JPH062605B2 - Method for producing crystallized glass article - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for producing a crystallized glass article, and more particularly to a method for producing a crystallized glass article having high strength and little variation.

[Conventional technology]

Crystallized glass does not contain any pores like glass, has a wide range of expansion coefficient from negative expansion coefficient to positive high expansion coefficient depending on the type of precipitated crystal phase, high heat resistance positive, high elasticity,
It has various excellent properties such as high strength and high hardness, and by taking advantage of these properties, it has been put to practical use in various fields such as heat-resistant tableware, cooker top plates, and reflector mirror blanks.

In addition, recently, crystallized glass has a transparency equivalent to that of various substrate materials, structural materials or glass,
It is increasingly used as a transparent material for windows or covers of various devices which replaces glass.

Among these applications, crystallized glass is often used after grinding / polishing in applications where dimensional accuracy, flatness, or transparency that does not distort an image when transparent is required. .

Although crystallized glass requires a longer processing time than glass because it has a lower processing speed than glass, the same steps as glass, namely diamond grinding, grinding with a lapping agent such as SiC or alumina, polishing with CeO ₂ slurry, etc. It is possible.

[Problems to be solved by the invention]

However, since crystallized glass generally has higher hardness and higher water resistance than glass, not only the processing speed is low and the time required to obtain a mirror surface is long, but it is visually polished until it is judged to be a mirror surface. However, there is a problem that invisible minute scratches, that is, latent scratches are likely to remain on the surface. In this way, the latent scratches are likely to remain in the crystallized glass, and when a mirror-finished product is etched with diluted hydrofluoric acid or the like, invisible minute scratches are enlarged and visually confirmed. This can be confirmed. The residual of such latent scratches is not preferable because it causes a decrease in the strength of the crystallized glass article. Therefore, in order to prevent the strength reduction due to the residual of such latent scratches, the polishing time may be increased from several times to 10 times or more in some cases, or in order to shorten the polishing time, In the normal glass grinding / polishing process, the transition from grinding with the No. 1000 lapping agent to the polishing process is performed after grinding with the No. 1000 lapping agent, for example, lapping agents with finer grain size, for example, No. 1500-2000 lapping. It was necessary to add grinding with an agent. However, a significant change in these grinding / polishing steps causes a significant increase in processing cost and is not preferable in practice.

[Means for solving problems]

In order to solve the above problems, the present invention brings a surface-polished glass article into contact with a silicon dioxide supersaturated solution of hydrofluoric acid to deposit a silicon dioxide film on the surface of the crystallized glass article.

The method of display polishing carried out in the present invention is a method of display polishing usually carried out, for example, after wet grinding with a lapping agent or the like.
It is a method of wet-polishing with a slurry such as CeO ₂ .

The present invention particularly exhibits its effect on the production of a crystallized glass article requiring a mirror surface, and the final surface state of the surface polishing of the crystallized glass performed in that case is judged to be insufficiently polished by the usual method. It does not matter even if it is in the state of being struck (the state in which latent scratches remain). Examples of such a state include a surface state of a crystallized glass article that has been polished for about 100 to 10% to several times the time required to polish a glass article having the same composition into a mirror surface by the same method. To be done.

Further, the shape of the crystallized glass article is not limited to the plate shape and the rod shape,
Any shape such as a tubular shape or a tubular shape that can be brought into contact with a silicon dioxide supersaturated solution of hydrosilicofluoric acid can be used.

Silicon dioxide supersaturated solution of hydrosilicofluoric acid used is silicofluoric the equilibrium of silicon dioxide saturated solution H ₃ BO ₃ of hydrochloric acid, A
It can be prepared by transferring it by a method of adding an additive such as (OH) ₃ . The hydrofluoric acid solution used is
A concentration of 0.5-3.5 mol / mol is preferred to obtain a good deposition rate. When boric acid (H ₃ BO ₃ ) is used as an additive, it is preferable to add 2.0 × 10 ^-2 mol or more to 1 part of the hydrosilicofluoric acid aqueous solution having a concentration of 0.5 to 3.0 mol /. Preferred to gain speed.

The supersaturated solution of hydrosilicofluoric acid in silicon dioxide is brought into contact with the crystallized glass by a commonly used method such as a spray method, a coating method or a dipping method, but the reaction time until the intended deposited film is obtained is relatively long. Since it takes a long time, it is preferred to use the dipping method for contact.

The silicon dioxide coating deposited on the crystallized glass material is
Its precipitation effect is remarkable, and the productivity is good.
A film having a thickness of m is preferable.

[Action]

The present invention is believed to operate as follows. In other words, when crystallized glass with latent scratches on its surface is contacted with a silica supersaturated aqueous solution of hydrosilicofluoric acid, precipitation of SiO ₂ occurs with the surface as a nucleation site, and the surface is coated with a SiO ₂ film. . At this time, since the hydrosilicofluoric acid aqueous solution, which is the source of precipitation of SiO ₂ , has a low viscosity, it penetrates even into the inside of minute latent scratches in the crystallized glass article produced by grinding and polishing. Therefore, the precipitation of SiO ₂ also occurs inside the latent scratch, and as a result, the latent scratch is filled with SiO ₂ and its influence on the strength is substantially not recognized.

