JPS5860666A - Fine fused quartz sintered body - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a sintered body made from fused silica. Hypoallergenic fused silica glass products have a small coefficient of thermal expansion (5X
10-'/℃) high chemical resistance, high softening temperature,
It has characteristics such as high transmittance in purple 9J and visible light, and is widely used in various physical and chemical instruments, lenses, prisms, acid-resistant containers, etc.

However, these O products are not suitable for large-scale production because they melt at high temperatures, are very expensive, and have poor force formability.

On the other hand, sintered bodies made of fused silica as the main raw material can be obtained using the same manufacturing method as ordinary refractories, so they are considered industrial products that take advantage of their low expansion and other 0% qualities, and have been used for various O applications for a long time. .

The raw material itself is 118
Since it does not have a chemical structure, it is generally mixed with alumina, colloidal silica, etc., and castable or slurry is added.
, cast and then sintered. Therefore, low swelling-O
Even if a product can be obtained, it is difficult to obtain a product with a low porosity.

In addition, fused quartz powder (sintering requires a sintering aid, such as kaolin). KoO
It is said that it is possible to obtain a sintered body with relatively low porosity and zero porosity when using a sintering aid like 1, but devitrification due to the alkaline content contained in the sintering aid is a major problem. Become.

Unless the alkali content of Nano is reduced as much as possible, fused silica tends to undergo devitrification, especially at a high temperature of 1000°C. In other words, it transforms into β-cristobalite, which has a larger coefficient of thermal expansion than fused silica, and the zero difference is one of the causes of cracks in the product. Furthermore, Oβ-cristobalite is 24
At around 0℃, it changes to low-temperature type Oα-cristobalite,
4*O volume decreases, which also causes falsification of products.

In addition, in order to increase sinterability, it has been proposed to mix a small amount of ultrafine powder, or to mix it with acids such as boric acid, phosphoric acid, salts thereof, and other O binders. It is necessary to pay attention to the ratio, and the reality is that products with low porosity are difficult to use.

The present invention was discovered as a result of intensive research in view of the above points, and it is possible to obtain a sintered body 1 with low porosity and low thermal expansion with extremely simple formulation and low temperature sintering. It was a success.

That is, the present invention provides a sintered body formed by sintering O fused silica powder of substantially 100 mesh or less, wherein BsOmFi contained in the sintered body has a weight of 1 to 25 ib, 81
0. The ratio of the metal lid is over 99%, and the alkaline component is less than 1% r:L as RIO, and the thermal expansion coefficient at 0 to 700°C is 15.
The gist is a dense fused silica sintered body characterized by X10-7/°C or less and a porosity of 7 or less.

Thus, in the sintered body of the present invention, no special sintering aid is required, and the a-acid raw material [
It is possible to achieve low porosity simply by blending, but the B103 component of the fused silica raw material and the selection of the particle size of 0 seem to be important factors for this.

First, chemical components in the sintered body (weight, same below)
As,? ? o sio at a rate exceeding -.

The total amount of Bxoso and Bxoso is preferably 995- or more. For this reason, the quartz grains have a high purity of 810
．． It is necessary to use a system that contains almost nothing other than B and Os results.

In particular, regarding alkaline components (R, O) such as Nano, if the analyzed value in the sintered body is more than α1 υ, it will not result in devitrification of quartz O and will not achieve the purpose. Can not. More preferably, it is substantially free of f105 or less.

Regarding the B=01 component, O may be included in the quartz powder in advance, but it is usually best to mix it separately from the quartz powder.

B = os acid component The oxide and I7 may be mixed in advance, but usually boric acid (HmB
It is suitable to use it as a boric acid compound (Os) or a boric acid compound. This boric acid component also acts as a sintering aid, and it was completely unexpected that low porosity could be achieved with just this boric acid component.

In the present invention, the ratio of DB and On in the sintered body is 1 to 2.
It is necessary to set it to 59G, because if it is less than 1-G, it will not sinter. On the other hand, if it is too high, it will be possible to sinter at a reasonably low temperature, but the sintered body will be easily softened, and it will not be possible to sinter at a high temperature. This is because only 0 can be obtained, which is inappropriate as a sintered body of the present invention suitable for the intended use.

Oka, the more desirable B201 component θ node is 4 to 15.

In addition, in the present invention, the B, O, and components can be blended in powder form without being added as additives, and in particular, as described later, when used as fine powder like quartz powder, it is easier to obtain desired results. It has been found that the suitable grain weight is substantially less than 100 mesh, especially when the majority is 1.
The above is the use of O ultrafine powder under son mesh.

