CA2193999A1 - Borosilicate glass - Google Patents
Borosilicate glassInfo
- Publication number
- CA2193999A1 CA2193999A1 CA 2193999 CA2193999A CA2193999A1 CA 2193999 A1 CA2193999 A1 CA 2193999A1 CA 2193999 CA2193999 CA 2193999 CA 2193999 A CA2193999 A CA 2193999A CA 2193999 A1 CA2193999 A1 CA 2193999A1
- Authority
- CA
- Canada
- Prior art keywords
- glass
- weight
- bao
- mgo
- cao
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
Links
Classifications
-
- C—CHEMISTRY; METALLURGY
- C03—GLASS; MINERAL OR SLAG WOOL
- C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
- C03C3/00—Glass compositions
- C03C3/04—Glass compositions containing silica
- C03C3/076—Glass compositions containing silica with 40% to 90% silica, by weight
- C03C3/11—Glass compositions containing silica with 40% to 90% silica, by weight containing halogen or nitrogen
-
- C—CHEMISTRY; METALLURGY
- C03—GLASS; MINERAL OR SLAG WOOL
- C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
- C03C3/00—Glass compositions
- C03C3/04—Glass compositions containing silica
- C03C3/076—Glass compositions containing silica with 40% to 90% silica, by weight
- C03C3/089—Glass compositions containing silica with 40% to 90% silica, by weight containing boron
- C03C3/091—Glass compositions containing silica with 40% to 90% silica, by weight containing boron containing aluminium
- C03C3/093—Glass compositions containing silica with 40% to 90% silica, by weight containing boron containing aluminium containing zinc or zirconium
Landscapes
- Chemical & Material Sciences (AREA)
- Life Sciences & Earth Sciences (AREA)
- Engineering & Computer Science (AREA)
- Chemical Kinetics & Catalysis (AREA)
- General Chemical & Material Sciences (AREA)
- Geochemistry & Mineralogy (AREA)
- Materials Engineering (AREA)
- Organic Chemistry (AREA)
- Glass Compositions (AREA)
Abstract
The invention relates to a borosilicate glass with a linear thermal expansion between 20 and 300 ~C of 3.9 to 4.5*10-6 K-1 for the production of laboratory, household, pharmaceutical container, lamp and flat glass and other special technical glasses which can be fully electrically melted and conditioned in cold-top conditions. For fixing the glass composition, this requires, besides the attainment of the desired glass properties, a consideration of the specifics of the fully electric melting process and therefore results in a limited range of variation of several glass oxides, the exclusion of the use of some raw materials, the choice of suitable refining agents, etc. The composition of the glass is SiO2 + ZrO2 77,0 to 81,0 % wt.; B2O3 + Na2O + K2O
+ CaO + MgO + BaO 16,0 to 18,5 % wt.; of which Na2O + K2O + CaO + MgO + BaO
5,4 to 7,0 % wt.; of which CaO + MgO + BaO to 0,9 % wt.; Al2O3 3,7 to 4,9 %
wt.; Cl- 0,05 to 0,4 % wt.; CeO 0,0 to 1,0 % wt.; with the relations: ratio CaO + MgO + BaO / ZrO2 0,0 to 1,5; ratio Na2O + K2O + CaO + MgO + BaO / B2O3 +
SiO2 + Al2O3 + ZrO2 0,060 to 0,075. Only NaC1 or KC1 is used as a refining agent. A change between this glass and borosilicate glass 3.3 is reversible, repeatable as often as desired and possible within a short time.
+ CaO + MgO + BaO 16,0 to 18,5 % wt.; of which Na2O + K2O + CaO + MgO + BaO
5,4 to 7,0 % wt.; of which CaO + MgO + BaO to 0,9 % wt.; Al2O3 3,7 to 4,9 %
wt.; Cl- 0,05 to 0,4 % wt.; CeO 0,0 to 1,0 % wt.; with the relations: ratio CaO + MgO + BaO / ZrO2 0,0 to 1,5; ratio Na2O + K2O + CaO + MgO + BaO / B2O3 +
SiO2 + Al2O3 + ZrO2 0,060 to 0,075. Only NaC1 or KC1 is used as a refining agent. A change between this glass and borosilicate glass 3.3 is reversible, repeatable as often as desired and possible within a short time.
