JPH05213674A - Ceramic material - Google Patents

Abstract

PURPOSE:To obtain a ceramic material suitable for use as a substrate material for a magnetic head and having slidability, wear resistance, high toughness, high heat conductivity, excellent machinability and such electrical properties as low specific resistance and low triboelectric chargeability. CONSTITUTION:This ceramic material contains 3-40wt.% silicon carbide particles in the base consisting of 25-60wt.% TiN and the balance beta-Si3N4 or beta-sialon.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ceramic material, and more particularly to a substrate ceramic material suitable for a thin film magnetic head having excellent durability and wear resistance.

[0002]

2. Description of the Related Art In recent years, magnetic heads, especially thin-film magnetic heads, are rapidly becoming popular in order to meet the increasing demand for higher recording and higher density in the field of magnetic disk devices. The thin-film magnetic head has a structure in which a thin-film element for recording and reproducing magnetic signals is formed on the rear end surface of a ceramic slider that serves as a substrate, and the slider is driven by a high-speed rotation (20-40 m / s) of a magnetic disk. It has a function of writing and reading data on and from the magnetic disk by utilizing the fact that it slightly floats above the surface of the magnetic disk (0.2 to 4 μm) by riding on the generated air laminar flow.

Therefore, the slider cannot obtain a sufficient air laminar flow when starting and stopping the rotation of the magnetic disk.
It always slides on the magnetic disk to perform so-called CSS (contact start stop) operation. Further, even if the slider is flying normally, it is inevitable that the flying height and the flying posture are disturbed by external factors such as vibrations and the intervention of dust. The flying height is becoming smaller in order to increase the recording density, and such disturbance causes the slider to collide with the magnetic disk rotating at a high speed more and more times.

From these points, it is important to improve the slidability of the slider of the magnetic head in order to improve the CSS performance. Furthermore, it is essential that the surface of the slider is smooth, has no pores, and has good wear resistance.

The magnetic head is frictionally charged when it comes into contact with and slides on the magnetic disk as described above. If the charge amount becomes excessively large, noise may occur in the magnetic transducer signal winding, and the flying height of the magnetic head may change. Therefore, it is desirable to configure the slider of the magnetic head with a material that does not cause frictional charging as much as possible.

A magnetic head slider is disclosed, for example, in JP-A-55.
Although it has an extremely complicated structure as shown in 163665, in order to make this magnetic head with high productivity, the slider constituent material is machinable, that is, the cutting resistance at the time of processing is small, and the cutting blade. It is important that there be no clogging and that neither cracks nor chipping occur.

As a conventional slider material, Al ₂ O ₃ based ceramics are widely known from the viewpoint of good formability of a thin film element, and there are many proposals for improvement. For example, JP-A-61-158
862, JP-A-60-231308, JP-A-60-18
3709, JP-A-60-179923, and slider materials containing ZrO ₂ as a main component are disclosed, for example, in JP-A-60-171617 and JP-A-63-278312.
As shown in JP-A-60-66404, improvement of sliding characteristics and wear resistance is attempted.

[0008]

[Problems to be Solved by the Invention] However, the above A
A slider made of l ₂ O ₃ -TiC has excellent machinability and wear resistance, but when processing a slider with a high precision and complicated shape, it does not have many cracks and chippings, which reduces the processing yield, resulting in higher fracture toughness, There is a strong demand for improvement in sliding characteristics.

A slider containing ZrO ₂ as a main component is Al ₂
Compared to O ₃ -TiC, it has better sliding characteristics, but is said to have poor wear resistance and machinability. As described above, various slider materials have been proposed, but there is a strong demand for a material having excellent sliding properties, wear resistance, and fracture toughness and excellent machinability.

[0010]

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems and provides a substrate material for a thin film magnetic head, which is suitable as a ceramic material, particularly as a slider. That is, the present invention is essentially
25-60% TiN and balance β-Si ₃ N ₄ and / or β-
A ceramic material containing sialon as a main component and further containing silicon carbide particles having a size of 5 to 20 μm and / or plate-like silicon carbide particles having a maximum diameter of 5 to 50 μm and a thickness of 1/3 or less of the maximum diameter. Is provided.

