JP2759763B2 - Cordierite-based crystallized glass and method for producing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a high-strength material requiring heat resistance and impact resistance, and various materials requiring fine processing and precision processing, for example, electronic component materials, substrate materials for magnetic disks, The present invention relates to a crystallized glass suitable for use as a material for machine parts and the like, and a method for producing the same.

[0002]

2. Description of the Related Art Conventionally, cordierite-based crystallized glass has been known to be composed of SiO ₂ —Al ₂ O ₃ —Mg containing a crystal nucleating agent.
Various types are known which are obtained by melting and heat treating raw glass based on an O-based composition. These crystallized glass materials generally contain cordierite-based crystals (Mg ₂ Al ₄ Si ₅ O ₁₈ ) as a main crystal phase. Advanced characteristics are required. Precipitated crystals are fine and have excellent precision processing, precision polishing characteristics and mechanical strength. When Na ₂ O and K ₂ O components are contained in the material, these ions are diffused in various processing steps during use, and the characteristics are changed, so that the Na ₂ O and K ₂ O components are substantially contained. Do not contain. The raw glass is easy to be melted and refined, so that it does not contain striae, bubbles and foreign matter (inclusion) in the material, and has a high degree of optical homogeneity. The crystallization temperature of the raw glass is low and the mass production is excellent.

The above-mentioned conventional cordierite-based crystallized glass is disclosed, for example, in Japanese Patent Application Laid-Open No. 55-37496.
Discloses a SiO ₂ containing a TiO ₂ component as a nucleating agent.
A crystallized glass in which La ₂ O ₃ , Pr ₂ O ₃ , and Nd ₂ O ₃ are contained in an —Al ₂ O ₃ —MgO-based glass is disclosed. Also, U.S. Pat. No. 4,304,603 and JP-Sho _{33-7543, SiO 2 -Al 2 O 3} -MgO based glass containing TiO ₂ component as a nucleating agent is disclosed. Further, Japanese Patent Application Laid-Open No. 63-112439 discloses a SiO ₂ containing a TiO ₂ .ZrO ₂ component as a nucleating agent.
₂ -Al ₂ O ₃ -MgO based glass is disclosed. However, all of the crystallized glasses in these publications require a high melting temperature of about 1520 ° C. to 1650 ° C., and it is difficult to obtain raw glass having excellent homogeneity. In addition, the crystallization temperature requires a high temperature of about 1100 ° C. to 1345 ° C., which has a drawback that mass production is difficult, and at the same time, precipitation of coarse crystals due to high temperature crystallization is inevitable.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to satisfy the above-mentioned demands, improve the drawbacks of the prior art, and further improve the melting properties and low-temperature crystallization characteristics of the raw glass. An object of the present invention is to provide a cordierite-based crystallized glass.

[0005]

The present invention SUMMARY OF] The intensive test results in order to achieve the above object, the SiO ₂ -Al ₂ O ₃ -MgO KeiHara glass where the TiO ₂ component and nucleating agent, Z
An nO component is an essential component, and B ₂ O ₃ , BaO, CaO, S
By introducing rO, the melting temperature of the raw glass is remarkably lowered, and the heat treatment conditions for crystallization can be lowered, and the crystal grains are found to be fine and excellent in compactness. Was.

The crystallized glass of the present invention is characterized in that, by weight percentage, SiO ₂ 38% to 50%, Al ₂ O ₃ 18% to
30%, MgO 10% to 20%, by weight ratio,
Al ₂ O ₃ /MgO=1.2 to 2.3, B ₂ O ₃ 0% to 5
%, CaO 0% to 5%, BaO 0% to 5%, SrO
0% to 5%, ZnO 0.5% to 7.5%, TiO _{2
4% ~15%, ZrO 2 0} % ~5%, As 2 O 3 and / or _{Sb 2 O 3 0% ~2%} , to melt the raw glass having the composition of, after forming, obtained by heat treatment The main crystal is a cordierite crystal.
The composition of the crystallized glass of the present invention can be expressed on an oxide basis similarly to the original glass, but the reason for limiting the composition range of the original glass as described above will be described.

