DE2611495A1 - HIGH STRENGTH, HARD GLASS MATERIAL AND METHOD FOR MANUFACTURING IT - Google Patents

Description

PATENT LAWYERS

DR. E. WIEGAND DIPL-ING- W. Ν! 5Λ, * ΔΝΝ ^

DR. M. KÖHLER DIPL-'iNG. C. GERNHARDT ^ 0 I 1 A 9 5

MDNCHEN HAMBURG

TELEPHONE: 555476 - 8000 MÖ N CH E N 2,

TELEGRAMS: KARPATENT MATH I LDENSTRASSE 12

TELEX: 529 068 KARP D

W 42 498/76 Zi / az 18 March 1S76

Pedro B. Macedo Bethesda, Maryland (V.St ».A.)

Theodore A. Litovitz Silver Spring, Maryland (V.St.A.)

High strength, hard material and process for its production

The invention relates to a new, high-strength and hard glass material that iöt in the ΓϋΙΙοη anv / endLar, in which a thermal shock leads to the breakage of conventional glass and Ker airdkmate ri alien or one of a higher temperature independent, increased strength is required. The term '' £ jias "used in this description covers scr -. 'Oiil completely glassy as well as partially devitrified "glasses, ζ, 3. ceramic materials,

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Ceramic materials have become popular because of their ease of manufacture and their relatively low manufacturing costs Long regarded as a "viable material. Two of its major limitations are their relative ones low strength and their inability to withstand thermal shock. This restricts the use of the ceramic materials for many structural purposes, such as cooking utensils, oven covers, radomes, windshields, fecster and containers, such as pipes and Tubes, so / ie storage or reaction vessels used for treatment or processing chemicals and other materials at high temperatures.

The traditional method of overcoming the weakness opposite the thermal shock is that ceramic materials with a low thermal expansion are used or developed. There are currently three viable solutions:

1. The use of pure fused quartz,

2. the use of borosilicate glass, such as "Vy c or" glass ,, Corning Glass Co., and finally

3. the use of glass ceramics.

The last solution also serves to increase strength. Each of the above solutions has its limits; the first two Solutions have such a low modulus of rupture that in many cases they cannot be used. The third solution (Glass ceramic) has all the desired thermomechanical properties, however, depends on a rather complicated manufacturing process which results in relatively expensive manufacture leads.

It is therefore mainly the spirit and purpose of the invention, a new glass material with the desired thermomechanical properties and a method for its economical production to accomplish.

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Pie desirable properties are:

1, high modulus of rupture, which corresponds to the modulus of rupture of borosilicate glass ("V3 ^r cor") »fused silica," Pyrex "glass, and most other common glass materials;

2. very low thermal expansion, which is less than the thermal expansion of "Pyrex" glass;

.5 »a high upper use temperature that is above the temperature of ceramics and glass, such as "Pyrex"., lies;

4. Controllable appearance, so that shapes can be produced that are transparent or opalescent or any other Have parbe;

5. Adaptability to relatively cheap manufacturing processes ;

6. Applicability for cooking utensils, oven covers, radomes, storage tanks, pipes and other cases where a high strength-to-weight ratio, inert behavior towards chemical substances and high temperatures required are.

An inexpensive process for the production of glass with a high proportion of silicon dioxide and therefore a low thermal expansion is first from Hood et al. (U.S. Patents 2,106,744 and 2,215,036). In this process, a any form of castable sodium borosilicate glass heat-treated, so that there is a color separation associated with one another standing liikrostructure is subjected. The alkali borate phase is naturally ionic and soluble in acids, v / ie HGl, while the other phase consists mainly of isovalently bound Silica with a small amount of BpO, consists and in HCl is insoluble. Since the alkali borate phase can be removed by acid leaching, some of the silicon dioxide remains rich skeleton or scaffolding back. In the Hood method

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this framework of silicon dioxide is brought to collapse or, compressed by heating it to a temperature close to the glass transition temperature T (about 95o ° C), PO that a homogeneous glass with a high content of silicon dioxide, a good chemical resistance, a high service temperature and a low coefficient of expansion arises.

In a separate, earlier application (US Serial No. 462,481) a method was described in which a phase separable glass is converted into a porous form. This porous shape is then converted into a dense glass article, which transversely to at least one cross-sectional axis has a uniform or non-uniform profile with regard to the composition comprises by adding modifying components to the porous i-'material and the article in a dense glass article is converted. The addition of such compositionally changing components became "molecular." Stopper "called.

Such a method is not only suitable for plugging porous matrices that are phase separated by leaching Glasses were made, but "also for other interconnected, porous structures irdt a patrix, which contains at least one material which is a glass network forms. A known method of making interconnected porous structures besides that mentioned above Phase separation is the deposition of chemical vapors * Such a process is for example in the DS-PS 2 272 342 and 2 326 059 described. U.S. Patent 3,859,073 ! describes in particular the production of a porous body and its subsequent impregnation with an additive.

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Such impregnation is smaller with a deposit Quantities of materials from relatively thin solutions connected in the pores of the porous body.

In the context of the present application, the molecular plug is used to improve the strength of the glass material, by creating a profile of the composition that runs through the thickness of the glass, which in turn to increase the profile of the thermomechanical Properties leads. Such a profile of the composition, which increases the resistance to thermal shock and the mechanical strength of a material hereinafter referred to as "reinforcement profile".

The invention r / ird in the following with reference to drawings explained in more detail. In the drawings show:

FIG. 1 shows a cross-section through a reinforced glass produced according to the invention with drawn in Areas A and B, which have different concentrations,

FIG. 2 shows a diagram of the course of the volume in

v.

Depending on the temperature, the different Glass transition temperatures for the Areas A and B shows

FIG. 3 shows a diagram of the course of the volume as a function of the temperature, which shows different coefficients of thermal expansion below the glass transition temperature for the areas Ά and B. FIG.

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FIG. 4 shows a schematic representation of a stepped profile (a) and a continuous profile (b),

FIG. 5 shows a diagram of the increase in weight as a function of time when a porous rod is stuffed with a concentrated solution of CsIIO ₃ in water at 100 ° C.,

FIG. 6 shows a diagram of the weight loss as a function of time when unstuffing a rod originally _{stuffed with a CsNO 3} solution at 100 ° C with water at 100 ° C,

Figure 7 shows two over the distribution of the refractive index

measured profiles of the composition for two rods, which were stored at 95 ° C for a period of 11 (curve 1) or 2o (curve 2) minutes.

FIG. 8 shows some profiles of the composition, measured via the distribution of the refractive index, for stuffed rods which were heated under vacuum at a rate of 15 (curve 1 \ , 3o (curve 2) or 50 ° C./hour (curve 3)).

The present invention can be used in three different ways to produce a reinforcement profile in the glass material be used:

1. In the first method, a profile of the composition at the glass transition temperature T is generated. This Procedure is mentioned in the T procedure below. A profile of the composition made by this method

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is schematic in Figure 1 !! is shown, in which the region B represents the silicon dioxide phase filled by molecular plugging and the region A represents the unstuffed, relatively pure silicon dioxide phase. Most of the network-changing modifiers dissolved in pure silicon dioxide cause the glass transition temperature T to drop.As can be ascertained by the thermal expansion, the difference in the temperature of the transition stone temperature T between area A made of relatively pure silicon dioxide and area B made of filled silicon dioxide is as shown in FIG 2 shown, strong influence on the volume / temperature curves of the two compositions. The small & close to B-CU present in glass A is sufficient to suppress the negative expansion area, which is the case with extremely pure

Silicon dioxide above the glass transition temperature T

for the glass A would be observed. The glass A is therefore only in comparison with the plugged glass B as pure silicon dioxide designated.

If the material shown in Figure 1 from the liquid State is albcooled out, that comes from pure silicon dioxide existing composition A on the surface of temperature T through the glass transition point, where the composition A becomes solid and a large decrease the coefficient of thermal expansion learns * The filled Composition B consisting of silicon dioxide in the innards) is dragging on but until the temperature T _ is reached with a liquid flow coefficients together · The Composition B is after reaching the temperature T _ ■ also a solid glass with a low Warxn expansion coefficient « The different expansion between the surface and the interior in the temperature range: '~ h between 3? "

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and T _B acts to compress the surface. This compressive stress must be overcome before the surface can be broken. The T profile, which is created by the molecular plugging of SiIi-

cium dioxide was achieved, therefore leads to an amplification the surface of the glass.

2, In the second method possible according to the invention, a profile of the expansion coefficient is generated. This procedure is described in the "Coefficient of Expansion" procedure below called.

The additive used as filler in area B (Figure 1) does not change the glass transition temperature T, but increases the expansion coefficient of the glass when the sample cooled from their glass transition temperature to room temperature has been, therefore, the area B shrinks to a greater extent Extent than the area A "resulting in a compressive stress A leads. This compressive stress increases the modulus of rupture of the sample {s, Figure 33 «

3. In the third »possible process according to the invention, is also a profile of the glass transition temperature T and a profile of the expansion coefficient is generated » This method is therefore a combination of the two above Procedure. This process is called "mixing process" below.

The method according to the invention, which is carried out by molecular Stopper leads to a strengthening of the glass, has certain similarities with the chemical tempering by ion exchange, However, there are significant differences. With the chemical

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Annealing occurs simultaneously with the ion exchange Profile of concentration and profile of compressive stress. Unfortunately, this fact limits the thickness of the strengthened surface layers considerably, because the tension forces in the surface are accelerated by the viscous flow decrease as the tension forces built up by diffusion can be. This limits the thickness of the area of compressive stress or compressive stress, so that chemically annealed Ceramic materials are prone to failure when scratches occur. The profile of concentration and the Surface loads are specified in various stages in molecular plugging, so that there is no limit for the production of thick surface layers there. The glass can therefore retain its strength even if if it got deep scratches.

In addition, it is possible in the method according to the invention, in addition to increasing the strength of a Glass article also to control its appearance. For example, when additives are added, these are as follows If the densification temperatures described do not easily dissolve, the sample may have a milky or opalescent appearance awarded. Such additives are refractory Oxides such as oxides of aluminum, alkaline earths, titanium, chromium, zirconium and zinc.

If colors are desired, an ion of transition metals can be used or rare earths. Under conditions of oxidation For example, copper and iron make the sample blue, brown or yellow. Under reducing conditions

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copper and iron make the sample red or green, cobalt makes the sample is usually blue and neodyne makes it purple.

