Glass, glass article, method of making the glass, use of the glass and flash lamp comprising the glass

Abstract

To solve the problems associated with flash lamps and the manufacturing of flash lamps.SOLUTION: Glass has a coefficient of thermal expansion in the temperature range from 20°C to 300°C of 4.5 ppm / K or less, a T4 temperature, defined as the temperature at which the glass has a viscosity of 104dPa s, at 1500°C or more, and a reboil propensity score of less than 10 measured in a reboil propensity test.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a glass, a glass article, a method for producing said glass, the use of said glass, and a flash lamp comprising said glass. The glass according to the invention is particularly suitable for a flash lamp comprising said glass. [Background technology]

[0002] Flashlamps have a variety of uses in medical, industrial and scientific applications.

[0003] Flash lamps are typically made from a fused silica / quartz or borosilicate tube designed as a U-shape with metal electrodes attached to both ends. During operation, high-voltage power is supplied to the tube through a conductive support that also serves as a mounting or lamp holder.

[0004] In order to connect the metallic conductive support of the metal electrodes to the tube wall of the flash lamp, special glasses have been developed, taking into account the large temperature changes that occur during use, and in particular the difference in the thermal expansion coefficients of the metal and the glass forming the tube.

[0005] Typically, the electrodes consist of tungsten or molybdenum and an intermediate sleeve of glass with a suitable thermal expansion coefficient, such as so-called grade seal glass, which is formed around the metal base before the metal base is introduced into the end of the lamp tube and sealed.

[0006] EP3613712 A1 discloses a lamp body comprising a tubular member made of glass or glass-ceramic material, a conductor introduced into the tubular member, and a glass material surrounding the conductor and connecting it to the tubular member, the glass material comprising sintered glass forming an airtight seal between the tubular member and the conductor and completely surrounding the conductor after being fused onto the tubular member.

[0007] U.S. Patent Application Publication No. 5,979,187 (US5,979,187 A) discloses a method for forming a glass-to-metal seal between one end of a glass tube for a flash lamp. In the method of U.S. Patent Application Publication No. 5,979,187, a metal rod terminated with an electrode is heated and molten glass sealing material is applied to form a beaded sleeve. The tube to which the electrode is to be attached is heated, and the sealing material is applied to the end of the tube, creating a dome of material that seals the end. Excess sealing material is then removed from the dome, leaving a ring of sealing material around the wall of the (open) tube end. The electrode and rod can then be inserted into the tube until the bead on the rod approaches the ring at the end of the tube, and the tube can be lowered (by rotation) to form a conical end, and the two then come into contact by movement of the bead relative to the ring while a positive gas pressure is maintained within the tube. The pressure between the inside and outside of the tube is balanced while the tube is lowered onto the bead to completely fuse the bead of the annulus. The tube is then pressurized, causing the sealing material to conform to the smooth, concave shape of the interior.

[0008] A problem associated with flash lamps and their manufacture is that the fusion between the electrodes and the glass tube is not stable due to extreme and rapid temperature changes, which affects the stability and shortens the lifespan of the manufactured flash lamps that undergo extreme and rapid temperature changes during their life cycle. [Prior art documents] [Patent documents]

[0009] [Patent Document 1] European Patent Application Publication No. 3613712 [Patent Document 2] US Patent Application Publication No. 5,979,187 Summary of the Invention [Problem to be solved by the invention]

[0010] SUMMARY OF THE INVENTION It is therefore an object of the present invention to solve the problems associated with flash lamps and their manufacture. [Means for solving the problem]

[0011] The subject matter of the present invention overcomes problems associated with and known from the prior art.

[0012] Summary of the Invention In a first aspect, the present invention provides a glass having a thermal expansion coefficient of 4.5 ppm / K or less in a temperature range of 20°C to 300°C and a viscosity of 10 4 The present invention relates to a glass having a T4 temperature of 1500°C or higher, which is defined as the temperature at which the glass has a viscosity of 1000 s in dPa·s, and a reboiling tendency score of less than 10 as measured in a reboiling tendency test.

[0013] In a related aspect, the present invention provides a glass having a coefficient of thermal expansion of 4.5 ppm / K or less within the temperature range of 20°C to 300°C, and a viscosity of 10 4 The present invention relates to a glass having a T4 temperature of 1500°C or higher, defined as the temperature at which the glass has a water content of at least 35 mmol / l, preferably at least 45 mmol / l, more preferably at least 55 mmol / l.

[0014] In another aspect, the present invention relates to a glass article comprising or consisting of a glass according to the present invention, said glass article being in the form of a rod, tube, ingot, disc, sheet or block.

[0015] In a further aspect, the present invention is a method for manufacturing glass, comprising the steps of: producing a glass melt of glass raw materials; adjusting the water content of the glass melt; cooling and / or shaping the glass melt to obtain a glass article. Including, The glass has a thermal expansion coefficient of 4.5 ppm / K or less in the temperature range of 20°C to 300°C, and a viscosity of 104 T4 temperature is defined as the temperature at which the material has a T4 temperature of 1500°C or higher. the glass has a water content of at least 35 mmol / l, preferably at least 45 mmol / l, more preferably at least 55 mmol / l, and / or The glass has a reboiling tendency score of less than 10 as measured in a reboiling tendency test. The present invention relates to the method.

[0016] In a further aspect, the present invention relates to the use of the glass according to the invention for bonding a glass article to a glass member.

[0017] In another aspect, the present invention relates to a flash lamp comprising a glass according to the present invention.

[0018] Description of the invention Re-boiling tendency test In a first aspect, the present invention provides a glass having a thermal expansion coefficient of 4.5 ppm / K or less in a temperature range of 20°C to 300°C and a viscosity of 10 4 The present invention relates to a glass having a T4 temperature of 1500°C or higher, which is defined as the temperature at which the glass has a viscosity of 1000 s in dPa·s, and a reboiling tendency score of less than 10 as measured in a reboiling tendency test.

[0019] The inventors have unexpectedly found that the thermal expansion coefficient in the temperature range of 20°C to 300°C is 4.5 ppm / K or less, and the viscosity of the glass is 10 4 The inventors have found that glasses having a T4 temperature of 1500°C or higher, defined as the temperature at which the glass has a viscosity of 100 dPa·s, and a reboiling tendency score of less than 10 as measured in a reboiling tendency test, improve the fusion between an electrode and a glass tube, for example, between a tungsten electrode and a quartz glass tube. The inventors have thereby demonstrated that glasses according to the present invention improve the stability and extend the life of manufactured flash lamps, which are known to undergo extreme and rapid temperature changes during their life cycle. In this regard, the inventors have also found that glasses or glass compositions according to the present invention benefit and / or improve the manufacture of flash lamps.