Description
21 ~,3~/~t9 Borosili~ Glass The invention concerns a 6Gro~ te glass having a linear U,erl.,al ex,ua"sion be~:een 20~C and 300~C of 3.9 to 4.5 x 10 6K '.
It is used for manufacturing laboratory glass, housecl~I glass, ~,har",~ce~ ~tic~l recept~cle glass, lamp glass, flat glass, as well as other industrial and optical high-quality glass produc'ts.
In accordance with the invention the new glass is used when a borosilicate glass with the ",e, ItiGI ,ed pro,uel ~ is to be man~ ~f~ red in known fully electrically heated melting plants according to the cold-top principle.
Many types of bor~silic~te glass are known in the state of the art. Theproperties that det~r",ine their use-value are high chel"ical lesiak~l ,ce, low thermal expansion, high U,er"~al fatigue r~sistance, and high mechanical stability.
Thus, borosilicate glass 3.3 is usually used for laboratory, housecraft and instrument glass in accordance with DIN ISO 3585 . This type of glass cGntc.;.,s only a little alkali (less than 5%), SiO2 more than 79% and B203 to approx. 13%. It has a thermal e~ansion of approx. 3.3x10 ~K
Fu, lhell"ore, sealing glass that contains boron is known. It has a high alkali and/or all~line earth CGI~IIt, as well as sor,-~tir"es ad.lit;G.,al further oxides.
The U,err"al e,.~l,sion of these types of glass is 3.6 to 5.2x10 ~'. A further 21 93~99 known group is that of so-called neutral ~vhar-"aceutical borosilicate glass. IncGnbd~l to the sealing glass it achieves the l,ighest chemical resis~nce values. Its alkali colltent is approx. 6.5 to 8.5% and 3.2% to 5.0~h alkaline earth, the thermal e~,uansiGl) is 4.8 to 5.1x10 ~K '.
It is known, as desc,il,ed in patent specificdtiGn DE 37 22 130, to replace the large range of types of bor~s.'i~~te glass by a glass, which satisfies most requirements, of thermal eA~ausion 4.0 to 5.0x10 ~< '. It is also known to improve and speci~'.se ~e.r~r.nance-det~r-..inir,g properties of borosilic~te glass by means of an o~tin,ised cGm~osition and partial use of additional oxides such as ZnO, SrO, CsO, Li20, etc., as desclil ed in, e.g., the patent specifications DE 42 30 607, DE 40 12 288 or DE 43 25 656.
In the case of industrial production of borosili~ ~ glass 3.3, bec~ ~se of improved ei~ergetic e~iciency, qualitative as well as ecol~gic~l advan69es, fullelect~ ic ll.elting after the cold-top process has prevailed. In this ~r~cess, the melting heat is gener~t~l in the interior of the melting bath by means of a flowof electlic current, whereby the surface of the n,elti"g bath is continuously belayed with new batch. Normally a stable, ~lficiel tly insulating layer forms, which also retains volatile s~ s~nces and re-s~ ~r~'ies them to the melter.
Owing to this su~.eriG. ity and its cost cuffing relevance, the known borosilicate glass is invesli5~t~d for fabrication acco~di"g to this ~ thod and i1~; devices.
Thus far it has not been possible to melt neutral ,.~har,n~ceutic~l borosilic~t~glass fully electrically, since the required refining agents As203 andJor Sb203 destroy the usual molybdenum rod hedtin~ electrodes. Initial a,~,uroacl.es toward a ~,rocess engineering problem solution are specified in DE-PS 43 13 217.
Borosilicate glass having a linear thermal expansion from 3.6 to 4.8x10 ~K 1 can only be melted full electrically under severe qualitative lin~itdtiolls. It melts significantly faster than borosilic~t~ glass with a thermal expansion of 3.3x10 6 K ' owing to higher flux cont~n~ ~alkali, alkaline earth and boron oxide).
However, bec~use for complete glass forllldtiGn, hGIllogenisdtion and refining, approximately the same melting temperatures are required despit~ the flux CG nlerlb, the efficiently insulating, cold batch layer required for the full electric cold-top ",elling ,~.rocess cannot arise in a stable ~)lanner; the heat bc.lance is disturbed. At the worst the process no longer al!Qws thç açhiçvçmçnt of thç
desir~d telnperat-lres, so that bubbly glass or u..i..ell_d particles leave the furnace.
