JPS6021931B2 - tempered glass products - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a new glass material and a method for producing the same which can be used in cases where thermal shock would destroy conventional or ceramic materials or where high strength irrespective of temperature is required. In this specification, glass is meant to include both fully transparent glass and partially opaque glass (eg, ceramics). Ceramics have long been considered useful materials because of their ease of manufacture and relatively low cost. However, the two most important drawbacks are the inability to withstand thermal shock and the relatively low strength. This applies to many structural materials such as cooking utensils, stove lids, radar domes, windshields, windows, containers such as pipes and tubes, and storage or reaction vessels for high temperature operation of chemical substances. This limits its use as a A common approach to overcome the drawbacks to thermal shock has been to use or develop ceramics with low coefficients of thermal expansion. There are currently three viable paths. '11 Use of pure fused silica■ Use of Vecor Note

[3] Note on the use of glass-ceramics - Coming Glass Co.
．． ) The third path is suitable for increasing strength. Each of the three paths above has its drawbacks. The first two have such poor modulus of rupture that they are not used in many applications. The third avenue (glass-ceramics) all have desirable thermal strength properties, but rely on fairly complex manufacturing processes, resulting in relatively high costs. The primary object of this invention is to provide a new glass material with desirable thermal strength properties and a method for producing it economically. The desired properties are as follows. [1} Bicol, fused silica, Pyrex
x) Higher rupture coefficient than Note and many other glass materials'
2) Low coefficient of thermal expansion, smaller than Pyrex; 3) Superior high temperature properties than ceramics and glasses like Pyrex; Controllable appearance, which can be manufactured into transparent, opaque or a variety of colors; 5) Relatively low cost. [6] Cooking utensils that require a high strength/weight ratio, chemical inertness and high operating temperatures;
Can be used in stove lids, radar domes, storage tanks, pipes, etc. Note: Pyrex is a registered trademark of Corning Glass Co. A low-cost method of manufacturing glass with high silica content (and therefore low coefficient of thermal expansion) is used in hoods. and others(
It was first developed by Nippon Etal. This is US Pat. No. 2,106,744 and 22,150.
No. 36. In this method, a shelf-sodium silicate glass that can be formed into a desired shape is heat treated so that it can undergo phase separation with a fine structure. The alkaline shelf salt phase is ionic and soluble in acids such as HCI. On the other hand, the other phase mainly consists of covalent bonds containing a small amount of &03 and is not soluble in HCI. Therefore, the alkaline salt phase is removed by acid leaching and
What remains is a skeleton rich in silica. In Hood's method, this silica skeleton is heated to a glass transition temperature Tg (approximately 950 pm).
) The bubbles are destroyed by heating to temperatures around ), yielding a low expansion, homogeneous glass with high silica content, good chemical durability, and high temperature serviceability. The inventors have already discovered that glasses capable of phase separation can be converted into porous bodies. This pore. A porous body can be converted into a solid glass body having a uniform or non-uniform composition cross-section in one cross-sectional axis by adding a modifying component to the porous material and causing bubble collapse to form a solid glass body. The present inventors have developed a method for adding essential ingredients to such compositions using molecular stuffing.
g). The inventors have demonstrated that such a method is applicable not only to the filling of porous matrices produced by reaching phase-separated glasses, but also to other internal channels having a matrix consisting of at least one glass network former. It has been found that the present invention can also be applied to vented porous structures. A known method of forming internal lotus-vented pore structures other than phase separation is chemical vapor deposition. Such methods are described in US Pat. Nos. 2,272,342 and 2,326,05y. In particular, US Pat. No. 3,859,073 shows the formation of a porous body and its subsequent impregnation with a dopant. In this invention, molecular packing is used to improve the strength of glass materials by introducing a compositional distribution across the thickness of the glass that in turn imparts increased heat-strength properties in the longitudinal section. Hereinafter, in this specification, such a composition distribution designed to enhance the thermal shock resistance and mechanical strength of the glass material will be referred to as a "strengthening distribution." There are three methods for creating a reinforcement distribution within a glass material according to the present invention: 1 First method using this invention (hereinafter referred to as Tg method)
Now, the distribution of the glass transition temperature Tg is created. Such a composition distribution is shown schematically in FIG. In the figure,
B is a silica phase doped by molecular packing,
A is an undoped, relatively pure silica phase. Many cross-network modifiers function to lower the glass transition temperature, Tg, when dissolved in pure silica. Tg of relatively pure silica region A and doped silica region B
The difference is determined by thermal expansion, so the 2
This has some effect on the volume-temperature curve of the two compositions. (In fact, the small amount of Zhen-03 present in glass A is sufficient to suppress the negative expansion castle observed above the Tg^ of extremely pure silica. Therefore, in the following, glass A is referred to as doped glass B. (It is called pure silica only when compared.) As shown in Figure 2, when the material in Figure 1 is cooled from the liquid state, the pure silica composition A on the surface passes through the glass transition point T&. It becomes hard and the coefficient of thermal expansion decreases significantly. However, the internal doped silica composition B has Tg
It continues to shrink due to the liquid expansion coefficient up to temperature B, becoming a solid glass with a low thermal expansion coefficient at the T saddle. Temperature range [
In the soft or T-axis, the differential expansion between the surface and the interior has the effect of placing the surface under compressive stress. This compressive stress must be resolved before the surface fails. In this way, the Tg distribution obtained by molecular packing of silica results in reinforcement of the silica surface. 2 In the second method using this invention (hereinafter referred to as the expansion coefficient method), a distribution of expansion coefficients is created. The dopant in part B of Figure 1 does not change the glass transition temperature Tg, but it does change the coefficient of expansion of the glass, i.e. when the sample is cooled from the glass transition temperature to room temperature, part B contracts more than A; resulting in compressive stress. This stress will increase the rupture modulus of the sample. (See FIG. 3) 3 In the third method (hereinafter referred to as the mixed method) using the present invention, the Tg distribution and the expansion coefficient distribution are created simultaneously. A mixed method is therefore a combination of the above two methods. The molecular packing reinforcement method of this invention has some similarities with chemical tempering by ion exchange, but there are significant differences. In the chemical tempering method, as ion exchange occurs, a concentration distribution and a compressive stress distribution are created at the same time. Unfortunately, this method also limits the thickness of the reinforced surface layer due to the fact that the rate of surface stress resolution due to viscous flow eventually exceeds the rate of stress generation due to diffusion. This limits the thickness of the compressive stress zone and, as a result, chemically tempered ceramics are susceptible to scratching. In molecular packing, concentration distribution and surface stress are introduced in separate steps. Therefore, there are no obstacles to producing thick surface layers. This allows the glass to retain its strength even when subjected to deep scratches. In addition to increasing the strength of glass products, this invention can be used to control the appearance. For example, if a dopant that does not readily dissolve at solidification temperatures (discussed below) is added, a sample with a milky or opalescent appearance will be obtained. Such dopants are soluble, such as oxides of aluminum, alkali metals, titanium, chromium, zirconium and zinc.
It is a thick oxide. If color is desired, transition metal or rare metal ions can be used. For example, under oxidizing conditions, copper and iron turn the sample blue and brown or yellow, respectively. Under reducing conditions, copper and iron also make the sample red and green, respectively. Generally, cobalt makes the sample blue and neodymium makes it purple.
