JP3148783B2 - Method for evaluating tribological characteristics of magnetic recording media - 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 recording medium for evaluating the tribological characteristics of a magnetic recording medium when information is recorded on the magnetic recording medium or reproduced from the magnetic recording medium by a floating magnetic head. The present invention relates to a method for evaluating tribological characteristics of a recording medium.

[0002]

2. Description of the Related Art For example, in a hard disk drive which is a mainstream of an external storage device of a large-sized computer to a notebook-type personal computer, a magnetic head for recording / reproducing information from / on a disk as a magnetic recording medium is usually a floating type. A magnetic head is used. The operating method of this floating magnetic head is such that when the apparatus is started / stopped, the head slider of the magnetic head is in contact with the disk, and when the apparatus is started up to a rotation speed of not less than a predetermined value, the head is actuated by airflow. This is a so-called CSS (Contact Start Stop) method in which the slider gradually rises.

[0003] In principle, the CSS system cannot avoid intermittent or complete contact sliding of both the head slider and the disk when the apparatus is started or stopped, so that various tribological phenomena derived therefrom are caused. At present, the reliability of the apparatus has been significantly impaired.
Among them, a particularly worrisome problem is that a frictional force generated in a contact sliding state between a head slider and a disk (hereinafter, referred to as HDI) causes mechanical abrasion damage to the disk side and causes magnetic layer damage. "Head crash phenomenon", which destroys itself, and the head slider and the disk, both of which have been subjected to ultra-precision machining with a center line average roughness of several nanometers to several tens of nanometers, are attracted and the spindle that rotates the disk "Stiction phenomenon" which makes it difficult to start up.

[0004] These tribological phenomena which hinder the normal functioning of the hard disk drive are accurately evaluated, and the HDI
The determination of tribological characteristics in the above is an essential elemental technology in the development of a magnetic recording medium and a magnetic head slider. Among them, the mechanical durability of magnetic recording media is positioned as the most important factor that affects the reliability of the device, so there are several methods, such as the CSS test, which is a test method that is closest to the actual use of the device. Such durability evaluation methods have been proposed so far.

Here, a method of evaluating the durability of a magnetic recording medium that has been proposed so far will be briefly summarized.

[0006] The tribological phenomenon that occurs in HDI is as follows.
It is thought that the magnetic recording medium may cause a head crash in the worst case through several processes in stages. That is, the frictional force generated by the HDI increases for some reason, and the frictional force reaches a state sufficient to damage the surface of the magnetic recording medium. It is supposed that the increase in the frictional force is caused by, for example, depletion of the lubricant applied on the surface of the magnetic recording medium.

Therefore, in a conventional tribological evaluation test of a magnetic recording medium, the point is how to monitor the change in the surface state until the occurrence of abrasion damage, and the change in the state is considered to be accurately reflected. The emphasis has been on evaluating the "frictional force" over the test time.

The evaluation of the frictional force is, for example, compared with a method of directly monitoring a change on the surface of a magnetic recording medium by an ellipsometer or the like (see J. Appl. Phys. 70 (10), 15 November, (1991) 5647). However, it is very simple, and the frictional force in HDI is detected by a load cell or a strain gauge attached to the head attachment portion, and a normal value is applied to the head slider (hereinafter referred to as a head load). ) Is used as an index to determine whether tribological characteristics are good or bad (IEEE Trans. Magn. Vol. 24, No. 6, November, (1988) 2638).
A typical example is a so-called CSS durability test.

In the CSS durability test, a pattern in which a head slider is floated on a magnetic recording medium, the state is maintained for a certain period of time, and then the head slider is landed on the magnetic recording medium is repeatedly performed. The coefficient of friction for each number was examined by the above method, and the point at which scratches that could be visually confirmed on the magnetic recording medium began to occur, that is, the number of CSS tests where the coefficient of friction exceeded 1.0 was referred to as the CSS durability number. Is what you do.

[0010] A drag test has been proposed in which the head slider does not take off and land as in the CSS test, but is continuously slid in contact with the magnetic recording medium. This is basically the same as the above-mentioned CSS test in that the friction coefficient is monitored every time.