[0020] In a preferred embodiment, the glass has a thermal expansion coefficient of 4.5 ppm / K or less, 4.0 ppm / K or less, 3.5 ppm / K or less, or 3.0 ppm / K or less, measured in the temperature range of 20°C to 300°C according to DIN ISO 7991:1987. In a preferred embodiment, the glass has a thermal expansion coefficient of 0.4 ppm / K or more, 0.5 ppm / K or more, 0.6 ppm / K or more, 0.7 ppm / K or more, or 0.8 ppm / K or more, measured in the temperature range of 20°C to 300°C according to DIN ISO 7991:1987. In a related embodiment, the glass has a thermal expansion coefficient of 0.4 ppm / K to 4.5 ppm / K, 0.5 ppm / K to 4.0 ppm / K, 0.6 ppm / K to 3.5 ppm / K, or 0.7 ppm / K to 3.0 ppm / K.

[0021] The thermal expansion coefficient is preferably selected to compensate for the difference between the thermal expansion coefficient of the quartz glass and that of the metal used, for example, in the production of flash lamps it is advantageous if the glass has a thermal expansion coefficient that lies between that of the quartz glass and that of the electrode metal, for example tungsten or molybdenum.

[0022] In a preferred embodiment, the glass has a viscosity of 10 4 In one embodiment, the glass has a T4 temperature of 1500°C or higher, 1550°C or higher, 1600°C or higher, or 1650°C or higher, defined as the temperature at which the glass has a viscosity of 10 4 In a related embodiment, the glass has a T4 temperature of 1900°C or less, 1850°C or less, 1800°C or less, or 1750°C or less, defined as the temperature at which the glass has a viscosity of 10 4 The T4 temperature, defined as the temperature at which the hardness is 1500° C. to 1900° C., 1550° C. to 1850° C., 1600° C. to 1800° C., or 1650° C. to 1750° C. The T4 temperature can be measured in accordance with ISO 7884-3:1998-02.

[0023] The T4 temperature depends on the glass composition (see the glass composition in the Examples section). For example, a large amount of alkali metal oxides, such as Na2O and KO, or alkaline earth metal oxides, lowers the T4 temperature of the glass composition, while an increase in the amount of SiO2 or Al2O3 raises T4. For example, adjusting the amount of alkali metal oxides can affect the temperature dependence of the glass viscosity; for example, limiting the amount of one or more alkali metal oxides to less than 4.0% by mass can contribute to achieving a T4 temperature of 1500°C or higher.

[0024] A suitably high T4 temperature can benefit the fusion of the quartz tube to the metal electrode when used as a sealing glass for producing, for example, a flash lamp.

[0025] The reboiling tendency test consists of the following steps: a.) preparing a glass rod made of glass, the glass rod having a length of 200-1000 mm, for example about 500 mm, and a circular diameter of 2.5-5 mm, for example about 3 mm; b.) Providing a burner, for example a burner type Zenit 114 / 2 ESL, c.) heating the glass rod by the burner to a critical temperature range having a lower critical temperature limit and an upper critical temperature limit, the lower critical temperature limit being 200°C above the softening point of the glass and the upper critical temperature limit being below the T4 temperature, preferably the critical temperature range being 1400-1700°C, and preferably at least half of the glass rod being heated to the critical temperature range; d.) forming the glass rod into a spiral such that all layers of the spiral are fused together; e.) optionally, maintaining the formed helix within said critical temperature range throughout the forming step; f.) cooling the formed spiral to room temperature with compressed air; and g.) establishing a reboiling propensity score, said reboiling propensity score being defined as the number of bubbles per glass rod, bubbles being preferably defined in accordance with DIN EN 1595:1997-05. Includes.

[0026] In one embodiment, step c.) comprises heating the glass rod to a critical temperature range using a burner, wherein the lower limit of the critical temperature is 200°C above the softening point of the glass and the upper limit of the critical temperature is below the T4 temperature, preferably the critical temperature range is 1400-1700°C, and a glass rod having a length of 800 mm and a circular diameter of 3 mm is heated to the critical temperature range up to at least 400 mm of its length.

[0027] In one embodiment, step c.) comprises heating the glass rod to a critical temperature range using a burner, wherein the lower limit of the critical temperature is 200°C above the softening point of the glass and the upper limit of the critical temperature is below the T4 temperature, preferably the critical temperature range is 1400-1700°C, and a glass rod having a length of 800 mm and a circular diameter of 5 mm is heated to the critical temperature range up to at least 200 mm, preferably 250 mm, of its length.

[0028] In a related embodiment, step c.) comprises heating the glass rod with a burner to a critical temperature range, wherein the lower limit of the critical temperature is 200°C above the softening point of the glass and the upper limit of the critical temperature is below the T4 temperature, preferably the critical temperature range is 1400-1700°C, to produce molten droplets or molten drops having a drop or drop diameter of at least 20 mm, preferably at least 30 mm.

[0029] In one embodiment, step g.) comprises establishing a reboiling propensity score, said reboiling propensity score being defined as the number of bubbles per glass rod, a bubble being defined according to DIN EN 1595:1997-05, said reboiling propensity score being determined by measuring the number of bubbles per glass rod within 125 mm of any part of the formed spiral. 3Fewer than 10 bubbles per 125mm in any part of the formed spiral 3 Fewer than 6 bubbles per 125mm in any part of the formed spiral 3 Fewer than 3 bubbles per 125mm in any part of the formed spiral 3 Fewer than two bubbles per or 125mm in any part of the formed spiral 3 There is less than one bubble per piece.

[0030] For the evaluation and / or quantification of step g.), air bubbles appearing at the layer interfaces of the spiral are ignored.

[0031] In one embodiment, step g.) comprises establishing a reboiling propensity score, said reboiling propensity score being defined as the average number of bubbles per glass rod, bubbles being defined according to DIN EN 1595:1997-05, said average reboiling propensity score being greater than or equal to 125 mm 3 Less than 10 bubbles per 125mm 3 Less than 6 bubbles per 125mm 3 Less than 3 bubbles per 125mm 3 Less than 2 bubbles per 125mm 3 There is less than one bubble per piece.