To obtain a bonito-colored appearance, elements that donate free electrons could be used. These are, for example, germanium, tin, lead and bismuth, all of which are used in a reducing atmosphere. In addition, the presence of colloidal metal deposits of precious metals will create various smoke color shades. In any method for forming the glass products of this invention, the formation of the porous matrix constitutes a value-adding step, but losses (e.g. breakage) after this step are would reduce economic yield. It has also been difficult to identify the factors leading to losses resulting from fractures, such as the formation of cracks and the appearance of bubble-like, light-scattering centers within the final product. In order to obtain increased yields and satisfactory and reliable control of the refractive index, we hereby demonstrate that the previous steps require operating in a special manner and sequence that has not yet been shown. The method was improved. In terms of yield, as in the production of conventional glass products, changes in methods do not necessarily result in a product without defects, nor do they guarantee that all such products will remain unbroken until subsequent processing steps. It is. The increase in yield means that the inventors have found a way to improve the statistical chance that glass ash or other glass products will remain unbroken until subsequent processing. However, this means that statistically acceptable products cannot always be guaranteed even when all the basic steps of the invention are employed. As already pointed out, the improvement lies not only in terms of yield, but also in ensuring that the desired refractive index profile is obtained to a satisfactory degree. This is mainly based on the following findings. That is, to obtain the best results, the step of depositing the solid material into the pores should be carried out in a manner that does not involve evaporation of the solvent, and the product should be prepared so that the subsequent heating step removes the solvent from the pores. It is essential to increase the temperature and, if necessary, the deposit should be adjusted so that the desired refractive index profile is achieved. The inventors have also found that certain dopants give particularly advantageous results due to their physical properties while achieving satisfactory products. and leaching, special care should be taken to reduce losses during processing of the glass rod.
The present inventors have found that cracks in the product occur due to one of the following factors. 'a - Inaccurate glass composition; b' Inaccurate heat treatment conditions for phase separation; and 'c' Inaccurate leaching. Guidance is given below on how to select operating conditions to reduce losses due to cracking and drying. This invention relates to a method of producing a desired distribution of reinforcement in a glass article as a function of its dimensions by adding strength modifying components (hereinafter referred to as dopants) to a porosity matrix having lotus vents. The method includes the steps of immersing a porous matrix in a solution of dopant, separating the dopant within the matrix, removing the solvent (if necessary, and decomposition products) from the matrix, and collapsing the porous matrix. It consists of a step of forming into a shell, and the special features of this method are 1.
Part or all of the dopant is precipitated by a method that does not involve evaporation of the solvent, and solvent removal is not initiated until after substantial formation of the solvent and removal of the solvent (if necessary, and decomposition products). The heat supply rate is adjusted to achieve and/or maintain the desired strengthening distribution within the glass article. The sequence of steps to obtain a particular reinforcement distribution is outlined below. The entire process begins with a porous product that has through-holes. That is, the steps are as follows. The '1' dopant is deposited into the pores by a non-evaporative process. This precipitation consists of [a' thermal precipitation, which reduces the solubility of the dopant or dopant compound in the solvent by lowering the temperature enough to cause the dopant or dopant compound to precipitate, and [b' changing the pH of the solution to the point of deposition]. to let;
Chemical deposition, such as replacing the original solvent with a solvent in which the dopant or dopant compound is only slightly soluble, or introducing a chemical that reacts with the dopant or dopant compound to form a less soluble dopant species. Contains. From now on, the term solvent will be used to denote a chemical species that is at some stage a liquid that fills the pores. ■
Final solvent removal begins only after deposition is nearly complete. '3' The rate at which heat is supplied to remove the solvent (and decomposition products if necessary) is adjusted to achieve and/or maintain the desired reinforcement distribution within the glass article. An outline of steps and groups of steps suitable for producing a stepped distribution (see Figure 4a) and a continuous distribution (see Figure 4b) is shown below. The process starts with a porous product and uses a thermal product of the dopant or dopant compound. Staircase distribution '1}
'a- Immersing the porous matrix in a solution of the dopant or dopant compound. {b} Depositing the dopant by lowering the temperature. 'c} Immersion in a solvent for the dopant to partially redissolve and diffuse the dopant from the matrix. (
Only the dopant that has settled near the outer surface of the product is removed in this step. )'d} Step of evaporating the solvent. 'e} Process of heating to a temperature that collapses the pores. or ■ {a} Immersing the porous matrix in a solution of the dopant or dopant compound. 'b} Process of mirroring the dopant due to temperature drop. 'c' Partial drying of the porous glass rod. 'd
} The process of soaking in a solvent for the dopant and partially redissolving the dopant to diffuse it out of the matrix. (Only the dopant deposited near the outer surface of the product is removed in this step.) [e} Evaporating the solvent. 'f} Process of heating to a temperature that collapses the pores. Continuous distribution (a) Immersion of the pore matrix in a solution of the dopant or dopant compound. [b} Immersion in a solvent for the dopant at a temperature approximately equal to the temperature at which filling of the dopant into the pores occurs. The product remains in the solvent for a pre-calculated time. By repeating step B with varying dopant concentrations, the time history of diffusion is controlled to create the desired dopant distribution in the product. [d' Step of accumulating the dopant in the pores by lowering the temperature. [e- Step of evaporating the solvent. {f} Step of heating to a temperature that collapses the pores. As shown above, as a dopant It is preferred to use materials with solubility properties such that the desired concentration of dopant in the pores can be achieved by diffusing a solution of dopant into the pores at a certain temperature and then simply lowering the temperature and allowing the solution to accumulate. .Such a method is related to thermal accumulation.This method may be employed, but other methods may also be employed.Therefore, the present invention uses as a starting material:
With a suitable porous matrix, the strength modifying components are separated from the solution by lowering the solution temperature.
A method of manufacturing a glass article having a desired reinforcement distribution is included. As a method other than the thermal mirror method, there is a method in which the solute is precipitated by chemical means without relying on temperature drop. In this method, the common ion effect is used to reduce the solubility and deposit the solute (e.g. CsN03
The water solubility of decreases in the presence of 1N HN03. ). Reduction in solubility can also be achieved by exchanging the solvent, thus allowing deposition to occur in a manner that does not involve evaporation of the solvent. These methods include the addition of a suitable precipitating agent that reacts with the dopant or produces an appropriate change in pH. It is also possible to use a method that combines the steps of both thermal deposition and chemical deposition means.
This method is particularly useful when one or more dopants or dopant compounds are introduced into the pores. The present invention avoids any settling procedure involving evaporation of the solvent as a sole secondary procedure. This is because such methods do not yield consistent results. In direct evaporation methods, the solution evaporates from the surface of the product, causing the dopant to migrate from the surface into the interior. There is also a gravity-based vertical displacement method that deposits the dopant at the bottom of the product. Both of these effects tend to produce unfavorable distributions. It is fundamental to adjust the heating rate to avoid destroying the initial reinforcement distribution or damaging the lotus vent structure. Creating sufficient pressure to destroy intact structures is possible by generating steam or gas in an uncontrolled manner. Therefore, it is better to avoid letting the temperature of the solvent reach the boiling point where a large amount of vapor is likely to be generated. Various heating ranges and methods of controlling the heating to reach the desired results are shown below. Control of the solvent removal process is necessary to avoid undue destruction of the pore structure. i.e., initiating solvent removal at room temperature or below using a lock-proof method, and avoiding rapid changes in temperature that would cause excessively rapid generation of solvent vapor in an enclosed space. It is necessary to take precautions such as: The usual solvent removal method when the solvent is water is to place the product in a desiccator at about 2°C for about 2 hours, or at a temperature slightly above 0°C (
For example, by placing the product in a vacuum for about 4 hours (at 4° C.) and then increasing the temperature. Also, in some cases, the heating rate is maintained or reduced to a very low value so that the product remains within a certain temperature range for a sufficient period of time to ensure the continuation of the particular result that occurred before heating. I found it necessary to do so. In other respects, it may be preferable to move rapidly from one temperature to another, such as a temperature at which solvent removal is complete and pores are collapsed. Later in this specification, guidelines for aqueous systems are given, which are:
Something that is equally applicable if organic solvents or other non-aqueous systems or mixtures of such systems are used.