In the present invention, the particle size of the heavy-walled fused silica used is substantially 100 mesh or less, similar to BIO and the raw material, and it is particularly preferable to use it as an ultrafine powder with a majority of 300 mesh or less.

If the particle size is larger than this, 12) B
This is thought to be because the reaction surface area with the raw material, O, becomes smaller, and this is because the grain size of the raw material is large. This can be seen from the fact that O devitrification is likely to occur.

It has also been found that if coarse θ particles are mixed, the sintered body tends to become porous, making it difficult to achieve the desired densification (low porosity).

The present invention is obtained essentially only from fused quartz and BxOs raw materials, and O is formed by molding these Q powders using a normal press or rubber press extrusion molding, and then firing them. It was also discovered that dense sintered bodies can be produced by firing at low temperatures.

That is, it was found that the appropriate firing temperature is 800 to 1400°C. This is because if it is above 1,400°C, fused silica tends to crystallize and the sinterability becomes poor, while if it is below goo°C, the limit for use is only 0.8°C or below. The firing temperature FiB and O8 need to be set at a higher temperature if there are fewer components. B, On O is determined by the O content.

In addition, the most desirable condition for firing is to make the atmosphere free of alkaline components or to have a very small amount of alkaline components. This is because it is actually valid to obtain OK.

As for the 9th means, the baked molded body is accommodated in a small Saya material such as 1- or less, and baked, and the Saya and molding are alkali components RL1G66.
When baking in a tunnel kiln, etc., where there is a large amount of alkali, the air should be purified. be.

In addition, the present invention makes it possible to obtain a dense fused silica sintered body with low porosity while maintaining low swelling, and its physical properties include a porosity of 7 or less. The coefficient of thermal expansion from 0 to 700°C is 15 x 10"
Anything below '7/C is quite possible.

In conventional sintered bodies, most of them have a porosity of 8 or more, and most of them have a porosity of 1096 or more, and in special methods, porosity of about 5 or less Although there have been reports that such a compound has been obtained, none has been obtained using a simple compounding method 1c such as O of the present invention, and in fact, no such O has been commercialized.

In addition, the coefficient of thermal expansion can be obtained at 15 × 10-17°C or less, so the coefficient of thermal expansion of quartz glass itself (
sxlo-7/℃) is close to l/)T.

Furthermore, it has sufficient properties such as compressive strength and chemical resistance.
The present invention has great value and value as an industrial product.
4! LL, that's what I'm doing.

Practical row 525 mesh or less O fused quartz powder and boric acid (HmBO
s) was mixed as shown in Table 1, and then press-formed in Amsler at 200 h/ex snow pressure to a size of 10 m≠×2 a■ (^ s) to form a pod material containing almost no alkaline component O. and fired at the firing temperatures shown in Table 1.

The results of measuring the physical properties of the nine sintered bodies obtained are shown in Table 2.

First schedule levy 1 2 5 4 5 6
7” Boric acid (wt-) 0 2 10
15 20 30 40 Firing temperature (t:) 14
00140013501!1501100800500
(Note) 11,417 is a sample for comparison.

Table 2 Sample 1' 2 S 4 5
6 7' Analysis value (wt%) Sin199.79a39589 (1587,28[1
372,1B! OsO1,25,99,01119,4
272R, Or101 and below, same left, same left, same left, same left, same air hole book (5G) Yaki & 5 5.2 2.7 2-0
11 18 Bulk specific gravity 1.8 1.9 1.9
2.0 2.0 2.0 (Note) Hot sulfur # (90℃),
10 - Soaked in sulfuric acid (90℃) for one month to improve compressive strength, thermal expansion coefficient, and porosity.

Claims (1)

[Claims] 1. A sintered body obtained by sintering O-bath fused quartz powder of substantially 100 meshes or less, wherein B contained in the sintered body is
2O5Fi weight% is 1 to 25 rumored, 810 and B1
Content F′i of 01? The ratio exceeds 9.1, and the alkaline component has a ratio of less than rL1sK as R and O.
And the coefficient of thermal expansion at 0 to 700°C is 15 x 1
A ljk dense fused silica sintered body characterized by having a porosity of 0-'/c or less and a porosity of 7- or less. 2. Fc obtained by using fused quartz powder with a mesh size of 50 to 300 and firing at a temperature of 800 to 1400°C.
%W+- Fused quartz sintered body as described in Section 1 of Fukumu no Misaki Issei.