[0011]

The above-described conventional method for evaluating tribological characteristics of a magnetic recording medium, in particular, CS
The S test intentionally creates a state that is closest to the actual use of the magnetic recording device, and compared to the actual service life of the magnetic recording device itself that is guaranteed when the magnetic recording device is mounted on a computer and functions. Although it is a test that the durability of a magnetic recording medium can be predicted in a relatively short time,
Each had the following problems.

That is, the time required for the head slider to take off and land for one CSS test is about several tens of seconds, and it is necessary to perform the standard number of tests (up to several hundred thousand). Approximately 2 weeks of test time is required.
This can be said to be a very short time compared to the useful life of the magnetic recording device, but is not necessarily short from the viewpoint of the efficiency of research and development of the magnetic recording medium, and further reduction in the test time is desired.

[0013] In addition, higher durability is required at the same time as higher recording density, higher speed access, and downsizing of the magnetic recording medium. Therefore, the number of tests must be set higher. Further, in order for the head slider to completely float above the magnetic recording medium, it is necessary to rotate the disk at a high speed of about several thousand rpm. It is difficult to accelerate the disk to the rotation speed region in a short time. Therefore, the current CSS test cannot shorten the time required for one CSS operation, and it is practically difficult to improve the test efficiency.

As described above, it can be said that the friction coefficient obtained from the current evaluation method reflects the result of the change in the surface state of the magnetic recording medium or the head slider in its absolute value. However, it is practically impossible to derive original information such as what kind of phenomenon actually occurred in HDI from only the parameters based on only the change in the friction coefficient. It is also conceivable that tribological phenomena that cannot be caught by parameters alone are also induced during CSS operation. Therefore, there has been a demand for a parameter capable of evaluating the surface state in HDI, which is assumed to have changed with the number of tests, with higher sensitivity and in real time.

The present invention has been made in view of the above background, and provides a method for evaluating the tribological characteristics of a magnetic recording medium, which is capable of predicting the tribological characteristics of the magnetic recording medium in a very short time and more sensitively. It is intended for that purpose.

[0016]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, a method for evaluating tribological characteristics according to the present invention uses a floating magnetic head to record information on a magnetic recording medium or information recorded on a magnetic recording medium. A method for evaluating the tribological characteristics of a magnetic recording medium in the case of performing reproduction of a magnetic recording medium, wherein a relative movement between a magnetic recording medium and a test piece composed of the floating magnetic head or a floating body identical or similar to the flying magnetic head is started. Thereafter, the relative movement speed is gradually increased to perform a levitating start operation for levitating the test body on the magnetic recording medium, or gradually from the state in which the test body levitates on the magnetic recording medium. Performing a levitation traveling stop operation of reducing the relative movement speed and stopping the levitation traveling operation, and at the time of the levitation traveling start operation, the test specimen is Determine the friction energy expressed by the product of the average value of the frictional force and the contact sliding distance that occurs when the test specimen and the magnetic recording medium are in contact sliding until the levitation travel is performed, or At the time of the levitating stop operation, the relative moving speed is reduced from a state in which the test body is levitating, and the levitating travel of the test body is released, so that the test body and the magnetic recording medium come into contact with each other. The frictional energy expressed as the product of the average value of the frictional force generated between the test piece and the magnetic recording medium and the contact sliding distance from the time of moving to the stop of the relative movement was determined. The tribological characteristic of the magnetic recording medium is evaluated based on one or both of the friction energies.