The following criteria can be adopted to select an appropriate dopant from among a large group of intensity-modifying components. {a' The dopant must be soluble in the solvent at an appropriate concentration so as not to adversely affect subsequent steps after filling. (b- The dopant must be capable of coalescing with the matrix either as a precipitate or as a subsequent thermally generated decomposition product. {c} The dopant must be capable of being lost from the matrix before the pores collapse. The physical or chemical state shall not change. Legs For high strength, the following additional conditions apply:
'11 When adopting the Tg method to create reinforcement distribution,
The dopant must be one that reduces the glass transition temperature of the porosity matrix. [21] When employing the expansion coefficient method to create a reinforcement profile, the dopant must be one that increases the expansion coefficient of the porous matrix. [3' When adopting a blending method to create a reinforcement profile, the dopant must be one that decreases Tg and increases the expansion coefficient at the same time. Since high light transmission is not required in this invention, compounds of many elements can be used as dopants. For example, there is no limit to the selection of dopants to create a Tg distribution. Two useful dopants are N and &03, which lower the Tg of the matrix by 80° C. and 4 pi, respectively. Other dopants that can be used to create the Tg distribution include oxides of lithium, potassium, shelmetium, phosphorus, germanium or phosphorus, or chlorides, silicates, shelmets, phosphates or germanates. There are salts such as, but not limited to. There are many dopants that can be used to increase the thermal tonicity of the matrix. For example, cesium oxide increases the coefficient of expansion of the matrix by 0.76 per mole percent. Other dopants that can be used include, but are not limited to, oxides or salts of heavy metal elements such as barium, lead, thallium, bismuth, thorium, and uranium. In addition, oxides or salts of elements such as rubidium, strontium, antimony and tin can also be used. Other dopants and dopant compounds can also be used as long as they meet the above criteria. It is not possible to list all combinations of dopant elements, however, such selection of useful combinations based on the guidelines provided is considered to be within the established criteria. When choosing a solvent, it is necessary to consider the following: 'a} A solvent that does not damage the porous matrix. [b} Solvents that can be substantially removed by pyrolysis accompanied by displacement with other solvents, evaporation, or oxidation (or high temperature reaction with a chemically active atmosphere). 'c} To achieve the desired level of dopants in the pores carried out by molecular packing,
A solvent capable of sufficiently dissolving a dopant compound or a combination of dopant compounds. 'd} When using the thermal deposition method, the dopant solution is
Such solvents have a sufficiently high temperature dependence of solubility to cause subsequent accumulation of dopant within the pores when cooled. [e' A solvent that, when used for overburdening by a solvent displacement method, has the special solubility properties required by the method. 'f' A solvent that is economically low cost and can be dried quickly. Although it is not possible to test all solvent combinations,
However, it has been found that solutions of water, alcohols, Kents, ethers, mixtures thereof and salts may be used, meeting the above solvent selection criteria well. In general, for reasons of ease and convenience, and the first step of the post-doping solvent removal step, it is better to carry out at or below room temperature, so there is usually no need to cool the pore-filled product. Therefore, it is better to adopt thermal deposition method. Preferably, the dopant used is water soluble, and the substance is highly soluble at temperatures on the order of 100 qo such that upon cooling to room temperature or below, a substantial amount of the substance separates, thus steep solubility coefficient (steepsolub) as appropriate for target deposition.
Preference is given to those having a rudder mcjent). More detailed guidance regarding solvent selection is provided by reference to Table 1. Table 1 shows the solubility of dopants in solvents at various temperatures. As already indicated, a number of guidelines need to be taken into account in selecting a scheme to obtain the desired result, and these can therefore be illustrated with reference to Table 1. First, in order to obtain the desired dopant concentration in the product that gives a significant increase in strength, a solution with a sufficiently high concentration of dopant must be found by appropriate selection of dopant compound, solvent and temperature. . In order to subaccumulate the dopant or dopant compound,
It is necessary to use a solvent with sufficiently low solubility. There is also a current need to remove substantial amounts of dopant from designated areas of the product, such as in the armor pouch of glass products, in which case solvents with intermediate solubility are useful. Such dopant removal, as opposed to molecular packing, is called unstuffing (stMfing). Hereinafter, this will be referred to as de-dopantization. Appropriate control of solubility for accurate deposition of dopants or dopant compounds can be achieved in a number of ways. ○'
For solvents in which the solubility of the dopant or dopant compound is highly dependent on temperature, thermal deposition methods are most appropriate. Thermal product method has the additional advantage of being able to block diffusion in the shortest time, thus making it possible to determine the desired composition distribution with a high degree of accuracy. This is shown in Table 1 when the dominant is CsN03. There, the solubility varies from the desired filling level at 95°C to 4°C.
℃ to the desired level of dopant removal. '21 Pillow product and thermal product due to common ion effect. The order product is caused or further enhanced by common ion effects. For example, when the dopant is a nitrate, the concentration of nitrate ions in the solvent solution is increased by adding another source of nitrate ions to the solvent (eg, nitric acid). This reduces the solubility of the nitrate dopant. (See CSNO in Table 1)
{3} Deposition by solvent displacement. Precipitation occurs by replacing a highly soluble solvent with a less soluble solvent. The high solubility of nitrates in water allows water to be used as a solvent for filling operations. Replacement of the water with an alcohol, ketone, ether or combination thereof resulted in the formation of the dopant. Typical solubility is shown in Table 1. {41 Change in dopant compound. The solubility range of the dopant compound can be varied by selecting different anions. For example, CsN
The solubility in water can be increased by replacing 03 with Cs2(C03)2. (See line 7 of Table 1) Table 1 Solubility 1-Projetyl Temperature Compound 9/100 Slight Solution Day 20 Methanol Ethanol Panole Mo'N03 (℃) 1.0SN〇3 >100
100 green onions
>952. 〃 10 100%

43. ″ 4
1 stipulation
44. 〃 1 30% 70
*45
・0sN〇3 10 70* 30 shots
226.
〃 1 15* 85*
227.0s200
3 >100 100%
228-〃
10 95%
5* 229. 〃
1 After 52 48%
2210・Pb(Japanese○3)2
>100 100%
>7011. 〃 1
0 30% 70%
2212. ″15%
95*
2213. La(N〇3)3 >100 100%

2214. ″ 10
15% 85%
2215. ″ 1
10 grandchildren 90 case 2
216-Nd(N〇3) 20
10% 90% 2217
- 〃 1
7 shots 93% 2218.
Ba(N03)2 32 100%
9519.
〃 10 100*
2220.
〃 5 100*
021. AI
○3)3 63.7 100 grandchildren
2222-day 3B〇3 27.6 100%
10023-
〃 6-35100%
22 As already pointed out, when carrying out the method of the present invention on the porous through-hole structure formed by phase separation and subsequent leaching of suitable glasses, it is possible to achieve salable purposes with good economic yield. In order to achieve a consistently satisfactory product, it is necessary to optimize the various stages of the method and to find correlations between the various parameters at each stage. The guidance needed by those skilled in the art is based on the following steps. m Selection of glass composition and heat treatment to obtain proper phase separation. '2' Leaching and washing. {3' stuffhng '4} Dopant removal (if necessary). ■ Drying and solidification. The guidelines given in steps 3-5 apply to all matrices, not to matrices made from phase-separated glasses. Glass composition and heat treatment time and temperature In order to obtain a satisfactory product, the glass composition must be separated into equal volume ratios when heat treated at a specific temperature, and when maintained at that temperature, a glass composition with the desired pore size should be obtained. It is necessary to select a phase-separable composition that provides a structure. Much guidance can be given to those skilled in the art in that regard. Thus, the inventors have found it convenient to select such compositions from alkali metal shelf silicate glasses. Further guidance regarding suitable compositions is then provided, as discussed below. A number of compositions suitable for use in the production of porous glasses for various purposes have been reported (see U.S. Pat. ), but they are not usually intended for strengthening by methods based on phase separation and IJ coaching of the soluble phase. The inventors have discovered that only a narrow range of known compositions are suitable for reinforcement purposes.