The SiO ₂ component is formed by heat treatment of the raw glass.
Cordierite (Mg ₂ Al ₄ Si ₅ O ₁₈ ) as main crystal
Although it is a very important component that forms a system crystal, if the amount is less than 38%, the precipitated crystals of the crystallized glass obtained will be unstable, and if it exceeds 50%, it will be difficult to melt the raw glass. Preferably, it is in the range of 42% to 47%. The Al ₂ O ₃ component is a very important component that generates cordierite (Mg ₂ Al ₄ Si ₅ O ₁₈ ) -based crystal as a main crystal by heat treatment of the raw glass. At the same time as precipitation becomes difficult,
The melting of the raw glass becomes difficult. On the other hand, if it exceeds 30%, the meltability becomes difficult, and the devitrification resistance also deteriorates. Preferably, the content is in the range of 22% to 27%.

[0008] The MgO component is a very important component that generates cordierite (Mg ₂ Al ₄ Si ₅ O ₁₈ ) -based crystals as main crystals by heat treatment of the raw glass. At the same time as precipitation becomes difficult,
The melting of the raw glass becomes difficult. On the other hand, if it exceeds 20%, precipitation of the above crystals becomes difficult, and the devitrification resistance also deteriorates. However, the weight ratio between the Al ₂ O ₃ and MgO components needs to be in the range of 1.2 to 2.3 in order to obtain a desired crystal. If the weight ratio is less than 1.2, it is difficult to obtain a desired crystal. On the other hand, when the ratio exceeds 2.3, melting of the raw glass becomes difficult. The TiO ₂ component is indispensable as a nucleating agent, but if the amount is less than 4%, desired crystals cannot be formed, and if it exceeds 15%, the devitrification resistance is deteriorated. Preferably, it is in the range of 8% to 12%.

The ZrO ₂ component is effective as a nucleating agent, but if its amount exceeds 5%, the desired crystals become coarse and the denseness decreases, and at the same time, the melting of the raw glass becomes difficult.
Preferably, it is 3% or less. The ZnO component is an important component for improving the meltability of the glass, but if its amount is less than 0.5%, it becomes difficult to melt the raw glass and also to obtain a desired crystal. 7.5%
If it exceeds, the devitrification resistance is deteriorated, and it is also difficult to obtain a desired crystal. Preferably, it is in the range of 1% to 4%.

The components CaO, BaO, SrO and B ₂ O ₃ are effective components for improving the melting property of glass, preventing partial milky whitening during glass forming, and suppressing coarsening of precipitated crystals. is there. However, CaO, BaO, SrO
And the total amount of one or more of the B ₂ O ₃ components is 0.
Below 5%, their effects are not sufficient. In addition, Ca
If each of O, BaO, SrO and B ₂ O ₃ exceeds 5%, desired crystal precipitation becomes difficult, and the crystals become coarse and the compactness is reduced. Preferably, it is 3% or less. The As ₂ O ₃ and / or Sb ₂ O ₃ components can be added as a fining agent during glass melting, but a total amount of one or two of these is less than 2% is sufficient. In addition to the above components, La ₂ O ₃ , Gd ₂ O ₃ , CeO ₂ , and Y _{2 as long as} the desired properties of the crystallized glass of the present invention are not impaired.
The O ₃ component to 3% of one or more in total, Fe ₂
One or more coloring components such as O ₃ , Cr ₂ O ₃ , MnO ₂ , and CuO can be added up to 3% in total.

Next, a feature of the method for producing a cordierite-based crystallized glass according to the present invention is that a glass having the above composition is melted at a temperature of 1500 ° C. or less, molded, cooled, and cooled.
A primary heat treatment is performed at a temperature in the range of 00 ° C to 800 ° C, followed by a secondary heat treatment at a temperature in the range of 900 ° C to 1000 ° C. Further, the heat-crystallized glass is usually wrapped by a generally known method, and the surface roughness of the polished glass is 50 ° or less.

[0012]

Examples Next, examples of the cordierite-based crystallized glass of the present invention will be described together with comparative examples.
Table 1 shows examples of the composition (No. 1 to No. 10) of the cordierite-based crystallized glass of the present invention and comparative compositions (No. 1 to No. 1) of the conventional cordierite-based crystallized glass.
Regarding 3), the melting temperature of the raw glass, the primary heat treatment temperature and time for reheating the glass after melting and cooling, and the secondary heat treatment temperature and time, the crystal phase and crystal grain size, and the It shows the measurement results of the surface roughness (Ra).

