JPH05246763A - Ceramic sintered compact - Google Patents

Abstract

PURPOSE:To provide a ceramic sintered compact having slidability, wear resistance, high heat conductivity, excellent machinability and such electrical properties as low specific resistance and low triboelectric chargeability and suitable for use as a substrate material for a magnetic head. CONSTITUTION:This ceramic sintered compact is a dense sintered compact having <=2mum average grain size and contg. 10-75wt.% alpha-SiC, 20-70wt.% one or more kinds of compds. selected among the carbides and borides of Ti, Zr and Nb and 5-20wt.% Al2O3 and/or Y2O3.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ceramic sintered body, and more particularly to a ceramic sintered body suitable for a substrate material for a thin film magnetic head which is excellent in 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. A 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 rides on an air laminar flow generated by high speed rotation of a magnetic disk. It has a function of writing / reading a record to / from a magnetic disk by utilizing the fact that it slightly floats above the surface of the magnetic disk. Therefore, the slider does not obtain a sufficient air laminar flow when starting and stopping the rotation of the magnetic disk, so that the slider always slides on the magnetic disk to perform a so-called CSS 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 things, 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. Further, 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 Japanese Patent Application No. 163665, in order to make this magnetic head with high productivity, the slider constituent material has a machinability, that is, a small cutting resistance at the time of machining and a cutting force. It is important that the blade is not clogged or cracked or chipped.

As a conventional slider material, Al2O3 series ceramics are widely known from the viewpoint of good formability of thin film elements, and many proposals for improvement have been made. For example, JP-A-61-158
862, JP-A-60-231308, JP-A-60-18
3709, JP-A-60-179923 and the like, and slider materials containing ZrO2 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.

[0006]

[Problems to be Solved by the Invention] However, the above A
The slider made of l2O3-TiC has excellent machinability and wear resistance, but when processing a slider with a high precision and complicated shape, it has less cracks and chippings, which reduces the processing yield, resulting in more fracture toughness and sliding characteristics. It is strongly desired to improve

Further, a slider whose main component is ZrO2 is Al2
It has better sliding properties than O3-TiC, but is said to be inferior in 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.

As a result of earnest research on the above problems, the present invention is one method of improving the toughness of a ceramic material in order to improve the machinability of a substrate for a thin film magnetic head, but it is slidable and resistant. It was found that excellent machinability can be obtained by combining a specific material composition having good wearability and having a fine fracture toughness even if the fracture toughness is small.

[0009]

The present invention has been made to solve the above-mentioned problems, and provides a substrate material for a thin film magnetic head suitable as a ceramics sintered body, particularly as a slider.

That is, in the present invention, 1 to 10% to 75% by weight of (1) α-SiC (2) Ti, Zr, Nb is selected from carbides or borides.
Provided is a ceramic sintered body characterized by containing 20 to 70% of one or more kinds (3) 5 to 20% of one or more kinds selected from Al2O3 and Y2O3.

In the present invention, α-SiC, which is excellent in sliding characteristics, wear resistance, high strength and high thermal conductivity, is used as one main constituent phase, and Ti, Zr, A substrate suitable for a magnetic head, which is composed of a uniform and fine-grained sintered body in which one or more kinds of Nb carbide and boride are dispersed as another main constituent phase and which has excellent sliding characteristics, wear resistance, and machinability. The material can be obtained.

The sintered body of the present invention is basically composed of three components. (1) The first component is α silicon carbide.
(2) The second component is one or more selected from carbides or borides of Ti, Zr, Nb, and (3) the third component is Al2O3,
It is one or more selected from Y2O3.

The sintered body of the present invention preferably comprises only these three kinds of components, but may contain a small amount of other components as long as the objects and effects of the present invention are not impaired. Further, even if it is composed essentially of these three kinds of components, for example, unavoidable impurities mixed in during the powder mixing process of the raw material powder may be contained.

