JP2000185939A - Glass composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a glass of high specific modulus. SOLUTION: In the glass composition, the composition ranges of the main components are adjusted to the following: 35 wt.%<=SiO2<=60 wt.%, 10 wt.% <=Al2O3 <=30 wt.%, 8 wt.%<=MgO<=30-wt.%, 1 wt.% <=Nb2O5<=10 wt.%, 1 wt.%<=TiO2<=15 wt.%, and 1 wt.%<=ZnO<=15 wt.%.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a glass composition, particularly a glass composition suitable for crystallized glass. More specifically, it relates to the composition of a crystallized glass magnetic disk.

[0002]

2. Description of the Related Art Conventionally, as a substrate for a magnetic disk,
Aluminum substrates and glass substrates have been put to practical use.
Among them, a glass substrate has received the most attention because of its excellent surface smoothness and mechanical strength. As such a glass substrate, a chemically strengthened glass substrate in which the surface of the glass substrate is strengthened by ion exchange, and a crystallized glass substrate in which a crystal component is precipitated on the substrate to strengthen the bond are known.

[0003]

By the way, the recent demand for the performance of the substrate is becoming stricter day by day.
In particular, there is a demand for an improvement in performance with respect to strength directly related to deflection and warpage during high-speed rotation. This can be represented by the specific elastic modulus (= Young's modulus / specific gravity) of the substrate material, and the higher the numerical value, the more desirable. Therefore, an object of the present invention is to provide a composition in which the specific elastic modulus of glass is improved.

[0004]

Means for Solving the Problems In order to achieve the above object, the invention described in claim 1 provides a composition range of a main component,
SiO ₂ is 35 wt% or more and 60 wt% or less, A
l ₂ O ₃ is 10 wt% or more and 30 wt% or less, Mg
O is 8 wt% or more and 30 wt% or less, Nb ₂ O ₅ is 1 wt% or more and 10 wt% or less, TiO ₂ is 1 w
It is characterized in that the content is not less than t% and not more than 15 wt%, and the content of ZnO is not less than 1 wt% and not more than 15 wt%.

According to a second aspect of the present invention, there is provided a glass substrate obtained by melting and crystallizing the glass composition according to the first aspect, wherein a crystal phase precipitated is garnitite, cordierite, or the like. , Mullite.

[0006]

Embodiments of the present invention will be described below. In the glass substrate of the embodiment according to the present invention, the composition range of the main component is 35 wt% or more of SiO ₂ and 6
0 wt% or less, Al ₂ O ₃ is 10 wt% or more and 30 w
t% or less, MgO is 8 wt% or more and 30 wt% or less, Nb ₂ O ₅ is 1 wt% or more and 10 wt% or less, T
It is characterized in that iO ₂ is 1 wt% or more and 15 wt% or less, and ZnO is 1 wt% or more and 15 wt% or less.

[0007] SiO ₂ is a glass-forming oxide and is a constituent of crystals. If the composition ratio is less than 35% by weight, the meltability deteriorates. If the composition ratio exceeds 60% by weight, the glass becomes a stable state, so that it is difficult to precipitate crystals.

[0008] Al ₂ O ₃ is a glass intermediate oxide and is a component of the crystal. If the composition ratio is less than 10% by weight, the number of precipitated crystals is small and the strength cannot be obtained.

[0009] MgO plays a role as a flux and is a component of the crystal. If the composition ratio is less than 8 wt%, the number of precipitated crystals is small and strength cannot be obtained. If the composition ratio exceeds 30 wt%, the crystal phase is difficult to precipitate and the devitrification resistance deteriorates.

[0010] Nb ₂ O ₅ acts as a flux, improves the meltability and improves the strength. If the composition ratio is less than 1 wt%, no improvement in strength can be expected, and if it exceeds 10 wt%, the specific gravity increases and the specific elastic modulus decreases.

TiO ₂ is an important component acting as a nucleating agent and improves the strength. When the composition ratio is less than 1 wt%, the function as a nucleating agent cannot be expected, and the strength cannot be improved. When the composition ratio exceeds 15 wt%, the devitrification resistance deteriorates.

[0012] ZnO acts as a flux, improves the meltability, and is a component of the crystal. Composition ratio is 1wt%
If the amount is less than the above, melting becomes difficult, and if it exceeds 15% by weight, the devitrification resistance becomes poor.

The manufacturing method will be described below. Raw materials containing the composition of the main components of the finally produced glass substrate are thoroughly mixed at a predetermined ratio, and the mixture is put into a platinum crucible, and the mixture is mixed for about 155.
Melt at 0 degrees. After melting, it is poured into a mold to form a rough shape. This is annealed to room temperature. Subsequently, the temperature is maintained at the indicated primary heat treatment temperature and primary treatment time (heat treatment), and crystal nucleation is performed. Subsequently, the crystal nucleus is grown while maintaining the temperature at the secondary heat treatment and the secondary treatment time. By cooling this, the desired crystallized glass is obtained.

The glass substrate obtained by the above manufacturing method has a main component of SiO ₂ of 35% by weight or more and 60% by weight.
wt% or less, and in Al ₂ O ₃ is more than 10 wt% 30 wt
% Or less, MgO is 8 wt% or more and 30 wt% or less,
Nb ₂ O ₅ ≧ 1 wt% and ≦ 10 wt%, TiO
₂ is 1 wt% or more and 15 wt% or less, ZnO is 1 w
Since the content is set to not less than t% and not more than 15 wt%, it is possible to obtain a very high specific elastic modulus.