One representative such composition is shown in US Pat. No. 3,843,41, which is often undesirable. For example, a number of known glasses within the preferred range of U.S. Pat. No. 41, and shown below, were drawn perpendicularly to an 8 rib diameter bar at a rate of 1 inch per minute. Although these glasses phase separated, all of the compositions in Table 0 cracked upon leaching. Table 11 Known composition Na20 B203 Si02 AI2038 that cracked during leaching
30 62 08 35 57 0 8 40 52 0 10 30 60 0 10 35 55 0 10 40 50 0 10 30 59 1 10 35 54 1 10 40 49 1 Note Numbers are mole%.In particular, the following was also found. . {11 As shown in U.S. Pat. No. 3,843,341,
All shelf sodium silicate glass compositions drawn into rods cracked during leaching. The same was true for the compositions within the composition range indicated as the preferred composition range in the above patent. ■ US Patent No. 374
Many of the shelf sodium alumina silicate glass compositions shown in No. 3341 cracked when processed as described above. The same was true for compositions within the preferred composition range. '
3} Many of the glass compositions in the preferred composition range shown in US Pat. No. 2,221,70y cracked when processed as described above. Many of the silica-based glass compositions mentioned above have proven unsatisfactory due to the need to ensure satisfactory yields of product. However, the inventors have discovered a wide range of useful glass compositions that have not yet been demonstrated. In addition, the inventors have discovered a set of criteria that can be applied to fix other specific ranges of phase-separable glass compositions that give satisfactory yields of product. From a commercial point of view,
Although almost all silicate glass systems exhibit a phase-separated composition range, it is most convenient to use shelf-alkali silicate IJ glasses because they exhibit a wide phase-separated composition range. In order to obtain a satisfactory product, it is necessary to select the composition as follows. '1' A composition that separates into two phases, a high silica phase and a low silica phase, by heat treatment. Preferably, the low silica phase is dissolved in a suitable solvent. ■
A composition that separates into phases with approximately equal volume ratios by heat treatment at a specific temperature, and when that temperature is maintained, it becomes Rentsu Microstructure. Glue A composition that melts easily and is easily purified by conventional methods. ■ A composition that is relatively easily molded and exhibits little phase separation during the molding process. Below, a systematic procedure for selecting a suitable composition is presented. [1' Almost all oxalic acid glass systems exhibit a compositional range of phase separation. However, shelf-alkali silicate glasses that exhibit a wide phase-separated composition range have commercial value. The low silica phase of glasses in this composition range can be easily dissolved by a single acid solution.
Also, it is now necessary to add pond components such as aluminum oxide to improve certain properties of these glasses. However, in phase separation, certain oxides are undesirable because they enter the low silica phase and are difficult to dissolve with a single acid solution. Thus, only those that do not substantially reduce the solubility of the low-silica phase are suitable other components. '2} After determining the glass system (along with the dopant), next we determine the compositional immiscible region C and its coexistence temperature Tp.
need to be determined. Tp (C) is a temperature equal to or higher than the temperature at which the glass (C) is uniform. Methods for determining Tp are described in the known literature. (For example, W. Haller, D. J. Bl.
ackb mountain n, F. E. WagSPffand R. J
．． “Na20-B203rSi02” by Charles
"Metastable, immiscible surfaces of systems" J. Amer. Cerem.
Soc 53 [1}, Kiichi 9 (1970)) [3] It is necessary for the present inventors to determine a composition C, which exhibits an equilibrium volume fraction of about 50% at at least a certain heat treatment temperature. I discovered that. Let this temperature be 9 (C,). The method for determining this temperature is as follows. 'a} Select three (or more) temperatures T, , T2, T3 (approximately 5 and 0 apart from each other). Insect <T2kuT, KuT. (C,) The temperature of the glass sample is T,,
At T2 and T3, heat treatment is performed for a long time until the color becomes white. [b--The volume fraction V(T) of one phase (the same phase was selected for all samples) of these heat-treated samples was measured using an electron microscope. {
c} A plot of volume fraction V(T) versus heat treatment temperature T was created. By interpolation (or extrapolation), the volume fraction is 50 (soil 5
)% (ie, To(C,)) was determined. [4
} After knowing Tp(C) and To(C,), it is necessary to determine the composition range (C2) within the composition range C, as shown below. {a) 575002T. (C2) 50 and 0 feet 750℃2Tp (C2) and 60
0:00 pm These temperatures are chosen to avoid long heat treatment times. Of course, other ranges can be selected if long-term heat treatment times of one week or more are acceptable. ■ The composition range C2 is further narrowed by the requirement that it be easily purified during melting. This requires that the viscosity of the melt at high temperatures must be sufficiently low. A narrower range of this C2 is defined as C3. That is, all glasses belonging to C2 are further properly refined. We have found, for example, that a convenient point of view for identifying glasses that can be purified is at least 28% B20
It has been found that glasses containing 3 can be satisfactorily purified. ■Although easily purified and phase separated at a volume fraction of 50%, the composition of C3 is not entirely desirable. That is, there is an additional requirement that the desired composition should exhibit little phase separation during the molding operation. The degree of phase separation during the forming process is influenced by the viscous properties of the glass at and below the coexisting temperature, the dimensions of the product being formed, and the cooling rate. In order to determine the composition C4, which exhibits little phase separation on cooling at and below the coexistence temperature, products with wall thicknesses of several orders of magnitude are
It is cooled at a slow enough rate to prevent the development of large thermal stresses. The degree of phase separation that occurs in these products can then be determined. Within the composition range C3 that does not undergo phase separation during the molding process, there is a composition range 4 that is more limited. A composition satisfying this condition preferably has a Tp of 710 to 600°C, more preferably 695 to I000. '7}
The final criterion is to ensure that there is sufficient compositional difference between the two separated phases for effective leaching. Therefore, only the composition C* that satisfies the following conditions within the composition range of C4 is selected. Tp(C*)-T. (C*)
Now that the desired composition range C* has been found, any composition Co can be selected. The heat treatment temperature and time for this particular composition of Co is determined by the following procedure. 'a- The Co heat treatment temperature is set equal to ~(Co), ie the temperature at which the volume fractions of the two phases are equal. If C* is chosen correctly according to the above criteria, this temperature is not so low that the time required to obtain a suitable microstructure for leaching becomes too long and uneconomical. Similarly, this temperature is not too high either. If it is too high, the following can be said. [1] Deformation of the glass occurs during heat treatment. [2] If the heat treatment temperature is 160 qo or higher, which is higher than the glass transition point, the phase separation will be rapid and the controllability of the phase separation will be poor. According to these requirements, the heat treatment temperature TH is preferably limited to the following range. 575q○>TH(C.)=T. (C.)>50,000 {bl T days (Co) was determined, so the heat treatment is determined by the conditions that provide a microstructure suitable for leaching. Heat treatments are carried out at different times. That is, ra (1 hour) < t2 (2 hours) < ra (3 hours), etc. The time tma beyond which the lotus suitability of the structure begins to fail
x can be determined by electron microscopy. The size of the phase that can be leached is determined by micrographs and the preferred heat treatment time is less than tmax, but the size of the microstructure at that time is at least 150A, preferably less than 300A. We applied the above criteria to shelf-alkaline silicate systems and identified certain features of the composition range that contribute to good yields of the final product and especially those with a certain thickness, such as phase separation during molding. Or problems arising from insufficient phase separation in the phase separation process could be overcome. Phase separation during molding of glass products from the melt, and insufficient phase separation or destruction of Rentsu's slow structure during phase separation heat treatment, are caused by the leaching process of the phase-separated glass and the drying process of the leached and filled glass. This results in cracking of the glass during subsequent steps such as. Here, it has become clear that the composition of the composition that provides the best yield falls within the wide range shown below. (All numbers are mol%) Wide range Preferred range S
i02 48-64 4 9.5-59B2
03 28-42 33-37th 20
4-9 6.5-8AI203
0-3 0-2.0〃 0
-1.0 0.20-0.8o
0-3 0-2.48 〇-
〇-5 〇之 ○・1-11〇
〇． 2-0. 8 In the table above, Q is AI20
3 concentration (mol%), x is p + (1'3) Q one, and p is relative ○/R20 (A20 is K20, RQO and C
The sum of the mol% concentration of s20, R20 is Li20, Na2
0, K20, RQO, and the total amount of mol% concentration of Cs20), and the input is the ratio Li20/R20. Since the presence of N203 in the glass affects the results,
First, we will discuss glass that does not contain N203. Under these conditions, the total amount of peak 203 in the range shown in the table is applied to R20, namely Li20, Na20, K20, RQO and Cs20, so that the wide range of p is 0.
1 to 1.0. If the concentration of K20 is zero, the upper limit of the range of p is 0.8. Lithium glass tends to become opaque, so its chemical (Li20
) is preferably not used. In this case, R20 is the sum of the concentrations of Na20, K20, Rb20 and Cs20. All other limitations and conditions remain. Rubidium and cesium glasses are more expensive than those made from sodium and potassium. They can be excluded from an economic point of view. At that time, R20 is the sum of Na20 and K20. All other limitations and conditions remain. When more than 0.5 mol of AI203 is present in the glass, R2
A wide range of 0 is between 6 mol% and 9 mol%. The most economically preferred composition with an AI of 203 is N
It is composed of R20 consisting only of a20 and K20, or R20 consisting only of Na20. The glass compositions shown in Table m were identified using the above criteria and were found to be satisfactorily used in the molecular packing method of the present invention. That is, these glass compositions provided satisfactory control of the pore structure after phase separation and bleaching, and good yields of the final product. Table plate ratio 57.7 35 5.7 0 0
0 1.6 0 1.6 0 0.53
X 56 36 4 4 0
0 0 0.50 0 0. 50 67
0 illusion 56 36 6 2 0 0 0 250 0
25710 dishes 53 38 8 0
0 0 1.0 0 1.0 0 33
681 Another key feature of this invention is the leaching of a shelf silicate glass that is capable of phase separation. Before leaching, leaching is carried out in order to remove dirt on the surface, or to remove the surface layer of the glass which has a composition quite different from the inside due to the volatilization of components such as 03 and N during molding. Approximately 1
It is better to apply sand etching. The concentration of the acid solution, the amount of the leaching solution, and the leaching temperature have no direct relationship to the progress of leaching. In leaching, it is fundamental to contact the product with a sufficient amount of leaching solution to dissolve the soluble phase. Leaching rate is usually controlled by adjusting temperature. The glass should be at a temperature above 80 qo, preferably above 90°C. Also, N
It is desirable to use an acid solution saturated with H4CI or an equivalent compound that can reduce the concentration of water in the acid leaching solution. Since the thickness of the outer layer swelled by the leaching treatment causes damage to the inner hardening layer, the use of the acid solution reduces loss due to cracking of the product by controlling the swelling of the hardening layer. It has been found that the rate of leaching, and the redeposition of shelf salts into the pores of the glass during leaching, can be regulated by controlling the concentration of shelf salts in the acid leaching solution. Glass combs (length: 0 ground, diameter: 8 sides) heat treated at 550 mm for 1 hour and 30 minutes with a leaching solution containing 327.3 nights of NH4CI, 33.6 M of HCI per night of water, and varying amounts of B203. , composition 57% Si02, 35%
&03, 4% Na20 and 4% K20), the leaching speed at 9yo was measured. As a result, it was found that when the amount of B2Q in the leaching solution increased, the leaching time became longer. The results are shown in Table W below. N 61.5 642±50 spots. 7 725 Sat 50106
．． 1 It is thought that reprecipitation of shelf salts into 11670±50 pores leads to destruction. This can be avoided, for example, by replacing the leaching solution with increasing shelf salts. However, this requires large amounts of leaching solution.
For example, in order to keep the leaching time from exceeding 60 ppm, 1550 ml of leaching solution is required per 100 mm of glass. However, this increases costs and also creates pollution. To this end, it has been found convenient to provide a cold trap so that excess material is continuously removed from the solution as it enters the solution from the product being leached. Cold traps are effective at speeding up the process even at temperatures several degrees below the glassware temperature. Preferably, the temperature of the cold trap is 20°C lower than the temperature of the glassware. When NH4CI is present, the acid solution
It is convenient to choose a cold trap temperature that continues to saturate. Without the presence of N-ratio CI or an equivalent compound in the leaching solution, glass rod breakage can be suppressed to a low level. However, since statistically there is an equally low level of glass twill failure when N ratio CI is present, the amount of NACI should be greater than or equal to 1% by weight, preferably 2% by weight. The most convenient method for determining the appropriate leaching time is to leaching the glassware and measuring the mass of the product at time intervals until little or no weight loss is observed. Leached products are usually washed with deionized water. Certain compositions of glass exhibit silica gel deposits within the pores, which can be removed by cleaning with NaOH. It has also been found that this deposition can be minimized by composition selection. The compositions in Table M alleviate this problem, especially those with at least 4 silica. If the porous matrix is produced from the already mentioned phase-separable glasses or by e.g. chemical vapor subthinning methods, the selection of appropriate conditions for filling and dedopuntation is
This can be done according to the guidelines shown below. The dependence of Tg or coefficient of expansion on the concentration of dopant or dopant compound can be determined by a literature review or by appropriate experimentation. These determine the optimal concentration of dopant or dopant compound required by the glass product. A sufficient amount of dopant or dopant compound must be dissolved in the fill solution to reach the desired concentration at a particular fill temperature and time. These parameters can be determined by the following procedure. '1} Determination of the filling temperature of porous glass products [a} Determine the dependence of the solubility of the dopant or dopant compound in a suitable solvent on temperature. (b) The filling temperature is between the temperature at which the solution of 'a' is saturated with the desired concentration of dopant or dopant compound and the boiling point of the solution. ■ Determining the filling time of porous glass products The filling time depends not only on the concentration, temperature and composition of the dopant solution, but also on the size of the microstructure of the porous glass product. The procedure given here is for a given set of dopant solution, temperature and microstructure of the glass rod. For changes in any of these variables, this procedure should be repeated or modified appropriately according to guidelines. [a- Measure the diameter (ao) of the porous glass rod and immerse it in the dopant solution. [b} Monitor the weight of the porous glass twill as a function of time. {c) Weight change of the feature with respect to time t y(t) = [n(
By plotting t)·n(〇)]/[n(o)-n(o)], the time to beyond which the weight hardly changes is determined. n(o), n(t), n(target) are the initial weights, respectively.