A preferred embodiment of the present invention is such that the content of silicon carbide particles in the material which is a sintered body is 3% by weight (hereinafter the same).
40%, and another preferable embodiment is the use as a substrate material for a magnetic head. That is, the present invention is lubricity,
For imparting conductivity with β-Si ₃ N ₄ and / or β-sialon, which are excellent in wear resistance, high strength and high toughness, as the main constituent phase
It is a ceramic material composed of a sintered body in which TiN and silicon carbide particles having excellent characteristics of high toughness are dispersed, particularly a substrate material for a thin film magnetic head.

The definition of the silicon carbide particles preferably used in the present invention will be explained with reference to FIG. First, spherical granular particles
5 to 20 μm, and the silicon carbide particles of the slightly long granular particles 1 have a minor axis diameter (distance d when sandwiched between two parallel lines to be the minimum distance) as shown in FIG. 1 (a). Defined as 20 μm. Further, the plate-like silicon carbide particles 1 are also preferable in the present invention, and when explained based on FIG. 1 (b), the maximum diameter φ 5 to 50 μm indicates the size of the particles and the thickness t is 1/3 or less of the maximum diameter. Is defined as

The plate-shaped silicon carbide particles can be obtained by single-crystallizing a mixture of SiO ₂ and carbon by the Acheson method for a sufficient time. In the present invention, the main components are (1) TiN and (2) β-Si ₃ N ₄ and / or β-sialon, which will be described below.

In the present invention, TiN which is the main component is preferably 25 to 60% in the sintered body, which is necessary for imparting conductivity, and when (2) the component is β-Si ₃ N ₄ . Is necessary for the formation of fine columnar crystals of β-Si ₃ N ₄ and toughness. If it is less than 25%, the electrical conductivity is insufficient and 60%.
This is because if it is above, it is difficult to sinter and the toughness cannot be sufficiently exhibited. Desirably, TiN is 30 to 50%.

Next, β-Si ₃ N ₄ or β-sialon which is the component (2) will be described. In general, the preferable content of these components in the sintered body is the component (1). The relationship between TiN and the silicon carbide (SiC) particles as the component (3) is 20 to 60%, preferably 30 to 50%.

[0016] First As the raw material leads to β-Si ₃ N ₄ used in the present invention is appropriate to use a fine powder of α-Si ₃ N _4, as the α-Si ₃ N ₄ raw material powder thereof 5 in
~ 40 vol% β-Si ₃ N ₄ may be included, preferably
It is 5 to 20% by volume. This is from α to β at 40 volume% or more
The formation of fine columnar crystals due to the transformation to γ is low, high strength and high toughness are not obtained, and β-Si ₃ N ₄ content of 5% by volume or less
The reason is that α-Si ₃ N ₄ containing α cannot be produced, and 5 to 40% by volume produces a fine columnar crystal phase associated with the transformation from α to β, so that high strength and high toughness can be obtained. is there. It is suitable that the raw material has a purity as high as possible, preferably 99% or more and fine, preferably an average particle size of 5 μm or less, particularly 1 μm or less.

TiN, which also gives the TiN phase, has a purity of 99
% Or more and average particle size 5 μm or less, especially 1 μm or less is preferable. Further, as a raw material for producing the β-sialon phase used in the present invention, a mixture mainly containing fine powder of α-Si ₃ N ₄ , AlN, Al ₂ O ₃ or the like is usually suitable. It is appropriate that these raw materials have a purity as high as possible, preferably 99% or more and fine, preferably an average particle diameter of 5 μm or less, particularly 1 μm or less. Similarly, the TiN that produces the TiN phase should have a purity of 99% or more and an average particle size of 5 μm or less, particularly 1 μm or less.

In the present invention, one of the present sintered bodies is composed of a β-sialon phase and a TiN phase as main components, and the β-sialon in this case has the above-mentioned α-sialon. This is easily possible by appropriately selecting the compounding ratio of Si ₃ N ₄ , AlN, and Al ₂ O ₃ . For example α-Si ₃ N
₄ , the amount ratio of AlN and Al ₂ O ₃ is preferably 2: 1: 1, and preferably the amount ratio of 2: 1.5: 1 with slightly increased AlN is strength,
A material with excellent fracture toughness can be obtained.

In the sintered body of the present invention, sialon (Si-Al-O-
The reason why N) is preferably β-sialon is α-
Sialon (Si, Al of Si-Al-ON part of Y, Ca, Mg,
This is because the strength and fracture toughness are higher than those obtained by solid solution of Li, La, etc.).
It is considered that α-sialon easily forms a liquid phase.