[0015]

Next, a specific example of the embodiment will be described. Material composition ratio (unit: wt%) constituting the glasses of the first to fourth embodiments, primary heat treatment temperature and primary treatment time, secondary heat treatment temperature and secondary treatment time, main precipitated crystal phase,
Table 1 shows the precipitated crystal phase, specific gravity, Young's modulus, and specific elastic modulus. Table 2 shows a comparative example with the same data as in Table 1.

[0016]

[Table 1]

[0017]

[Table 2]

The glass composition of the first embodiment is as follows: 39 wt% of SiO ₂ , 27 wt% of Al ₂ O _3, and 8.5 w of MgO.
t%, Nb ₂ O ₅ 5 wt%, ZnO 11 wt%, Ti
The composition ratio of O ₂ is 9 wt% and Sb ₂ O ₃ is 0.5 wt%.

The raw materials are prepared so as to have the above composition ratio, and the primary processing temperature is 800 ° C., the primary processing time is 2 hours, the secondary processing temperature is 1000 ° C., and the secondary processing time is 4 according to the above-mentioned manufacturing method.
As a result of the treatment with time, a glass substrate having a characteristic of a specific elastic modulus of 46.8 was obtained in which the main crystal phases were garnite, cordierite, and mullite.

The glass composition of the second embodiment is as follows: 49.4 wt% of SiO ₂ , 11.5 wt% of Al ₂ O ₃ , 25 wt% of MgO, ₂ wt% of Nb ₂ O ₅ , 1 wt% of ZnO,
The composition ratio of TiO ₂ is 11.1 wt%.

The raw materials are prepared so as to have the above composition ratio, and the primary processing temperature is 820 ° C., the primary processing time is 4 hours, the secondary processing temperature is 1000 ° C., and the secondary processing time is 2 in accordance with the above-mentioned manufacturing method.
As a result of the treatment over time, a glass substrate having a characteristic that the precipitated crystal phase was garnite and cordierite and the specific elastic modulus was 48.3 was obtained.

The glass composition of the third embodiment is as follows: 46% by weight of SiO ₂ , 15% by weight of Al ₂ O ₃ and 18% by weight of MgO.
%, 3 wt% of CaO, 4 wt% of Nb ₂ O ₅ , 1.2 wt% of ZnO, 12.3 wt% of TiO ₂ , and 0.5 wt% of Sb ₂ O ₃ .

The raw materials are prepared so as to have the above composition ratio, and the first processing temperature is 770 ° C., the first processing time is 2 hours, the second processing temperature is 1050 ° C., and the second processing time is 2 hours according to the above-mentioned manufacturing method. As a result of the treatment, a glass substrate was obtained in which the precipitated crystal phases were cordierite and garnite and the specific elastic modulus was 48.5.

The glass composition of the fourth embodiment is as follows: 56% by weight of SiO ₂ , 17% by weight of Al ₂ O ₃ , and 10% by weight of MgO.
%, Nb ₂ O ₅ at 7 wt%, ZnO at 2 wt%, TiO ₂
Is 8 wt%.

The raw materials are prepared so as to contain the above composition ratio, and the primary processing temperature is 780 ° C., the primary processing time is 4 hours, the secondary processing temperature is 970 ° C., and the secondary processing time is 4 according to the above-mentioned manufacturing method.
As a result of the treatment with time, a glass substrate having a characteristic that the precipitated crystal phase was garnet and mullite and the specific elastic modulus was 45.7 was obtained.

Next, a comparative example shown in Table 2 will be described. In Comparative Example 1, since Nb ₂ O ₅ was below the lower limit of the specified range, the amount of precipitated crystals was small and the specific elastic modulus was 4%.
Only 4.2 was obtained. In Comparative Example 2, Al ₂ O
₃ exceeds the upper limit of the specified range, so that the melting temperature becomes high, devitrification occurs, becomes non-uniform, and hardly crystallizes. In Comparative Example 3, since SiO ₂ exceeds the upper limit of the specified range, it is stable as glass, cannot be cast, and cannot be crystallized.

[0027]

According to the present invention, a glass substrate having a specific elastic modulus of 45 or more can be obtained.

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4G062 AA11 BB01 BB06 DA05 DA06 DB04 DC01 DD01 DE03 DE04 DF01 EA01 EB01 EC01 ED03 ED04 EE01 EF01 EG01 FA01 FB03 FB04 FC01 FD01 FE01 FF01 FG01 FG03 F01G01 F0101 HH01 HH03 HH05 HH07 HH09 HH11 HH13 HH15 HH17 HH20 JJ01 JJ03 JJ05 JJ07 JJ10 KK01 KK03 KK05 KK07 KK10 MM27 NN33 QQ06 QQ16 QQ20 5D006 CB04 CB07 DA03 FA00

Claims (2)

[Claims] 1. The composition range of a main component is as follows: SiO ₂ is 35 wt% or more and 60 wt% or less; Al ₂ O ₃ is 10 wt% or more and 30 wt% or less; MgO is 8 wt% or more and 30 wt% or less; A glass composition characterized in that ₂ O ₅ is 1 wt% or more and 10 wt% or less, TiO ₂ is 1 wt% or more and 15 wt% or less, and ZnO is 1 wt% or more and 15 wt% or less. 2. A glass substrate obtained by melting and crystallizing the glass composition according to claim 1, wherein a crystal phase precipitated is at least one of garnite, cordierite, and mullite. A glass substrate, characterized in that: