JPS63103842A - Glass ceramic product, manufacture and thermal crystalline glass - Google Patents

Abstract

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

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Field of Application) The present invention relates to a glass-ceramic product, a method for manufacturing the same, and a thermocrystalline glass.

BACKGROUND OF THE INVENTION Glass-ceramic products are traditionally produced by precisely controlled heat treatment of precursor glass products.

Therefore, conventional glass-ceramic products were manufactured by the following three general steps. First, a vitrification batch of the planned composition is melted, then this molten mass is cooled to a low temperature (at the limit, usually below the transition range), and at the same time it is formed into a glass article of the desired shape, and finally The glass article is then subjected to a heat treatment designed to induce crystallization (the transition range is defined as the temperature at which the molten material transforms into an amorphous mass, generally considered to be around the annealing point of the glass). ) The initial glassware is subjected to a two-step crystallization heat treatment, which involves bringing the glassware to a temperature within or slightly above the limits of the transition range for a sufficient time to generate numerous nuclei in the glass. The temperature is then raised to a level that reaches the softening point of the glass, usually higher, to induce crystal growth in the nuclei.The crystals formed during the two-step heat treatment are of normal size or uniformity. , the final product generally consists of a large number of crystalline materials.

When a glass product is heated to a temperature above its transition range,
It is well known that the viscosity of glass becomes sufficiently low that the product becomes susceptible to thermal deformation.

The severity of this phenomenon clearly increases as the temperature reaches and exceeds the softening point of the glass.

The crystals generated in the glass-ceramic exhibit a melting point higher than the softening point of the precursor glass. As a result, in order to transform the parent glass product into a glass ceramic, the transition range of the glass is such that it crystallizes sufficiently during heat treatment to provide sufficient internal structure to support the product. Care must be taken to minimize thermal distortion when increasing the temperature above. It must also be noted that the composition of the glass remaining in the product is constantly changing so that its components become a complete part of the crystals during the heat treatment process. In most cases, the viscosity of the residual glass is greater than that of the parent glass.

That is, its transition range is higher than that of the parent glass.

However, thermal deformation is still a problem. This is particularly problematic for products such as dinner plates that are large and have a narrow cross-sectional area. This type of product required the use of molds or supports during heat treatment of the precursor glass product to ensure the desired shape in the final product.

Furthermore, in order to crystallize the glass product as it is, the temperature is rapidly raised to a temperature above the transition range and within the softening point range of the glass. Therefore, for industrial economics, it is necessary to raise the crystallization temperature to as high a temperature as possible and as quickly as possible. Such a method obviously increases the risk of thermal distortion of the precursor glass article. Research has therefore continued to find glass compositions which can be rapidly crystallized as is and which exhibit only minimal and preferably virtually no thermal distortion. These studies were particularly conducted in the area of tableware products where the primary objective is not to require supports to support the product during heat treatment of the parent vitreous body.

The purpose of the present invention is to add 2O-Na 2O-Mg 0-C to the system.
We find a very narrow range of glass compositions in a 0-3i 02-AQJ2O3 F.

This composition can readily crystallize directly into a glass-ceramic in which potassium fluoride richterite primarily constitutes the only crystalline phase. The degree of thermal deformation during the crystallization heat treatment of the parent glass is very small, and there is no need to use a holder to maintain the dimensions of the table product even for a table plate with a diameter of about 28 cm. Furthermore, glass-ceramic products have an aesthetic appearance that is particularly pleasing as tableware, exhibiting a slight translucency reminiscent of delicate English porcelain. Tableware products made from precursor glass bodies made from the compositions of the invention can be heat treated until complete crystallization by a short time program of 2 hours.

Means for Solving the Problems In order to achieve the above-mentioned objects, the composition of the present invention has the following properties: S i02 81-70 Na Z O1,5-
3A! uz 03 2.75-7 KZ O2,5
-5MgO 12.5-16 Na 2 to 2O+
O<7CaO4,75-9F
2-4 is the main component.

The compositions of the invention undergo liquid-liquid phase separation when the molten mass is cooled to a glass body (slow cooling produces a dense opal glass).

The creation of this phase separation, which greatly increases the viscosity of the glass, is an important factor for obtaining highly crystallized opaque glass-ceramics with very little thermal deformation and short crystallization heat treatment. Therefore, it was observed that during heat treatment the thermal deformation of the parent glassware decreased proportionally showing a much greater tendency towards phase separation. Furthermore, viscosity measurements performed during the crystallization heat treatment program showed that phase separated glass bodies actually retained a higher viscosity during heat treatment than those without phase separation. This phenomenon is thought to be due to the difference in viscosity of the residual glass matrix. Similarly, the opacity of the final glass-ceramic generally increases as the phase separation of the precursor glass increases.