Any element containing free electrons can be used to obtain a smoky appearance. Examples for such elements are germanium, tin, lead and bismuth in a reducing atmosphere. It also leads the presence of colloidal, metallic precipitates of precious metals to various smoky tones.

In any method of making the glass articles according to the invention, making the porous matrix is one value-adding process step, so that losses and damage, for example breakage, after this process step reduce the economics of the commercial process. It is difficult to determine the factors causing the Loss and damage from breakage and cracking or the appearance of light scattering centers or nests such as the Cause inclusions or bubbles in the finished article.

IM an increased economic yield and a better one Controlling the refractive index profile in a consistent and satisfactory manner became the process steps noted and improved that in a particular way and in a particular consequence not yet disclosed are to be carried out.

In view of the yield and economy, it should be noted that in the normal manufacture of a glass article Process changes do not necessarily mean that every molded or shaped article is free from defects. Procedural changes. Nor do they guarantee that these articles

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all of the subsequent procedural steps survive. The term "increased yield" is intended to express that a way has been found how the statistical prospects of a staff or other item of surviving the ^TT levels can be improved. However, this is on a statistical basis and there can be no guarantee that an acceptable product will always be obtained even using all the essential steps of the process of the invention. As indicated above, the improvement relates not only to the yield, but also to ensuring that a desired reinforcement profile is consistently and satisfactorily achieved.

This is mainly due to the finding that it for best results it is essential that the Process step for depositing the solid material in the Pores are exerted using a process that is not associated with evaporation of the solvent, and that the subsequent heating stage to increase the Temperature of the article to remove the solvent from the pores and, if necessary, the decomposition products is to be controlled so that a desired gain profile is achieved, maintained or generated "

It was also found that when making a certain additions to the satisfactory article particularly advantageous due to their physical properties Lead to results «

If the porous article to be stuffed is divided by three phases of a glass and subsequent leaching

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is available, it is advisable to take certain precautions to minimize losses and damage during the processing of the rod. It was determined, that cracking in this form of the invention Procedure can be caused by one or more of the points listed below:

(a) Incorrect glass composition;

(b) Incorrect heat treatment for phase separationj and

(c) Incorrect leaching.

In the following an indication is given, such as the glass composition and the process conditions are chosen to avoid the loss due to cracking in the subsequent process steps in the manufacture of the porous Reduce the die and the subsequent stuffing and drying.

The invention relates to a method for producing a desired reinforcement profile in a glass article as a function of the dimensions of the glass article
in which a component changing the strength is embedded in a porous iiatrize with interconnected pores, the walls of which consist of at least one glass network

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constituent component and, if desired, from components are formed, which modify the glass network. The component that changes the strength is described in the following "Additive" called. The invention relates in particular to a method in which the porous liatrize in a solution of a Additive is immersed, which is deposited in the die, and in which the solvent and, so far required, the decay products are removed from the porous matrix and the porous matrix has a dense shape obtained, the process being characterized in that part or all of the additive is carried out by a process can be reflected that does without evaporation of the solvent that one with the removal of the Solvent does not start until a substantial amount of precipitation has taken place and that one can determine the extent with to which the heat for removing the solvent and, if necessary, the decomposition products is supplied, so regulates that the desired reinforcement profile is achieved and / or secured in the glass article.

The procedural steps and the sequence of procedural steps, which have proven to be useful for the production of a special profile are shown below, whereby in all cases a porous article with interconnected pores was assumed.

The invention comprises the following process steps:

(1) The additive is in the Poicn by evaporation Process steps down. These evaporation-free Process steps include (a) thermal deposition, in which by lowering the terroerature of the gecko

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the solubility of the additive or the compound of the additive in the solvent is sufficiently reduced is to cause deposition of the additive or the compound of the additive, and (b) a chemical Precipitation, such as changing the pH of the solution to the point of precipitation, replacing the original solvent by a solvent in which the additive or the compound of the additive is less soluble, or introducing a chemical substance into the solution, which is with the original additive or the compound of the additive reacts to produce a less soluble species of additive. Of the in the term "solvent" used below denotes a chemical substance which at any stage is the liquid that fills the pores.

(2) Only then does one start the final solvent

to be removed when the precipitate is essentially complete.

(3) The extent to which the heat is used to remove the solvent and, if necessary, the decomposition products is fed is controlled in such a way that the desired reinforcement profile is obtained and / or secured in the glass article.

The process steps and the sequence of process steps required for the production of graduated profiles (Figure 4a) and of continuous profiles (Figure 4b) are useful, are shown below, with a porous article and thermal deposition of the additive or a compound of the additive is assumed.

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Graduated profile

(1)

(a) Immersing the porous mold in a solution of the additive or compound of the additive.

ib) Precipitation of the additive due to a drop in temperature.

(c) immersion in a solvent for the additive, to partially loosen the additive again and remove it from the die. In this process step, only the additive is removed that is deposited in close proximity to the surface of the article.

(d) Evaporation of solvent.

(e) heating to compression temperature.

(2) Alternatively:

(a) Immersing the porous die in a solution of the Additive or the compound of the additive,

(b) Precipitation of the additive due to a drop in temperature.

ic) partial drying of the porous rod.

Cd) immersion in a solvent for the additive, to partially loosen the additive again and remove it from the die. In this process step only the additive that is in the immediate vicinity of the surface of the Article.

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ie) Evaporation of any remaining solvent.

if) heating to compression temperature. Continuous profile

(ft) immersing the porous die in a solution of the Additive or a compound of the additive.

(b) immersion in a solvent for the additive at a temperature substantially equal to is equal to the temperature at which the plugging took place. The article remains a precalculated one Time in the solvent.

(e) Repeating step (b) with different baths Concentration of the additive. The diffusion time can be controlled to the desired in the article To generate the profile of the additive. "

(D) Precipitation of the additive in the pores by temperature drop.

(e) Evaporation of the solvent.

(f) heating to compression temperature.

For the additive, a material is preferred whose solubility properties are such that the desired Concentration of the additive in the pores can be achieved that a solution of the additive at a certain Diffuse temperature into the pores and then lower the additive by a simple drop in temperature.

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lets beat «This process is called thermal deposition designated. Although this method is preferred, other procedures are also feasible. the The invention therefore comprises a method of manufacturing a glass article with a desired reinforcement profile below Use of a suitable porous Ilatrize as starting material, in which a component which changes the strength of a solution is obtained by lowering the temperature of the solution fails.

The dissolved substance can also be precipitated by chemical measures instead of the drop in temperature. The well-known ionic action was used to reduce the solubility and to bring about the precipitation of the dissolved substance, ie the solubility of CsMO- in water is reduced in the presence of IN ENT-. The exchange of solvents has also been used, veto, to lower the solubilities and to bring about precipitation by measures that do not require evaporation of the solvent. These measures include the addition of a suitable precipitating agent that reacts with the additive or brings about a suitable change in the pH value. A combination of process steps consisting of thermal and chemical precipitation nutrients was also used. This is particularly useful in deü cases in which more than one additive or more than one compound of the additive is introduced into the process. It avoids all precipitation processes that involve evaporation of the solvent as the only means of achieving precipitation, since the use of such processes has not been able to achieve consistent results. It is believed that this is due to the following factors.

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In the direct evaporation process, the solution evaporates from the surface of the article, thereby transporting the additive from the interior of the article to its surface is brought about. There is also a vertical transport due to gravity, which creates a build-up of the additive air. Bottom of the article. These effects together lead to the creation of undesirable profiles.

It is essential to control the amount of heating so that either a destruction of the initial Verstärkunqsprofils or damage to the structure with the ^v with each other communicating pores is avoided ..

It is possible that through an uncontrolled escape steam or gas creates a pressure that is sufficient to Destroying the pore structure. It is therefore avoided that the solvent reaches its boiling point when large amounts of steam must arise. Various heating options are described below to show how the heating is to be controlled in order to achieve the desired result.

The control of the process step for removing the solvent is based on the necessity of destruction of the porous structure and to avoid confusion of the distribution of the additive in the pores. The precautions consist in that the removal of the solvent is hot

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Room temperature or below by a cook-free process, avoiding any sharp temperature change that would cause the solvent vapor to escape rapidly in a confined space. Suitable methods to start with for removing the solvent are, for example, that the object, if the solvent is water, is placed in a desiccator at about 22 ° C. for about 24 hours or at temperatures slightly above ⁰ ° C. (for example 4 ° C) is placed in a vacuum for four hours and then the temperature is started. It has been determined that it is necessary in some cases, einzusrellsn c ^ s degree of heating to a "ehr low value or decrease, so da.Q the items in a particular temperature range above one Ze-i t.spanne remains which is sufficient to ensure that ¹ ; special processes have occurred before the germination process is continued. In other places it is advantageous to move quickly from one temperature to another, for example when the removal of the solvent has been completed up to the compression temperature. In the later course of the study, some pointers will be given with regard to an aqueous system, but the information given also applies to the system in which organic solvents or other non-aqueous systems or mixtures of these systems are used.

The following criteria can be used to select a suitable additive from the larger group of den To select components that change the refractive index.

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(a) The additive must be in appropriate concentrations be soluble in a solvent which does not interfere with the subsequent process steps after the plugging.

(b) The additional means must either be used as precipitate or be incorporated into the die as a thermally induced precipitate.

(c) The additive must not change its physical or chemical state before compaction in such a way that it can fall off the die.

(d) In order to achieve high strength, the the following additional conditions must be observed:

1. If the T process is used to create a reinforcement profile, the additive must have the glass transition temperature of the porous matrix.

2. When using the coefficient of thermal expansion related method to create a reinforcement profile is, the additive must have the coefficient of elongation of the porous Increase the die.

3. When the mixing process to create a reinforcement profile is used, the additive must lower the glass transition temperature T and at the same time the coefficient of expansion raise.

Because in the context of the present invention a high light transmission not required, connections can

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most of the elements are used as additives. For example, the choice of additive for creating a T profile is not critical. Two suitable additives are Na-O ^ and Bp, which lower the glass transition temperature T of the die for each percent of the additive to 80 ⁰ C and 4o ° C. Other suitable additives for producing a T profile include oxides of salts such as chlorides, silicates, borates, phosphates, and germanates of lithium, potassium, boron, phosphorus, germanium and arsenic. The additives which can be used in the context of the invention, however, are not restricted to the substances listed above.

