JPS5849633A - Crystalline glass having high strength and low expansion - Google Patents

Abstract

PURPOSE:To provide the titled glass having low thermal expansion and high mechanical strength, and useful as an industrial material, by heat-treating a glass material composed of specific amounts of SiO2, Al2O3, Li2O, TiO2, F and As2O3. CONSTITUTION:The objective glass is prepared by heat-treatment of a glass material composed of 50-73(wt)% SiO2, 12-35% Al2O3, 2-10% Li2O, 0.1-6% TiO2, 0.1-6% F, and 0.05-8% As2O3, wherein SiO2+Al2O3+Li2O+TiO2+F+ As2O3 is >=90%, SiO2+Al2O3+Li2O is >=81%, and the content of Na2O, K2O, CaO, MgO and B2O3 is <=5% and that of PbO, ZnO, BaO, SrO and P2O5 is <=3%. The crystalline glass obtained by this process has a thermal expansion coefficient of <=25X10<-7>/ deg.C between 50 and 500 deg.C, can be cut, machined or ground without loss of the mechanical strength, and has excellent heat resistance and thermal-shock resistance.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention particularly relates to a crystallized glass having high mechanical strength and low thermal expansion. More specifically, the present invention relates to crystallized glass having high mechanical strength that can be advantageously used as an industrial material.

Conventionally, low thermal expansion crystallized glass having a coefficient of thermal expansion of approximately 30
□It is well known that the main component is Thai koto or sowara. The mechanical strength, particularly the bending strength, of such crystallized glass has been limited to approximately 2,000 to 3,000 kg/cd. On the other hand, it is a crystallized glass with a different crystal structure, and has high mechanical strength such as bending strength of 500~
Products with a value of around 60,001 cg/m have also been developed, or have a thermal expansion gF of 70 to 80XlO"'.

(50 to 500°C) or more than 7 degrees Celsius, and the thermal stability or thermal shock resistance was poor. Therefore, such crystallized glass is an unsuitable material for, for example, industrial materials that require high temperatures and high loads. Under these circumstances, low thermal expansion crystallized glass with high strength was developed, for example,
5. Special Publication Showa 45-4870° Special Publication Showa 46-5835. It was proposed in various publications such as Special Publication No. 4fl-42918,
All of these crystallized glasses have structures in which internal crystals and surface crystals are different, and have a high mechanical strength due to the surface compressive stress caused by the difference in thermal expansion 4XN number of each crystal. That's what you're getting. Therefore, these crystallized glasses have a fatal flaw in that they cannot maintain their strength when compressive stress is released through processing such as cutting, cutting, polishing, etc. It has been almost impossible to use it for materials that require particularly high mechanical strength.

In view of these realities, the inventors of the present invention have adopted these materials as industrial materials, even after undergoing secondary processing such as cutting, cutting, polishing, etc.
As a result of extensive research in order to provide a material with almost no decrease in mechanical strength, we discovered a new high-strength, low-expansion crystallized glass whose high mechanical strength is based on the inherent strength of the crystalline material, not due to surface compressive stress. Ta. That is, the present invention is disclosed in Patent No. 8.
No. 54465 (Special Publication No. 5l-22926) Ming, 111I
Focusing on the synergistic effect of IC and Mu5203 described in the book,
It is based on the knowledge that the combination of their coexistence and a crystal nucleating agent results in finer and more abundant nucleation in a specific glass body, and based on this, the generation of fine crystals.

The purpose of the present invention is to obtain aoxlo ``e (50-500℃
), the mechanical strength does not decrease even after secondary processing such as cutting, cutting, polishing, etc., and still maintains high mechanical strength. Expandable crystallized glass is a total offering.

The gist of the present invention necessary to achieve the above object is 8% by weight.
i0250~73%, Mu120,12~85%, Li
2O2~1O%, Tie20.1~6% and Fo, 1
6%, 18□030.05 to 8% as essential components. In the obtained crystallized glass, what contributes most to the increase in strength is the above components, especially the coexistence of F and 0203, and the combination of the crystal nucleating agent T i 02, and the structure. L generated thereby
There is a large amount and dense presence of i20・mu1203・48i02 crystals.