In laboratory experiments, the parent vitreous body was tested in its transition range (260
When heated above 0°C, diopside (ca Mg51□O
mica fluoride (composition KMg 2,5
A metastable phase of Si (close to 40+oFz) forms first and transforms to potassium fluoride richterite at high temperatures (29508-1050°C).

BaO up to about 1.596 and 2.5% P20. is included to reduce the tendency of the glass to devitrify.

Some AS2O3 and/or Sb2O3 is present in amounts up to 1% to act as refining agents.

Amounts of Fe2O3 up to 0.5% give the glass-ceramic a slightly yellow color. Amounts of 0.15 to 0.2% produce colors very close to those of English Weshwood porcelain. Assuming that the yellow color is caused by the presence of Fe+3 ions,
To oxidize the glass and stabilize the redox state, As2O3 and/or 5b2o3 and NaN are added to the batch.
Preferably, an oxidizing component such as O3 is included. Other conventional glass colorants such as CeO2, Coo, cr2
o3. Cu0. Mn 02 , Ni 0. Ti 0
2, and V2O5 can be used in small amounts (typically less than 1% total) to adjust color, chromaticity, and total reflectance factors.

A2O3, P2O5 and to a lesser extent 5
io2 and F give phase separation. In contrast, alkali metal oxides and to a lesser extent alkaline earth metal oxides tend to prevent phase separation. The following equation was used as an indicator of the tendency of phase separation of glass composition.

As 2O R increases in Na 2O+, the phase separation tendency increases and thermal deformation decreases correspondingly. It has been experimentally determined that glasses having an R factor of about 0.6 or less have a small phase separation and that the parent glass body undergoes significant thermal deformation when heat treated to produce a glass ceramic.

The concentrations of MgO and F need to be adjusted to avoid thermal deformation of the parent glass. Since Mg 2 O is the main component of potassium fluoride richterite, if the amount is too small, crystallization will be insufficient and instead thermal deformation will be excessive. Fluorine provides the desired crystallization, but also acts as a flux when present in the residual glass.

In glasses with R<0.9, when the fluorine content exceeds 3.25%, significant sagging is observed. This is probably the maximum amount that can be mixed into the crystal.

The opacity of the final glass-ceramic is highly dependent on the amounts of A42O3 and alkali metal oxides.

More precisely, Aiz 03 levels of about 2.75% or less lead to low opacity products. Similarly, the increase in alkali metal oxide concentration increases from 7% Na2O+ to 2
O causes a decrease in transparency, resulting in very low transparency.

L1□O must be substantially absent from the composition. In laboratory tests, approximately 0.5% Li
It has been shown that the presence of 2O often causes cracking during the crystallization heat treatment.

This risk is particularly high for compositions exhibiting large phase separation.

Since Li2O imparts crystallization of the mica phase, the theory is that the cracking observed leads to sudden crystallization of the mica at temperatures at which the glasses of the invention exhibit high viscosity.

Glass compositions with an R factor of 0.6 or more are 110 depending on the composition.
0 to 1360℃ (approximately 10,000 poise and 40 degrees Celsius, respectively)
Opal liquid phase (phase separated liquid phase) in the range of 0 poise viscosity)
shows. The opalization liquidus increases in proportion to the increase in R index. Therefore, in order to use conventional equipment for glass production, an R index of 0.9 or less is preferred.

The glasses of the invention exhibit a crystallization liquid level in the temperature range of 1160 DEG to 1260 DEG C., corresponding to viscosities of 3000 and 800 poise, respectively.

As previously mentioned, the precursor glass body can be heated very quickly at a temperature with little thermal distortion. However, in the case of other glass-ceramics, if the temperature is raised too quickly, the thermal deformation will be large and the glass will crack. Therefore, to ensure very small thermal distortions, the temperature of the parent glass body must be raised from about 700 DEG C. to a temperature in the crystallization range (950 DEG -1050 DEG C.) over a period of 30 minutes or more. A period of up to 30 minutes, typically 10 to 15 minutes, in the crystallization range is sufficient to reach substantially complete crystallization.