There are many additives that can be used to increase the thermal expansion of the die. For example, increases the cesium oxide changes the expansion coefficient the factor o.76 each?! ol% cesium oxide. Other suitable additives include oxides or salts of the heavy elements, such as barium, lead, potassium, bismuth, thor and uranium. The additives are not limited to the substances mentioned above »In addition, oxides or salts of rubidium, Strontium, antimony and tin can be used.

Other additives and mixtures of additives can be used so long as the above criteria are met are fulfilled. It is impossible to enumerate all possible combinations of elements for the additive, but it will assumed that, based on the information given above, a selection of useful combinations in the Is within the capabilities of a person skilled in the art.

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When selecting the solvent, the following considerations are important. The selected solvent

(a) should not damage the porous matrix,

(b) should be a means that essentially does either by exchange with another solvent, by evaporation or by a thermal decomposition with a subsequent oxidation or by one under high temperature any reaction taking place with chemically active atmospheres can be removed;

(c) should have sufficient solubility for the additive ! compound or combination of additive compounds have so that the desired values for the additive in the pores by molecular Stopper can be achieved;

(d) should be such that when the thermal Precipitation method, any additive solutions in the solvent have a sufficiently high temperature dependence of solubility so that the additive is deposited in the pores during cooling will"

(e) should be such that when the precipitate is produced by solvent exchange, the specific solubility properties are as they are needed for the procedure;

(f) should be given in light of economic considerations be cheap and dry quickly.

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It is impossible to use all possible combinations of solvents to check. However, it has been found that water, alcohol, ketones, ethers, mixtures thereof and salt solutions in these solvents can be used in a satisfactory manner, meeting the above criteria for the selection of a particular solvent.

In general, thermal deposition is preferred because it is easy and convenient and because it is of The advantage is that the first stage of the subsequent step is to remove the solvent after plugging Room temperature or below, and because it is usually necessary to keep the stuffed or filled in Item to cool.

The additives are preferably water soluble and have a steep solubility coefficient, i.e. that Material at temperatures of the order of 100 ° C is very soluble, and that on cooling to room temperature or below a considerable "tightness of the material is deposited so that such additives are suitable for thermal deposition or thermal deposition.

Further precise guidelines regarding the number of years Solvents are given in Table I below, in which the solubility of various additives in solvents at various temperatures is given.

As already mentioned above, when choosing a certain manufacturing process, a desired end product must be achieved a number of guidelines must be observed, which can be explained using Table I.

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To achieve the desired concentration of the additive in the article and thus a considerable increase To achieve strength, a solution with a sufficiently high concentration of additive must be carried out by a suitable selection of an additive compound, a solvent and the temperature found v / ground to the additive or to knock down the additive compound, the use of solvents with one is sufficient low solubility required. It is often necessary considerable amounts of the additive from certain areas of the article, for example in the surface area of a glass article to remove. In this case, solvents with medium solubilities are useful. Such removal of the In contrast to molecular plugging, additive is called destacking. Appropriate control of the Solubilities for an appropriate separation of the additive or the additive compound can be achieved by a Number of procedures can be achieved.

1) Thermal deposition is best for solvents whose solubility for the additive or the additive connection is strongly temperature dependent. The thermal deposition has the further advantage that the diffusion is brought to a standstill in the shortest possible time, so that a profile with a desired concentration is obtained can be frozen with high accuracy.

This is shown for the additive CsNO ₃ in Table I, the solubility being from a desired one. Stuffing value at 95 ° C changes to a desired destuffing value at 4 ° C.

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2) Precipitation through the usual ionic action and thermal deposition. The precipitation or deposition can be caused or further intensified by the usual ionic effect. For example, when the additive is a nitrate, the concentration of nitrate ions in the solution is increased by adding another source of nitrate ions to the solvent (e.g., HNCU acid). This reduces the solubility of the nitrate additive (see CsNO ₃ , Table I).

3 \ Separation by solvent exchange. The separation or precipitation is triggered by the fact that a solvent with low solubility is exchanged for a solvent with higher solubility. The high solubility of nitrates in water makes it possible that water can be used as a solvent for the stuffing process. The exchange of Kasser with alcohols, ketones or ethers or combinations caused the additive to separate out. Typical solubilities are shown in Table I.

4) Change of additional means connection. The range of solubility of the additive compounds can be changed by choosing a different ion, for example the CsHO _{3 is} replaced by Cs ₂ (CO _{3 I 2} , in order to increase the solubility in water (see Table I, line 7} «

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Table I.

link CsNO ₃ Soluble
speed
g / loo ml of solution H _? 0 Metha
nol Etha
nol 1-propa-
nol Diathy1-
Ther ENT ₃ tem
pera
door 1. Il loo loo% > 95 2. M. Io loo% 4th 3. H 4th 1 normal 4 4th CsNO ₃ 1 3o% 7o% 4th m 5. η
Cs ₂ CO ₃
η Io 7o% 3o% 22nd iO9841 6th
7th
8th. N 1
> loo
Io 15%
loo% 85%
95% 5% 22nd
22nd
22nd O 9. Pb (NO ₃ J ₂ 1 5 2% 48% 22nd OO Ιο. Il > loo loo% > 7o -α 11. ι « Io 3o% 7o% 22nd 12th La (NO ₃ ) ₃ 1 5% 95% 22nd 13th M. > loo loo% 22nd 14th "1 Io 15% 85% 22nd 15th Nd (NO ₃ )
. ■ · 1 lo% 9o% 22nd 16.
17th Ba (NO ₃ ) ₂ 2o
1 7% 9o%
93% 22 k>
22 2 18th Il 32 loo% 95 - * 19th ι · Io loo% 22 CD 2ο. Al (NO ₃ J ₃ 5 loo% O ^m 21. H 3110 3 63.7 loo% 22nd 22nd Ii 27.6 loo% loo ?.: \. G, 35 loo'i 22nd

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If the method according to the invention is a porous Structure is carried out by the phase separation of a suitable glass with a subsequent leaching it is necessary to optimize the various stages of the process in order to achieve a consistent and satisfactory, Salable end product with good economic Achieve yield, and the various, occurring To relate parameters to each other.

The factors on which the man of the practice must orientate are:

(1) Choice of glass composition and heat treatment. - Development to achieve a suitable phase separation;

(2) leaching and washing;

(3) stopper;

(4) unclog as necessary; and

(5) drying and solidifying.

The guidelines given in procedural steps 3 to 5 apply to all üatrices, * - not only to those which are made from a phase-separated glass.

1) Glass composition, time and temperature of heat treatment.

To make a satisfactory product, it is necessary to choose a phase separable composition, which during heat treatment at a certain temperature

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temperature separates into fractions of almost equal volume and develops a structure with interconnected forums of a desirable size if the glass assembly is kept at the temperature mentioned above It is expedient to choose compositions from the range of alkali metal borosilicate glasses Further information on suitable compositions is given below.

Many compositions have been found suitable for use in the manufacture of porous glasses for various purposes (see U.S. Patents 2,272,342, 2,346,059, 3,859,073, and 3,831,640). As a rule, however, these compositions are not used for reinforcement purposes using a process which relies on phase separation and leaching of the soluble phase. It has been found that only small ranges of the known compositions are suitable for reinforcement purposes. For example, U.S. Patent 3,843,341 discloses such compositions which are for the most part unsatisfactory. A number of glasses from the preferred range of US _{Pat. No. 3,843,341 and from the earlier Corning disclosures (see} Table II below) were drawn vertically into 8 µm rods at a rate of 2.54 cm / s. These rods were subjected to phase separation, as can be seen from the disclosure, but all composition! Table II cracked during leaching "

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Table II

Known compositions that after leaching are torn.

Na ₂ O ^B 2 ° 3 SiO ₂ Al ₂ O ₃ 8th 3o 62 0 8th 35 57 0 8th 4o 52 0 Io 3o 6o 0 Io 35 55 0 Io 4o 5o 0 Io 3o 59 1 Io 35 54 1 Io 4o 49 1

All concentrations are given in mol%.

In particular, it was found that

1. All compositions in the range of the sodium borosilicate system, disclosed in U.S. Patent No. 3,843,341 and into rods in the manner described above after leaching are cracked. This also applies to the area that is preferred in this patent specification has been specified;

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2. Many of the compositions disclosed in U.S. Patent No. 3,843,341 in the area of the sodium-alumina-borosilicate system cracked when treated as described above. This was also the case with the compositions in the preferred range.

3. Many of the preferred compositions disclosed in U.S. Patent 2,221,709 ruptured when in the above were treated in the manner described.

Although the largest range of borosilicate compositions disclosed to date because of the need for a satisfactory yield of the end product was unsatisfactory, particular ones could be found in this broad range Compositions are found that are useful and were not previously described. In addition, a number of criteria have been found that are used can to other certain limited areas of phase separable Specify glass compositions which give a satisfactory yield of the product.

From an economic point of view and because of the big one The range of phase separation that they have, it is most expedient to work with alkali borosilicate glasses, although almost all silicate glass systems have composition ranges with phase separation.

To achieve a satisfactory _n product, it is necessary to choose a composition

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(1). which, with a suitable heat treatment, turn into separates two phases, one of which is rich in silica and the other is poor in silica, the the latter advantageously in a suitable one Solution 1 is soluble;

(2) during a heat treatment with a beetinxiten. Temperature in z: / 3i phases with approximately equal volume of parts separates and a microstructure forms with intercommunicating pores if they are maintained at a certain temperature will j

(3) the with the help of conventional measures easily is meltable and easily refined;

(4) which is relatively easy to shape and none has significant phase separation during the molding process.

The systematic procedure for selecting a suitable composition is set out below.

(1) Almost all silicate glass systems have composition ranges with a phase separation. Of economic importance however, are the alkali borosilicate glasses, which have a large area of phase separation. The silicon dioxide The poor phase of these glasses can easily be dissolved by simple acidic solutions. It is often necessary to add other components, such as Alura.ni-a1r.Gx7d, indefinite To modify the properties of these glasses. Some

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However, oxides are undesirable because they help in phase separation lead to the phase poor in silicon dioxide and difficult to dissolve by simple acidic solutions make «Therefore only these other components are suitable which do not significantly reduce the solubility of the low-silica phase,

(2) When the decision on the glass system together with the additives has been made, the immiscible areas of the composition (C) and their associated temperatures (Tp) are next determined. Tp (C) is the temperature over which a glass (C) is homogeneous. The methods for determining Tp are well described in the literature (cf. for example W. Haller, DH Blackburn, FE, Wagstaff and RJ, Charles, "! -! Etastable immiscibility surface in the system IJa ₂ G-3_O _.- SiO" J. Amer. Ceram. Soc. 5-3 (1), 34-9 (197o)).