If alkali and alkaline earth are added as usual as the carLGnale, whichdepending on origin is co~ i.lindt~d with sulphate, the carbon dioxide and sulphur dioxide arising during melting cannot be completely removed ~rom ~e melter. On the one hand, the released gas q~a~ti~s are re!ative!y hjgh f,or the tough borosilic~te glass. On the other hand, the high s~l ~hility of C02 andS02 C~ uses excessively high gas resiciues in the glass. From other glass, it isknown that the sol! ~bility of C02 and S02 increases with the basicity module (ratio of network transformers to network f~,r",er~). If one lralls,~)oses this regularity to bolosilicate glass, the higher C02 or S02 solubility of the alkaliand alkaline earth rich borosilicate glass toi"pared with borosilic~t~ glass 3.3is then plausible. At the latest as reboil glass, C02 and S02 is again released and appears as seeds or bubbles in the finished giass. Suitable refining agents, such as As203 and/or Sb203, can remove these gases in combination with further oxidants, they are, however, unus~'e in fully electrically heated furnaces owing to their destructive effect upon molybdenum electrodes. Owing to their high alkaline earth conte, It~, the gl~sses described, e.g., in patent specil~c~tiG"s DE 42 30 607, DE 37 22 130 and DE 25 656, have this decisive disadvank3ge.
In additioll, further, partially used oxides such as PbO, SnO, CuO, NiO, CdO, FeO, Cr203 and ZnO act corrosively upon the Mo t~e~ lechodes.
Measures to protect the ele~t,o ies, such as the known r;,~tl,od for direct-current passivation, are ruied out bec~ ~se of the required use of known noble metal devices in the feeder.
Furthermore it is known that the full electric cold-top Illelti~ pr~ess, in which the melting ten-perarture for every type of glass is deterr"ii ,ed and is especi~lly 21 9:39~9 high in the case of borosilic~tç glass can only be used for a specific range of glass viscosity and electric cond!~ctibili~r. A excess electric condu~tibility of the glass at the usual ",elti"~ temperature owing to high alkali or alkaline earth co, Itenb causes high current and energy densities overl,edli"y electrode wear and blisters can occur. In the event of excessively low electric conductibility an il ,creasi. ,9 part of the current flows through the stone ",at~rial. Fxcessive glass viscosity requires ul-~cce,c1-hly high temperatures for refi"i"5~ or only enables this only incon":letely in a too thin-bodied glassunr"elted particles or unrehned melted l"dlerial are frequently mixed into the finished glass. The full clectlic cold-top method proven for borosilicate glass 3.3 is consequently not transferable to other gl~sses which at comparable ,nelti"~ .".,~r~tures ha~e Ji~rent viscosities and condu~ ities without significant cGnsequences. Many known types of L~r~,sili~c~ glass with a linear thermal ex,uansion ~reater than 3.9x10 CK ' have e.g. a total alkali p~us alkaline earth content of more than 7%1 also that from patent specifi~iion DE
37 22 130. They cannot be melted bubble-free at the required ",eltin~
te""xr~tlJres over 1550~ C with the proven full electric cold-top prvcess.
From the ~ ll ,o.ls known state of tne art references for fixing and controllingthe redox po~,ltial of ~Grosilic~te glass are not known.
~1 ~399~
It is the object of the invention to specif~r a soft borosilic~t.e glass of thermal expansion 3.9 to 4.5x10 6K~' of high che~"ical resislal~ce, which can be fabri~ated under the advan~eol~s eco logi~al and enerye~ic conditions of ~e known full ele ~IIic cold-top process.
In aGcGr~l~a. ,ce with the invention this object is solved therein that it has aprocessing temperature at 10 4 dPa s of 1200 to 1 270~C, a \riscosity at 15~0 C of 1 O~'to 102 ~dPa s, a specific electric r~sisl~nce at 1 550~C of 20 to 33 ....cm and an electric conductivity at 1 550~C of 3.0 to ~.0 ~/m, melts under cold-top conditions at approx. 1 600~C with 0.3 to 0.5 mm/min, and has the following basic col"position:
SiO2 + ZrO2 77.0 to 81.0 weight %
B203 + Na20 + K20 + CaO + MgO + BaO 16.0 to 18.5 weight %
of which Na20 + K20 + CaO + MgO + BaO 5.4 to 7.0 weight %
of which CaO + MgO + BaO to 0.9 weight %
Al203 3.7 to 4.9 weight %
Cl O.OS to 0.4 weight %
with the relations:
Ratio CaO + MgO + BaO 0.0 to 1.5 ZrO2 "- 21 q399~
Ratio Na20 + K20 + CaO + MgO + BaO 0.060 to 0.075 B203 + SiO2 + A1203 + ZrO2 Adva,ltcgeous embodi,.,eilt~ are specified in s~ cl~NIs 2 to 5.