[0032] In one embodiment, step g.) comprises establishing a reboiling propensity score, said reboiling propensity score being defined as the number of bubbles per glass rod, said bubbles having an equivalent spherical diameter of at least 0.5 mm and less than 2.0 mm, said reboiling propensity score being defined as the number of bubbles per glass rod having an equivalent spherical diameter of at least 125 mm in any portion of the formed spiral. 3 Fewer than 10 bubbles per 125mm in any part of the formed spiral 3 Fewer than 6 bubbles per 125mm in any part of the formed spiral 3 Fewer than 3 bubbles per 125mm in any part of the formed spiral 3 Fewer than two bubbles per or 125mm in any part of the formed spiral 3 There is less than one bubble per piece.

[0033] In one embodiment, step g.) comprises establishing a reboil propensity score, said reboil propensity score being defined as the average number of bubbles per glass rod, said bubbles having an equivalent spherical diameter of at least 0.5 mm and less than 2.0 mm, said average reboil propensity score being greater than or equal to 125 mm. 3 Less than 10 bubbles per 125mm 3 Less than 6 bubbles per 125mm 3 Less than 3 bubbles per 125mm 3 Less than 2 bubbles per 125mm 3 There is less than one bubble per piece.

[0034] The quality and stability of the seal in a flash lamp, i.e., the fusion bond between the electrodes and the quartz glass, can be impaired or adversely affected if the reboiling tendency test is not passed.

[0035] The reboiling tendency test is performed on a glass rod (sample) made of a glass according to the present invention. The glass rod can be described by its length and width, assuming a cylindrical shape. While the length of the glass rod is not critical to the test, the glass rod typically has a length of about 500 mm. Based on the cylindrical shape, the glass rod has a circular diameter, for example, a circular diameter of about 3 mm is suitable for the test. Those skilled in the art will know the boundaries and limits of both the length and the circular diameter of the glass rod for properly performing the underlying reboiling tendency test.

[0036] Similarly, those skilled in the art can select and prepare a suitable burner and know how to use the burner to establish a critical temperature range for heating the glass rod, which has a lower critical temperature limit and an upper critical temperature limit. As part of the test, the lower critical temperature limit is 200°C above the softening point of the glass, and the upper critical temperature limit is below the T4 temperature. In general, it is preferred that the critical temperature range be 1400-1700°C, and that at least half of the glass rod be heated to the critical temperature range.

[0037] After the critical temperature range is established (for at least half of the glass rod), the glass rod is formed into a spiral so that all layers of the spiral are fused together. All layers of the spiral are essentially in one plane (FIG. 1). Those skilled in the art will recognize that the temperature and dimensions of the sample are selected so that the glass can be formed into a spiral, i.e., the viscosity is low enough to give the glass the desired shape, but not so low that the glass deforms or sags uncontrollably. Optionally, the formed spiral is held at or within the critical temperature range throughout the entire forming step. The formed spiral is then cooled to room temperature by compressed air. Those skilled in the art know and understand that the cooling rate is important for the test, and that a cooling rate that is too high can confound the reboiling tendency test and the resulting test results.

[0038] In a preferred embodiment, the glass has a reboiling propensity score measured in a reboiling propensity test on a glass rod, wherein the reboiling propensity score is less than 10. The reboiling propensity score is equal to the number of bubbles observed per glass rod after the test, bubbles being preferably defined according to DIN EN 1595:1997-05. Optionally, the reboiling propensity score is less than 6 or less than 3. The reboiling propensity score may be calculated as the average of reboiling propensity tests performed on a total of 3, 6, 9, or 12 samples.

[0039] In one embodiment, the glass has a thermal expansion coefficient of 0.4 ppm / K to 4.5 ppm / K, 0.5 ppm / K to 4.0 ppm / K, 0.6 ppm / K to 3.5 ppm / K, or 0.7 ppm / K to 3.0 ppm / K within a temperature range of 20°C to 300°C, and a viscosity of 10 4 It has a T4 temperature of 1500°C or higher, defined as the temperature at which it has a viscosity of 1000 dPa·s, and a reboiling tendency score of less than 3 as measured in a reboiling tendency test.

[0040] In one embodiment, the glass has a thermal expansion coefficient of 0.4 ppm / K to 4.5 ppm / K in a temperature range of 20°C to 300°C, and a viscosity of 10 4 The material has a T4 temperature of 1500°C to 1900°C, 1550°C to 1850°C, 1600°C to 1800°C, or 1650°C to 1750°C, which is defined as the temperature at which the material has a reboiling tendency score of less than 10 as measured in a reboiling tendency test.

[0041] In one embodiment, the glass has a water content of at least 35 mmol / l, at least 40 mmol / l, at least 45 mmol / l, at least 50 mmol / l, or at least 55 mmol / l. In one embodiment, the glass has a water content of 250 mmol / l or less, 200 mmol / l or less, 150 mmol / l or less, 125 mmol / l or less, or 100 mmol / l or less. Accordingly, in a related embodiment, the glass has a water content of 35 to 250 mmol / l, 40 to 200 mmol / l, 45 to 150 mmol / l, 50 to 125 mmol / l, or 55 to 100 mmol / l.

[0042] Without being bound by any theory, it has been found that a water content of at least 35 mmol / l, at least 40 mmol / l, at least 45 mmol / l, at least 50 mmol / l or at least 55 mmol / l can help reduce the tendency of the glass to re-boil upon repeated multiple (re)heating and / or manufacturing of the glass.

[0043] Glass Composition In one embodiment, the glass contains SiO2 in an amount of 70.0 mass% or more, 72.0 mass% or more, 74.0 mass% or more, 76.0 mass% or more, 78.0 mass% or more, or 80.0 mass% or more. In one embodiment, the glass contains SiO2 in an amount of 90.0 mass% or less, 89.0 mass% or less, 88.0 mass% or less, 87.0 mass% or less, or 86.0 mass% or less. In one embodiment, the glass contains SiO2 in an amount of 70.0 mass% to 90.0 mass%, 72.0 mass% to 89.0 mass%, 74.0 mass% to 88.0 mass%, 76.0 mass% to 87.0 mass%, or 78.0 mass% to 86.0 mass%.

[0044] In one embodiment, the glass is a borosilicate glass containing SiO2 in an amount of 70.0 to 90.0% by mass, 72.0 to 89.0% by mass, 74.0 to 88.0% by mass, 76.0 to 87.0% by mass, or 78.0 to 86.0% by mass.