[0017]

In the above configuration, the friction energy is
It was confirmed that it had an extremely high correlation with tribological characteristics such as the number of times of durability in a conventional CSS durability test. Therefore, it is possible to determine the tribological properties such as durability in a very short time without performing a long-term test such as the CSS durability test.
In addition, it has been confirmed that the degree of the friction energy that changes depending on the change in the surface state (tribological characteristics) of the magnetic recording medium is larger than other physical quantities such as a friction coefficient. It is possible to sensitively detect a change in tribological characteristics due to abrasion damage of the medium or the like.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The schematic structure of this embodiment is that the relative movement speed is gradually increased after the relative movement of the magnetic head slider and the magnetic disk as the magnetic recording medium is started, and the magnetic head slider is caused to fly above the magnetic disk. Levitation start operation (hereinafter referred to as CSS start operation)
The average frictional force generated between the magnetic head slider and the magnetic disk during the contact sliding travel period from the start of the relative movement to the time when the magnetic head slider flies above the magnetic disk during the SS start operation. The value FA and the distance L of the contact sliding travel during the contact sliding travel period are obtained, and the friction energy E (= F
A · L) is obtained, and the tribological characteristics of the magnetic disk are evaluated based on the value of the friction energy E. Hereinafter, first, an apparatus for performing the method of the present embodiment will be described, and then, the method of the present embodiment will be described.

2 to 4, a magnetic disk 1 as a magnetic recording medium is provided with a disk rotating spindle 3a of a rotating device 3 provided in a disk friction / wear tester.
The disk 3 is rotated by driving a motor 3c having the disk rotation spindle 3a as a rotation axis.

On the magnetic disk 1, a magnetic head slider 2 is arranged. The magnetic head slider 2 has a suspension 4 made of an elastic member.
The suspension 4 is fixed to a mounting table 5b provided at a distal end of the head mount 5 via a mounting member 4a mounted to a base end of the suspension 4. The head mount 5 is provided with an arm 5c formed of an elastic member at the tip of a main body 5a capable of adjusting the position in the horizontal direction and the vertical direction, and the mounting base 5b is fixed to the tip of the arm 5c. It is a thing. In this case, the suspension 4 is fixed to the head mount 5 such that its longitudinal direction is substantially perpendicular to the longitudinal direction of the arm 5c.

A strain gauge 6 is attached to an intermediate portion of the arm 5c of the head mount 5, and an output of the strain gauge 6 is sent to a personal computer 9 through a strain amplifier 7 and an A / D converter 8. It has become.

In the configuration described above, the magnetic head slider 2 applies an appropriate pressing force (head load) by the elastic force of the suspension 4 when the spindle 3a is stopped.
Contacting the surface of the magnetic disk 1 with the spindle 3
a, the contact sliding travel continues on the magnetic disk 1 until the rotation speed reaches a predetermined rotation speed, and between the magnetic head slider 2 and the magnetic disk 1 when the rotation speed reaches the predetermined rotation speed. When the levitation travel is performed by the action of the generated airflow, and when the spindle 3a is stopped, the rotation speed of the spindle 3a starts to decrease, and when the rotation speed reaches a predetermined rotation speed, the levitation travel state shifts to the contact sliding travel state. And stop.

The strain gauge 6 detects a rotational force acting on the magnetic head slider 2. That is, when the magnetic head slider 2 is in sliding contact with the magnetic disk 1, the frictional action between the magnetic head slider 2 and the magnetic disk 1 causes the magnetic head slider 2 to move.
The frictional force acting in the rotation direction of the magnetic disk 1 acts on the magnetic disk 1.
Accordingly, the arm 5c of the head mount 5 is deformed according to the frictional force. Since the strain gauge 6 outputs a voltage signal corresponding to the deformation, the friction force can be measured by measuring the voltage signal.

In this embodiment, at the time of the CSS start operation, the frictional force at each time point in the short contact sliding traveling period of about several tens of seconds is accurately obtained to obtain the average value FA of the frictional force. It is necessary to determine the sliding travel distance L. Therefore, after the voltage signal (analog signal) transmitted from the strain gauge 6 is amplified by the strain amplifier 7, it is digitized by the A / D converter 8, and the sampling interval Δt
(If the measurement time is t and the number of samples is n, △ t
= T / n) according to the voltage V (i) (i = 1 to n)
Is incorporated in the personal computer 9. In addition, the force applied to the head slider 2
The relationship with the voltage output from the strain gauge 6 through the strain amplifier 7 is calibrated in advance, and the friction force F at each observation time is calculated from the observed voltage value according to the calibration curve.
(I) (i = 1−n) is calculated.

