JPH03193640A - Crystallized glass - Google Patents

Abstract

PURPOSE:To form uniform crystallized glass having practically no pores, a low melting temp. and a high coefft. of thermal expansion after heat treatment and hardly causing devitrification by rendering a specified glass compsn. and depositing carnegieite and/or nepheline crystals by heat treatment. CONSTITUTION:Glass contg., by weight, 37.0-49.5% SiO2, 19.0-31.0% Al2O3, 0.2-8.0% B2O3, 18.0-29.0% Na2C, 3.0-13.0% MgO, 3.2-13.0% TiO2 and 1.0-4.0% ZrO2 is heat-treated. By this heat treatment, carnegieite and/or nepheline crystals are deposited and the title crystallized glass is formed.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to crystallized glass for a thin film magnetic head substrate used in a magnetic storage device, and in particular as a magnetic head substrate for OA, VTR, and audio equipment. Preferably used.

[Prior Art] In general, a 1ill magnetic head is made of magnetic WiI such as sendust, permalloy, amorphous metal, etc. on a non-magnetic substrate.
I! It is manufactured by vapor deposition, sputtering, etc. This non-magnetic substrate is hard, has excellent wear resistance, and has a coefficient of thermal expansion (α) of ioo~200X10.
Necessary conditions include -7/°C and substantially no pores.

In particular, the coefficient of thermal expansion is 100, which is close to that of the magnetic thin film.
A material as high as ~200X10'/'C is required. For example, Japanese Patent Publication No. 62-15495, Japanese Patent Publication No. 63-31
421, carnegiite (Na20-A12
03.2SiO2) and nepheline (Na20.Al2O
3.2SiO2) is precipitated, 118.8 to 188.9
It is disclosed that a crystallized glass having a coefficient of thermal expansion of x10-7/°C is obtained.

[Problems to be Solved by the Invention] However, the crystallized glass described in Japanese Patent Publication No. 62-15495 has the disadvantage that the melting temperature of the glass is as high as 1500° C. or higher because MaO is not included as a glass component. Furthermore, there is a drawback that the glass tends to devitrify and the precipitated crystals become non-uniform, making it difficult to obtain crystallized glass having a uniform coefficient of expansion. Also, the above-mentioned Special Publication Publication No. 63-31
In the crystallized glass described in Publication No. 421, there is no B2O3 as a component of the glass, and P205 is 2 to 22 as a nucleating agent.
Due to the large amount of P20 present in wt%, P20 is present during glass melting.
S volatilizes and the composition changes, and as a result, the glass tends to devitrify, the precipitated crystals become non-uniform, and it is difficult to obtain crystallized glass having a uniform coefficient of expansion.

Therefore, an object of the present invention is to have a low melting temperature for producing glass as a starting material, to prevent the glass from devitrification, to have a large thermal expansion coefficient after heat treatment, and to have a uniform thermal expansion coefficient. The present invention provides a crystallized glass having substantially no pores.

[Means for Solving the Problems] The present invention has been made to achieve the above object, and the crystallized glass of the present invention has a 5i02 of 37% by weight.
．． 0-49.5%, Al2O3 19.0-31.0%
, B2O3 is 0.2~8゜0%, Na2O is 18.0~
29.0%, MgO 3.0-13.0%, T i 0
2 is 3.2~13゜0%, ZrO2 is 1.0~4.0%
treatment of sulcalas containing carnegiite crystals and/or
Or, it is characterized by being formed by precipitating nepheline crystals.

Next, the reasons for limiting each component will be described.