[0045] In one embodiment, the glass comprises one or more or all of the following components in weight percent: 70.0% to 90.0% SiO2, 0.0% to 25.0% B2O3, 0.0% to 10.0% Al2O3, 0.0% to 10.0% of one or more alkaline earth metal oxides, 0.0% to 7.0% of one or more alkali metal oxides.

[0046] In one embodiment, the glass comprises one or more or all of the following components in weight percent: 75.0% to 87.0% SiO2, 8.0% to 22.0% B2O3, 1.0% to 7.0% Al2O3, 0.25% to 5.0% of one or more alkaline earth metal oxides, 0.0% to 5.0% of one or more alkali metal oxides.

[0047] For purposes of the present invention, alkali metal oxides are specifically meant to include Li2O, Na2O, and K2O, and alkaline earth metal oxides are specifically meant to include MgO, CaO, BaO, and SrO.

[0048] In one embodiment, the glass comprises, by weight, 0.0% to 10.0%, for example 1.0% to 9.0%, 2.0% to 8.0%, 3.0% to 7.0%, or 4.0% to 6.0% of one or more alkaline earth metal oxides.

[0049] In one embodiment, the glass contains one or more alkali metal oxides in a weight percentage of 0.0% to 7.0%, e.g., 0.5% to 6.5%, 1.0% to 6.0%, 1.5% to 5.5%, or 2.0% to 5.0%. In one embodiment, the glass contains one or more alkali metal oxides in a weight percentage of 0.0% to 5.0%, e.g., 0.1% to 4.5%, 0.2% to 4.0%, 0.3% to 3.5%, or 0.4% to 3.0%. In one embodiment, the glass contains one or more alkali metal oxides in a weight percentage of 0.0% or more, 0.1% or more, 0.2% or more, 0.3% or more, or 0.4% or more. In one embodiment, the glass contains one or more alkali metal oxides in a weight percentage of 5.0% or less, 4.5% or less, 4.0% or less, 3.5% or less, or 3.0% or less.

[0050] In one embodiment, the glass comprises, in weight percent: SiO2 70.0%~90.0% B2O3>0.0%~25.0% Al2O3>0.0%~10.0% BaO 0.0%~5.0% CaO 0.0%~3.0% K2O 0.0%~5.0% Na2O 0.0%~5.0% Li2O 0.0%~1.0%.

[0051] In one embodiment, the glass contains B2O3 in an amount of 1.0% by weight or more, 2.0% by weight or more, 4.0% by weight or more, 6.0% by weight or more, or 8.0% by weight or more. In one embodiment, the glass contains B2O3 in an amount of 25.0% by weight or less, 22.0% by weight or less, 20.0% by weight or less, 18.0% by weight or less, 15.0% by weight or less, or 12.0% by weight or less. In one embodiment, the glass contains B2O3 in an amount of 1.0% to 25.0% by weight, 2.0% to 22.0% by weight, 4.0% to 20.0% by weight, 6.0% to 18.0% by weight, or 8.0% to 15.0% by weight.

[0052] In one embodiment, the glass contains Al2O3 in an amount of 1.0% by weight or more, 2.0% by weight or more, 3.0% by weight or more, or 4.0% by weight or more. In one embodiment, the glass contains Al2O3 in an amount of 10.0% by weight or less, 9.0% by weight or less, 8.0% by weight or less, 7.0% by weight or less, or 6.0% by weight or less. In one embodiment, the glass contains Al2O3 in an amount of 0.0% to 10.0% by weight, 1.0% to 9.0% by weight, 2.0% to 8.0% by weight, 3.0% to 7.0% by weight, or 4.0% to 6.0% by weight.

[0053] In one embodiment, the glass contains, by weight, 0.0% to 5.0% BaO, e.g., 0.5% to 4.5%, 1.0% to 4.0%, 1.5% to 3.5%, or 2.0% to 3.0%. In one embodiment, the glass contains, by weight, 0.0% or more, 0.5% or more, 1.0% or more, 1.5% or more, or 2.0% or more BaO. In one embodiment, the glass contains, by weight, 5.0% or less, 4.5% or less, 4.0% or less, 3.5% or less, or 3.0% or less BaO.

[0054] In one embodiment, the glass contains, by weight, 0.0% to 3.0%, e.g., 0.2% to 2.8%, 0.4% to 2.6%, 0.6% to 2.4%, 0.8% to 2.2%, or 1.0% to 2.0% CaO. In one embodiment, the glass contains, by weight, 0.0% or more, 0.2% or more, 0.4% or more, 0.6% or more, 0.8% or more, or 1.0% or more CaO. In one embodiment, the glass contains, by weight, 3.0% or less, 2.8% or less, 2.6% or less, 2.4% or less, 2.2% or less, or 2.0% or less CaO.

[0055] In one embodiment, the glass contains 0.0% to 5.0% by weight of KO, e.g., 0.5% to 4.5%, 1.0% to 4.0%, 1.5% to 3.5%, or 2.0% to 3.0%. In one embodiment, the glass contains 0.0% or more, 0.5% or more, 1.0% or more, 1.5% or more, or 2.0% or more by weight of KO. In one embodiment, the glass contains 5.0% or less, 4.5% or less, 4.0% or less, 3.5% or less, or 3.0% or less by weight of KO.

[0056] In one embodiment, the glass contains 0.0% to 5.0% NaO by weight, e.g., 0.5% to 4.5%, 1.0% to 4.0%, 1.5% to 3.5%, or 2.0% to 3.0%. In an alternative embodiment, the glass contains 0.0% to 3.0% NaO by weight, e.g., 0.1% to 2.5%, 0.2% to 2.0%, 0.3% to 1.5%, or 0.4% to 1.0%. In one embodiment, the glass contains 0.0% or more, 0.1% or more, 0.2% or more, 0.3% or more, or 0.4% or more NaO by weight. In one embodiment, the glass contains 3.0% or less, 2.5% or less, 2.0% or less, 1.5% or less, or 1.0% or less NaO by weight.

[0057] In one embodiment, the glass contains, by mass, 0.0% to 1.0%, e.g., 0.1% to 0.9%, 0.2% to 0.8%, 0.3% to 0.7%, or 0.4% to 0.6% LiO. In one embodiment, the glass contains, by mass, 0.0% or more, 0.1% or more, 0.2% or more, 0.3% or more, or 0.4% or more LiO. In one embodiment, the glass contains, by mass, 1.0% or less, 0.9% or less, 0.8% or less, 0.7% or less, or 0.6% or less LiO.