Using this system, the change of the frictional force F (i) (i = 1-n) with respect to the disk rotation time t during the contact sliding period at the time of starting the CSS is shown in FIG.
As a result, a frictional force measurement curve (also referred to as a slider levitation curve) shown by a solid line is obtained.

When this frictional force measurement curve is divided into three regions A, B, and C as shown in FIG. 1, the following is obtained. That is, in the area A, the frictional force gradually increases with the start of disk rotation, but in this area A, the buoyancy applied to the head slider 2 is not sufficient, and the head slider 2 and the magnetic disk 1 are almost completely brought into contact with each other. Becomes Next, after the frictional force reaches a maximum value at a certain position, in the region B, the frictional force decreases with the disk rotation time. This is because the head slider 2 gradually rises to the HD.
This indicates that the contact sliding at I is alleviated, and the frictional force is apparently reduced. And the dick rotation time is t _T (Ta
(ke-Off Time), the peripheral speed becomes sufficient for the head slider 2 to completely fly above the magnetic disk 1,
In the area C thereafter, the frictional force becomes almost zero.

The fact that the frictional force does not become completely zero after the head slider 2 floats is a force that the head slider 2 or the suspension 4 fixing the head slider 2 receives by the action of the air flow induced by the rotation of the disk.
This is not the frictional force associated with DI sliding contact. Therefore, H
The tribological characteristics between DIs are mainly reflected in the areas of A and B in this frictional force measurement curve, that is, HD.
It is presumed that I is a region in which contact sliding occurs. Here, it is considered that the tribological characteristics are reflected on some physical quantities. Ideally, if all the physical quantities can be observed, the complete tribological characteristics can be known. However, actually, the observable physical quantities are limited. In this embodiment, a frictional energy E, which is a physical quantity represented by a product of two physical quantities of an average value FA of a frictional force, which is a physical quantity observable in the areas A and B, and a distance L on which the frictional force acts, is obtained. In this way, the tribological characteristics reflected on the two physical quantities are evaluated. Hereinafter, FA, L and E are calculated by the above-described system.
A method for obtaining the following will be described.

First, the contact sliding distance L can be expressed by the following equation (1).

L = 0.5 · at · _{T T} ² (1) a: Disk rotational acceleration t _T : Take-Off Time In the above equation (1), the disk rotational acceleration a is the spindle 3a of the rotating device 3. By observing the rotation of. Also, Take-Off Time t
_T can be determined as the time required from the start of disk rotation until the head slider 2 completely floats.

However, as shown by the solid line in FIG.
Friction force measured curve, since the weak variation of the frictional force is directly reflected, there is a fine zigzag, it is difficult to determine the t _T accurately. Therefore, in this embodiment, a frictional force smoothing curve f (i) as shown by a dotted line in FIG. 1 is obtained from the measured frictional force curve by using the moving average method described below, and its time derivative df / dt is the point where the 0 to employ a method of defining and t _T.

In the moving average method, a frictional force measurement curve is assumed to be composed of n discrete values F (i), and N
"Weight function" w consisting of (= 2m + 1) discrete points
(J) (where j = -m, ...,-1,0,1, ...,
This is a method of calculating a smoothed value f (i) from the following equations (2) and (3) by applying m).

[0032]

(Equation 1) For w (j) in the above equations (2) and (3), an optimal distribution function is used for smoothing according to the observed waveform, including a rectangular function. Here, w (j) is used. )
= 1 is used.

In practice, f at each sampling point i
Time derivative of (i) {f (i) −f (i + 1)} / △
examined t, obtains locate the f (i) in which the value becomes 0 from the data, a multiplied by the sampling time △ t to the sampling number n _T at that time as t _T. Once t _T is determined, the contact sliding distance L can be determined by substituting this into the above equation (1).

Next, the average frictional force FA is determined. First, the area Acontact (shown by oblique lines) drawn by the frictional force smoothing curves in the regions A and B in FIG. 1 is calculated based on the following equation (4). Next, the obtained Acontact is also used in the following (5).
As shown in equation Dividing the sampling number n _T where the disk rotation time becomes t _T. As a result, the average frictional force FA is obtained.