Examples of the SiO ₂ coating method include a method using an alkyl silicate and a method using a silane gas, in addition to the method according to the present invention. However, even if the SiO ₂ coating is performed by these methods, the effect of eliminating the effect of the present invention on the strength of latent scratches cannot be obtained. Effect because, SiO ₂ film obtained by these methods, which was deposited on certain size SiO ₂ particles surface, SiO ₂ as obtained by the process of the present invention fills up latent scratches tip It seems that there is no.

Hereinafter, the present invention will be described in more detail based on examples.

〔Example〕

 Example 1 SiO in wt%₂65.0, A₂O₃22.5, Li₂O4.5, Na₂O1.0, TiO₂2.
0, ZrO₂2.5, P₂O 51.5, As₂O₃Glass made of 1.0 at 5 ℃ /
Heated to 850 ℃ for 4 minutes and kept at 850 ℃ for 4 hours, β-quartz solid solution
As a transparent crystallized glass containing the body as the main precipitated crystal phase
It was Using a diamond saw, set this to a bottom of about 5 mm and a length of about 5
Cut into a rod of 0 mm and grind with lapping agent of No. 400 SiC, No. 1000 alumina, and then vertical 5 mm width 5
CeO on 4 sides of 0 mm₂Polished with slurry. About 1 each
After 5 minutes, the scratches caused by the grinding process disappeared visually and
Judged The rod-shaped samples thus obtained were divided into four groups,
One group is 2mol /, 200cc hydrofluoric acid silica saturated water solution
0.5 mol / H in liquid₃BO₃1 to the processing solution with 30cc of aqueous solution added
It was immersed for 6 hours. As a result, its surface is about 150 nm thick
Sano SiO₂A film had formed. In this way, SiO₂Ko
The strength of the bent rod-shaped sample was measured by three-point bending.
Decided For comparison, one of the remaining three groups was ground.
・ In the state where it is polished, the second group is dip
Method (SiO₂5% concentration converted to
30 minutes at 500 ℃
Minute calcination), CVD method (monosilane 5%, N₂95% mixed gas
Surface onto the substrate heated to 500 ° C)
About 120 nm thick SiO₂After forming the film, similarly 3 points
Its strength was measured by bending. The results are shown in Table 1.

The one coated with SiO ₂ by the method of the present invention exhibited higher strength and lower variation compared to the one not coated with SiO ₂ . Further, when the SiO ₂ coating was performed by dipping or CVD, the increase in strength due to the coating was not observed as in the case of the SiO ₂ coating by the method of the present invention.

Example 2 A glass having the same composition as in Example 1 was heated to 1150 ° C. at 5 ° C./min and held at 1150 ° C. for 2 hours to give a white opaque crystallized glass containing β-spodumene solid solution as the main precipitated crystals. From the crystallized glass thus obtained, a rod-shaped polished sample having a bottom surface of about 5 mm square and a length of about 50 mm was prepared by the same procedure as in Example 1, and divided into two groups. One group was 200 cc, 2 mol / hydrogen fluoride. The surface of the acid was saturated by dipping it for 16 hours in a treatment solution prepared by adding ₃₀ c of 0.5 mol / HBO ₃ aqueous solution to the silica saturated aqueous solution.
After coating with a 150 nm thick SiO ₂ film, the other group was ground and polished, and its strength was measured by three-point bending.

The three-point bending strength of the product not coated with SiO ₂ was 1560 kg / cm ²
On the other hand, the SiO ₂ coated product exhibited a three-point bending strength of 2340 kg / cm ² .

〔The invention's effect〕

According to the present invention, it is clear from the examples as well that the influence on the strength of latent scratches remaining in the crystallized glass ground and polished in a process similar to that of frosted glass is eliminated, and it is equivalent to the case where no latent scratches are included. A crystallized glass article having strength can be obtained. Further, although the above-mentioned examples were performed on the crystallized glass containing β-quartz and β-spodumene, the method for producing a crystallized glass article according to the present invention is not limited to the above-mentioned crystallized glass and is applicable to any crystallized glass. it can.

Claims (3)

[Claims] 1. A method for producing a crystallized glass article, which comprises contacting a surface-polished crystallized glass article with a silicon dioxide supersaturated solution of hydrofluoric acid to deposit a silicon dioxide film on the surface of the crystallized glass article. . 2. A surface-polished crystallized glass article is immersed in a hydrosilicofluoric acid solution that has been made into a silicon dioxide supersaturated state by adding boric acid to a silicon dioxide saturated solution of hydrofluoric acid. A method for producing a crystallized glass article according to claim 1. 3. The method for producing a crystallized glass article according to claim 1, wherein the silicon dioxide film has a thickness of 50 to 200 nm.