Below is a preferred range of compositions that represents the best compromise between the physical properties of the final product and the melt formability of the precursor glass composition. These glasses are particularly advantageous from a processing point of view as they exhibit sufficiently high opalization and crystallization liquidus viscosities to be easily formed into glass articles by conventional glass forming techniques. For example, it can be supplied and molded at a viscosity of several hundred poise without excessive devitrification.

St 02 63 68 KZ 0 3.5
4.75A9Jz 03 3-4.75 Na 2
O+KZ OMg O13-15<6.75 Ca O5,25-7,58a O0,25-1,25
Naz 0 2 2.75' Pz 05 0
．． 5 1.5F, 2.25-3.25
Comparison with the Prior Art US Pat. No. 4,4Ei7.039 describes the production of glass-ceramic articles containing potassium fluoride richterite as the predominant crystalline phase. These products have large toughness, large mechanical strength, small thermal deformation, and weight%
5in250-70 K2O2-12MgO
8-25 LI2O2-0-3Ca 0 4-
15 Amen2O3 0-7Na2O 2-9
It is described that the main component is F3-8.

Although the broad composition ranges disclosed overlap with those of the present invention, we are not aware of narrow composition ranges that can crystallize very quickly and with little thermal deformation as such. In fact, a temperature increase rate of 200° C./hour to the crystallization temperature and a minimum heating time of 30 minutes at the crystallization temperature are described. In contrast, the temperature of the glass body of the present invention can be increased at a rate of up to 600°C/hour, and substantially complete crystallization cannot be reached at 15°C.
Does not require more than a minute. The compositions of the embodiments described in said patents are not within the scope of the products of this invention.

U.S. Pat. No. 4,608,348 describes the production of glass-ceramic products with high toughness and very low thermal distortion, containing potassium fluoride richterite as the predominant crystalline phase, but also containing significant amounts of cristobalite. . A composition giving such a product has, in weight percent, St 02 65-69 Na z O1,5
-3,5AQ,2O3 0,75 6.5 KZ O
4,2-6,0Mg O13,5-17,58a OO
．． 5Ca O3-4,8PZ 05 0-2.5N
The main component is a2O2-0.52,0F 34 5.5.

The CaO content is lower than that required for the compositions of the invention.

F 6 Q is high and LiO2 is a necessary component. Furthermore, while a substantial amount of cristobalite is necessary for glass-ceramics, the presence of cristobalite is unnecessary and undesirable in the products of this invention.

EXAMPLES Table I records a number of glass compositions in parts by weight on an oxide basis and illustrates the compositional parameters of the present invention. Since the sum of the ingredients in each composition is close to approximately 100, for practical purposes the values recorded are considered to represent weight percentages. Since fluorine is not known to combine with cations, this is simply referred to in the table as fluorine, in accordance with current practice in material analysis of glasses.

The actual ingredients in the glass-making batch consist of any material, oxide or other compound, which when melted together converts into the desired oxide in the exact proportions.

Approximately 2500 grams of batch ingredients were mixed, placed in a platinum crucible, and melted at 1500° C. for 4 hours. The melt was shaped into 1 cm thick bars and then transferred to an annealing operation at 600°C.

Although the compositions given as examples in Table I represent studies conducted in the laboratory, the example compositions according to the composition parameters of the present invention are suitable for conventional processing of melt forming glass on a large scale. Can be melt-molded using equipment. Table 1 also shows the R index corresponding to each composition.

Table 1 St 0266.066.965゜986.765.2
85.5611i, 7A exemption 2O33. B 3.53°7
4.33.83.73.8MgO13.713.413
．． 913.514.313.613.8CaO6,26
,48,46,46,36,95,4Nano 2.3
204.24 in 2.22.52.22.42.32.3
．． 13.83.84.34.34.2BaO1,01,
01,00,91,01,01,1p2o,1.11.
01.2O, 71.21.21. ．． 2AS2O30.2
5-------- Fe2O30.16-------- F 2.62.52.72.92.62.62.6R
0.72O, 710, 780, 870, 750, 740
, 77 Table ■ (continued) A9J2O33.5 3.9 5.0 5.0
3.8 5.0 3.4Mgo 13.8
13.6 13J 13.3 14.6
13.6 14.6CaOG, 8 6.8 6
．． 4 B, 4 5.0 B, 5 7. lN
2O in a2O1,92,32,22,22,32,22,3 3.1 4.1 3.4 3.4
3.5 4.1 3.9BaO1,0--0,9
0,91,00,9P2O5 1.5 1.2
− − 2.1 1.0 1.5
F 3.0 2.6 3.0 3.
0 3.5 2.7 3. OR1,00,800
,890,890,980,950,79A exemption 2O3
2. B 3.4 3.8 3.7
3.7MgO 13.6 13.3
12.8 13.8], 3.5Ca
O6,26,26,3B,3 6.4Naz O
2O to 2, 22, 12, 22, 73, 2 4.
1 4.1 4.3 4J 3
．． 5BaO0.90.9L, 0 1.0
Q, gP2O5 1.0 1.0 1
．． 2 1.2 1.4F
2.7 3.5 2.7 2.7
2.6R0.570,710,770,700,7B
To determine the resistance to thermal deformation of each composition, a length of 9
Measure and cut a rod measuring 5cm wide, 1cm wide and 5M thick from the annealed glass rod. The rods are then placed on ceramic supports with a spacing of 0.8 cm and placed in an electric furnace operating at 72O<0>C. The temperature is then increased to 800°C at a rate of approximately 0°C/min. The temperature is then increased to 1000°C at a rate of approximately 6°C/min and held at this temperature for 15 minutes. Next, the electric current to the furnace is turned off and the furnace is allowed to reach 800° C. at an appropriate speed (approximately 0° C./min). The sample is then withdrawn from the furnace.