In the case of the borosilicate glass according to the invention specific experiences wim the specified process and its devices are to be observed.
Although the principle relatio"ships l,etween glass properties and cGIl~posiliGnof borosilic~te glass are known, the ,vr~cess-linked limitdtiGIls lead to a new,per se cont,ddictoiy and U,erefore thus far unusual objective.
The new glass belongs to the group of chel"ically resistant bor~silicate glass, ch-dr~cl6rised by the following properties: -- linear lher",al ex~a"sion between 20~C and 300~C:
3.9 to 4.5x10 K~' - l.al ~srorI"dtiGn teln,uerdtLIre: over 540~C
- hydrolytic resi~nce per DIN 121 1 1:
1 st ctass - acid resist~nce per DIN 12116:
1 st class - Iye resistance per DIN 52322:
2nd class Owing to its use as ,~har-"~cellffc~l andJor housecraft glass, the glass is credt~d without toxic heavy-metal oxides. It CG nt. i~s components to increase '- 21 93~99 the brilliancy and can be ~ d. In order that it can be melted fully ele~ bically in the known fu,l,aces it may contain no PbO, SnO, CuO, NiO
CdO FeO Cr203 ZnO As203 andtor Sb203.
For eco'ogi~l ~asons no fluorides are used as refining agents.
In order to maintain a low gas content in tne glass, during ~"elti.,~ e or no carbon ~ cide and no sulphur dioxide is ~ le~;e~l.
In order to avoid the failure of noble metal built-in parts the glass does not have a r ad~ l condition. The ability for influel~cin!a by means of the usual oxidisil,g burner adjual",el-t is not available in the case of fully el~bically heated " ,~lt;. ,9 plants. For ecological reasol~ the usual addition of nitrates (02 separdtiG" and oxi- l~t;Gn of polyvalent ions) is ruled out be~use of their relea3e of NOx.
In ~ddition to the ,,I,~sical chemical glass prope,ties, the CGIl.pO~it;ol, of the borosilicate meltable fully electrically under cold-top conditions also accountsfor ,l)r~ess-linked require",en~.
AccGruling to the inven~on the full electric cold-top pr~cess is usable for borosilicate glass with a ll,er",al expansion to 4Sx10 ~' and enables a good glass quality if high t~."p~r~hre physical cl.ara ~,ia~cS such as viscosity and conductivity lie, for pr~ess r~asons in the proximity of those of a borDsi~ ? glass 3.3. In order that stable cold-top conditions prevail, the batchis melted at more or less the same rate used for borosilicate glass 3.3.
It is used for manufacturing laboratory glass, housecl~I glass, ~,har",~ce~ ~tic~l recept~cle glass, lamp glass, flat glass, as well as other industrial and optical high-quality glass produc'ts.
In accordance with the invention the new glass is used when a borosilicate glass with the ",e, ItiGI ,ed pro,uel ~ is to be man~ ~f~ red in known fully electrically heated melting plants according to the cold-top principle.
Many types of bor~silic~te glass are known in the state of the art. Theproperties that det~r",ine their use-value are high chel"ical lesiak~l ,ce, low thermal expansion, high U,er"~al fatigue r~sistance, and high mechanical stability.
Thus, borosilicate glass 3.3 is usually used for laboratory, housecraft and instrument glass in accordance with DIN ISO 3585 . This type of glass cGntc.;.,s only a little alkali (less than 5%), SiO2 more than 79% and B203 to approx. 13%. It has a thermal e~ansion of approx. 3.3x10 ~K
Fu, lhell"ore, sealing glass that contains boron is known. It has a high alkali and/or all~line earth CGI~IIt, as well as sor,-~tir"es ad.lit;G.,al further oxides.