(3) It was found that the compositions (C,) determines who is supposed to achieve an equilibrium of the volume fraction of about 50% at at least one heat treatment temperature. Let this temperature be To (C,). The procedure for determining this temperature is as follows:

(a) Selecting three or more temperatures such as .d T ₃ , the condition

T ,, T- and T ₃ , which are 5o ° apart _r so that

T ₃ <T _{2 1} p ₁

is fulfilled, whereupon the heat treatments of the glass samples are carried out until the glass samples at the temperatures T 1, T and T _{3 become} white.

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(b) Measure the volume fractionally V (T) of these heat-treated samples with the aid of the electron microscope, wherein one of the phases of each sample is measured and care is taken that the same phase is selected for all samples will.

(c) recording the ^v oluir.enfraktion V (T) over the temperature T of the Wärnebehandlung, wherein the temperature is determined by interpolation or extrapolation, in which the volume fraction of about 5o% - 5% (ie, temperature To (C)) .

(4) Knowing the temperatures Tp (C) and To (C ₁ ), one determines the composition range C- within the range C ,, so that

a) 575 ⁰ C ^ To (C ₂ ) T / 500 ° C and

b) 75o ° C-5-Tp (C ₂ )? / ooo ° C.

These temperatures are chosen so that there are no long times for the heat treatment. It can of course Other areas can also be elected, if one is ready is to accept long times of the order of a week or more for the heat treatment.

(5) The composition range C ₂ is further given by

narrowed the condition that the composition should be easily refined upon melting. This makes it necessary that the viscosity of the melt at high temperature should be sufficiently low. This is mentioned in the following sub-area of C ₂ # CJ (ie. Of all _{glasses belonging to C 2} , which can also be refined in a suitable manner). For example, it has been found that a suitable characteristic for determining a refinable glass is

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that the glasses contain at least 28% B_O-, can be refined in a satisfactory manner.

(6) Not all compositions of C ₃ are desirable, even if they are easily refined and have a phase separation with a volume fraction of 50%. Another condition is that the desired composition does not have any significant phase separation during the deformation process. The extent of the phase separation during the deformation process is influenced by the viscosity properties of the glass in the range at and below the coexist: temperature as well as by the processing of the shaped object and by the cooling rate.

To determine such compositions C ₄ , which do not show any significant phase separation when cooled by and below the coexistence temperature, articles with wall thicknesses in the order of a few millimeters are cooled sufficiently slowly to avoid the development of large thermal stresses. The degree of phase separation in these articles can then be determined. The compositions in area C ₃ , which show no phase separation during this deformation process, can then be classified in area C. The compositions which meet this condition preferably have a temperature Tp between 71o and 600.degree. C., more preferably between 695 and 64o.degree.

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<7) The last criterion used ensures that it

sufficient difference in composition between two separate phases, so that the leaching gives a good effect «For this purpose only such compositions C selected, which meet the following condition within area C:

TptC *) - To (C ⁺ )? 75 ° C.

When the desired composition range C has been found, any composition Co can be selected, which lies in this area C. The appropriate temperature for the heat treatment and the time for this particular one Composition Co can then be found by the following measures.

(a) The heat treatment temperature for Co becomes set equal to the temperature To (Co), i.e. the temperature at which the volume fraction of the two phases is the same. If C has been chosen according to the above criteria, this temperature will not be so low that the time to achieve a suitable microstructure by leaching does not become too long and uneconomical. On the other hand, the temperature will not be too high, otherwise

(_ 1_ / deformation of the glass occurs during the heat treatment;

I ^ 2_ / the phase separation takes place quickly when the temperature of the heat treatment is far, for example more than 160 ° above the glass transition temperature. The rapid phase separation reduces the ability to control the phase separation. These conditions limit the preferred temperature T "of the heat treatment to the following range:

575 ° C S T ₁₁ (Co) = To (Co)> 500 ° C

ti

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(b) When the temperature T _H (Co) has been found, the duration of the heat treatment is determined by the condition that a microstructure suitable for leaching is formed.

Heat treatments are carried out with different periods of time, i.e. t, (1 hour) <- t2 (2 hours) <.t ^ (3 hours) ,,, With the help of the electron microscope it is possible to see the To determine the time t, after which the mutual comparison

ITiHX

bond of the structure begins to break. The size of the leachable Phase is measured with the help of micrographs and the preferred times for heat treatment are those which are below t, but in which the size of the 1-Ükrocefüges is at least £ 150 and preferably less than 3oo S.

The above criteria are found in the alkali borosilicate system, so that certain properties of the composition ranges It can be determined which end products, especially such end products, produce good results that have a considerable thickness, taking into account the difficulties caused by the phase separation occur during molding, or insufficient phase separation should be avoided if the phases are separated. The phase separation during the manufacture of the glass article from the melt and insufficient phase separation or a breakdown of the interconnected structure during the heat treatment for phase separation in one or both of the following process steps, namely during the leaching of the phase-separated glass and cause cracking or ice formation during drying of the leached and clogged glass contribute.

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261 14 9

It was found that the compositions with the best results are those falling within the broad range of compositions below, all of which Percentages Ko1% are:

wide range preferred range

SiO ₂ 48 - 64 49.5 - 59 B ₂ O ₃ 28 - 42 33 37 R ₂ O 4 - 9 6.5 - 8th Al ₂ O ₃ O - 3 O 2, ο P. O - Ι, ο ο, 2ο- ο, 8 O - 3 O 2.4 λ O - ο, 5 O X ο, Ι - Ι, ο ο, 2 - ο, 8

Here, cC denotes the Al ₂ 0 ₃ concentration in Γο1% ^ χ = ^ + (1/3) <£ -λ, ρ the ratio of A ₃ OZR ₃ O in KoI%, A ₃ O the sum of the concentrations in * 'ol% of K ₃ O, Fb ₂ ^{0 1} ^ ^d Cs-O; R ₃ O is the sums of the concentrations in mol% of Li ₃ O, Na ₃ O, K ₃ O, Rb ₃ O, and Cs ₃ O; and / Ida's relationship with Li

Since the presence of Al ₃ O ₃ in the glass affects the results considerably, we should first discuss the glasses that do not _{contain Al 3} O ₃ , under these conditions the ranges given above with an Al ₃ O ₃ level of zero, with R ₂ O as the sum of all alkali metal oxides Li ₃ O, Na ₃ O, K ₃ O, Rb ₃ O, Cs ₂ O and Pit a wide range for ρ between o, l and l, o is suitable. If the concentration for K ₃ O is zero, should the upper limit of the range for y? lie at o, S.

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Lithium glasses tend to devitrify, so it is often not practical to use this chemical. In this case, R ₃ O becomes the sum of the concentrations of Na ₂ O, K ₂ O, Rb ₂ ^{O and} Cs ₂ O. All of the above limits and
Conditions are maintained.

Rubidium and Caesiuing glasses are more transparent than glasses with sodium and potassium. They can be omitted for economic reasons. Thus R_0 becomes the suir-me of Na-O-, and K-O. All of the above limits and conditions are retained.

If more than o, 5 Γο1% Al-O .. are present in the glass, will the broad range for R-O is taken between 6 and 9 I'ol%.

The most economical compositions with Al ₃ O ₃ have an RO that consists only of Na ₂ O and KC or only of Na ₂ O.

The glasses listed below in Table III have the above criteria and are suitable for molecular Stopper according to the invention, since a satisfactory control of the phase separation and a satisfactory pore structure after leaching using these compositions as well as a good overall yield of the finished product can be achieved according to the invention.

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Tabel

III.

From laughare compositions SiO ₂ B ₂ O ₃ Na ₂ OK ₂ O

163 30 5 2

II 63.7 29.4 6.3 ο, 6

III 61.2 34 2 2.8

IV 6ο, 7 35.1 2 2.2

V 59.7 33 5.4 1.9

VI 59.3 34.3 1.6 4.8

VII 58.4. 34 5.6 0

VIII 59.1 34 4.9 0

IX 57.7 35 5.7? 0

X 56 36 4 4

XI 56 36 6 2

XII 53 38 8 0

0 0 0 0 0 0 2 0 0 0 0 0

CS ₂ O

0 0 0 0 0 0 0 2 0 0 0

^Λ1 2 ^Ο 3

ο ο ο ο ο ο ο

1.6 0

ο Ι, ο

0.29 0

ο, Io 0

0.58 0

ο, 52 0

ο, 26 0

ο, 75 0

ο, 26 0

ο, 29 0 0

ο, 5ο 0

ο, 25 0 0

0 0 0 0 0 0 0 0

1.6 0 0 0

1, O 0

ο, 29

ο,

0.58

0.52

ο, 26

0.75

ο, 26

ο, 29

0.53

ο, 5ο 67ο

ο, 25 71ο

ο, 33

CTi

00

cn

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Another aspect of the present invention is concerned with the leaching of phase separable borosilicate Gläsem. It is advisable to etch the glass with dilute hydrofluoric acid for about 10 seconds before leaching in order to remove any contamination on the surface or a surface layer of the glass due to the volatilization of components such as BO or Na ₃ O during manufacture of the glass has a slightly different composition than the inside of the glass.

The concentration of the acid solution, the amount of the leach solution and the temperature during leaching have a direct influence on the progress of the leaching process. It is essential to ensure that a sufficient amount of caustic solution is contacted with the glass article to dissolve the soluble phase. The extent of the leaching can be regulated in a suitable manner by adjusting the temperature accordingly. The temperature of the glass should more than 80 C, preferably about 90 ⁰ C ₇ being. As can be seen from GB-PS 44 2 5 26, it is desirable to use an acid solution which is saturated with NH.Cl or other equivalent compounds which reduce the concentration of water in the acidic leach solution. This helps control any "gush" of the treated layer and substantially reduces the risk of loss due to pitting of the article when the inner, untreated layer becomes under tension because of the thickness of the swollen outer layer.

It has been found that the extent of leaching and the deposition of borates in the pores of the glass during the leaching can be controlled by adjusting the concentration

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the borate salts in the acidic leach solution is controlled.