[0058] In one embodiment, the glass contains 1000 ppm by weight or less of Fe2O3, 500 ppm by weight or less of Fe2O3, 200 ppm by weight or less of Fe2O3, 100 ppm by weight or less of Fe2O3, 50 ppm by weight or less of Fe2O3, or 20 ppm by weight or less of Fe2O3. In one embodiment, the glass contains 1 ppm by weight or more of Fe2O3, 2 ppm by weight or more of Fe2O3, 3 ppm by weight or more of Fe2O3, 5 ppm by weight or more of Fe2O3, 7 ppm by weight or more of Fe2O3, or 10 ppm by weight or more of Fe2O3. In one embodiment, the glass contains 1 to 1000 ppm (by mass) of Fe2O3, 2 to 500 ppm (by mass) of Fe2O3, 3 to 200 ppm (by mass) of Fe2O3, 5 to 100 ppm (by mass) of Fe2O3, 7 to 50 ppm (by mass) of Fe2O3, or 10 to 20 ppm (by mass) of Fe2O3.

[0059] In one embodiment, the glass comprises, in weight percent: SiO2 75.0%~87.0% B2O38.0%~22.0% Al2O3 1.0%~7.0% BaO 0.0%~3.0% CaO 0.0%~2.0% K2O 0.0%~3.0% Na2O 0.0%~3.0% Li2O 0.0%~1.0%.

[0060] In one embodiment, the glass comprises, in weight percent: SiO2 77.0%~87.0% B2O38.0%~13.0% Al2O3 3.0% to 7.0% BaO 0.0%~3.0% CaO 0.0%~2.0% K2O 0.0%~3.0% Na2O 0.0%~1.0% Li2O 0.0%~1.0%.

[0061] In one embodiment, the glass is free of one or more or all of lithium, magnesium, potassium, calcium, sodium, lead, arsenic, and antimony.

[0062] When this description refers to a glass that is free of a component, or does not contain a particular component, including the hypothetical case of 0% by weight of that component, it should be understood that the component may be present at most as an impurity. This means that it is not added in a significant amount and is not intentionally added. The term "component" refers to the elemental species itself as well as any molecule containing that element. An insubstantial amount should be understood as less than 100 ppm by weight, preferably less than 50 ppm, and most preferably less than 10 ppm, of all intentionally added components.

[0063] In one embodiment, the glass has one or more or all of the following properties: Thermal expansion coefficient of 0.5 ppm / K or more in the temperature range of 20°C to 300°C · Moisture content 100mmol / l or less, · Density 2.30g / cm 3 below, A strain point of 550°C or higher, and / or Electrical volume resistivity T at 250°C measured according to DIN 52326:1986-05 k100 At least 10 8Ω·cm, preferably at least 10 10 Ω·cm.

[0064] In one embodiment, the glass has a density of 2.30 g / cm 3 Below 2.25g / cm 3 Below, 2.20g / cm 3 Below, 2.15g / cm 3 or less than 2.10 g / cm 3 In one embodiment, the glass has a density of 1.85 g / cm 3 More than 1.90g / cm 3 More than 1.95g / cm 3 More than 2.00g / cm 3 or more, or 2.05 g / cm 3 In one embodiment, the glass has a density of 1.85 g / cm 3 ~2.30g / cm 3 , 1.90g / cm 3 ~2.25g / cm 3 , 1.95g / cm 3 ~2.20g / cm 3 , 2.00g / cm 3 ~2.15g / cm 3 , or 2.05 g / cm 3 ~2.10g / cm 3 It has.

[0065] In one embodiment, the glass has a viscosity of 10°C, also known as the T13.5 temperature. 13.5 The glass has a strain point of 550°C or more, 600°C or more, or 650°C or more, defined as the temperature at which the glass has a viscosity of 10 s, also known as the T13.5 temperature. 13.5 The strain point, defined as the temperature at which the modulus of elasticity is 550°C to 800°C, 600°C to 750°C, or 650°C to 700°C, is

[0066] In one embodiment, the glass has an electrical volume resistivity T at 250° C. measured according to DIN 52326:1986-05 k100 At least 10 8 Ω·cm, preferably at least 10 10 Ω cm, and / or T at 250°C k100 10 12 Ω·cm or less, preferably 10 11 In one embodiment, the glass has an electrical volume resistivity T k100 10 8 Ω·cm~10 12 Ω·cm, preferably 10 10 Ω·cm~10 11 It has a resistance of Ω·cm.

[0067] In one embodiment, the present invention provides a glass having a coefficient of thermal expansion of 4.5 ppm / K or less in the temperature range of 20°C to 300°C and a viscosity of 10 4 The present invention relates to a glass having a T4 temperature of 1500°C or higher, defined as the temperature at which the glass has a water content of at least 35 mmol / l, preferably at least 45 mmol / l, more preferably at least 55 mmol / l.

[0068] In one embodiment, the present invention provides a glass having a coefficient of thermal expansion of 0.4 ppm / K to 4.5 ppm / K, 0.5 ppm / K to 4.0 ppm / K, 0.6 ppm / K to 3.5 ppm / K, 0.7 ppm / K to 3.0 ppm / K, or 0.8 ppm / K to 2.5 ppm / K within a temperature range of 20°C to 300°C, and a viscosity of 10 4 The present invention relates to a glass having a T4 temperature of 1500°C or higher, defined as the temperature at which the glass has a water content of at least 35 mmol / l, preferably at least 45 mmol / l, more preferably at least 55 mmol / l.

[0069] In one embodiment, the present invention provides a glass having a coefficient of thermal expansion of 4.5 ppm / K or less in the temperature range of 20°C to 300°C and a viscosity of 10 4The present invention relates to a glass having a T4 temperature, defined as the temperature at which the glass has a T4 value of 1500°C to 1900°C, 1550°C to 1850°C, 1600°C to 1800°C, or 1650°C to 1750°C, and having a water content of at least 35 mmol / l, preferably at least 45 mmol / l, and more preferably at least 55 mmol / l.

[0070] In one embodiment, the present invention provides a glass having a coefficient of thermal expansion of 4.5 ppm / K or less in the temperature range of 20°C to 300°C and a viscosity of 10 4 The present invention relates to glass having a T4 temperature, defined as the temperature at which the glass has a viscosity of 1,500°C or higher, and a water content of 35 to 250 mmol / l, 40 to 200 mmol / l, 45 to 150 mmol / l, 50 to 125 mmol / l, or 55 to 100 mmol / l.

[0071] Glass articles In another aspect, the present invention relates to a glass article comprising or consisting of a glass according to the present invention, said glass article being in the form of a rod, tube, ingot, disc, sheet or block.