The weight at time t and the weight at infinite time (an extremely long time). 'd - With the same dopant solution and the same temperature, the time t required to fill another porous glass comb of diameter a is given by the following equation: t=shi[ki]2 Example A porous glass hakama was filled with a concentrated aqueous solution of CSNQ (solution 100 kites [per 120 min CsN03]) at 100°C. The radius of the glass twill was 0.42 skin. Weight increase as a function of time was measured. The results are shown in FIG.
It can be seen that after about 200 minutes, the weight of the glass skein hardly changes. Thus, a suitable filling time for this glass rod is about 4 hours. [31 Determination of the dedopant time to create a continuous distribution in porous glass products by the total amount of dedopant In order to create a continuous distribution, the filled glass products made in '21 were partially de-dopanted by diluting them in a solvent. Become a dopant. This needs to be done at a temperature that does not cause the dopants to heat up. The dedopantation time depends on temperature, microstructure and desired compositional distribution. For example, the procedure presented here is for a given filling temperature and parabolic distribution. [a} Dedopantation studies were performed at the temperature at which the glass rods were loaded by monitoring the weight change as a function of time while the glass rods were immersed in the solvent. 'b} Equation '1} was plotted against the feature change y(t). n(〇-n(〇)...[1} y(t)=n(target)-n(o)'c- The dedopant time to depends on the desired distribution. It is now in the following range. For distributions of other shapes, similar equations for y(et al.) hold.Example: Porous cells filled at 100 °C with a concentrated solution of CsN03 (solution 100% per 120% CsN03) A glass rod was selected. It was then dedopantized in 100° water and the weight loss was monitored as a function of time. The results are shown in Figure 6. The range of dedopantation times can be calculated from the graph. {4) Determination of the dedopant temperature and time for creating a step distribution by thermal deposition The dedopant temperature for a step distribution depends on the desired strength of the product and the dopant solution. Since the coefficient of expansion (or high Tg) of the surface layer should be as low as possible, the dedopant temperature is typically a few degrees above the freezing point of the dopant solution. The time required for dedopantation depends on the thickness of the surface layer to be compacted, as well as parameters such as the dedopant temperature, the concentration of the previously used filling solution and the size of the microstructure of the porous glassware. Here the procedure is based on a predetermined set of these variables. If the values of any of these parameters change, the entire procedure will need to be repeated and adjusted according to this guideline. If the desired surface layer thickness is d and the wall thickness of the product is a (>d), then the following equation holds. Y=4
No. [1-(No. g)] g is a geometric factor, and when g = 1, it is cylindrical, and when g = 0, it is flat. By knowing Y, you can correctly determine the dedopant time by following the steps below. (a) A study of dedopantation in a desired solution at a desired temperature was carried out by monitoring the weight change y(t) of the charge as a function of time. (b 'We plotted the change in weight of the feature (formula m) with respect to time. 'c - From the above plot, the time to when y (ra) = Y
I found out. This is the desired dedopantation time. The practical application of the dedopantization procedure is often to reduce the dopant concentration in the outer layer of the product so as to obtain the desired reinforcement distribution. As mentioned above, this means that, for example, if the actual filling is 9yo
by replacing the dopant solution with a dopant-free solvent at the same temperature, or by replacing the dopant solution with water or dilute nitric acid if the system is aqueous. This can be done by At that time, the dopant tends to diffuse outward, so
The dopant concentration in the cross section of the porous matrix varies. Of course, the time required for dedopantation depends on the volume to be treated, but in the case of a glass product with a thickness of 8 mm, about 20 to 3 G minutes are required. Then, it is preferable to stop the dedopantation by replacing the solution surrounding the glass particles with the cold solvent. Alternatively, in the case of water-soluble systems, nitric acid cooled with water or ice at a temperature near the freezing point is used. In the case of water-soluble systems, it has been found that the endpoint can be controlled by measuring changes in the electrical conductivity of the water used for dedopantation. [5- Drying or Solvent Removal Drying has two problems that affect the economics of the process and the quality of the product. These are cracks in the porous glass structure and changes in the dopant composition distribution. The occurrence of cracks is a statistical problem,
Despite the drying procedure, samples may remain during the process. However, in order to operate the process on a commercial scale, it is necessary to employ procedures that minimize cracking and improve process economics. Such procedures should be such as to prevent dopants from migrating from within the product to the surface resulting in undesirable dopant distribution. Due to the movement of the dopant, the dopant concentration in the central region decreases and the refractive index in the peripheral region increases.
As mentioned above, the resulting dopant distribution is dependent on dedopantation. Since an appropriate dopant distribution has been obtained in the presence of a solvent in the pore structure, it is essential to dry, that is, remove the solvent, without changing the dopant distribution to an undesirable state. A breakdown of the drying process revealed that there are many factors that influence this process. They are shown below. [Generation of a' gas The gas generation sources are the solvent, the dopant decomposition product, and the dissolved gas. If gas evolution is rapid due to rapid heating or insufficient gas removal, the differential pressure created within the pores can destroy the glass and/or transport dopants from inside the glassware. Resulting in. {b} Most of the size-changing solvent is removed from the porous glass, but the solvent layer attached to the surface remains chemically bound to the surface of the porous glass. When they observed this effect using water, they found that this layer persisted up to high temperatures. This phenomenon can also occur with other solvents. The sample shrinks as this layer is removed. If large differential shrinkages occur in the porous structure, the stresses can increase to the point of cracking. [C
) Decomposition of the Dopant Compound The dopant used in the form of a solution is generally a compound that decomposes thermally. In this invention, a dopant compound is selected that decomposes before the temperature at which the Z-pore collapses. This decomposition process is generally accompanied by the evolution of large amounts of gas. Generally, in order to prevent the occurrence of cracks and the movement of dopants, it is desirable to control the degree of heating during heating to a temperature range in which decomposition occurs. [d- Mass transfer occurs at several stages of the drying process. When the product is first dried, the dopant that remains in solution migrates to the surface and is deposited there as the solvent evaporates. If the solvent evaporates violently or boils, even the precipitated dopants can be displaced. After decomposition, if the dopant crystals are small, they are transported in the gas phase. If the dopant has sufficient vapor pressure, redistribution of the dopant through the gas phase will occur. If the dopant is a liquid, it will be redistributed by gravity. Below is an outline of a preferred method that appropriately solves these problems. The initial removal of most of the solvent is accomplished by employing conditions where no boiling occurs. In the case of aqueous solutions, two approaches were used. One method is to first dry the porous glassware with settled dopant in a desiccator (under 1 atmosphere) at 220°C for 2 hours and then place it in a drying oven. Another method consists of placing the product in vacuum at a temperature below 1030°C and above the freezing point of the solution. In this method, when an aqueous solution of CsN03 was used as a dopant, it was found to be convenient to carry out the reaction at 4° C. for 24 hours. To further reduce the occurrence of cracks, it has been found convenient, when using an aqueous solvent, to wash the product at the end with a non-aqueous solvent that does not react with the glass. A suitable solvent is, for example, methyl alcohol. It has also been found that it is preferable to slowly warm the glassware maintained below 100 to room temperature under vacuum and hold it for typically 2 hours before transporting it to the drying oven. In the case of non-aqueous solutions of dopants, it has been found suitable to place the glassware under vacuum at room temperature for two periods and then to transport it to a drying oven. This speeds up the process compared to methods using aqueous solutions. In the drying oven, the sample is heated under vacuum to a high drying temperature at a heating rate of no more than 3 pi/h, preferably 15°C/h, since a low heating rate can reduce cracking and avoid dopant redistribution. Heating is desirable. A suitably low heating rate will dictate the economics of the process. In some cases, it may be cost effective to accept a higher breakage rate in order to increase the rate of product production throughout the process. However, the increase in heating rate must also be balanced against the increased risk of destroying the desired reinforcement distribution of the crack-free product. High drying temperatures depend on the porous glass matrix. It is determined by the following facts: That is, the bubble destruction should not be too high or too low. Otherwise, the drying rate would be too slow to be economically useful. Appropriate values can be found by first crushing the pores of an unfilled product and measuring its glass transition temperature Tg. and preferably 50 oo below the glass transition point.