The U,err"al e,.~l,sion of these types of glass is 3.6 to 5.2x10 ~'. A further 21 93~99 known group is that of so-called neutral ~vhar-"aceutical borosilicate glass. IncGnbd~l to the sealing glass it achieves the l,ighest chemical resis~nce values. Its alkali colltent is approx. 6.5 to 8.5% and 3.2% to 5.0~h alkaline earth, the thermal e~,uansiGl) is 4.8 to 5.1x10 ~K '.
It is known, as desc,il,ed in patent specificdtiGn DE 37 22 130, to replace the large range of types of bor~s.'i~~te glass by a glass, which satisfies most requirements, of thermal eA~ausion 4.0 to 5.0x10 ~< '. It is also known to improve and speci~'.se ~e.r~r.nance-det~r-..inir,g properties of borosilic~te glass by means of an o~tin,ised cGm~osition and partial use of additional oxides such as ZnO, SrO, CsO, Li20, etc., as desclil ed in, e.g., the patent specifications DE 42 30 607, DE 40 12 288 or DE 43 25 656.
In the case of industrial production of borosili~ ~ glass 3.3, bec~ ~se of improved ei~ergetic e~iciency, qualitative as well as ecol~gic~l advan69es, fullelect~ ic ll.elting after the cold-top process has prevailed. In this ~r~cess, the melting heat is gener~t~l in the interior of the melting bath by means of a flowof electlic current, whereby the surface of the n,elti"g bath is continuously belayed with new batch. Normally a stable, ~lficiel tly insulating layer forms, which also retains volatile s~ s~nces and re-s~ ~r~'ies them to the melter.
Owing to this su~.eriG. ity and its cost cuffing relevance, the known borosilicate glass is invesli5~t~d for fabrication acco~di"g to this ~ thod and i1~; devices.
Thus far it has not been possible to melt neutral ,.~har,n~ceutic~l borosilic~t~glass fully electrically, since the required refining agents As203 andJor Sb203 destroy the usual molybdenum rod hedtin~ electrodes. Initial a,~,uroacl.es toward a ~,rocess engineering problem solution are specified in DE-PS 43 13 217.
Borosilicate glass having a linear thermal expansion from 3.6 to 4.8x10 ~K 1 can only be melted full electrically under severe qualitative lin~itdtiolls. It melts significantly faster than borosilic~t~ glass with a thermal expansion of 3.3x10 6 K ' owing to higher flux cont~n~ ~alkali, alkaline earth and boron oxide).
However, bec~use for complete glass forllldtiGn, hGIllogenisdtion and refining, approximately the same melting temperatures are required despit~ the flux CG nlerlb, the efficiently insulating, cold batch layer required for the full electric cold-top ",elling ,~.rocess cannot arise in a stable ~)lanner; the heat bc.lance is disturbed. At the worst the process no longer al!Qws thç açhiçvçmçnt of thç
desir~d telnperat-lres, so that bubbly glass or u..i..ell_d particles leave the furnace.
If alkali and alkaline earth are added as usual as the carLGnale, whichdepending on origin is co~ i.lindt~d with sulphate, the carbon dioxide and sulphur dioxide arising during melting cannot be completely removed ~rom ~e melter. On the one hand, the released gas q~a~ti~s are re!ative!y hjgh f,or the tough borosilic~te glass. On the other hand, the high s~l ~hility of C02 andS02 C~ uses excessively high gas resiciues in the glass. From other glass, it isknown that the sol! ~bility of C02 and S02 increases with the basicity module (ratio of network transformers to network f~,r",er~). If one lralls,~)oses this regularity to bolosilicate glass, the higher C02 or S02 solubility of the alkaliand alkaline earth rich borosilicate glass toi"pared with borosilic~t~ glass 3.3is then plausible. At the latest as reboil glass, C02 and S02 is again released and appears as seeds or bubbles in the finished giass. Suitable refining agents, such as As203 and/or Sb203, can remove these gases in combination with further oxidants, they are, however, unus~'e in fully electrically heated furnaces owing to their destructive effect upon molybdenum electrodes. Owing to their high alkaline earth conte, It~, the gl~sses described, e.g., in patent specil~c~tiG"s DE 42 30 607, DE 37 22 130 and DE 25 656, have this decisive disadvank3ge.
In additioll, further, partially used oxides such as PbO, SnO, CuO, NiO, CdO, FeO, Cr203 and ZnO act corrosively upon the Mo t~e~ lechodes.