[0072] In one embodiment, the glass article has a length and a width, and the relative deviation in moisture content is at most 10% and / or at most 5 mmol / l, the relative deviation in moisture content being defined as the difference between the maximum and minimum moisture content in the article as measured by IR spectroscopy.

[0073] In one embodiment, the glass article has a length and a width, and the relative deviation in water content is at most 10% and / or at most 5 mmol / l, the relative deviation in water content being defined as the difference between the maximum and minimum water content in the article as measured by IR spectroscopy at an absorption maximum at about 2700 nm, the absorption maximum preferably being identified in the IR absorption spectrum in the wavelength range of 2500 to 6500 nm.

[0074] In one embodiment, the glass article can have a cylindrical or rod-like shape, and the glass article has a length and a width. In one embodiment, the glass article has a length of 5 cm or more, 10 cm or more, 15 cm or more, or 20 cm or more, and / or a length of 200 cm or less, 150 cm or less, 100 cm or less, or 50 cm or less. In one embodiment, the glass article has a length of 5 cm to 200 cm, 10 cm to 150 cm, 15 cm to 100 cm, or 20 cm to 50 cm. In one embodiment, the glass article has a width of 1.0 cm or more, 1.5 cm or more, 2.0 cm or more, or 2.5 cm or more, and / or a width of 20 cm or less, 15 cm or less, 10 cm or less, or 5 cm or less. In one embodiment, the glass article has a width of 1.0 cm to 20 cm, 1.5 cm to 15 cm, 2.0 cm to 10 cm, or 2.5 cm to 5 cm.

[0075] In one embodiment, the glass article can have a cylindrical shape, wherein the glass article has a length of 5 cm to 200 cm and a width of 1.0 cm to 20 cm, a length of 10 cm to 150 cm and a width of 1.5 cm to 15 cm, a length of 15 cm to 100 cm and a width of 2.0 cm to 10 cm, or a length of 20 cm to 50 cm and a width of 2.5 cm to 5 cm.

[0076] In one embodiment, the glass article can have a rod shape, wherein the glass article has a length of 5 cm to 200 cm and a width of 1.0 cm to 20 cm, a length of 10 cm to 150 cm and a width of 1.5 cm to 15 cm, a length of 15 cm to 100 cm and a width of 2.0 cm to 10 cm, or a length of 20 cm to 50 cm and a width of 2.5 cm to 5 cm.

[0077] The water content can be determined by IR spectroscopy based on the OH stretching vibration at about 2700 nm, for example using a commercially available Nicolet FTIR spectrometer. Absorption can be first measured in the wavelength range of 2500-6500 nm, and then the absorption maximum can be determined at about 2700 nm (or in that range). The absorption coefficient α is determined by the sample thickness d and the internal transmittance T iand reflectance P, calculated using the following formula: α=1 / d·lg(1 / T i )[cm -1 ], In the above formula, T i =T / P, where T is the transmittance. c=α / ε where ε is the extinction coefficient. For a water content in the range of 25 to 80 mmol / l, ε = 110 l mol -1 cm -1 (H. Frank and H. Scholze, “Glastechnische Berichte”, vol. 36, issue 9,350 pages).

[0078] In one embodiment, the glass article has a relative deviation in water content of at most 10%, at most 8%, at most 6%, at most 4%, or at most 2% and / or at most 5 mmol / l, at most 4 mmol / l, at most 3 mmol / l, at most 2 mmol / l, or at most 1 mmol / l. In one embodiment, the glass article has a relative deviation in water content of at least 0.2%, at least 0.4%, at least 0.6%, at least 0.8%, or at least 1.0%, and / or at least 0.1 mmol / l, at least 0.2 mmol / l, at least 0.3 mmol / l, at least 0.4 mmol / l, or at least 0.5 mmol / l.

[0079] In one embodiment, the present invention relates to a set of glass articles, each of which has a moisture content of at least 35 mmol / l, at least 40 mmol / l, at least 45 mmol / l, at least 50 mmol / l, or at least 55 mmol / l, and / or a moisture content of 250 mmol / l or less, 200 mmol / l or less, 150 mmol / l or less, 125 mmol / l or less, or 100 mmol / l or less. Accordingly, in one embodiment, there is provided a set of glass articles, each of which has a moisture content of 35 to 250 mmol / l, 40 to 200 mmol / l, 45 to 150 mmol / l, 50 to 125 mmol / l, or 55 to 100 mmol / l.

[0080] In one embodiment, a set of glass articles is provided, wherein the uniformity of moisture content within the set is defined by the difference between the maximum moisture content measured for any glass article in the set and the minimum moisture content measured for any glass article in the set, where this difference is 5 mmol / L or less. In a preferred embodiment, the uniformity of moisture content within the set is measured by IR spectroscopy at an absorption maximum at about 2700 nm, preferably identified in an IR absorption spectrum in the wavelength range of 2500 to 6500 nm.

[0081] In one embodiment, a set of glass articles is provided, wherein the uniformity of moisture content within the set is defined by the difference between the maximum moisture content measured on any glass article in the set and the minimum moisture content measured on any glass article in the set, where this difference is 5 mmol / l or less, 4 mmol / l or less, 3 mmol / l or less, 2 mmol / l or less, or 1 mmol / l or less, and / or the difference is 0.1 mmol / l or more, 0.2 mmol / l or more, 0.3 mmol / l or more, 0.4 mmol / l or more, or 0.5 mmol / l or more. Thus, in one embodiment, there is provided a set of glass articles, wherein the uniformity of moisture content within the set is defined by the difference between the maximum moisture content measured in any glass article in the set and the minimum moisture content measured in any glass article in the set, and this difference is between 0.1 mmol / l and 5 mmol / l, 0.2 mmol / l and 4 mmol / l, 0.3 mmol / l and 3 mmol / l, 0.4 mmol / l and 2 mmol / l, or 0.5 mmol / l and 1 mmol / l.

[0082] It is advantageous for end users, such as flash lamp manufacturers, to work from a set of glass articles that have moisture content uniformity within the above boundaries and limits. This has many benefits for the reliability and repeatability of the manufacturing process and the manufactured products.

[0083] In one embodiment, a set of glass articles is provided, wherein the number of glass articles in the set is at least 10, at least 50, at least 100, or at least 200, and / or up to 1000, up to 500, or up to 300 glass articles.