5102 forms a glass skeleton and is a component of carnegiite crystal (Na20-A1203.2Si02) and/or nepheline crystal (Na20.A1203.2SiOz), and if this amount is less than 37゜Qwt%, the glass tends to devitrify. , which is not preferable because the amount of crystal precipitated m is reduced. Moreover, if the content exceeds 49.5 wt%, the glass becomes stable and the crystals become difficult to precipitate even after treatment, which is not preferable. Al2O3 is also a component of the crystal,
If this amount is less than 19.0 wt%, the crystals are difficult to precipitate, and if this amount exceeds 31.0 wt%, the glass tends to devitrify, which is not preferable. B203 is a component that forms a glass skeleton, and by including this B2O3, the glass before crystallization becomes less likely to devitrify. This sign is 012w
If it is less than t%, there is little effect in suppressing the stall, and this spread is 8.
．． When it exceeds Qwt%, the glass becomes stable and the crystals become difficult to precipitate even after treatment. Furthermore, B during glass melting
This is not preferable because it increases the volatilization of 2O3 and makes it difficult to obtain uniform crystal precipitation. Na2O is a component of the crystal,
It lowers the melting temperature of glass.

If this amount is less than is, %, the effect of lowering the melting temperature will be small, and the precipitation of the crystals will also be reduced, which is not preferable. Further, if the amount of this sludge exceeds 29.0 wt%, the chemical durability of the crystallized glass deteriorates, which is not preferable. Mg
o is a component that lowers the melting temperature of the glass and suppresses devitrification. If this amount is less than 3.0 wt%, the effect of lowering the melting temperature of the glass and suppressing devitrification will be small;
If it exceeds wt%, the crystals become difficult to precipitate, which is not preferable. T i 02 acts as a nucleating agent to precipitate the crystals, and if this amount is less than 3.2 wt%, it has little effect as a nucleating agent;
Exceeding this is not preferable because a large amount of TiO2 or crystals containing TiO2 will precipitate. ZrO2 also acts as a nucleating agent to precipitate the crystals.

If this amount is less than 1.0 wt%, the effect as a nucleating agent is low, and if this amount exceeds 4.0 wt%, the glass tends to devitrify, which is not preferable. T i 02 and ZrO2
Both act as nucleating agents, but uniform crystals are precipitated when the amounts of TiO2 and ZrO2 are about the same or when the amount of TiO2 is larger.

In addition, as other components, A is used as a defoaming agent for glass melt.
S203 and 5b203 can be added in an amount of 1.0 wt% or less. Even if the defoaming agent exceeds 1.0 wt%, the effectiveness as a defoaming agent does not change.

[Examples] Next, Examples of the present invention will be described, but the present invention is not limited to these Examples.

(Example 1) As raw materials, S io2, A I (OH)3, H2B
O3, MqCO3, Na2CO3, NaNO3, TiO
2. Using ZrO2 as raw material, SiO2 is 41, □wt%
, Al2O3 is 27.0wt%, B2O3 is 0.5wt
%, Na2O is 22.5wt%, MaO is 3.7wt%
, 3.7 wt% TiO2 and 1.6 wt% ZrO2 were adjusted and mixed so that the glass weight was 100q, placed in a platinum crucible, and melted at 1430°C for 4 hours. Thereafter, the glass melt was cast onto a steel plate at about 200°C. At this time, there was no devitrification of the glass. 60 in advance
The mixture was placed in an annealing furnace maintained at 0°C and cooled to a greenhouse to obtain glass as a starting material.

No crystals were present in the resulting glass.

The characteristics of this glass are determined by the Japan Optical Glass Industry Association standard JOGTS.
-1975, the glass transition point (
TO> was 605°C, yield point (Ts) was 695°C, thermal expansion coefficient (α) was 1o9xio'/°C, and specific gravity was 2.57.

This starting material glass was cut into a size of about 30 x 301M and heat treated in an electric furnace to crystallize it. The crystallization schedule is 2 from room temperature to 600℃.
The temperature is increased at 50℃/h, and from 600℃ to 1050℃ it is 9
The temperature was raised at 0°C/h, held at 1050°C for 1.5 hours, and then cooled to room temperature at 180°C/h.

When a part of the obtained crystallized glass was crushed and the precipitated crystals were examined by X-ray diffraction, it was found that carnegiite (Na20-A
1203・2S1o2) and neferine (Na2C1Δ
1203.2S102) was confirmed to be precipitated.

In addition, the characteristics of the obtained crystallized glass were measured based on the Japan Optical Glass Industry Association standard JOG [S-1975].
Thermal expansion coefficient (α) is 137X10-7/℃, Knoop hardness (Hk) is 520 Kg TrLTrL2, specific gravity (S
, G,) was 2.63. These values were consistent within the error range everywhere in the crystallized glass. Further, this crystallized glass had substantially no pores.