[0013]

[Table 1]

[Table 1]

[Table 1]

[Table 1]

Here, the melting conditions are measured by mixing and mixing raw materials such as oxides, carbonates, and nitrates so as to obtain 2500 g of glass, and setting the temperature in advance according to the difficulty of melting due to the difference in composition. After charging into a platinum crucible in a set furnace, the mixture was melted with constant stirring, and visually observed to be almost defoamed. The obtained glass was subjected to a two-stage heat treatment to obtain a crystallized glass.
All of these crystallized glasses have cordierite as a main crystal as a result of X-ray diffraction, and have β-quartz solid solution and Cornelpine (M
gO, Al ₂ O ₃ , SiO ₂ ). In preparing a sample for measuring the surface roughness (Ra), the crystallized glass was treated with abrasive grains having an average particle size of 9 to 12 μm for about 10 minutes to 20 minutes.
Lapping for about 30 minutes and then polishing with cerium oxide having an average particle size of 1 μm to 2 μm for about 30 to 40 minutes.

As can be seen from Table 1, the melting conditions of the raw glass in the embodiment are 1450 ° C. or less, the volatile components such as B ₂ O ₃ are hardly dissipated, and the conditions 1 for the raw glass of the comparative example are as follows.
It is more advantageous than 500 ° C. to 1650 ° C., and the homogeneity of the crystallized glass obtained is much better. In the case of the comparative example, the first heat treatment temperature and the second heat treatment temperature in the heat treatment are 900 ° C. to 950 ° C. for the former and 1100 ° C. to 1 ° for the latter.
In contrast to the need for heat treatment in a high-temperature range of 300 ° C., in the case of the embodiment, the former enables heat treatment in a low-temperature range of 700 ° C. to 800 ° C. and the latter in a range of 900 ° C. to 1000 ° C.,
Excellent industrial stable mass productivity. The crystal grain size of the comparative example is 11.0 μm or more, which is coarse, whereas the crystal grain size of each of the examples is 10 μm or less, which is fine and excellent in denseness. Also, the surface roughness (Ra) of the comparative example is 60 ° or more in the case of the comparative example, while the surface roughness (Ra) of each of the examples is 50 ° or less. .

[0016]

As described above, according to the present invention, cordierite based crystallized glass of the present invention, the predetermined the SiO ₂ -Al ₂ O ₃ -MgO based composition in which the TiO ₂ component and nucleating agent (Al ₂ O ₃
/ MgO) is obtained by subjecting a raw glass co-existing by giving a weight ratio, making a specific range of a ZnO component an essential component, introducing a BaO, CaO, SrO, B ₂ O ₃ component and the like. It has excellent meltability, good homogeneity, and can be crystallized in a low temperature range, and its crystal grain size is also fine and excellent in compactness. It is particularly useful for various materials that require processing and precision processing.

Claims (4)

(57) [Claims] 1. The composition according to claim 1, wherein said SiO _{2 is} 38% to 50% by weight.
_{%, Al 2 O 3 18%} ~30%, 10% MgO ~20
%, But in terms of weight ratio, Al ₂ O ₃ /MgO=1.2 to
_{2.3, B 2 O 3 0%} ~5%, CaO 0% ~5%, B
aO 0% to 5%, SrO 0% to 5%, ZnO 0.1%.
_{5% ~7.5%, TiO 2 4} % ~15%, ZrO 2 0
% ~5%, As ₂ O ₃ and / or Sb ₂ O ₃ 0% ~2
%. A cordierite-based crystallized glass obtained by melting, shaping, and heat-treating a raw glass having a composition of%, and containing a cordierite-based crystal as a main crystal. 2. SiO ₂ 42% to 47% by weight.
_{%, Al 2 O 3 22%} ~27%, MgO 13% ~18
%, But in terms of weight ratio, Al ₂ O ₃ /MgO=1.2 to
_{2.3, B 2 O 3 0%} ~3%, CaO 0% ~3%, B
aO 0% to 3%, SrO 0% to 3%, ZnO 1%
_{~4%, TiO 2 8% ~12} %, ZrO 2 0% ~3
%, As ₂ O ₃ and / or _{Sb 2 O 3 0% ~2%} , cordierite based crystallized glass according to claim 1, characterized in that it consists of the composition of the. 3. The cordierite-based crystallized glass according to claim 1, wherein the crystal grain size is 10 μm or less, and the surface roughness (Ra) obtained by polishing is 50 ° or less. 4. The raw glass according to claim 1 or 2 is melted at a temperature of 1500 ° C. or less, molded, cooled, subjected to a primary heat treatment in a temperature range of 700 ° C. to 800 ° C., and subsequently to 900 ° C. A method for producing a cordierite-based crystallized glass, comprising performing a second heat treatment in a temperature range of from about 1000 ° C to about 1000 ° C.