In order to obtain the sintered body of the present invention, as a main ingredient, a raw material which provides TiN which is the component (1) and β-sialon or β-Si ₃ N ₄ which is the component (2) is used as the main component. (3) Silicon carbide particles having a size of 5 to 20 μm as a component are added so as to be 3 to 40%, preferably 10 to 30% to form a mixed powder, and the maximum diameter is preferably 5 to 50 μm.
It is desirable to form a mixed powder by adding plate-like silicon carbide particles having a thickness of 10 to 40 μm and 1/3 or less of the maximum diameter so as to be 3 to 40%, preferably 10 to 30%.

If the size and amount of silicon carbide particles are smaller than 5 μm, the effect of improving fracture toughness is not recognized, and if it is larger than 20 μm, the density of the obtained ceramic sintered body is low and densification cannot be achieved. .. If the size and addition amount of the plate-shaped silicon carbide particles are smaller than 5 μm, the effect of fracture toughness is not recognized, and if it is larger than 50 μm, the density of the ceramics sintered body is low and it is not densified. 10-40 μm is desirable.

If the amount of silicon carbide particles or plate-shaped silicon carbide particles added is less than 3%, the effect of fracture toughness is not sufficiently recognized, and if it is used as a substrate for a thin film magnetic head, the abrasion resistance required therefor is rather a little. Will be inferior. On the other hand, if it exceeds 40%, the density of the obtained ceramic sintered body is low and sufficient densification cannot be achieved.

In addition to these components, the present invention uses MgO, Al ₂ O ₃ , Mg as a sintering aid especially when the component (2) is Si ₃ N _4.
One or more of O.Al ₂ O ₃ and Y ₂ O ₃ is β-Si ₃ N ₄ ,
It is useful to add 1 to 10% of the total amount of TiN and silicon carbide particles or plate-shaped silicon carbide particles, and it is possible to improve the high strength and high toughness of the properties of the sintered body. Limiting the amount of sintering aid to 1-10% is not effective in promoting sintering if it is 1% or less, and if it is added 10% or more, local grain growth occurs and a fine and uniform structure can be obtained. This is because it cannot be done, and it is preferably set to 2 to 8%. In the present invention, components other than these components may be contained to the extent that the characteristics of the sintered body of the present invention are not impaired, of course, but it is desirable to keep the amount as small as possible.

Although the present invention has the above-mentioned constitution, in order to produce the sintered body of the present invention, the mixed powder formed by these constituents is thoroughly mixed and dried, and the mixture is filled in a graphite mold. However, a sintered body can be obtained by using hot pressing in a vacuum or in a neutral reducing atmosphere. Also, a small amount of binder is added to the above-mentioned mixed powder and granulated by a spray dryer, and the granulated product is subjected to CIP molding, and pressureless sintering or pre-firing HIP (si) in a vacuum or non-oxidizing atmosphere.
nyter HIP) and capsule HIP (encapsulated in capsule)
Even if the same effect is obtained. This hot press and HI
When P is used, the firing temperature is 1600-1800 ℃ and the firing time is 0.5
~ 2 hours is appropriate.

[0025]

In the present invention, the substrate composed of β-Si ₃ N ₄ -TiN-specific particles of silicon carbide particles has an α-Si ₃ N ₄ content of α-Si ₃ N ₄ during sintering.
-Si ₃ N ₄ is transformed to β-Si ₃ N ₄ to form a fine columnar crystal phase with a high aspect ratio, and conductive Ti is contained in the structure.
A structure in which N is uniformly dispersed, and β-sialon-Ti
The substrate composed of N-specific particles of silicon carbide particles is a structure in which conductive TiN is uniformly dispersed in the structure of β-sialon having high lubricity, high strength, and high toughness. It has a structure in which long rod-shaped silicon carbide particles or plate-shaped silicon carbide particles having a high aspect ratio are uniformly dispersed in the structure. It is considered that these structures significantly prevent cracks in all directions and significantly improve fracture toughness.

By using the present invention as a substrate material for a thin-film magnetic head, it is rich in lubricity, has high strength and high toughness, and has high thermal conductivity. Therefore, it has good machinability and sliding characteristics, and has good heat dissipation and sliding friction. It is considered that it is possible to obtain a material having excellent abrasion resistance and a low specific resistance, and thus having excellent triboelectricity.

[0027]

EXAMPLES The present invention will be described below based on examples.