[0035]

(Equation 2) From the contact sliding distance L and the average frictional force FA calculated by the above method, the friction energy E is calculated by the following equation (6).

E = FA · L (6) Next, a description will be given of the result of obtaining the friction energy of a plurality of magnetic disks having different tribological characteristics from each other by the above-described method.

First, a magnetic disk used for the measurement was manufactured as follows.

That is, as shown in the partial cross-sectional view of FIG.
After forming the iP plating layer 14 to a thickness of 20 μm by an electroless plating method, a concentric mechanical texture 15 was applied to the NiP layer 14 using a wrapping tape. At that time, a SiC abrasive grain type (GC # 3000, average abrasive grain size:
5 μm) using a wrapping tape and rotating the disk sample attached to the texturing device at a rotation speed of 20 μm.
Texture processing was performed at 0 rpm, a tape feed speed of 50 cm / min, and a tape pressure of 1.0 kgf / cm ² . The surface irregularities produced by this texturing were 5 nm in RMS (root mean square roughness).
Then, on the NiP layer on which the mechanical texture 15 has been applied, Cr is 100 nm as an underlayer 16, and CoNiCr is 50 nm on the underlayer 16 as a magnetic layer 17.
Then, carbon was laminated as a protective layer 18 on the magnetic layer 17 by sputtering to a thickness of 10 nm. At the time of sputtering these layers, argon gas having a purity of 99.9% was used as an atmosphere gas, gas pressure: 5 mTorr (gas flow rate, Ar: 10 SCCM), input power: 100 W, back pressure: 10 ^-7 Torr, and no substrate heating. The film formation is performed under the following conditions. Further, a lubricating layer 19 is formed on the protective layer 18, and is formed of PEPE (Fomblin) as a lubricant.
AM2001), and HCFC (AK-225 made by Asahi Glass) was used as the solvent, and the average film thickness was 2 nm by a dipping method.

The magnetic disk manufactured by the above process was used as a disk.

The RMS of the texture in FIG.
A magnetic disk produced in the same manner as the magnetic disk except that was changed to 7 nm was used as a disk.

The RMS of the texture in FIG.
A magnetic disk produced in the same manner as the disk except that the thickness was changed to 9 nm was used as a disk.

The RMS of the texture in FIG.
A magnetic disk produced in the same manner as the disk except that the thickness was changed to 11 nm was used as a disk.

The RMS of the texture in FIG.
A magnetic disk produced in the same manner as the disk except that was set to 13 nm was used as a disk.

Then, the RM of the texture in FIG.
A magnetic disk produced in the same manner as the disk except that S was set to 15 nm was used as a disk.

Next, FIG. 6 shows the average frictional force FA and the contact sliding distance L obtained by using the above-mentioned system for the magnetic disks 1 to 6 thus prepared.

As is apparent from FIG.
There is no significant difference in the average frictional force FA between the two, but there is a tendency to noticeably increase the contact sliding distance L as the RMS value increases. It is presumed that this is because, as the variation in the height of the surface irregularities increases, the floating of the slider is not stabilized during the CSS operation, and as a result, the contact sliding distance L is increased. From this result, it can be seen that the friction energy also increases substantially with the increase of the RMS value in proportion to the contact sliding distance L.