[0084] method In a further aspect, the present invention is a method for manufacturing glass, comprising the steps of: producing a glass melt of glass raw materials; adjusting the water content of the glass melt; cooling and / or shaping the glass melt to obtain a glass article. Including, The glass has a thermal expansion coefficient of 4.5 ppm / K or less in the temperature range of 20°C to 300°C, and a viscosity of 10 4 T4 temperature is defined as the temperature at which the material has a T4 temperature of 1500°C or higher. the glass has a water content of at least 35 mmol / l, preferably at least 45 mmol / l, more preferably at least 55 mmol / l, and / or The glass has a reboiling tendency score of less than 10 as measured in a reboiling tendency test. The present invention relates to the method.

[0085] In one embodiment, producing a glass melt of glass frits includes providing a batch or mixture of oxides, which may be selected from the list of SiO, BO, AlO, one or more alkaline earth metal oxides, and one or more alkali metal oxides, and heating the batch or mixture of oxides to melt them.

[0086] In one embodiment, cooling the glass melt to obtain a glass article is performed at a glass transition temperature T g 50℃ below the glass transition temperature T g In one embodiment, the cooling of the glass melt to obtain the glass article is carried out at an average cooling rate of at least 1 K / min, 2 K / min, 5 K / min, 10 K / min, and / or at an average cooling rate of 100 K / min or less, 75 K / min or less, 50 K / min or less, or 25 K / min or less, within a temperature range of 150°C above the glass transition temperature T g 50℃ below the glass transition temperature T g The cooling is carried out within a temperature range of 150°C or above at an average cooling rate of 1 K / min to 100 K / min, 2 K / min to 75 K / min, 5 K / min to 50 K / min, or 10 K / min to 25 K / min.

[0087] In one embodiment, adjusting and / or controlling the water content of the glass melt comprises one or more of the following steps: holding the glass melt at an elevated temperature for a time sufficient to obtain the water content; selecting the SiO2 content in the glass so as to obtain said water content, controlling the water vapor concentration in the atmosphere above the glass melt so as to obtain said water content; controlling the temperature of the glass melt to obtain the water content; A method is provided which includes:

[0088] In one embodiment, two or more of the above steps are performed to adjust and / or control the water content. In one embodiment of the method, adjusting and / or controlling the water content of the glass melt comprises holding the glass melt at an elevated temperature for a time sufficient to obtain said water content. In a preferred embodiment of the method, adjusting the water content of the glass melt comprises holding the glass melt at a temperature of at least 1600°C for at least 1 hour, at a temperature of at least 1700°C for at least 1 hour, at a temperature of at least 1800°C for at least 1 hour, at a temperature of at least 1900°C for at least 1 hour, at a temperature of at least 1600°C for at least 2 hours, at a temperature of at least 1700°C for at least 2 hours, at a temperature of at least 1800°C for at least 2 hours, at a temperature of at least 1900°C for at least 2 hours, at a temperature of at least 1600°C for at least 5 hours, at a temperature of at least 1700°C for at least 5 hours, at a temperature of at least 1800°C for at least 5 hours, at a temperature of at least 1900°C for at least 5 hours, at a temperature of at least 1600°C for at least 10 hours, at a temperature of at least 1700°C for at least 10 hours, at a temperature of at least 1800°C for at least 10 hours, or at least 1900°C for at least 10 hours.

[0089] In one embodiment of the method, adjusting the water content of the glass melt comprises selecting an SiO content in the glass to obtain said water content. In a preferred embodiment of the method, adjusting the water content of the glass melt comprises selecting an SiO content in an amount of 70.0 to 90.0 mass %, 72.0 to 89.0 mass %, 74.0 to 88.0 mass %, 76.0 to 87.0 mass %, or 78.0 to 86.0 mass %, based on the total mass of the glass frits.

[0090] In one embodiment of the method, adjusting the water content of the glass melt comprises controlling the water vapor concentration in an atmosphere above the glass melt to obtain said water content. In a preferred embodiment of the method, the water vapor concentration in the atmosphere above the glass melt is such that a partial pressure exerted by the water vapor is at least 0.02 MPa, at least 0.05 MPa, at least 0.1 MPa, at least 0.25 MPa, at least 0.5 MPa, or at least 1.0 MPa. In one embodiment of the method, the water vapor concentration in the atmosphere above the glass melt is such that a partial pressure exerted by the water vapor is 10 MPa or less.

[0091] A sufficient water vapor concentration in the atmosphere above the glass melt can help to establish a desired water content in the glass, for example, at least 35 mmol / l, at least 40 mmol / l, at least 45 mmol / l, at least 50 mmol / l, or at least 55 mmol / l. The water vapor concentration can be established by a well-defined overpressure in the atmosphere above the glass melt as well as a well-defined temperature. The overpressure in the atmosphere above the glass melt can be adjusted, for example, in a suitable furnace, by partially or completely closing nozzles and / or openings in the furnace. A well-defined overpressure in the atmosphere above the glass melt can be established, for example, by burning natural gas or synthetic gas and, optionally, by adjusting the degree of exhaust gas purging.

[0092] In one embodiment of the method, adjusting the water content of the glass melt comprises controlling the temperature of the glass melt to obtain said water content. In a preferred embodiment of the method, adjusting the water content of the glass melt comprises establishing a temperature of the glass melt of at least 1600°C, at least 1700°C, at least 1800°C, or at least 1900°C.

[0093] The temperature of the glass melt has several effects as part of the process. Generally, the water solubility in the glass melt increases with increasing temperature. Furthermore, at elevated temperatures, the viscosity of the glass melt decreases, which accelerates diffusion and convection processes and affects the solubility and dissolution process of water in the glass melt.

[0094] use In a further aspect, the present invention relates to the use of the glass according to the invention for bonding a glass article to a glass member.

[0095] In one embodiment there is provided the use of the glass according to the invention, wherein the glass is used as a glass sealing material for fusing a metal electrode, such as a tungsten or molybdenum electrode, to a glass tube, such as a quartz glass tube.

[0096] flash lamp In another aspect, the present invention relates to a flash lamp comprising a glass according to the present invention.

[0097] In one embodiment, there is provided a flash lamp comprising a metal electrode and a tube, the tube preferably comprising or consisting of glass, e.g., quartz glass, and further comprising a sealing glass which is a glass according to the present invention.

[0098] In one embodiment, there is provided a flash lamp including a metal electrode and a tube, wherein the metal electrode and the tube are joined by a sealing glass that is the glass of the present invention. In one embodiment, there is provided a flash lamp including a tungsten or molybdenum electrode and a quartz glass tube, wherein the tungsten or molybdenum electrode and the quartz glass tube are joined by a sealing glass that is the glass of the present invention.