The extent of leaching at 95 C was measured for glass rods with a length of Io cn, a diameter of 8 mn and a composition of 57% SiO ₂ , 35% B ₂ ° 3 ' ^{4% Na} 2 ° ^ ^{10 4% K} 2 ° ^{had 1} ^ ¹⁰ ! ¹ Z ² hours had been subjected to a heat treatment at 55o ° C with leaching solutions which contained 327.3 g NH ₃ Cl, 33.6 ml HCl per liter drum and various amounts of B_0. It was found that the leaching time increased as the BO. Content in the leaching solution increased. The results are compiled in the following »

Table IV

Amount of Boric Acid Leaching Time (minutes)

(g / liter)

O 425 - 5o

41.2 625 - 5o

61.5 642 * 5o

84.7 725 * 5o

Io6, l 167o * 5o

It is believed that the repeated deposition of borates in the pores also contributes to the breakage of the rods. This can be avoided, for example, by replacing the leaching solution when the concentration of the borate sips. However, this requires large amounts of leach solution.

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For example, if one does not want the leaching time to exceed 660 minutes, the volume of leaching solution per 100 ml glass must be on the order of 1550 ml. However, this can add cost and potentially be a source of contamination. It is therefore zwec? Vorzusahen <moderate _# Abscheidvorrichtuncr a cold, so that excess material is continuously removed from the solution as it passes from the leached product to the solution. The cold separator accelerates the process, even if it is only a few degrees below the temperature of the glass article. The temperature of the cold separator is preferably 20 C below the temperature of the glass article. If NK.Cl is present, it is useful to choose a temperature for the cold separating device at which the acidic solution remains saturated with NH.Cl. It is possible to work with lower fraction of the rods without KH.Cl or other equivalent compounds in leaching is present ". In general, however, it is expedient least Io wt .-% NH ₄ Cl, preferably 2o by weight % should be used as it has been statistically determined that there is even less rod breakage when NH.Cl ^. is present.

The most convenient way to determine an appropriate leach time is to take an article and subject it to a leach treatment, measuring the mass of the article at intervals until little or no further weight loss is observed.

The article once leached is conveniently washed with deionized water. With certain compositions, there may be a build-up of silica gel in the pores. This deposition of silica gel can be removed by washing

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" ⁴³ " 261U95

be eliminated with NaOH. It is possible to make by appropriate selection of the compositions of this deposition to a minimum. The compositions shown in Table III alleviate this problem, especially the compositions with a minimal content of silicon dioxide,

If the porous? "Atrize either from a protruding called phase-separable glass or has been produced by the deposition of a chemical vapor once the selection of the suitable conditions for stuffing and un-stuffing is made on the basis of the following guidelines will.

The dependence of the glass transition temperature T or the expansion coefficient on the concentration of the additive or the additive compound can be found on the basis of Determine the literature or by means of suitable experiments. It becomes the optimal concentration of the additive or additives connection that is required in the article. There must then be sufficient additive or additive compound be dissolved in the stopping solution, so that the desired concentration at a certain stopping temperature and stopping time is achieved. These parameters can be determined by the following procedure. ·

1) determining the plug temperature of porous articles,

a) Determining the dependence of the solubility of the additive or the additive compound in a suitable one Solvent from the temperature.

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" ⁴⁴ " 261U95

b) The range of the plug temperature is between the high temperature of the solution from (a) and the temperature at which the desired concentration of the additive or the additive compound in the solution from (a) is saturated . -

2) · Determine the stuffing time of porous articles

The stuffing time not only depends on the concentration,

the temperature and the composition of the additive - solution -, but also the size of the Kik ro ge add ε in the porous article. The procedure given here applies to a specific additive solution, temperature and microstructure of the rod-shaped article. If any of these variables are changed, the procedure must be repeated or appropriately modified according to the guidelines given.

a) Measure the diameter (a) of a porous rod and immerse the rod in the additive solution.

b) monitoring dss weight of the bar as a function of time.

c) Determine the time t, after which the weight does not increase significantly, in that the fractional weight change y (t) = ^ ~ K (t) - M (o] / / ^ "V ( ⁰⁰ J - r (o) _7 over the time t aufstracer, is, where I '. (O), K (t) and" ( ^CO ) the corresponding weights ar. Beginning, at time t and after very represent a long time.

d) The L_it t. the other porous ones for stuffing one another Rod with the diameter a and with the same additional side1 solution at the same temperature is required is:

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. 45 - 261H95

example

A porous rod was stuffed with a concentrated solution of CsNO ₃ in water (120 g CsNO ₃ per 100 ml of the solution) at 100 C. The radius of the rod was 0.42 cn. The weight gain as a function of time was measured. The results are shown in FIG. It can be seen that the weight of the stick did not increase significantly after about 200 minutes. The suitable tamping time for this rod is therefore four hours,

3) Determining the destuffing time to produce a continuous profile in a porous article by thermal Separation,

In order to make a continuous profile, the article stuffed according to the above item (2) is partially unclogged by dipping the item in the solvent. This should be done at a temperature at which the additive does not precipitate. The time required for unclogging depends on the temperature, the microstructure and the desired profile of the composition. The one described here Procedure applies to a specific plug temperature and a certain parabolic profile,

a of Entstccfvorgan-as at a temperature at which the rod under üotrvachung the weight change as a function of time gastopft ^r) performing an assay; vird immersed urde _# while the rod in the solvent..

6,09841 / 0877

" ^4β '- 261Η95

b) applying the fractional change in y (t) over time ts

_r M (t) - -M (Q)

c) The time t for unclogging depends on the desired profile . The time is often:

-y (t _o ) ^ 2/3.

For profiles of other shapes, a similar equation can be worked out _{for y (t o).}

example

A porous rod is chosen, which is concentrated with CsNO.j 'solution (12o g CsNO per loo ml solution) at 100 ° C in has been stuffed in the manner described above. The rod was then unstuffed in water at 1qo ° C, with the Weight loss of the rod as a function of time was monitored. The results are shown in FIG. The area the unblocking times can be taken from the graph.

4) Determine the temperature and time to unclog the Rod for the production of a stepped profile thermal deposition.

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The temperature for un-plugging to produce a step-like profile depends on the desired strength in the article and on the additive solution. As a possible low expansion coefficient or the highest possible glass transition temperature T in the surface layer If desired, the temperature of the disposal pot is a few C-wheels above the freezing point of the additive solution.

The time required for the deadening depends on the thickness of the surface layer to be pressurized such as also depend on such parameters as the decapping temperature, represent the concentration of the stopper solution used and the size of the microstructure in the porous article. This one The procedure described applies to certain sizes of these Variables. If the value of any of these parameters is changed, the entire procedure must be repeated and accordingly set according to the guidelines below.

The desired thickness of the surface layer is "d" and the wall thickness of the article is "a". Let it be:

T = 4 I IX - (f) ₃ 7,

where g is a geometric factor, "where g = '1 for cylindrical Shapes and g = O for plates. Knowing Y, it is possible to determine the appropriate destuffing time through the following to determine the procedure described.

(a) Carry out an examination of the decongestion process in the desired solution at the desired temperature, where the fractional weight change y (t) as a function of Time is monitored.

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(b) Distribution of the fractional weight change over time (see equation 1) *

(c) reading the time t from the graph, where for the time 'applies:

y (t _o ) = υ.

This is the desired unclogging time.

The practical purpose of the Entstopfvorganges is to be seen in most cases that the concentration of the additive is reduced in the outer layers of the article in order to achieve the desired reinforcement profile.

When the actual plugging with a saturated solution of an additive at 95 ° C has been completed, leave this can be achieved, for example, by adding the additive solution by the solvent containing no additive at the same temperature or, in the case of an aqueous one System ^ is replaced by water or Dilute Nitric Acid. The additive then diffuses outwards so that the concentration changes over the cross section of the porous matrix. The time required for unclogging is of course of the treated Volume dependent. An article with a wall thickness of 8 mm takes about 20 to 30 minutes. The decongesting process is conveniently interrupted by the fact that the liquid surrounding the article by a cold solvent or, im Case of an aqueous system, by water rr.it a temperature near freezing point or replaced by an ice-cold nitric acid. In the case of an aqueous system, is it is possible to control the end point by measuring the change in conductivity of the water used for unclogging will.

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5) drying, i.e. removing the solvent,

Two problems arise during drying, namely the economic efficiency of the process and the quality of the product affect. These problems are the cracking of the porous glass structure and the changes in the profile of the composition of the additive. Tearing is a static problem

and it is possible that there are samples showing the method survive regardless of the drying process. For a In order to operate economically, however, it is necessary to provide a measure which reduces tearing to a minimum and so improves the economy of the process. Such a measure should preferably also avoid that the profiles change such that additive is brought from the interior of the article to the surface thereof, as this is usually the case does not lead to a desired profile. This leads to a decrease in the concentration of the additive in the Center of the article and to an increase in the concentration of the additive at the side edges of the article. As above indicated, the profile obtained depends on the unclogging. When you have obtained a suitable profile and in the porous If the structure is still solvent, it is essential to dry the object, i.e. the solvent to a Way to remove which does not change the achieved profile to an undesirable course.

An analysis of the drying process revealed that a number of prior knowledge influences the process. These precursors are:
i

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(a) The evolution of gas. The gas sources can be the solvent, the decomposition products of the additive and dissolved Be gases. When the gas evolution due to rapid heating or is too strong due to insufficient gas removal, the differential pressures created in the pores can break the glass and / or remove the additive from the

Carry out inside the article,

(b) The resizing. When the bulk of the solvent out the porous glass is removed, a solvent layer can with remain chemically bonded to the porous surface of the porous glass. This effect was

observed with water and it was found that the Layer persists up to high temperatures. This can also occur with other solvents. When this shift removed, the sample will shrink. If there is sufficient shrinkage difference, the porous structure can be used Loads occur that lead to tearing

(c) decomposing the additive compound. The additive available in solution is usually a compound which thermally decomposes. There were additive compounds chosen, which is before the compression temperature (collapsing temperature). This decomposition is usually associated with a large evolution of gas. It is common desirable to control the extent of the heating process, while going through the temperature range, in which decomposition takes place to prevent biting and transport of additive.

609841/0877

(d) Mass transport can occur at various points in the drying process. During the initial drying of the article, the additive that remains in solution may be transported to the surface and deposited there as the solvent " ¹ " is evaporated -'If the crystals of the additive are small after decomposition, they can be carried through the gas phase. If the additive has a considerable vapor pressure, redistribution of the additive through the vapor phase can occur. If the additive becomes a liquid, a redistribution of the additive can occur Distribution take place due to gravity.