On the other hand, FIG. 7 is a graph showing the coefficient of friction at each CSS count when a CSS endurance test was carried out on the above-mentioned disks through the conventional method. FIG. It is the table | surface which showed the CSS durability number obtained by the test. As is clear from FIG. 7, as the RMS value of the texture increases, the coefficient of friction with respect to the number of CSSs increases remarkably, and as is clear from FIG. It can be seen that it decreases.
This is presumably because the RMS value was increased, that is, the unevenness of the surface unevenness became remarkable, so that the load applied to each projection was increased and the magnetic disk was likely to be damaged. In this CSS test, the magnetic disk 1 was clamped by the clamp 3b at a tightening torque of 1.5 kgfcm using the apparatus shown in FIG.
After mounting the head slider 2 on the air bearing surface (A
The head slider 2 is mounted on the magnetic disk 1 such that the center of the end of the magnetic disk 1 on the BS side (BS surface) is 17.5 mm from the center of the magnetic disk 1, and a CSS as shown in FIG. This is based on the pattern. In this case, the friction coefficient μ at each CSS count was obtained by holding the head slider on the magnetic disk for about 30 seconds, rotating the magnetic disk three times at 1 rpm, calculating the arithmetic average of the frictional force during the rotation, and then calculating the head load. Indicates the value obtained by dividing the arithmetic average value. The head used for this measurement is an IBM 3370 type in-line head, the head load is 6.5 gf, and the material of the head slider is Al ₂ O ₃ —TiC. This measurement was performed in a clean room with a cleanliness of 100.
At that time, the room temperature was 24 ° C., and the humidity was 40% RH. H.

FIG. 10 is a graph showing the relationship between the endurance frequency NE obtained by the conventional CSS endurance test and the friction energy E obtained by the method of this embodiment. As is apparent from FIG. 10, the frictional energy decreases monotonously with the increase in the number of times of CSS durability, and it is understood that there is an extremely high correlation between the two. Therefore, even if a long-term durability test such as the CSS durability test is not performed, only the friction energy E in the initial state before the durability test is examined, and the CSS
It is possible to obtain information about durability equivalent to the information obtained in the durability test. This makes it possible to predict the durability of the medium in a very short time, that is, to know one of the tribological characteristics.

FIGS. 11 to 16 show a change in the friction coefficient μ and the friction energy E in each of the CSS tests by performing a CSS endurance test on the magnetic disk ₁ and 2 (each data shows CSS: friction coefficient μ ₁ and the frictional energy E ₁ is a graph showing the results of measuring the relationship is normalized). In this case, the conditions in the CSS durability test and the measurement conditions of the friction coefficient and the friction energy are the same as those in the previous case.

As is clear from FIGS. 11 to 16,
In any of the magnetic disks to, the number of tests is C
Until the SS endurance is reached, the change in the friction energy is more remarkable than the coefficient of friction, indicating that the latter is more sensitive to the change in the surface state of the magnetic disk than the former. This is because the friction energy takes into account two physical quantities of frictional force and contact sliding distance, which are physical quantities that reflect tribological properties, while the friction coefficient takes into account one of the physical quantities that reflect tribological properties. This is presumed to be because the former is evaluating the tribological phenomenon in HDI from a more diversified viewpoint.

In the above-described embodiment, during the CSS start operation, the head slider and the magnetic disk are moved from the start of the relative movement between the magnetic disk and the head slider to the time the head slider runs on the magnetic disk. Although an example of obtaining the friction energy expressed as the product of the average value of the frictional force generated when contact sliding and the contact sliding distance is raised, this is from the state where the test piece is floating and running. The test is performed during a period from the time when the floating movement of the test body is released due to the decrease of the relative movement speed and the slide movement of the test body and the magnetic recording medium is brought into contact until the relative movement stops (CSS end operation period). Even if the frictional energy expressed as the product of the average value of the frictional force generated when the body and the magnetic recording medium slide in contact with each other and the contact sliding distance can be obtained, almost the same results can be obtained. It has been certified.

In the above embodiment, the weighting function w (j) having a rectangular distribution is used in the moving average method for obtaining the frictional force smoothing curve from the frictional force measurement curve.
In order to calculate a more optimal smoothing curve, for example, another weighting function calculated by a polynomial fitting method may be used.

In the above-described embodiment, the contact sliding distance is calculated by calculating the disk rotation time at which the time differential coefficient df / dt of the smoothing curve becomes zero. More accurate Take-Off according to the force measurement curve
Of course, other methods such as a frequency domain method may be used to calculate Time.