Table 1 shows the results of various measurements performed on crystallized samples.

For example, the degree of sagging experienced by a bar with a thickness of 5 ml/lJ was measured. Experiments on thermal deformation experienced by a 28 cm table plate showed that a heat sag of 0.75 mrn in the above test was the maximum that could be tolerated to crystallize the plate as is without the use of a former.

Opacity is inversely proportional to the diffuse transmittance of a 2.75 cm thick crystallized sample. The diffused transmittance shown in Table 3 is shown on an arbitrary scale. On this scale, English Wedgwood porcelain exhibits a diffuse transmittance that falls within the 90-1100 interval. Diffuse transmittance was arbitrarily evaluated to have to be below 160 which is acceptable for table products.

Modulus of rupture (MOI?) was measured on polished samples using conventional techniques. The value is shown in MPa.

The opalization liquidus temperature (Opal), ie the phase separation liquidus, in °C was estimated by the amount of light reflected by the glass during cooling of the melt. At that temperature, Pa,
The viscosity of the glass indicated by s was measured from a viscosity curve obtained by measuring a melt in a conventional manner.

The crystallization liquidus temperature (cryst), expressed in °C, was measured by a conventional method. The samples were subjected to isothermal treatment and then observed with an optical microscope. Again, the glass viscosity expressed in Pa and s at that temperature was determined as SF3 from the conventional viscosity curve measured with glass.

Table ■ Diffuse transmittance 130 153 150 109
145 141 160~IOR83-83--
- ○pal nnlselfl, ξ [Shiba: -1160-122O
---Viscosity 600-22O
- - -Cryst.

-122O-1240--- Viscosity 2O0 - 160 -
- - Diffuse transmittance 60 138 150
100 - 100MOR7B ----76 pa1 Company 138012O0-12O0-1240 Viscosity
30 240 - 280 - 140
Cryst.

;122O122O-1240-1240 viscosity
160-160-140
Diffuse transmittance 165 31B 242 275
295254MOR83-----pal 叡124011401280-, -- Viscosity 9O-90---Cryst.

Company 122O---- Viscosity 12O - - - -
One example 1 is almost similar in color to English Wedgwood porcelain. In the measurement of diffuse transmission using a white background on a sample with a thickness of 3.8 mm, for Example 1, x-0,
3135, Y-OJ233, Y-86%, and x -0,313 for a sample of British Wedgwood porcelain.
9, V-0,3232, Y-86% color copinate (Illuminant C) was provided.

Examples 1-7 fall within the preferred composition range.

Examples 8-14 fall within the operable compositional range, but outside the preferred range. Examples 15-19 are outside the specified range.

To be precise, the Aaz 03 content of Example 15 is too low.

The F content of Example 16 is too high. The amount of MgO in Example 17 is insufficient. Each of these examples exhibits excessive heat sag and strong diffuse transmission.

The total content of 2O in Na Z O+ is too high in Example 16, and the content of Na2O2- in Example 19 is too high.

These two examples exhibit strong diffuse transmission.