The proportion of each of these components as a sintered body is 10 to 75% in (1) and 20 to 70 in (2) in terms of weight% (hereinafter the same).
%, (3) is 5-20%, preferably (1) is 25-
60%, (2) 30-60%, (3) 10-15%.

The first component, silicon carbide, is preferably α-SiC, and α-SiC containing β-SiC is not preferable for obtaining a fine crystal structure of the present sintered body. Α-Si as a raw material
C is as pure as possible, preferably 99% or more, and finely divided, preferably having an average particle size of 1 μm or less, more preferably 0.5 μm or less.

The second component Ti, Zr, Nb carbides and borides serve to impart conductivity and antistatic properties, and the raw material powder thereof has a purity of 99% or more and an average particle size of 1 μm. It is preferably 0.5 μm or less. Second component Ti, Z
The content of carbides and borides of r and Nb is 20 to 70% by weight for fine crystal structure and conductivity. If it is 20% or less, the conductivity is insufficient, and if it is 70% or more, it is sintered. It is difficult to do so, and it is preferably 30 to 60%.

The third component of the present invention functions as an auxiliary agent for accelerating the sintering of the present sintered body, and particularly functions to control the crystal of α-SiC in the sintered body to a fine structure. Has a purity of 99% or more and an average particle size of 1 μm or less, especially
Those having a thickness of 0.5 μm or less are preferably used. The third component, Al2O3 and Y2O3, is useful in 5 to 20% in the sintered body. If it is less than 5%, it has no effect on the promotion of sintering, and if it is added in 20% or more, abnormal grain growth occurs locally. However, it is not possible to obtain a fine and uniform crystal structure.
~ 15%.

The present invention has a fine crystal structure in which α-SiC is the main constituent phase and Ti, Zr, Nb carbides and borides are uniformly dispersed in the structure as the other main constituent phase. The sintered body of the present invention preferably has an average crystal grain size of 2 μm or less, more preferably 1 μm or less, from the viewpoint of precision machinability. If the average crystal grain size is larger than 2 μm, chipping tends to occur during machining, and the smoothness and surface roughness of the machined surface are reduced, which is not preferable.

The sintered body of the present invention has the above constitution,
In order to produce the ceramics of the present invention, α-
It is effective to mix SiC powder with at least one of Ti, Zr, Nb carbides and borides and at least one selected from Al2O3 and Y2O3 at a predetermined ratio, and further finely crush the mixture. Is. That is, these raw material mixtures can be pulverized by using SiC balls until the particle size becomes 1 μm or less, preferably 0.5 μm or less.

The sintered body of the present invention can be obtained, for example, by filling the mixture in a graphite mold and hot pressing in a vacuum or a non-oxidizing atmosphere such as Ar. In addition, a small amount of binder is added to the above-mentioned mixed powder, and the mixture is granulated by a spray dryer, and the granulated product is molded by CIP.
The same effect can be obtained by (sinter-HIP) or capsule HIP (encapsulated in a capsule). The firing temperature is 1800
〜2200 ℃, and the firing time is usually 0.5 to 5 hours.

[0021]

As described above, the sintered body of the present invention has a fine α-SiC crystal structure excellent in slidability, wear resistance, high thermal conductivity, and high strength, which is a conductive carbide of Ti, Zr, Nb. A sintered body in which a boride is uniformly dispersed and which has an appropriate fracture toughness due to the introduction of residual stress caused by α-SiC and a difference in thermal expansion between them, and as a magnetic head substrate by the interaction of these. It is considered that it has particularly excellent machinability, and that it also exhibits excellent characteristics such as sliding characteristics as a magnetic head, abrasion resistance, heat dissipation, and triboelectrification.