It is advisable to choose a high drying temperature between and 15,000. More preferably, 75 below the glass transition point, 12
A narrow range of 0:00 is good. The next stage of drying is to dry the glass under this high drying temperature for 5 to 20 field hours, preferably 4
It is to maintain 0 and 12 insect temples. During this period, the glass can be kept under vacuum or under a gas atmosphere selected according to the desired optical properties of the final product, such as the color absorption spectrum, for example. At high drying temperatures (i) multivalent ions, especially transition metal ions, to control the state of ionic valence; and (ii) to control the state of valence or zero ionic valence of noble metals, a reducing atmosphere or an oxidizing Any atmosphere can be adopted. For example, Cu20 gives blue, Cu+ gives red, and Cu gives brown. Passing gas around the product is desirable as it aids in the drying process. If the decrease in hydroxylion concentration is not significant, this retention period can be removed. A reduction in hydrogen ion concentration (or moisture) results in increased transmission of longer wavelength infrared radiation, increased transmission of ultraviolet radiation, and lower DC and AC conductivity losses. According to a preferred procedure, a porous glass article having a glass transition temperature of 725q0 is heat treated at 625°C (100 minutes below the glass transition temperature) for 9 hours with oxygen gas flowing around the sample. '6} When the fixed drying process is completed, the pores of the product are immediately crushed. The temperature of the product is rapidly raised to a temperature at which solidification occurs.
Solidification is complete when the pores of the product are collapsed and the product is cooled to room temperature. If the product is to be further processed by reheating above the solidification temperature, the solidification step must be carried out at or below atmospheric pressure. If I do not,
Gas generation is likely to occur during reheating, resulting in the formation of bubbles. If the matrix is produced from a glass capable of phase separation, it is desirable to heat the porous glass sample under reduced pressure of oxygen (approximately 1/5 bar) to 825 oo, where solidification occurs. Examples of the present invention will be shown below, but these are not intended to limit the invention in any way. Examples 1-V Example 1-V shows an example in which a porous matrix was treated with solutions of dopants at various concentrations and solidified into glasses with different concentrations of dopants. A general procedure and subsequent processing to produce a porous matrix from a phase-separable glass is provided below. Each example also illustrates the use of different dopants in a range of concentrations, different solidification temperatures, and different final glass compositions. Melting and Forming A glass with a composition of 4 mol% Na20, 4 mol% K20, 36 mol% B203 and 56 mol% Si02 was melted and heated to produce a homogeneous melt, which was drawn. using a cooling coil with a diameter of 0.7 to 40.8
Obtained the enemy's glass rod. The heat-treated glass rod was heat-treated at 550 qC for 2 hours to cause phase separation. Etching before leaching: Each glass rod was etched in a 5% HF solution, and then washed with water for three times. Leaching glass comb containing 2% by weight of NAC1
Leaching was carried out at 95°C by CI. The leaching time was chosen in advance to reach a stage where the rate of weight loss was almost zero.
The coaching time selected in these examples was greater than 3 field hours. During leaching, the shelf acid concentration of the leaching agent was maintained below 50 qo by providing a cold spot at 40 qo, which speeds up the leaching and increases the shelf acid concentration within the pores of the matrix. A re-drying oven of the compound could be avoided. The temperature of 40° C. is chosen so that there is no drying oven for the N ratio CI from the leaching solution. This temperature is above the saturation temperature of the CI so that a suitable amount of N is maintained in solution to greatly reduce sample destruction. Washing The leached material was washed with deionized water. The washing cycles were conveniently controlled by determining the concentration of iron in the effluent. For convenience, washing was carried out at room temperature using one volume of water per volume of glass. In discontinuous operation, the water should be changed about 6 to 8 times, giving a wash time of about 3 days. It is better to simply replace the filling wash water with the filling solution, which is an aqueous solution of each dopant, for a smooth transition from the last washing step to the filling step. This is done by draining the water and filling the tube containing the porous glass comb with the filling solution. In Examples 1 to N, when the sample was removed from the filling solution and cooled to 2 or 0, the dopant was partially precipitated in an amount corresponding to the water solubility of 2 in the residual solution filling the pores. did. (For example, 10 ml of Ba(N03)2 per 100' solution remaining is dissolved in the water in the pores after thermal deposition at 220 ml of Ba(N03)2 per 100' solution remaining. Yunori BQ is dissolved in the water in the stomata.
) The remainder of the dopant was deposited during the drying process, which was initiated by placing the porous product in a desiccator at atmospheric pressure for 2 hours at 2°C. Drying was then continued under vacuum in an oven heated to a high drying temperature (previously defined) at a salt ramp rate of 1 o/h. This high drying temperature was determined by the method described above, and was 625° C. for the sample used in Example 1 without and ShiW. Holding Time The glass shim was then maintained at a temperature of 625 oo for 96 hours with ambient oxygen gas flow. Upon completion of the solidification hold time, the temperature of the glass rod rises rapidly to a high temperature (given in each example) at which bubble collapse occurs under reduced pressure of oxygen (approximately 1/L). . In Example 1, mother 0 is used as the dopant. If the dopant does not re-act at higher temperatures, it will be immiscible with the base glass at the bubble bursting temperature, rendering the glass opaque. In Example 0, &03 is used as a dopant. B203 is desirable for strengthening glass using the Tg method because it reduces the glass transition temperature. Example m
In this case, P is used as a dopant. Pbo decreases the glass transition temperature and increases the expansion coefficient. Example
1 Example m Molecularly packed dopant (Pp(N03)2, day 3803 aqueous solution) with mother ○1 B203 Glass comb number 7, P(NQ)2 of 40 min per 100cc of water
85 by dopant solution consisting of and 10 Yuhi 3803
Filling at oo for 1 hour and bubble bursting at 82500. Example Molecule-filled dopant (axis (N03) 2, melon B03 aqueous solution) by W Jijyu B203, glass comb number 8, Ba (N03) 2 of 12 min per 100 cc of water
85q by dopant solution consisting of and 6 evening sun 3803
Filling for 4 hours at o and pore destruction at 830°C. Example V The above examples all involve uniform doping (doping) of a glass rod.
ping). As described above, the dopant concentration in the outer layer of the glass spores is reduced by leaving the glass shavings for a sufficient period of time for the dopant solution to diffuse into the pores so as to obtain a certain compositional distribution in the bubble-broken glass scombs. Is possible. By the procedure already described, two porous glasses were prepared and a solution of 100'
It was immersed in an aqueous solution of CsN03 at a concentration of 120 ml at 95 ml for over 4 hours. Next, add 95 glass twills.
Transferred to q0 water and left for 11 and 20 minutes, respectively. Then, after a predetermined period of time has passed, each glass shank is
℃ water for 1 minute to create a thermal product of CsN03. The solvent was then removed and the glass rod was bubble-busted as described above. It was measured by the obtained refractive index. The composition distribution is shown in FIG. Several porous glass slats prepared by the above method of Examples were soaked in CsN03 and Cs2C03 solutions as shown in Table V at 95'0 for over 4 hours. Next, these glass rods were dedopantized to obtain a stepped refractive index profile. The time required for dedopantization was determined using Figure 3. (In other words, in the case of glass comb sample 13, y=
(to)=0.50, and according to Figure 3, to=300
(min)) The filled glass rods were de-dopantized by dilution in ice water for 300 minutes, then the water was removed and the glass shims were bubble-ruptured as described above. Table V shows the Cs20 concentration measured by the refractive index in the central part of the glass shank.