The following is an advantageous method for appropriately solving these problems and difficulties. The removal of the original volume of the solvent must be carried out under conditions in which no boiling takes place. In the case of aqueous solutions, two methods have proven to be useful.In the first method, the initial drying of the porous glass article with the deposited additive takes place in a desiccator at atmospheric pressure and 22 ° C for a period of 24 hours, after which the glass article is placed in a drying oven will. In the second method, the object is placed in a vacuum at temperatures below lo ° C. and above the freezing point of the solution. It has been found that 4 ° C is suitable for a period of 24 hours when CsNO, in ^T .-. ^T AEL ** strength solution is used as an additive. To further reduce the risk of cracking, it is advisable to use

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of aqueous solvents the article of a final wash with a non-aqueous solvent to subject the does not react with the glass. An example of a suitable solvent is methyl alcohol

Ee is useful for the articles that are in a vacuum below lo ° C had been kept to warm slowly to room temperature and at room temperature for about 24 hours under vacuum BEFORE putting the items in a drying oven will·

If non-aqueous solutions of additives are used it is advantageous to place the articles in a vacuum at room temperature for about 24 hours and then in a Stuck drying oven. This speeds up the process considerably compared to an aqueous process.

In the case of the drying oven, it is desirable to bring the samples to the upper drying temperature with a vacuum Speed below 30 ° C / hour, preferably 15 ° C / hour. to heat, as a low heating speed increases the likelihood considerably reduces cracking and prevents redistribution of the additive.

The selection of a suitable, slow heating speed depends on the economics of the process. It may be cost effective in some cases «a higher proportion to accept breakage in order to increase the throughput of the articles through the processing system, any increase in However, heating rate must also counteract the increased risk

609841/0877

the destruction of the desired profile of reinforcement in the unbroken articles.

The upper drying temperature depends on the porous glass matrix. This upper drying temperature should on the one hand not be too high to cause the pore structure to collapse to avoid and on the other hand not be too low, otherwise the drying speed in terms of Economy is too low. A suitable value can be found by not using an additive filled article collapses first and the glass transition temperature T measures. The upper drying temperature becomes then preferably chosen so that it is between 5o and 15o C below the temperature of the glass transition. A closer one Range between 75 and 125 ° C is preferred.

The next stage of the drying process is that the glass is held at or near this upper drying temperature for a period of time. The glass can during this time, depending on the desired optical properties, such as color absorption spectra, in the end product either under vacuum or kept under a selected gas atmosphere. At the upper drying temperature you can either use a reducing or use an oxidizing atmosphere to 1. the valence states of the polyvalent ions, especially the Ions of the transition metals, and 2. the metallic or ionic To control the valence states of the precious metals. Example

2+
wise, Cu gives a blue color, Cu + a red color, and Cu a brown color. It is advisable to run Os around the article, as this aids the drying process. If the reduction in the hydroxyl concentration is not important, this holding time can be dispensed with. With this one

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The preferred method for high oxidation states is a porous glass article with a glass transition temperature T of 725 ° C at 6 25 ° C (loo ° C below the glass transition temperature) heat treated for 96 hours while dry oxygen gas is passed around the sample. The procedure for low oxidation states corresponds to the above procedure with the exception that instead of a dry oxygen atmosphere a vacuum is used.

(6) compaction.

When the above drying process is finished, the article is ready to collapse or collapse. can be condensed. The temperature of the article is rapidly increased to a point where compaction entry. When the pores have collapsed, it is the compaction ends, after which the article can be quenched to paum temperature. The compression must be at atmospheric Pressure or below can be carried out if the article is to be processed further by heating it above the compression temperature, otherwise easily gas development occurs when the heating is repeated and bubbles form «

When the die is made of a phase separable glass it is desirable to heat the porous glass samples at reduced pressure (about 1/5 bar) up to 825 ° C, where compression occurs.

The following examples explain the molecular Stopper according to the invention, but without restricting the invention.

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Examples 1 to 5 illustrate the use of various concentrations of additives in vä Solutions in the treatment of a porous matrix resulting in a compacted glass with different concentrations

the additive lead. The general method of manufacture the porous matrix made of phase-separable glass and the subsequent treatment are in the following Paragraphs described. The numbered examples show the use of different additives in a concentration range, the collapse or compression temperature. ren and the final overall glass composition.

Melting and molding

A glass with a composition in I'ol% of 4 NaO-, 4 KO, 36 B ₃ O ₃ , 56 SiO ₂ was melted and stirred to a homogeneous melt, from which rods or rods with a diameter in the order of o, 7 to 0.8 cm have been pulled

Heat treatment with a cooling coil

The drawn rods are vcn at .55 ° C for the duration of subjected to a heat treatment for two hours in order to separate the phases bring about.

Etching before deir. Leaching

Each bar was etched Io seconds ± ~ * 5% HF, after which it was washed 3o seconds in water.

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Leaching

The rods were leached at 95 ° C. with 3N HCl with 2o wt .-% NH.Cl. The time was chosen on the basis of previous attempts to reach a level at which the amount of weight loss has dropped to almost zero. The leaching time of the rods in these examples was chosen to be over 30 hours. The boric acid concentration in the leaching agent was kept below 50 g / l during the leaching process by providing a cold spot at 40 ° C., thereby accelerating the leaching process and avoiding any further deposition of boron compounds in the pores of the die . 40 ° C was chosen so that no NH.Cl precipitates out of the leaching solution, since this temperature is above the saturation temperature of the NH.Cl present in order to keep a suitable amount in solution and greatly reduce fractures.

To wash

The leached material is washed twice with deionized water. Washing is beneficial at Carried out at room temperature, using 10 parts by volume of water to 1 part by volume of glass.

Plug

In the case of aqueous solutions of additives (see Examples 1-6) , it is advisable to proceed gently and smoothly from the last Kasch step to the stuffing process, inde ... the water is simply replaced by the stopping solution. This is done by

609841/0877

261H95

that the water from the last wash is drained and the tube containing the porous rod is filled with the stopping solution.

In Examples 1 to 4, the samples were removed from the stop solution and cooled to a temperature of 22 ° C / at which the additional agent partially precipitated, with an amount corresponding to the aqueous solubility at 22 ° C in the liquid remained in solution, which filled the pores. A solution of Io g Ba (NO) _2/1 ^ο ° ^m l was dissolved example after the thermal deposition at 22 ° C in water in the pores. A solution of 6 g of H ₃ B0 ₃ / loo ml also remained dissolved in water in the pores. The remainder of the additive was deposited during the drying process, which was initiated by placing the porous article in a desiccator at 22 ° C and atmospheric pressure for 24 hours. The drying process was then carried out under vacuum in <e, inem-. Oven continued, its temperature at 15 C / h. was increased to the upper drying temperature. This upper drying temperature was determined in the manner described above and was 625 ° C. for the samples in Examples 1 to 8.

Hold time

The rods were then held at a temperature of 6-25 ° C. for 10 hours. When oxidized states were desired, dry oxygen gas was circulated around the rods, and when reduced conditions were desired, were the rods held in vacuum.

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compression

At the end of the holding time, the temperature of the rods became rapidly increased to a high temperature given in each example at which the collapse of the pores in either an oxygen atmosphere under reduced pressure of about 1/5 bar or in vacuum, depending on whether oxidized or reduced conditions were desired.

In Example 1, BaO was used as an additive. This BaO is not miscible with the base glass at the compression temperature causing the breakdown of the pore structure and has the effect that the glass has an opalescent effect, provided that it is not worked up again at higher temperatures. In example 2, B ₃ O _{3 is used} as an additive. This BO ₃ lowers the glass transition temperature and is therefore suitable for reinforcing the glass using the T process. In example 3, PbO is used as an additive. This PbO lowers the nias transition temperature and increases the elongation coefficient and produces a milky white glass article under oxidizing conditions. Examples 3 and 4 demonstrate the use of more than one additive to achieve both strength and a desired appearance.

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Example 1

Lo
sungs
medium ₃
g / loo cm
H ₂ O Molecular Darning
tempe-
rature
( ⁰ C) Peat with BaO Weight% 12th Additives 85 Ba (NO ₃ ) ₂ in water 6.86 Rod-
No. t
StOOf-
z sit
(Hours.) Condensing
management
tempera-
door Together
settlement 91.1c 1 4th 8 2o 6, ο B ₂ O-. 2, o4 18th 85 93.11 SiO ₂ 6.7S o.82 BaO 9o, 18 2 4th 8 2o 6, o B ₃ O ₃ 3, o3 24 85 92.73 SiO ₂ 6.72 1.22 BaO 3 9.23 3 4th 8 3o 6.00 B _n O ₃ 4, cl 92.35 SiO ₂ 1.62 BaO

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261-95

BeisDiel 2

To-
sentence-
middle -
g / loo cm
H ₂ O 12th Molecular plug with B 2 ° 3 Darning
teinpe-
rature
( ⁰ C) Condensing
management
teitioera-
door*
( ⁰ C) Together
settlement
(Mol%) Wt% Ver
equal to 0
Rod Additional agent H ₃ BO ₃ in water - - 82o 6, o9 B ₂ O ₃
93.88 SiO ₂ 7th
93 Rod-
No. 4th 18th Darning
Time
(Hours.) 85 815 7.73 B ₂ O ₃ 8.83 - 92.27 SiO ₂ 91.17 5 24 4th 85 815 8.51 B ₂ C ₃ 9.71 -. . 91.49 SiO ₂ 9o, 29 6th 4th 85 8I0 9.28 B ₂ O ₃ lo, 5S 9o, 72 SiO ₂ 89 ^, 42 4th

6Q9841 / 0877

261U95

Example 3 Molecular Plugging with PbO +

Additive Pb (NO ₃ J ₃ and H ₃ BO ₃ in water

Bar no. 7 Filled with 40 g Pb (NO ₃ ) ₂ and Io g H ₃ BO ₃

per 100 cm H ₃ O at 85 ° C for a period of 12 hours. Compressed at 8 25 ° C.

Example 4

Molecular plugging with BaO +

Additive Ba (NO-O ₂ and H ₃ BO ₃ in water

Bar no. 8 Filled with 12 g Ba (NO ₃ J ₃ and 6 g H ₃ BO ₃

per loo cm H ₃ O at 85 ⁰ C for a period of 4 hours. densified at 8 3o ° C.

Example 5

v.