Measures to protect the ele~t,o ies, such as the known r;,~tl,od for direct-current passivation, are ruied out bec~ ~se of the required use of known noble metal devices in the feeder.
Furthermore it is known that the full electric cold-top Illelti~ pr~ess, in which the melting ten-perarture for every type of glass is deterr"ii ,ed and is especi~lly 21 9:39~9 high in the case of borosilic~tç glass can only be used for a specific range of glass viscosity and electric cond!~ctibili~r. A excess electric condu~tibility of the glass at the usual ",elti"~ temperature owing to high alkali or alkaline earth co, Itenb causes high current and energy densities overl,edli"y electrode wear and blisters can occur. In the event of excessively low electric conductibility an il ,creasi. ,9 part of the current flows through the stone ",at~rial. Fxcessive glass viscosity requires ul-~cce,c1-hly high temperatures for refi"i"5~ or only enables this only incon":letely in a too thin-bodied glassunr"elted particles or unrehned melted l"dlerial are frequently mixed into the finished glass. The full clectlic cold-top method proven for borosilicate glass 3.3 is consequently not transferable to other gl~sses which at comparable ,nelti"~ .".,~r~tures ha~e Ji~rent viscosities and condu~ ities without significant cGnsequences. Many known types of L~r~,sili~c~ glass with a linear thermal ex,uansion ~reater than 3.9x10 CK ' have e.g. a total alkali p~us alkaline earth content of more than 7%1 also that from patent specifi~iion DE
37 22 130. They cannot be melted bubble-free at the required ",eltin~
te""xr~tlJres over 1550~ C with the proven full electric cold-top prvcess.
From the ~ ll ,o.ls known state of tne art references for fixing and controllingthe redox po~,ltial of ~Grosilic~te glass are not known.
~1 ~399~
It is the object of the invention to specif~r a soft borosilic~t.e glass of thermal expansion 3.9 to 4.5x10 6K~' of high che~"ical resislal~ce, which can be fabri~ated under the advan~eol~s eco logi~al and enerye~ic conditions of ~e known full ele ~IIic cold-top process.
In aGcGr~l~a. ,ce with the invention this object is solved therein that it has aprocessing temperature at 10 4 dPa s of 1200 to 1 270~C, a \riscosity at 15~0 C of 1 O~'to 102 ~dPa s, a specific electric r~sisl~nce at 1 550~C of 20 to 33 ....cm and an electric conductivity at 1 550~C of 3.0 to ~.0 ~/m, melts under cold-top conditions at approx. 1 600~C with 0.3 to 0.5 mm/min, and has the following basic col"position:
SiO2 + ZrO2 77.0 to 81.0 weight %
B203 + Na20 + K20 + CaO + MgO + BaO 16.0 to 18.5 weight %
of which Na20 + K20 + CaO + MgO + BaO 5.4 to 7.0 weight %
of which CaO + MgO + BaO to 0.9 weight %
Al203 3.7 to 4.9 weight %
Cl O.OS to 0.4 weight %
with the relations:
Ratio CaO + MgO + BaO 0.0 to 1.5 ZrO2 "- 21 q399~
Ratio Na20 + K20 + CaO + MgO + BaO 0.060 to 0.075 B203 + SiO2 + A1203 + ZrO2 Adva,ltcgeous embodi,.,eilt~ are specified in s~ cl~NIs 2 to 5.
In the case of the borosilicate glass according to the invention specific experiences wim the specified process and its devices are to be observed.
Although the principle relatio"ships l,etween glass properties and cGIl~posiliGnof borosilic~te glass are known, the ,vr~cess-linked limitdtiGIls lead to a new,per se cont,ddictoiy and U,erefore thus far unusual objective.
The new glass belongs to the group of chel"ically resistant bor~silicate glass, ch-dr~cl6rised by the following properties: -- linear lher",al ex~a"sion between 20~C and 300~C:
3.9 to 4.5x10 K~' - l.al ~srorI"dtiGn teln,uerdtLIre: over 540~C
- hydrolytic resi~nce per DIN 121 1 1:
1 st ctass - acid resist~nce per DIN 12116:
1 st class - Iye resistance per DIN 52322:
2nd class Owing to its use as ,~har-"~cellffc~l andJor housecraft glass, the glass is credt~d without toxic heavy-metal oxides. It CG nt. i~s components to increase '- 21 93~99 the brilliancy and can be ~ d. In order that it can be melted fully ele~ bically in the known fu,l,aces it may contain no PbO, SnO, CuO, NiO
CdO FeO Cr203 ZnO As203 andtor Sb203.