[0022]

EXAMPLES The present invention will be further described with reference to examples. Α-SiC powder as raw material (purity 99% or more, average particle size 0.3μ
m), Ti, Zr, Nb nitride, or boride powder (purity 99%, average particle size 1 μm or less) and A as an auxiliary agent.
L2O3 powder (purity 99.9%, average particle size 0.5 μm) and Y2O3 powder (purity 99.9%, average particle size 0.5 μm) were crushed at a predetermined ratio in a SiC ball using an ethanol solvent in a ball mill for 24 hours. The mixed powder was dried with an evaporator and lightly crushed.

This powder was filled in a graphite mold of hot press and the pressure was 350 kg / cm 2 and the temperature was 1800 to 2200 ° C., respectively.
Hot pressed in Ar atmosphere for 1 hour, 60 mm φ × 5 mm
A sintered body having a thickness was obtained.

As the physical properties of the sintered body, the density was measured by the Archimedes method and divided by the theoretical density 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 (S
It was measured by the ingle Edge Pre-cracked Beam method). That is, a sample compliant with JIS R 1601 was prepared, and after applying an indentation by Vickers indenter pressurization, a load was applied to create a pre-crack and a 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 incision using a resinoite grindstone with a diameter of 0.28 mm and a diameter of 52 mm (a cutter with a diamond abrasive grain of 30 μm)
The feed rate was 5 mm / sec. Chipping depth is 2 μm
If it does not exceed, it does not substantially affect the slider quality and maintains satisfactory quality.
△ in case of exceeding μm and × in case of remarkable chipping
As shown.

The slidability and wear resistance were evaluated by a CSS test in which a 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 slidability was determined by the CSS test of the disk and the head, and the coefficient of friction was indicated by ◯ when the coefficient of friction was less than 0.5, by Δ when the coefficient of friction was greater than 0.5, and by x when the coefficient of friction was significantly large.

The wear resistance was evaluated by repeating the CSS test 10,000 times and checking for scratches on the rubbing surface of the magnetic head slider. As a comparative example, Al2O3-TiC 30% substrate and Y2O3 5.2 wt
% ZrO2-TiC 30% partially stabilized substrates were used for comparison. The respective results are shown in Tables 1 and 2.

[0029]

[Table 1]

[0030]

[Table 2]

The sintered bodies of Examples 1 to 14 were dense and had no pores, and average crystal grains in which fine crystals of carbides of Ti, Zr, Nb and boride were uniformly dispersed in the fine α-SiC structure. Diameter is 0.7 ~
It has a structure of 1.5 μm and has a low specific resistance.
Although the fracture toughness was not high, the machinability of the magnetic head slider was evaluated, and no cracking or chipping occurred at all, and the machinability was good. In addition, the sliding property and the wear resistance were excellent.

[0032]

EFFECTS OF THE INVENTION The sintered body of the present invention is used as a slider for a thin-film magnetic head, and has conductivity and moderateness in a fine α-SiC crystal structure excellent in slidability, wear resistance, high thermal conductivity and high strength. One or more of Ti, Zr, Nb carbides and borides are uniformly dispersed in order to impart toughness and densified with a fine crystal structure. Sliding property, wear resistance, especially machining It has excellent technical advantages, a small specific resistance, and a small triboelectrification property.

Since the sintered body of the present invention is excellent in heat resistance, oxidation resistance, corrosion resistance, chemical resistance, etc. in addition to the characteristics shown in Tables 1 and 2, it is used as an electrical member, a precision machine member, a corrosion resistant member, etc. Can also be used.

Claims (3)

[Claims] (1) 10% to 75% (1) α-SiC in weight% (2) 1 selected from carbides or borides of Ti, Zr, Nb
20 to 70% of one or more kinds (3) A ceramic sintered body characterized by containing 5 to 20% of one or more kinds selected from Al2O3 and Y2O3. 2. The method according to claim 1, wherein the component (1) is 25 to 60.
%, (2) component is 30 to 60%, and (3) component is 10 to 15%. 3. The sintered body according to claim 1, wherein the average crystal grain size of each component is 2 μm or less.