(Examples 1 to 19) As a raw material, α-Si ₃ N _{4 was used.}
(Α-Si ₃ N ₄ contains 10% by volume of β-Si ₃ N ₄ ) powder (purity 99 wt%, average particle size 0.5 μm), TiN powder (purity
99 wt%, average particle size 1 μm, silicon carbide powder (purity 99.9
wt% size 5 to 20 μm) or plate-like silicon carbide particles (purity 99 wt% maximum diameter 5 to 50 μm thickness 1/3 of maximum diameter)
Powder) and Al ₂ O ₃ powder as auxiliary agent (purity 99.9 wt
%, Average particle size 0.5 μm), Y ₂ O ₃ powder (purity 99.9 wt%,
Average particle size 0.5 μm), MgO powder (purity 99 wt% average particle size 1 μm), MgO · Al ₂ O ₃ powder (purity 99 wt% average particle size 1 μm)
m) was blended at a predetermined ratio and mixed for 2 hours with a nylon ball using an ethanol solvent in a ball mill. This mixed powder was dried with an evaporator to extract ethanol. The dry powder was crushed and passed through a sieve having a sieve mesh size of 150 μm to obtain a molding powder.

This powder was filled in a hot pressing graphite mold, and the pressure was 350 kg / cm ^{2 at a} temperature of 1600 to 1800 ° C., and hot pressing was performed for 1 hour in a nitrogen atmosphere.
A sintered body of m 2 was obtained.

As the physical properties of the sintered body, the density was measured by the Archimedes method and the theoretical density was divided to obtain the relative density, and the bending strength was measured according to JIS R 1601 "Bending test method for fine ceramics". The fracture toughness is SEPB method (Si
ngle Edge Pre-cracked Beam method). I.e.
A sample conforming to JIS R 1601 was prepared, and after applying an indentation by Vickers indenter pressurization, a load was applied to create a precrack and a pop-in (Pop-in) was detected with an earphone. Subsequently, coloring was performed to measure the precrack length, and a bending test was performed to measure the breaking load. After measuring the pre-crack length of the fractured sample, the fracture toughness was calculated by the fracture toughness calculation formula.

The Vickers hardness was measured by a Vickers hardness meter with a load of 300 g using a mirror-polished surface of a bending test piece. The specific resistance was measured by a 4-terminal method using a bending test piece. 60 mmφ × thickness 5 manufactured by the same method as above
The magnetic head slider was evaluated using a sintered body of mm 2.

The obtained sintered body was mirror-polished, cut with a diamond cutting grindstone, and fine chipping at the corners was observed with a microscope. This chipping test is wide
0.3 mm feed amount with 0.28 mm and 52 mm diameter resinoite grindstone (cutter with 30 μm diamond abrasive grains)
It was carried out at 5 mm / sec. When the chipping depth does not exceed 2 μm, the slider quality is not substantially affected and the satisfactory quality is maintained, and this is indicated by ○, and when it exceeds 2 μm, it is indicated by △ and marked chipping is indicated by ×. It was

The rubbing and abrasion resistance were evaluated by a CSS test in which the sintered body was cut into the shape of an actual thin film magnetic head and brought into contact with a magnetic disk to rotate the disk. The rubbing property was shown by ◯ when the friction coefficient was determined by the CSS test of the disk and the head, and when the friction coefficient was less than 0.5, it was shown by Δ, and when it was significantly large, by x.

The wear resistance was evaluated by repeating CSS trials 10,000 times and checking for scratches on the rubbing surface of the magnetic head slider. As a comparative example, Al ₂ O ₃ -TiC 30% substrate and Y ₂ O ₃ 5.2 wt
% ZrO ₂ -TiC 30% partially stabilized substrate was used for comparison. The respective results are shown in Tables 1 and 2.

[0035]

[Table 1]

[0036]

[Table 2]

As shown in Tables 1 and 2, according to the present invention, the density is high, the specific resistance is low, the hardness and the bending strength are high, and the fracture toughness is 2.3 to 3 times that of the Al ₂ O ₃ --TiC 30% substrate. ZrO ₂ -TiC 3
It is 1.2 to 1.6 times higher than that of the 0% substrate, and in the evaluation as a magnetic head slider, there are few pores on the surface when mirror-polished, and it is densified. Other than 19 are the best sliders with excellent wear resistance.

Further, the thermal conductivity is as high as 0.12 cal / cm.sec..degree. C. (Example 15), the frictional heat generated by sliding with the magnetic recording medium can be quickly dissipated, and the thermal shock resistance is also high. Therefore, a highly reliable thin film magnetic head can be obtained without causing a thermal change even if repeated thermal cycles are applied.