The above examples all relate to uniform plugging of a rod. If a rod has been given sufficient time to diffuse the additive solution into the pores, it is possible to reduce the concentration in the outer region of the rod in order to achieve a profile of the composition in the compacted rod. Two porous rods were produced according to the above process and immersed at 95 ° C. for more than four hours in an aqueous solution of CsNO ₃ with a concentration of 120 g CsNO ₃ and 1 g Fe (NO _{3 I 3} per 100 ml of solution Rods were then taken in water

609841/0877

26-95

Given £ 5 ° C and left in the water for 11 or 20 minutes. After this time in water, each rod was placed in water at ⁰ ° C. for 10 minutes in order to bring about the thermal deposition of CsNO- and an interception of Fe (NO-I _3. The rods were then treated to remove the solvent The composition profiles measured by the refractive index are shown in Figure 7. Due to the presence of reduced iron, the rod was green in color .

Example 6

Various porous rods produced in the manner described above are immersed in a series of solutions of CsNO ₃ and Cs ₀ CO ₃ according to Table V below for more than 4 hours at 95.degree. The bars were then un-plugged to create a step-like profile. The for

Unclogging time required was using the figure certainly. The time for which y (t) = 0.5 was, for example, 300 minutes for rod no. 13. The stuffed rods were thereby unclogged that they were immersed in ice water for 300 minutes. The water was removed and the rods were in the compressed manner described above. The Cs ^ O concentration, which resulted in the length of the rod and via the refractive index was measured is given in Table V.

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261U95

2o Table V Refractive index
in the middle of
Staff Rod no. 3o Darning solution 1.462 9 75 g Cs ₂ C0 ₃ / loo ml H ₃ O 1.475 Io 6o g Cs ₂ C0 ₃ / loo ml H ₂ O 1.488 11 12o g Cs ₂ C0 ₃ / loo ml _H2O. 1.475 12th g CsH0 ₃ / loo ml aqueous
solution 1.486 13th g CSNO / 100 ml aqueous
/ Solution

Example 7

In a longitudinally ar.en drying between the temperatures near ⁰ OC and 600 C above-pointed out the .Bedeutung when stuffed rods are used with additive. Here an example is shown in which the differences in the composition profiles due to different heating speeds can be seen. Some of the gas-plugged porous rods used in Example 5 were un-plugged to produce stepped profiles as in Example 6. After thermal deposition, the rods were dried in vacuo at 4 ° C. for a period of 24 hours. They were then placed under vacuum at speeds of 50, 30 and 15 ° C / hour. heated. The resulting profiles for the composition were measured on the profile of the refractive indices are shown in FIG. 8 Heating speeds

over loo ° C

the bars.

609841/0877

over 100 ° C per hour led to a notable break

Example 8

After the leaching and washing described in the introduction to Examples 1 to 4, a stuffed, porous rod was _{immersed for a period of four hours in a solution containing 120 g of Cs (NO 3} ) per 100 cm of water. The rod was then dried in a desiccator for 24 hours at paum temperature. The sample was stuffed uniformly. In order to generate a profile, the sample was then washed in water at 4 ° C. for two hours and then in 3N HNO _{3 for 30 minutes.} This is followed by drying in vacuo at the same temperature. After the bulk of the water was removed, the sample was slowly dried by progressively increasing the temperature as described in the preferred method according to the invention. At intermediate temperatures, the CsNO ₃ decomposes into Cs ₃ O and various nitrogen oxides. When the sample changes from the white to the clear state, the compaction is complete so that the sample can be removed from the oven. The sample has a surface tension above when examined at room temperature

2
7o3 kp / cm (Io 000 psi) and a coefficient of expansion of

3.1 χ Io / ° C. The usage temperature is over 700 ° C. The thickness of the pressurized layer is over 0.5 µm (20 mils). This rod has a greater strength than a similar rod _; made from fused silica.

Example 9

The choice of additive, solvent and Working conditions during the stuffing and unblocking, as well the combinations and exchanges of these parameters to achieve a desired end result or: the modification of the experience conditions. In veiter. Boundaries are changed. In the foregoing, the specialist name c-.r.n

F. η q π /. ι / η R 7 7

261 U35

given a guideline. This example shows some exchange options and combinations that have proven to be useful. The porous rods used were all made by the general procedure described above and solvent removal and heating were carried out under the preferred conditions.

The results obtained are given in Table VI below. The columns in this table have the following meanings:

Column Ii Column 2: Column 3: Column 4: column 5;

Column 6: Column 71

Additive used.

Concentration of the additive / 100 ml of solution. Solvent, i.e. that at the beginning of the Solvent used in the plug. Temperature in C and the time for the initial one Plug.

Solvent A; this is the solvent which is used to reduce the concentration and to achieve a change in the refractive index and also to trigger the deposition of the additive. ^ Temperature in ⁰ C and 25eit for the deposition and the change in the profile of the refractive index. Solvent B; this solvent is used, if necessary, to adjust the distribution of the additive in the die by adding a before starting the removal of the solvent

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further deposition is caused, thereby causing a greater decrease in the concentration of the additive close to the glass surface.

Column 8: temperature in ⁰ C and time to adjust the distribution of the additive by a further solvent treatment,

Column 9: Temperature data in ⁰ C at which the drying process began. The details "V" or "A" indicate whether the drying process took place in a vacuum (V) or in a desiccator at atmospheric pressure (A) for the first stage.

Column lo: composition in the form of the measured refractive indices.

Row Ij corresponds to bar no. 13 in the previous example 6 and was added for comparison with line 2, where an additional further Treatment with! - 'ethanol and water using the same stopping solution increased the difference in the refractive index.

Line 3: shows how to replace one compound with another, in this case by replacing CsNO ₃ with Cs-CO _3; Due to the higher solubility, the 3-pot process can be carried out at faun temperature.

Lines 4 through 9: show the use of different

Additives and solvent combinations.

Lines Io and 11: show the use of a genic

of additives.

Line 12: Shows the use of neodymium nitrate as an additive and the use of an organic one Solvent. By plugging with neodymium or other transition elements, the reinforced article colors are generated.

609841/0877

Tabel

VI

Additive·
middle

1. Cs (NO ₃ )

2. Cs (NO ₃ )
^ 3. Cs ₂ (CO ₃ )

-. 5. H., DO

. Ba (NO ₃ )

Plug

weight
Per
loo ml
solution

12o g

12ο g

5ο g

4ο g

Solution
middle

water

water

water

17.5 g of water
g of water

water

g of ethanol

g of water

Temperature and
Time

95 ° C 16 hours

95 ° C 16 hours

22 ° C 16 hours

25 ° C 4 hours

8 5 ° C 4 hours

22 ° C 16 hours

J, 16 hours

85 ° C 4 hours

6 7

Deposit

Solution, temperature mean, temperature and time

Solvent B

Temperature and time

dry

Start at ° C

Io

Refractive index

water
,Water

3 hours.

O ⁰ C 3 hours

o _r ^{4 C}

3o% water 0 ⁰ C 7o% methanol 3 hours.

Middle 1.486 edge 1.464

A ° r (ν) ^{center X} ' ^{489 4 C (v)} edge 1.4

92% meth. 22 ° C - 52% methanol 22 ° ..C 8% 1-Pro- 3 hours 43% 1-Propa- 3 hours. panol nol

22 ° C (V)

1.487

water

22 ° C
Io min.

3o% H ₂ O
7o% meth.

15% Jitha-22 ° C nol 85% 3 hours Diethyl ether

5% water 22 ° C 95% methanol 3 hours

lo% ethanol * 22 ° C 90% diethyl 3 hours ether

water

22 ° C 3 hours

25 ° C (A) 1 NJ
CD
i , 465 22 ° C (A) 1 CO
cn , 457 22 ° C (V) 1 , 465 '
σ 22 ° C (V) 22 ° C (A)

Table VI (continued)

1 3 . 2 3 4th 5 6th 7th Deposit Solution
medium B θ 9 Io I. cn Plug Tempe
rature
and
Time dry 1.464 Additive-
mittol 2 weight
Per
loo ml
Lctauncj _e- Solution
middle Tempe
rature
and
Zoit Solution
medium A Tempe
rature
and
Time· Beginning
at ° C Refractive
index 9. Al (NO ₃ ) 2 6o g water 25 ° C -
4 hours - .... 22 ° C (A) + 9 H ₂ O 3 22 ° C -
Io min. —— Io
CD .Ua (NO ₃ )
H ₃ BO ₃ 12 g
6 g water 85 ° C -
4 hours water 22 ° C -
Io min. - —-., 22 ° C (A) + X
CD .Pb (NO ₃ )
^U 3 ^BO 3 4o g
Io g water 85 ° C -
12 ⁷ hours water 22 ° C -
3 hours. - 22 ° C (A) OO .Nd (NO ₃ ) 2nd Floor 9o% Di-
ethyl-
ether 22 ° C -
16 hours Diethyl
; · Ther 22 ° C (A) Ethanol

'In this case, the stuffed rod 3 h then was 1 1/2 h., The solution B in. Long in

solutions A and B are immersed.

These glasses scattered the light when they were compressed and became clear when they were drawn into pasers

became·

261 H95

When a flat glass panel is reinforced according to the invention, this glass panel can be used as a window pane, which have a large temperature rise generated, for example, by solar heating, and at the same time considerable, for example can withstand pressure differences across its surface caused by strong winds.

Molded panels made from this material can be used as oven covers as they are both resistant to thermal shock of the heating element as well as the mechanical shock loads in the event of abuse and wear and tear.

An advantage of the method according to the invention over deir thermal annealing to reinforce glass is that the glass can be easily cut after reinforcement. The reason for this is that the tension in the center of the glass is much lower in the method according to the invention than can be maintained for an equivalent compressive stress on the surface during thermal annealing. The cause for this is the improved control of the load profile made possible by the invention. The thickness of the surface layer is advantageously less than 1/5 of the thickness of the glass article. The surface layer should be a Thickness of at least about 25o micrometers, preferably between 500 and 25oo micrometers, to avoid slack and loss to prevent the strength from scratches.

For example, the rod of Example 8 can withstand scratches and be cut with a diamond saw without that it splinters. While the interior of the glass produced according to the invention only 80%, preferably 85% silicon dioxide may contain, the surface layer of the glass according to the invention contains over 85%, preferably over 90% silicon dioxide.

