethyl amine, and aniline, etc. can be used as source gas of carbon. Although it is not a simple substance, the 4th oil, such as the 3rd oil, such as the 2nd oil, such as the 4th class of the Fire Service Law dangerous object, such as gasoline, the 1st class, kerosene, tele pin oil, camphor oil, and wood turpentine oil, and heavy oil, Gear oil, and cylinder oil, can be used effectively. Various kinds of above-mentioned carbon compounds can also be mixed and used. Methane, - carbon monoxide, carbon dioxide, etc. are preferred also in the above-mentioned source gas of carbon. When it is made to generate stably and the above-mentioned carrier gas makes plasma for it to to be not only important as a carrier who introduces the source gas of carbon into a plasma reaction system, but maintain, it is important. As such carrier gas, hydrogen gas, argon gas, neon gas, gaseous helium, Xenon gas, nitrogen gas, etc. are used. These may be used by a kind independent and may combine two or more sorts. Hydrogen gas, nitrogen gas, argon gas, etc. are preferred also in the above-mentioned carrier gas. from the ferromagnetic metal membrane side, the amount of absorbed water matter in that inside is considered as the composition decreased gradually or continuously, and this diamond-like carbon film 3 comes out of it to the surface side. That is, when there are many amounts of absorbed water matter in a film, membranous hardness becomes low and internal stress also becomes small, on the contrary, since membranous hardness becomes high and internal stress also becomes large when there are few amounts of absorbed water matter in a film, the amount of absorbed water matter by the side of a ferromagnetic metal membrane is increased, the amount of absorbed water matter by the side of the surface is considered as the lessened composition, and it comes out. The stress of the side which raises the hardness by the side of the surface in contact with a magnetic head etc. of a topcoat film, by this, and contacts ferromagnetic metal @2 is made small, and it is ferromagnetism. Adhesion nature with - metal membrane 2 is improved. Diamond-like carbon I8! When decreasing gradually the amount of absorbed water matter in 3, As the reaction conditions at the time of composition are changed in the shape of a step and shown in Drawing 2, it carries out by forming multiple thin film layers 3-1.3-2.3-3 (the amount of absorbed-water matter: 3-1>3-2>3-3) from which the amount of absorbed water matter differs from ferromagnetic metal $2 side, In this case, let the number of thin film layers be the proper number of two or more layers according to the purpose of using a magnetic recording medium or the quality of the material of base material l1 ferromagnetism metal membrane 2, thickness, etc. When decreasing continuously the amount of absorbed water matter in diamond-like carbon film 3, the reaction conditions at the time of 1 composition are changed continuously, and it carries out by forming, as shown in Drawing 3. Control of the reaction conditions at the time of compounding diamond-like carbon film 3, For example, when are based on RF plasma CVD method, and the amount of absorbed water matter performed by changing reactant gas composition, pressure, base material temperature, and/or high frequency injection electric power controls reaction conditions, it is Not glossy to make it change from about 30atom% among Kazuhara children %. When based on RF plasma CVD method, the source gas of carbon is supplied, for example by the flow for 0.1~500 cc/, and carrier gas is supplied by the flow for 1~1,000 cc/. Reaction stress, i.e., the pressure of the reaction interior of a room, is usually 10-5~103Torr, preferably 1 (it is 13~102Torr.). When this reaction pressure is lower than 1O-5Torr, the generation speed of a diamond-like carbon film may become remarkably slow. On the other hand, when higher 103 dishes than art, a diamond-like carbon film may not be formed. The heating temperature of a base material (ferromagnetic metal membrane) is usually room temperature~600degreeC, preferably room temperature~400degreeC. When this temperature is lower than room temperature, a diamond-like carbon film may not be formed. This with preferred setting high frequency injection electric power to IKW is because the effect equivalent to it cannot be acquired even if high frequency injection electric power exceeds IKW.

[Example] The result of an example and a comparative example is shown below. - Base material : it is 1000A vapor deposition by electron beam vapor deposition about A1 alloy board (thickness about 1.51 big buildings, outside 81nch) and ferromagnetic metal membrane 00 which formed the N i-P no 2 layer of thickness 15pm as a non-magnetic metal base layer. Meeting diamond-like carbon layer: Form with RF plasma CVD method of CHa<>H2. (Conditions) +1 reaction-pressure crab 10-'Torr1 substrate temperature = 100-degreeC-RF power: 120 W EXAMPLE The magnetic recording medium in which the diamond-like carbon film which compounds E1 membrane layer of three layers on condition of the following and in which the amount of absorbed water matter decreases from the ferromagnetic metal membrane side to the surface side as a whole was formed (thickness 15OA of each class, the whole thickness 45OA). Comparative example 1 The magnetic recording medium formed on the same conditions as an example except having formed the diamond-like carbon film on the same reaction conditions as the "ferromagnetic metal membrane side layer" in the above-mentioned example (diamond-like carbon film thickness 450A). Comparative example 2 The magnetic recording medium (diamond-like carbon film thickness 450A) formed on the same conditions as an example except having formed the diamond-like carbon film on the same conditions as the "surface side layer" in the above-mentioned example. Result By the contact start stop (CS S) examining method, the desquamative state of the diamond-like carbon film of an example and comparative examples 1 and 2 was observed.

[Effect of the Invention] By the present invention, the amount of hydrogen in a diamond-like carbon film is changed as mentioned above. Therefore, adhesion nature can be improved, film exfoliation and generating of a crack can be prevented, and mechanical strength can be raised. A diamond-like carbon film can be put in practical use as a topcoat film by this, and offer of the magnetic recording medium which was excellent in roadability, shock resistance, and abrasion resistance, and prevented noise generating and poor reproduction is enabled.

[Brief Description of the Drawings]

Drawing 1 shows the partial fault figure of the magnetic recording medium of the present invention, Drawing 2 shows the explanatory view of the first example of the present invention, and Drawing 3 shows the explanatory view of the second example of the present invention. l: Base material 2 2 ferromagnetism metal membrane 3: Diamond-like Carbon Film