From this, the crystallized glass of this example has a low melting temperature for producing the glass as its starting material, no devitrification, and a thermal expansion coefficient of 130xlO-7/°C after heat treatment.
There were virtually no pores.

(Examples 2 to 4) Instead of holding glass with the same composition as in Example 1 at 1050°C for 1.5 hours in the crystallization step (heat treatment),
00°C (Example 2), 1000°C (Example 3), 110
The sample held at 0° C. (Example 4) for 1.5 hours was crystallized (heat treated) in the same manner as in Example 1.

Carnegiite and nepheline were precipitated in the obtained crystallized glass. The characteristics were measured in the same manner as in Example 1. The results are shown in Table 1 together with Example 1. These values were consistent within the error range everywhere in the crystallized glass.

From this result, the crystallized glass of Examples 2 to 4 has a low melting temperature for producing the glass that is the starting material,
There was no devitrification, the coefficient of thermal expansion 7 after heat treatment was 139x10 to 147x10-7/''C, and there were substantially no pores.

Roughly speaking, the crystallized glass of Examples 1 to 4 has a thermal expansion coefficient that changes depending on the crystallization temperature, and in particular, the crystallization temperature is i oo
It had a minimum value between o and 1100°C.

(Examples 5 to 20) AS203 and 5b203 were added to the raw materials of Example 1.
A crystallized glass was obtained in the same manner as in Example 1, except that the glass composition and the holding temperature for crystallization were varied. In the obtained crystallized glass, carnegiite and/or nepheline were precipitated. Then, the characteristics were measured in the same manner as in Example 1. Table 1 shows these glass compositions and measurement results. These values were consistent within the error range everywhere in the crystallized glass.

From this result, the crystallized glass of Examples 5 to 20 has a low melting temperature for producing the glass as the starting material, no devitrification, and a thermal expansion coefficient of 135X10 to 158X10-7 after heat treatment. 'C, and there were virtually no pores.

(Comparative Example 1) Using the same raw materials as in Example 1, SiO2 was 40.5
wt%, Al2O3 is 29.5wt%, Na20 is 22
．． 2vt%, TiO+ 1.8wt%, ZrO2 1,
8vt%, ZnO is 4.2wt%, glass weight is 100
Adjust and mix so that it is 14g, put it in a platinum crucible,
Although the glass was melted at 30° C. for 4 hours, a uniform glass melt was not obtained.

(Comparative Example 2) Using the same raw materials and NaPO3 as in Example 1, Si
02 is 39.7wt%, Al2O3 is 23.5wt%,
MgO is 3.6wt%, Na2O is 23.0wt%, T
i 02 Ka3, 7wt%, P20s Ka6.5w
A glass serving as a starting material was prepared in the same manner as in Example 1 so that the starting material was t%. There were no crystals in the resulting glass.

This glass was heat-treated in the same manner as in Comparative Example 1 by holding it at 900° C. for 1.5 hours. The obtained crystallized glass was broken because the precipitated crystals were non-uniform.

(Margins below) Table 1 (Continued) [Effects of the Invention] As detailed above, the crystallized glass of the present invention has a low melting temperature, no devitrification, and does not require heat treatment to produce the glass that is its starting material. The resulting crystallized glass has a large and uniform coefficient of thermal expansion and is substantially free of pores.

In particular, the crystallized glass of the present invention can be preferably used as a substrate for a thin film magnetic head, since an appropriate coefficient of thermal expansion and hardness can be easily selected.

Claims (1)

[Claims] In weight%, SiO_2 is 37.0-49.5%, Al_
2O_3 is 19.0-31.0%, B_2O_3 is 0.
2-8.0%, Na_2O 18.0-29.0%, M
gO is 3.0-13.0%, TiO_2 is 3.2-13
．． 1.0% ZrO_2 and 1.0 to 4.0% ZrO_2 is treated to precipitate carnegiite crystals and/or nepheline crystals.