(Examples 21 to 39) α-Si ₃ N ₄ as a raw material
(Α-Si ₃ N ₄ contains 10% by volume of β-Si ₃ N ₄ ) powder (purity 99 wt% average particle size 0.5 μm), AlN powder (purity
99 wt% average particle size 1 μm), Al ₂ O ₃ powder (purity 99.9 wt
% Average particle size 0.5 μm), TiN powder (purity 99 wt% average particle size 1 μm) and silicon carbide powder (purity 99.9 wt% size 5
~ 20 μm) or plate-like silicon carbide particles (purity 99 wt% maximum diameter 5 to 50 μm thickness is 1/3 or less of the maximum diameter) are mixed in a predetermined ratio, and nylon balls are used in an ethanol solvent in a ball mill. Mixed for hours. This mixed powder was dried with an evaporator to extract ethanol. The dry powder was crushed and passed through a sieve having a sieve mesh size of 150 μm to obtain a molding powder.

This powder was filled in a hot pressing graphite mold and hot pressed at a pressure of 350 kg / cm ^{2 in a} nitrogen atmosphere at 1600 to 1800 ° C. for 1 hour to obtain a sintered body of 60 mmφ × 5 mm. The physical properties of the sintered body were measured by the same methods as described above, and the results are shown in Tables 3, 4, and 5.

[0041]

[Table 3]

[0042]

[Table 4]

[0043]

[Table 5]

As shown in Tables 3, 4, and 5, the present invention has a high density, a small specific resistance, a high hardness, a high bending strength, and a high fracture toughness as compared with the Al ₂ O ₃ --TiC 30% substrate. Double, ZrO ₂
-TiC is 30% higher than that of the substrate, and when evaluated as a magnetic head slider, pores on the surface when mirror-polished were hardly observed, and it was densified. Except for 39, it is the best slider as it has excellent wear resistance.

The thermal conductivity is 0.08 cal / cm · sec · ° C. (Example 3
6), the frictional heat generated by sliding with the magnetic recording medium can be quickly radiated, and the thermal shock resistance is also high, so no thermal change occurs even if repeated thermal cycles are applied, and reliability is high. It is possible to obtain a thin film magnetic head with high efficiency.

[0046]

INDUSTRIAL APPLICABILITY The present invention is a ceramic material suitable as a substrate for a thin film magnetic head, and is excellent in slidability, high strength, high toughness, high thermal conductivity and low resistance β-Si ₃ N ₄ or β-.
It consists of sialon and TiN as the main phase, and specific silicon carbide particles as a toughness-reinforcing material are dispersed uniformly in the structure. It has wear resistance and mechanical workability against sliding friction with the magnetic recording medium. It has the technical advantages of excellent heat dissipation and triboelectrification.

Since the sintered body of the present invention is excellent in heat resistance, magnetization resistance, corrosion resistance and chemical resistance in addition to the characteristics shown in Tables 1 to 5, it is used as a heat resistant structural member, electric member, precision machine member, corrosion resistant member and the like. Can also be used.

[Brief description of drawings]

FIG. 1 is an explanatory diagram that defines the dimensions of silicon carbide particles and plate-shaped silicon carbide particles in a material of the present invention.

[Explanation of symbols] 1 Silicon carbide particles

Claims (6)

[Claims] 1. A sintered body comprising (1) TiN (2) β-Si ₃ N ₄
And / or (3) a ceramic material containing β-sialon as a main component and (3) silicon carbide particles. 2. The silicon carbide particles according to claim 1, wherein the number of silicon carbide particles is 3 to 40.
A ceramic material that is% by weight. 3. The size of the silicon carbide particles in the billing port 2 is
Ceramic material in the form of granules of 5 to 20 μm or a plate with a maximum diameter of 5 to 50 μm and a thickness of 1/3 or less of the maximum diameter. 4. The TiN as the component (1) according to claim 1, 2 or 3, wherein 25% to 60% by weight in the sintered body.
Is a ceramic material. 5. The β-Si ₃ N ₄ and / or β-sialon which is the component (2) in any one of claims 1, 2, ₃ and ₄ is 20 to 60% by weight in the sintered body. Ceramic material. 6. The ceramic material according to claim 4, wherein the sintered body is a substrate for a thin film magnetic head.