Claims (1)

[Scope of Claims] 1) Potassium fluoride richterite essentially constitutes a single crystal phase, has a rod shape of 9 cm x 1 cm x 5 cm, and has a 6.8 c.
SiO_2 61-70 Na_2O 1.5-3 Al_2O_3 2 which exhibits sag of 0.75 mm or less at intervals of m during the crystallization heat treatment, is substantially free of Li_2O, and is expressed in weight percent based on oxides. .75-7 K_2O 2.5-5 MgO 12.5-16 Na_2O+K_2O <7 CaO 4.75-9 F 2-4 A highly crystalline glass-ceramic product characterized by having a composition containing as a main component. 2) Glass ceramic products are SiO_2 63-68 K_2O 3.5-4.75 Al_2O_3 3-4.75 Na_2O+K_2O
<6.75 MgO 13-15 BaO 0.25-1.25 CaO 5.25-7.5 P_2O_5 0.5-1
．． 5. The glass-ceramic product according to claim 1, the main component of which is 5Na_2O2-2.75F2.25-3.25. 3) Glass-ceramic products have an additional 0.5% Fe_2
O_3, and CeO_2, CoO, Cr_2O_3,
CuO, MnO_2, NiO, TiO_2, and V_
2. The glass-ceramic product according to claim 1, containing up to 1% in total of at least one metal oxide selected from the group consisting of 2O_5. 4) Can be directly crystallized in 2 hours to form a highly crystalline glass-ceramic product containing potassium fluoride richterite essentially as a single crystalline phase, measuring 9 cm x 1 cm x 5
cm rod-shaped, exhibiting a sag of 0.75 mm or less at 6.8 cm spacing during crystallization heat treatment, and said glass-ceramic article is essentially free of Li_2O, expressed in weight percent on an oxide basis; SiO_2 61-70 Na_2O 1.5-3 Al_2O_3 2.75-7 K_2O 2.5-5 MgO 12.5-16 Na_2O+K_2O <7 CaO 4.75-9 Having a composition mainly composed of F 2-4 A thermocrystalline glass characterized by 5) The glass ceramic is SiO_263-68 K_2O 3.5-4.75 Al_2O_3 3-4.75 Na_2O+K_2O
<6.75 MgO 13-15 BaO 0.25-1.25 CaO 5.25-7.5 P_2O_5 0.5-1
．． 5. The thermocrystalline glass according to claim 4, which contains 5Na_2O2-2.75F2.25-3.25 as a main component. 6) Fe_2O_3 with additional 0.5% glass, and CeO_2, CoO, Cr_2O_3, CuO, MnO
The thermocrystalline glass according to claim 4, containing up to 1% in total of at least one metal oxide selected from the group consisting of V_2O_2, NiO, TiO_2, and V_2O_5. 7) containing essentially caulimu fluorinated richterite as a single crystalline phase, in the form of a rod measuring 9 cm x 1 cm x 5 cm; 6.
In a method of manufacturing a highly crystalline glass-ceramic article exhibiting during a crystallization heat treatment a sag of 0.75 mm or less at intervals of 8 cm, the article comprises: (a) essentially free of Li_2O, expressed as weight percent on an oxide basis; and SiO_2 61-70 Na_2O 1.5-3 Al_2O_3 2.75-7 K_2O 2.5-5 MgO 12.5-16 Na_2O+K_2O <7 CaO 4.75-9 Vitrification mainly composed of F 2-4 melting the batch; (b) cooling the resulting melt to a temperature below the transition range and simultaneously forming a glass-ceramic article of the desired shape; and (c) leaving said glass article intact to promote crystal growth. A method for producing a highly crystalline glass-ceramic product, comprising the steps of holding the product at a temperature of 950° to 1050°C for a sufficient period of time. 8) The glass ceramic is SiO_2 63-68 K_2O 3.5-4.75 Al_2O_3 3-4.75 Na_2O+K_2O
<6.75 MgO 13-15BaO 0.25-1.25 CaO 5.25-7.5 P_2O_5 0.5-1
．． The method according to claim 7, wherein the main component is 5Na_2O2-2.75F2.25-3.25. 9) In addition, the vitrification batch contains up to 1% by weight of As_2O
The method according to claim 7, containing _3 and/or Sb_2O_3. 10) A method according to claim 7, wherein the vitrification batch further contains a small amount of oxidizing agent. 11) The method according to claim 7, wherein the time for holding at the temperature of 950° to 1050°C is at most 30 minutes. 12) Furthermore, the glass ceramic contains up to 0.5% Fe.
_2O_3, and CeO_2, CoO, Cr_2O_
3. The method according to claim 7, further comprising at least one metal oxide selected from the group consisting of CuO, MnO_2, NiO, TiO_2, and V_2O_5 in a total amount of up to 1%.