[0099] The use of the glass according to the invention as a sealing glass is advantageous because it provides an excellent sealing bond, i.e., fusion, between the electrodes and the glass tube, even during extreme and rapid temperature changes, thereby advantageously increasing the stability and lifespan of the manufactured flash lamp during its life cycle, i.e., during use, which undergoes such extreme and rapid temperature changes.

[0100] In one embodiment, the metal electrode comprises or consists of a metal selected from the list, for example tungsten and molybdenum. [Brief explanation of the drawings]

[0101] [Figure 1] FIG. 1 shows the spirals formed in the reboiling tendency tests obtained at temperatures of 1650°C, 1580°C, and 1420°C (from left to right). [Figure 2] Figure 2 shows glass rods subjected to the reboiling tendency test. Panel A shows a formed spiral that passed the test and received a rating of "1." Panel E shows a formed spiral that did not pass the test and received a rating of "5." Panels B-D show formed spirals with ratings of "2," "3," and "4," respectively. [Example]

[0102] Glass Composition The following glass compositions 1-5 are exemplary for the present invention, which are further characterized by their coefficient of thermal expansion (CTE) and T4 temperature.

[0103] [Table 1]

[0104] Re-boiling tendency test results Reboiling tendency tests were performed as described in the detailed description. Glasses were classified into categories of 5 (poor), 4 (acceptable), 3 (fair / moderate), 2 (good) and 1 (very good). All glasses tested have a T4 temperature of at least 1500°C.

[0105] The reboiling tendency score is calculated based on the 125 mm 3 The reboiling tendency score was quantified as the number of bubbles with a spherical equivalent diameter of at least 0.5 mm per 125 mm. 3 was calculated as the average value obtained from the volume elements of

[0106] [Table 2]

Claims

1. A glass having a coefficient of thermal expansion of 4.5 ppm / K or less within a temperature range of 20°C to 300°C, and having a T4 temperature of 1500°C or higher defined as the temperature at which the glass has a viscosity of 10 4 dPa·s, and having a reboiling tendency score of less than 10 as measured in a reboiling tendency test.

2. The glass according to claim 1, having a water content of at least 35 mmol / l, at least 45 mmol / l, or at least 55 mmol / l.

3. The glass according to claim 1, containing one or more or all of the following components by mass percentage: ・ 75.0% to 87.0% of SiO 2 , ・ 8.0% to 22.0% of B 2 O 3 , ・ 1.0% to 7.0% of Al 2 O 3 , ・ 0.25% to 5.0% of one or more alkaline earth metal oxides, ・ 0.0% to 5.0% of one or more alkali metal oxides.

4. The glass according to claim 1, containing the following by mass percentage: SiO 2 77.0% to 87.0% B 2 O 3 8.0% to 13.0% Al 2 O 3 3.0% to 7.0% BaO 0.0% to 3.0% CaO 0.0% to 2.0% K 2 O 0.0% to 3.0% Na 2 O 0.0% to 1.0% Li 2 O 0.0% to 1.0%.

5. The glass according to claim 1, which does not contain one or more or all of lithium, magnesium, potassium, calcium, sodium, lead, arsenic, and antimony.

6. ・ The coefficient of thermal expansion in the temperature range of 20°C to 300°C is 0.5 ppm / K or more, ・ The water content is 100 mmol / l or less, ・ The glass has a density of 2.30 g / cm 3 as follows, ・ The glass has a strain point of 550°C or more, and / or ・ The glass has an electrical volume resistivity T at 250°C measured in accordance with DIN 52326:1986-05 k100 of at least 10 8 Ω·cm, or has at least 10 10 Ω·cm, The glass according to claim 1.

7. A glass having a coefficient of thermal expansion of 4.5 ppm / K or less within the temperature range of 20°C to 300°C, and a T4 temperature of 1500°C or more defined as the temperature at which the glass has a viscosity of 10 4 dPa·s, and having a water content of at least 35 mmol / l, preferably at least 45 mmol / l, more preferably at least 55 mmol / l, said glass.

8. A glass article in the form of a rod, tube, ingot, disk, sheet or block, comprising or consisting of the glass according to any one of claims 1 to 7.

9. The glass article according to claim 8, having a relative deviation of water content of at most 10% and / or at most 5 mmol / l, said relative deviation of water content being defined as the difference between the maximum water content and the minimum water content measured by IR spectrometry in said article.

10. A set of glass articles, wherein said glass articles are the glass articles according to claim 8, and each of said articles has a water content of at least 35 mmol / l, said set of glass articles.

11. The uniformity of the water content within the set is defined by the difference between the maximum water content measured in any glass article within the set and the minimum water content measured in any glass article within the set, and this difference is 5 mmol / l or less. The set of glass articles according to claim 10.

12. The number of glass articles within the set is at least 10, at least 50, at least 100, or at least 200, and / or at most 1000, at most 500, or at most 300 glass articles. The set of glass articles according to claim 10.

13. A method for manufacturing glass, comprising the following steps: - Manufacturing a glass melt of glass raw materials, - Adjusting the water content of the glass melt, - Cooling and / or shaping the glass melt to obtain a glass article including, The glass has a coefficient of thermal expansion of 4.5 ppm / K or less within a temperature range of 20°C to 300°C, and the glass has a T4 temperature of 1500°C or higher defined as the temperature at which the glass has a viscosity of 10 4 dPa·s, The glass has a water content of at least 35 mmol / l, preferably at least 45 mmol / l, more preferably at least 55 mmol / l, and / or The glass has a reboiling tendency score of less than 10 as measured in a reboiling tendency test. The method.

14. Adjusting the water content of the glass melt is one or more of the following steps: - Holding the glass melt at an elevated temperature for a sufficient time to obtain the water content, - Selecting the SiO 2 content in the glass so that the water content is obtained. - Controlling the water vapor concentration in the atmosphere above the glass melt so that the water content is obtained; - Controlling the temperature of the glass melt so that the water content is obtained The method according to claim 13, comprising:

15. Use of the glass according to any one of claims 1 to 7 for joining a metal article to a glass element.

16. A flash lamp comprising the glass according to any one of claims 1 to 7.

17. A flash lamp comprising a metal electrode and a tube, the tube preferably comprising or consisting of fused quartz glass and further comprising a sealing glass, the sealing glass comprising the glass according to any one of claims 1 to 7.

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