609841/0877

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The glass articles produced in this way are in chemical Relatively inert and can be used, for example, in the form of baby food and blood plasma bottles -will. In both of these cases, sodium leaching is a problem when ordinary crown glass is used.

The present invention offers great advantages over thermal annealing when reinforcing a hollow article would like to. In thermal annealing, it is extremely difficult to finish the inner and outer surfaces of hollow objects to cool quickly and evenly.

In the above, preferred embodiments of Invention explained in more detail. It is assumed that various changes and modifications for are obvious to the person skilled in the art on the basis of the teaching given by the invention. All such changes and modifications fall within the scope of the present invention.

6098 41/0877

Claims (1)

Claims 1. Method of making opaque or colored, high-strength and hard glass articles, characterized in that a preform made of porous silicate or germinate glass is made with interconnected pores and one or more additives so non-uniform in the pores be deposited that the surface of the glass article is under compressive stress when the preform is in a has been condensed and cooled to maintain and control the opacity and color selected. 2. A method for producing a hollow, high-strength and hard glass article, characterized in that a hollow Preform is made of porous silicate or germinate glass with interconnected pores and one or more Additives are so unevenly deposited in the pores that after the compression of the hollow preform, the inner and The outer surfaces of the glass article are under compressive stress. 3. Process for the production of high-strength and hard glass articles, one dimension of which is at most l / lo of the smaller ones of the other two dimensions and in which the The product of the two major dimensions is greater than 0.09 m (1 square foot), characterized in that a preform made of porous silicate or germinate glass with interconnected pores and one or more additives are deposited in the pores in a non-uniform manner in such a way that, after the preform has been densified, all surfaces of the Glass article are under compressive stress to a depth that is not greater than 1/5 of the smallest dimension. 609841/0877 261U95 4 # Method according to one of claims 1 to 3, characterized characterized in that the additive meets the glass transition temperatures Preform changes non-uniformly in the way, is inside the preform. the casting transition temperature T on the surface is greater 3. Method according to one of Claims 1 to 4, characterized in that the additive changes the thermal expansion of the preform in such a way that the thermal expansion in the vicinity of the surface is less than in the interior of the article. $ · Method according to one of claims 1 to 3, characterized characterized in that the preform is a borosilicate glass. 7 »Method according to claim 6, characterized by a Preform with the following composition in mol% s 48-64% SiO ₂ 4-9% R ₃ O 28 - 42% "- O-B ₂ O ₃ 3%. where R ₃ O stands for the sum of Id-JD ₉ Na ₃ O, K ₃ O, Rb ₃ O, Cs ₃ O ₃ and a coexistence "temperature Tp between 71o and 600 ⁰ C is present. 8. The method according to opposition 7, characterized in that that the coexistence temperature "Fn" is between 695 and 64o ° C. 9. The method according to claim 6, characterized by a Glass composition with the following components on a mol% s basis 48-64% SiO ₂ 4-9% R ₃ O 28-42% B ₃ O ₃ O -3% Al ₃ O ₃ 609841/087? " ⁷³ " 261U95 where the composition has the following parameters: PO - l, o; oC O - 3; T ^ O-0.5; χ o, l - l, o where oC is the Al ₂ O ₃ concentration in mol%, χ = + (1/3) oC- K _and d s is the molar ratio of A ₃ OZR ₃ O, A2O is the sum of the concentrations in mol% of K ₃ O, Rb ₂ O and Cs ₃ O, R ₃ O is the sum of the concentrations in mol% of Li-O, and Cs-O and 7 "- represents the ratio of Li ₃ OZR ₃ O. 10. The method according to claim 9, characterized by a composition with 56% ³ IO ₃ , 36% B ₃ O ₃ , ^ ^{% K} 2 ° ^{un (} ^ ^ * Na ₃ O. 11. The method according to claim 6, characterized in that the concentration of boric acid in a leach solution by Separating the boric acid from the leach solution in a cold separator is reduced. 12. The method according to claim 11, characterized in that the temperature of the preform is kept above 80 ⁰ C and the cold spot (cold spot) has a temperature which is at least 2o ° C below the temperature of the preform. 13. The method according to claim 12, characterized in that the temperature of the glass preform is above 9o ° C and the temperature of the cold spot is between 35 and 50 ° C and the mineral acid is hydrochloric acid and the solution is at least Contains 2o wt .-% NH ₄ Cl. 14. The method according to claim 5, characterized in that that the additive is at least one oxide or salt of cesium, barium, lead, thallium, bismuth, thor, uranium, rubidium, strontium, Is antimony or tin. 609841/0877 261U95- 15. The method according to claim 4, characterized in that the additive is at least one compound which Contains boron, sodium, lithium, potassium, phosphorus, germanium or arsenic. 16. The method according to any one of claims 1 to 3, characterized characterized in that the additive by controlled diffusion into the pores of the preform in its pores is deposited. 17. The method according to any one of claims 1 to 3, characterized in that the additive is made by deposition a solution is deposited in the pores of the preform. 18. The method according to claim 17, characterized in that the additive is deposited substantially without evaporation of the solvent and the drying process is initiated after the deposition and the amount of heat is controlled to remove the solvent and, if necessary, the decomposition products from the pores to achieve a desired reinforcement profile in the glass article. 19. The method according to claim 18, - characterized in that only then is started with the removal of the solvent, if the deposition is substantially completed. 20. The method according to claim 18, characterized in that the additive is deposited or deposited by thermal measures. 21. The method according to claim 18, characterized in that the additive is deposited or precipitated by chemical measures. 609841/0877 261U95 22 · Method according to claim 18, characterized in: that the additive is replaced by an exchange of solvents is deposited or precipitated. 23 · The method according to claim 18, characterized in that that the additive by a combination of thermal Precipitation and chemical action is deposited. 24 · The method according to claim 18, characterized in that the article after knocking down and before heating to remove the solvent in another solvent is immersed to reduce the concentration of the additive in the outer layers of the article. Process according to Claim 18 , characterized in that the article is immersed in a solvent for the additive after being dipped in an additive solution and before the additive is knocked down, in order to change the concentration of the additive in the pores. 26. The method according to claim 18, characterized in that the solvent is removed under conditions at which no boiling occurs. 27. The method according to claim 13, characterized in that that the removal of the solvent is started in a vacuum below room temperature 28 · The method according to claim 18, characterized in that the solvent is water and the water before the start the drying process is exchanged for an organic solvent. 29. The method according to claim IS, characterized in, that the article after removing the? * asse of the solvent slowly with a Ceschv / indickeit below 100 ° C / hour. on a 60984170877 261U95 Temperature is heated, which is 5o to 15o C below the glass transition temperature of the unclogged and compacted glass used as a host. 30. The method according to claim 29, characterized in that that the preferred heating rate is below 20 ° C / hour. lies, 31. The method according to claim 29, characterized in that that the article is kept under vacuum during the heating process will. 32. The method according to claim 18, characterized in that the porous article is quickly brought to the temperature, in which the compression takes place after the removal of the solvent or any decomposition products present in the substantial has been terminated. 33. The method according to claim 32, characterized in that the last increase in temperature in a subatmospheric Printing is carried out. 34. The method according to any one of claims 1 to 3, characterized in that the additive is a compound of Cs
is. 35. The method according to claim 34, characterized in that the additive is CsNO-. 36. The method according to any one of claims 1 to 3, characterized in that 2 to 15 JSol% of the additive in the glass
are stored. 37. The method according to claim 36, characterized in that that 5 to 10 mol% of the additive are incorporated in the glass. 38. The method according to claim 18, characterized in that that the solvent consists of water, alcohols, ketones, ethers or mixtures thereof. 39. The method according to claim 38, characterized in that the solvent consists of water, alcohols or mixtures consists of this. 40. Procedure according to one of the. Claims 1 to 3, characterized characterized in that the additive is deposited in the pores by the deposition of a chemical vapor. 41. The method according to any one of claims 1 to 3, characterized in that a further additive for regulation the appearance of the article is admitted. 42. The method according to claim 41, characterized in that that the further additive consists of one or more transition metals or rare earth ions. 43. The method according to claim 41, characterized in that the further additive consists of one or more elements consists, which have free electrons, which lead to a smoky appearance. 44. The method according to claim 41, characterized in that That the further additive forms a colloidal, metallic deposit of a metal to give different shades of color to evoke. 6XJ9841 / 0877 ^"78 ~ 261U95 45. The method according to claim 41, characterized in that that the further additive is at least one oxide of aluminum, alkaline earth, titanium or chromium, to an opalescent or create a milky appearance * 46. The method according to claim 41, characterized in that the article is kept in a reactive atmosphere at the upper drying temperature or is heated to an insignificant extent at the upper drying temperature, which is in the range between 5o and 15o ° C below the glass transition temperature of the as The host used unstuffed and compacted glass to regulate the oxidation state of the coloring additives. 47. The method according to claim 46, characterized in that preferred Tem]
temperature is. that the preferred temperature 75 to 125 C below the glass cover 48. The method according to claim 41, characterized in that the increase in temperature from the upper drying temperature up to the collapse of the pore structure Compaction temperature in a reactive Atmosphere is made, the pressure of which is below atmospheric pressure and whose chemical composition se is chosen that the oxidation state of the coloring additive is regulated. 49. Article according to one of claims 1 to 3, characterized characterized, d = »ß the concentration of silicon dioxide over the whole glass is greater than 80 mole percent. 50. Article according to claim 46, characterized in that the concentration of B ₃ O _{3 is} at least 2 mol%. 609841/0877 261 U95 51 Article according to Claim 5o, characterized in that
that the concentration of silica over the whole
Glass is greater than 90 mole percent. 52. Article according to claim 3, characterized in that
that the article is a window pane 53 «Article according to claim 3, characterized in that the item is a windshield 54, article according to any one of claims 1 to 3, characterized characterized in that the article is a radome. 55. Article according to one of claims 1 to 3, characterized characterized in that the article is an oven cover. 56, article according to one of claims 1 and. 2, characterized in that the article is a tube. 57. Article according to one of claims 1 to 3, characterized indicated that the article is a cooking utensil 58 · Article according to one of Addresses 1 to 3, thereby characterized in that the article is a device for a chemical laboratory or a workshop. 59. Article according to one of claims 1 and 2, characterized marked, dp ** the article is a glass container. 60. Article according to one of claims 1 to 3, characterized characterized in that the article is a component. 61. Article according to one of claims 1 to 3, characterized in that the article is an electrical insulator. 609841/0877