Shown below. Table V Examples Skin As already mentioned, when using dopant-filled glass combs, it is important to dry at low speeds at temperatures between 0°C and around 60°C. This example illustrates the difference in composition distribution due to different heating rates. Some of the filled bubble-filled glass rods used in Example V were dedopanted to produce a stepped index profile as shown in Example W. After thermal deposition, the glass twill was dried under vacuum at 4° C. for 2 min. Next, heating was carried out under vacuum at heating rates of 50, 30, and 150 hours per hour. FIG. 8 shows the concentration distribution measured using the obtained refractive index distribution. A heating rate of 10,000°C per hour resulted in considerable breakage of the glass ridges. Example W A filled porous glass rod after leaching and washing as described in the first part of Example 1-W was soaked in 10 ml of water.
It was immersed in CsN03 solution of 120 g/0 cc for 4 hours. It was then dried in a desiccator for 2 hours at room temperature. Since the obtained sample was uniformly packed, it was then soaked in water for 2 hours at a temperature of 4 °C to introduce a certain distribution.
Washed with N03 for 30 minutes. It was then vacuum dried at the same temperature. Once most of the water was removed, the temperature was gradually increased and the sample was slowly dried as indicated in the preferred procedure of this invention. At intermediate temperatures, CsN
03 was decomposed into Cs20 and various nitrogen oxides. Solidification was complete when the sample turned from white to clear and the sample was removed from the oven. According to measurements at room temperature, the sample was 10
It had a surface stress of more than 00 Cape si, an expansion coefficient of 3.1 x 10-6/°C, and an operating temperature of more than 700°C.
The thickness of the compressed layer was over 20 mils. This final glass was stronger than a similar one made of fused silica. EXAMPLE K As already indicated, the choice of dopants, solvents, and loading and dedopant operating conditions, the combination and perversion of these parameters to obtain the desired results, or the modification of operating conditions, etc. can be varied widely. I can do it. This invention provides guidance to those skilled in the art, and this example illustrates substitutions and combinations of parameters that yielded satisfactory results. All porous glass rods used were manufactured by the general procedure previously described, and solvent removal and heating were performed under favorable conditions. The results obtained are shown in Table 1. Column and row notes for this table are listed below. 1st column Dopant used. 2nd column Dopant concentration per 10' solution. 3rd column Solvent, ie the solvent used in the first filling step. Column 4: Temperature (00) and time required for the first filling step. Column 5 Solvent A. This solvent is used to reduce the concentration and cause compositional changes and to cause dopant deposition. Column 6 Temperature (°C) and time required for change in dopant product and composition distribution. Column 7 Solvent B is used to properly adjust the dopant concentration in the matrix; by causing further deposition before solvent removal, a more complete reduction of the dopant concentration near the glass surface is possible. Column 8 Temperature (°C) and time required to adjust dopant distribution by further solution treatment. Column 9 indicates the temperature (°C) at which drying begins. (V) shows drying under vacuum, (A) shows drying at atmospheric pressure in a desiccator in the first stage. Column IQ Shows the measured values of composition by refractive index. The first row is the same as glass birch sample 13 in the example,
Contains a comparison with the second row. The second row includes further treatment with methanol and water, while using the same loading solution but increasing the difference in refractive index. 3rd line CsN03 is replaced with highly soluble Cs2C03. The filling operation can therefore be carried out at room temperature. 4) Using different dopant and solvent combinations9
I'm doing it. 10. Indicating the use of mixtures of dopants and 1.
1 line. Line 12 Neodymium nitrate is used as the dopasotho, and an organic solvent is also used. S Funabe” Kasumi Koiiso. S place q to ten skillful lotus groove bonito * YS S acid hog se'ya' Yumawari ant connection wide key. )'s Niwayama Koi Hajime S' day. ○Heartful growth is difficult to put into practice. . Such reinforced glass rods can be used as preforms to make high strength fibers used as reinforcing materials. If a flat glass sheet is strengthened according to the present invention, it can be used as a window that can withstand large temperature differences due to sunlight and pressure differences due to strong winds. Molded sheets of this material can withstand thermal as well as mechanical shocks and can therefore be used as stove tops. The advantage of this invention over the heat treatment method for tempered glass is that it can be easily cut after tempering. This is because the tension in the center can be maintained lower than in the heat treatment, which corresponds to surface compression. The reason for this is the improved control of stress distribution made possible by this invention. To prevent loss of strength due to scratches,
The thickness of the surface layer can be about 10 mils or more, preferably 10 to 20 mils. For example, the glass fins of the example skin can be cut with a diamond saw without breaking them, and can withstand scratches. In this invention, the interior of the glass is 80% (preferably 80%
Since the surface has a silica content of only 5% (5%) and more than 85% (preferably 90%) silica, glass products made in this way are chemically relatively inert and are suitable for use by infants and young children, for example. Can be used for food and dish containers. In all of these examples, removal of sodium by leaching is a problem when using normal soda-lime glass. Furthermore, if the total silica concentration is less than 80 mol %, it becomes difficult to melt the glass and molecular filling cannot be performed, which is not preferable.

[Brief explanation of the drawing]

Figure 1 is a cross-sectional area of tempered glass showing different concentrations in phase A and B, Figure 2 is a volume-temperature graph showing different glass transition temperatures in phase A and B, and Figure 3 is a Volume-temperature graph showing different thermal expansion coefficients under the glass transition temperature of phase and B phase, Figure 4 is a schematic diagram showing step distribution a and continuous distribution b, Figure 5
The figure is a 1-hour weight increase graph when a porous glass rod is filled with a concentrated aqueous solution of 10,000 CsN03.
The figure shows a 1-hour graph of weight increase when a glass rod filled with 100qC CsN03 solution is dedopantized with 100℃ water. Figure 8 shows the composition distribution measured by the refractive index distribution of two dedopantized glass rods. Figure 8 shows the filled glass rods heated under vacuum at heating rates of 15, 30, and 5000/hr, respectively. FIG. 3 is a diagram showing a composition distribution measured from a refractive index distribution when Fig. l Fig. 2 Fig. 3Fig. 4 Fig. 5 FIG. 6 F'9.7 Fig. 8

Claims (1)

[Claims] 1. From the inside so that the silica concentration is higher at the surface than inside, the total silica concentration is higher than 80 mol%, and the glass transition temperature is higher at the surface than inside due to a predetermined concentration distribution of the dopant. A tempered glass product made of glass with a glass transition temperature distribution that increases stepwise toward the surface. 2. The tempered glass product according to claim 1, which has a larger coefficient of thermal expansion on the inside than on the surface. 3. The tempered glass product according to claim 1, wherein the concentration of B_2O_3 in the entire glass product is 2 mol% or more. 4. The tempered glass product according to claim 3, wherein the silica concentration of the entire glass is 90 mol% or more. 5. The tempered glass product according to claim 1, wherein the product is a window. 6. The tempered glass product according to claim 1, wherein the product is a windshield glass. 7. The tempered glass product according to claim 1, wherein the product is a radar dome. 8. The tempered glass product according to claim 1, wherein the product is a stove top lid. 9. The tempered glass product according to claim 1, wherein the product is a pipe. 10. The tempered glass product according to claim 1, wherein the product is a cooking utensil. 11. The tempered glass product according to claim 1, wherein the product is a chemical experiment article. 12 Claim 1 that the above product is a glass container
Tempered glass products listed in section. 13. A tempered glass product according to claim 1, wherein the product is a structural material.