More specifically, the specification of the Patent No. 85446fi describes the L i20 8 i 0 □ series or the L i 0- A I
203-8 i In 02 series glass, F and 88°0
The combination of 3 acts as a nucleating agent, Li2O.28
Becomes the starting point for precipitation of I02 crystals 8-Although it is described that it becomes an extremely large number of crystal nuclei, the present invention is based on the combination of F and A m203 with LL, O-A 12
Li, 0.Li2O in 03-8i20 series glass
Nucleating agent T acting for the precipitation of 3.48i02 crystals
This is based on the knowledge that iO□ greatly contributes to the miniaturization and increase in the number of crystal nuclei in the generation of crystal nuclei. The identified l-120-mu t2o3-sto, system glass body is subjected to a certain heat treatment to convert F and mu I2O in the first step.
Due to the synergistic effect with 3, fine and large amounts of TiO□ (ruti/L/) crystal nuclei are generated, and L starts from the nuclei.
Precipitation of i2O.mu1203.48i0□ crystals begins, and the growth of the crystals progresses in the second stage. However, due to the extremely large number of nuclei, the growth of crystals interferes with each other (~, within a certain limit, the growth stops as a fine crystal,
Overall, the glass body is extremely good. & fine and large amount of l-12
It transforms into crystallized glass whose main component is 0.mu1203.48 i 02 crystals. L precipitated in this way
i2O Muji 20. -48IO Almost no homocrystal structure defects occur, which leads to maintaining and increasing the mechanical strength of the crystallized glass body. Furthermore, Li2O・Al□0.・4
The crystal itself of 8i02 is approximately -2,4XlO"'0 (25~
600°0), so in practice, in a crystallized glass body containing a matrix glass and 14tI crystals, a crystallized glass containing 40% or more of the above crystals has a thermal expansion coefficient of approximately 25 A thermal expansion coefficient within 500°0) can be obtained.The larger the content of the crystals, the smaller the thermal expansion coefficient of the crystallized glass body tends to be.

In the present invention, especially thermal expansion (approximately 25 x 10"0)
When trying to obtain a crystallized glass body with a crystallization temperature of 5O-y500 °O or less, it is necessary to contain 40% or more of β-subodumene crystals, and in this case, 8102 as a glass component is required.
Ten mu 1□0. Thousand Days 20 + TIO□10F + As2
It is necessary that the total of o3 is 90% or more, of which 8I02+Mu1□03+Li2O accounts for 81% or more.

The combined effect of F + Ag2O3 is particularly in synergistically achieving the formation of a large amount of crystal nuclei in the first stage of heat treatment and the miniaturization of crystals in the second stage.

That is, by increasing the content of the nucleation aid [7]F or A8゜03, it is possible to form a large number of nuclei and to make the crystals finer to some extent. , is not sufficient to achieve the above objective.

The bending elasticity of crystallized glass to which a combination of F component and AS□03 component is added is approximately 1.5 to 2.0 times greater than that of crystallized glass to which only one is added. can be understood from Tables 1 and 2 based on experimental data.

Table 1 (4s□03 in Table 1 is expressed as an external division ratio.) -? - Table 2 (1' in Table 2 is the external ratio.) 8- From Tables 1 and 2, AM, 0. The flexural strength of unformed crystallized 7gabs containing one of A8□03*k' is approximately 20150 kgAA + 1400 kg, respectively, while the flexural strength of unformed crystallized 7gaves containing one of A8 Mechanical strength increases dramatically to approximately 5000&i+
It can be seen that crystallized glass having a high bending strength of /- or more can be obtained. In addition, both data V1 in Tables 1 and 2 were measured on processed samples whose surfaces had been polished by approximately 1 nL''1, and are the average values for the number of samples (n-20). The strength of the unpolished sample was 8820 hkt1 in Table 1, 9/a+l m 3 4800, and 9/m.

In the present invention, 8i02 +mut, 0. +Li,
The essential components of O+ TiO2, F, and Mu8□03 are limited as described above, and the reason for the limitation is as follows.

When 8i0□ is less than 50%, the resulting crystallized glass has poor chemical durability, and precipitation of contaminant crystals becomes large, making it difficult to obtain desired mechanical strength and low thermal expansion.

If it exceeds 73%, the meltability and workability of the glass are poor and a homogeneous crystalline product is obtained, making it impossible to obtain the desired properties. Therefore, 8i0□ is limited to 50-73%.

Ml! If 0.03 is less than 12%, the liquidus temperature of the glass becomes high, which impedes workability, and the precipitation of contaminant crystals increases, making it difficult to obtain desired properties. 35%
When the temperature exceeds the above range, the glass becomes poorly soluble, workability becomes poor, and the desired crystalline product cannot be obtained. Therefore, A
12O3 is limited to 12-35%.

In the case of Li2O, if it deviates from the range of 2 to 10%, 30
It is not possible to obtain a crystalline product having a low expansion property of less than XIO'') (50-500°0).
-10%.

As mentioned above, TiO2 acts as a nucleating agent and becomes a source of extremely fine crystals. F if less than 0.1%.

Even with the synergistic effect of Mu8203, the absolute amount of nucleation is low, the desired amount of crystalline matter and its density are lacking, and sufficient mechanical strength cannot be obtained. If it exceeds 7%, the meltability of the glass deteriorates and devitrification does not occur, causing a large amount of homogeneous crystalline material to precipitate. Therefore, TiO□ is limited to a range of 0.1 to 7%.

F assists the nucleation of T + 02 in the presence of Mu8□03 and is necessary for the precipitation of a large amount of crystal nuclei. If it is less than 0.1%, even in combination with ^5203, support for TiO□ nucleation is insufficient and a sufficient amount of crystal nuclei cannot be obtained. 6
If it exceeds %, damage to the furnace material during glass melting will occur, and the volatilization of F from the molten zone will become significant, making the glass non-uniform and preventing the precipitation of homogeneous crystals.
F is limited within the range of 0.1 to 6%.

On the other hand, A8□03 assists the nucleation of the nucleating agent T i 02 together with ) and is indispensable for the formation of crystal nuclei and a large amount of desired crystals. Furthermore, some F during heat treatment for crystallization
It has the effect of preventing differential precipitation of internal crystalline substances and surface crystalline substances caused by volatilization. When it is less than 0.05%, even if a sufficient amount of F is present, it is difficult to support the formation of a sufficient amount of TiO□ crystal nuclei, thereby obtaining a dense microcrystalline body that achieves the above objective. I can't.

If it exceeds 8%, the crystalline material becomes brittle. Therefore, A
s□03 is limited to 0.05 to 8%.

Said 8i0□1203 +Li2O+ TiO2+
When the total of F+mu8□03 is less than 90% or f3
The total of i 02 + mu 1203 + L i20 is 81
When less than %, matrix glass.

The proportion of contaminant crystals increases and the desired β-
Since the proportion of microcrystals of subodumene decreases, it becomes difficult to obtain a sufficiently low expansion property. Therefore, especially 20X
When trying to obtain crystallized glass having a coefficient of thermal expansion of IO"" (50 to 500'0) or less, 8 i 02 + Mu 1,03 + Li, O + TiO2 + F + Mu 5203
The total of 93% or more, of which 8102+^1203
+ Li2O must account for 86% or more.

In addition, other Na2O, [20, Pbo, ZnO+
B aO,8r0゜0＆OI MFol B2O3,
I'20. etc., to an extent that does not significantly change the characteristics of the present invention, for example, tm*, 0. n2o1
0aO+ MIO* 5% or less Pb for B2O3
Q+ ZnO+ Ba1t 8r()t P2O6 may be added in an amount of 3% or less. These components are used to improve the meltability and workability of glass, but if they are included in a certain amount or more, they may cause problems such as an increase in the content of matrix glass and the formation and increase of contaminant crystals. Examples based on the invention will be described.

After bath-melting a batch of raw materials prepared as shown in Table 3 at 1500 to 1600°C for 3 to 6 hours, a diameter of about 61″1.
A round bar of o7F-nL was molded. This glass rod was heated at a heating rate of 500/min in an electric furnace to approximately 800°C.
The glass was maintained at a temperature of It was left to cool. The surface of the obtained crystallized glass rod is approximately 1? The flexural strength and thermal expansion coefficient of each sample were measured. Note that the measured values in Table 3 are based on the number of samples n = 2.
The average value based on 0 lines is shown.

As described in detail above, the present invention has 1- excellent heat resistance, which does not cause a decrease in mechanical surface strength even when subjected to secondary processing such as cutting, cutting, and polishing, which is not available in conventional crystallized glass; It is a crystallized glass that maintains thermal shock resistance, and is perfectly suited as a material for industrial materials, where the above-mentioned properties are required at increasingly higher levels year after year.

In addition, depending on the density and fineness of the crystals, the surface hardness of crystallized glass maintains a Vickers hardness (3009 load) of approximately 700 to 9//"1"2 regardless of whether or not it undergoes secondary processing. , as well as industrial materials such as mechanical parts and electronic parts, as well as building materials and decorative materials.

Its uses are extremely wide, including materials for daily necessities.

Patent applicant: Ishizuka Glass Co., Ltd.

Claims (1)

[Claims] l) 8i0250~73% in weight%, Mut, o312~
35%+Li2O2~lO%, TiO□0.1~6%
and Fo, 1-6%. A high-strength, low-expansion crystallized glass obtained by heat-treating a glass body containing 0.05 to 8% of Mu@2030 as an essential component. 2) 8 i 020m 1203 + L120 +
'rto□+F+mu11203 total is 90% or more, and 8i0. +Mu1203 +Li2O
81% or more of the high-strength, low-expansion crystallized glass according to claim 1.