[0054]

As described above in detail, the present invention provides a CSS
The frictional energy expressed as the product of the average value of the frictional force generated when the test piece and the magnetic recording medium slide in contact with each other in the start operation or the end operation and the contact slide distance are obtained, and the magnetic energy is calculated by the friction energy. It is designed to evaluate the tribological properties of the medium, and this friction energy is
Very good agreement with conventional CSS endurance test results, so that it is possible to judge the superiority of tribological characteristics in a very short time without performing a long-time test as in the past, so that the evaluation efficiency of the media is dramatically increased. It has made it possible to improve it. Further, by combining the CSS test and the present friction energy evaluation, it is possible to detect the change in the surface state of the medium more sensitively than the conventional evaluation of only the friction coefficient.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of a frictional force measurement curve.

FIG. 2 is a diagram showing a configuration of an apparatus for obtaining friction energy.

FIG. 3 is a partial side view of the rotating device.

FIG. 4 is a perspective view of a magnetic head slider.

FIG. 5 is a partial sectional view of a magnetic disk.

FIG. 6 is a diagram showing a measurement result of an average frictional force and a contact sliding distance from a disk.

FIG. 7 is a diagram showing a measurement result of a change in a coefficient of friction with respect to a disk or the number of CSSs.

FIG. 8 is a diagram showing a measurement result of a disk or CSS endurance count.

FIG. 9 is an explanatory diagram of a CSS pattern.

FIG. 10 is a graph showing a relationship between the number of times of endurance NE obtained by a conventional CSS endurance test and the friction energy E obtained by the method of this embodiment.

FIG. 11 is a graph showing the results of performing a CSS durability test on a magnetic disk and actually measuring the relationship between the friction coefficient μ and the rate of change of friction energy E at each CSS test.

FIG. 12 is a graph showing the results obtained by performing a CSS durability test on a magnetic disk and actually measuring the relationship between the coefficient of friction μ and the rate of change of friction energy E at each CSS test.

FIG. 13 is a graph showing the results obtained by performing a CSS durability test on a magnetic disk and actually measuring the relationship between the friction coefficient μ and the rate of change of friction energy E at each CSS test.

FIG. 14 is a graph showing the results obtained by performing a CSS durability test on a magnetic disk and actually measuring the relationship between the coefficient of friction μ and the rate of change of friction energy E at each CSS test.

FIG. 15 is a graph showing the results obtained by performing a CSS durability test on a magnetic disk and actually measuring the relationship between the friction coefficient μ and the rate of change of friction energy E at each CSS test.

FIG. 16 is a graph showing the results obtained by performing a CSS durability test on a magnetic disk and actually measuring the relationship between the coefficient of friction μ and the rate of change of friction energy E at each CSS test.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Magnetic disk, 2 ... Magnetic head slider, 3 ... Rotating device, 3a ... Spindle, 3b ... Clamp, 4 ... Suspension, 5 ... Head mount, 6 ... Strain gauge, 7 ...
Strain amplifier, 8 ... A / D converter, 9 ... Personal computer.

Claims (1)

(57) [Claims] 1. A method for evaluating tribological characteristics of a magnetic recording medium when information is recorded on a magnetic recording medium by a flying magnetic head or when information recorded on the magnetic recording medium is reproduced. The relative movement speed is gradually increased after the relative movement of the magnetic recording medium and the test body composed of the floating magnetic body or the same or similar floating traveling body, and the test body is levitated on the magnetic recording medium. Performing a levitation start operation, or performing a levitation stop operation to gradually reduce the relative movement speed and stop from a state in which the test object is levitation traveling on the magnetic recording medium, When the test specimen and the magnetic recording medium are in sliding contact with each other from the start of the relative movement to the time when the test specimen floats on the magnetic recording medium. The frictional energy represented by the product of the average value of the frictional force and the contact sliding distance to be obtained, or the relative movement speed is determined from the state in which the test body is levitating during the levitating stop operation. It is generated between the test specimen and the magnetic recording medium from the time when the floating movement of the test specimen is released and the test specimen and the magnetic recording medium come into contact with each other until the relative movement stops. The magnetic energy is obtained by calculating the friction energy expressed as the product of the average value of the frictional force and the contact sliding distance, and evaluating the tribological characteristics of the magnetic recording medium by using one of these friction energies or both friction energies. A method for evaluating tribological characteristics of a recording medium.