For eco'ogi~l ~asons no fluorides are used as refining agents.
In order to maintain a low gas content in tne glass, during ~"elti.,~ e or no carbon ~ cide and no sulphur dioxide is ~ le~;e~l.
In order to avoid the failure of noble metal built-in parts the glass does not have a r ad~ l condition. The ability for influel~cin!a by means of the usual oxidisil,g burner adjual",el-t is not available in the case of fully el~bically heated " ,~lt;. ,9 plants. For ecological reasol~ the usual addition of nitrates (02 separdtiG" and oxi- l~t;Gn of polyvalent ions) is ruled out be~use of their relea3e of NOx.
In ~ddition to the ,,I,~sical chemical glass prope,ties, the CGIl.pO~it;ol, of the borosilicate meltable fully electrically under cold-top conditions also accountsfor ,l)r~ess-linked require",en~.
AccGruling to the inven~on the full electric cold-top pr~cess is usable for borosilicate glass with a ll,er",al expansion to 4Sx10 ~' and enables a good glass quality if high t~."p~r~hre physical cl.ara ~,ia~cS such as viscosity and conductivity lie, for pr~ess r~asons in the proximity of those of a borDsi~ ? glass 3.3. In order that stable cold-top conditions prevail, the batchis melted at more or less the same rate used for borosilicate glass 3.3.
2~ ~3qqq In meltiny trials the fal'~ur;.,y of these values were proven:
- ~,rocessi"~ t ."perdture at 10~ dPa s:
1200 to 1270~C
- viscosity at 1550~C: 10Z ~to 10Z-YdPa s - sp~cific elect~ic ~ t~nce at 1550~C:
20 to 33 Ohrn cm - melting r~te of the batch without refuse glass:
0.35 to 0.45 mm/min.
By means of trial melts it was shown that the process linked high processi"
t~,l.per,Jt.lre speci~ed and the 1550~C vixosity could be achieved ~nth a conbnt of SiO2 plus ZrO2 of more than 77% and a content of A1203 of 3.5 to 5.096. ~t above 81% SiO2 plus ZrO2 ~e processi".J t~r",~rature and the VistG_ ~.y at 1 550~C incr~asa, but not to u..co, d.ollably high values and relicts of these difficultto melt cG~IlpGllel~ts must be recl~n~ with. Under 77% SiO2 plus ZrO2, the linear thermal ~A~U&. ,sicn i- ,clec.ses over 4.5x10 ~' wffl the Al203 cont~nt according to the inv~ . ~'bGI 1.
Furtl,e".,Gre it was ascell~;"6d that the process linked conductivity and the s~c;fic ~le_b ic re~ 3nce specifiv~l fix the ratio of the sum of alkalis plus alkaline earths to the sum from SiO2 ~ B203 + A1203 + ZrO2 at 0.060 to 0.075. Above that an ~ essive ele_t~ ic conductivity at 1 550~C over 5 S/m leads to a high current density below that under 3 Slm too much current 2~ 939~9 flows through the stone material.
The sum of all oxides effective as fluxes ~alkali + alkaline earth + B203) accelerates the melting behaviour. In order that the desired cold-top con.litiGns prevail at melt;ng temperatures over 1 ~0~C required for ~ri"i.~g i.e. the batchsur~ace required for insulation does not melt this flux quantity may not exceed 18.5%. In orderto acl,ieve a batch surface cG,n,uarable to bor~silicate glass 3.3 up to this value at least 0.6~h of the required SiO2 is repl~ed by ZrO2 which greater delays melting. Below 16~,6 flux the glass melts more slowly than borosilic~te glass 3.3 this would require e~(cessively high temperatures and the danger of the occurrence of residllal quarlz relicts. In dependei ,ce upon the variable alkaline earth content ex~lained below the melting behaviour is stabilised by a d~ined increase in ZrO2 in that the ratio of alkaline earth to ZrO2 is maintained below 1.5.
As is known the B203 CG ntent influences the chemical resia~ance and is limited downwardly by an ex&essive proceâsil Ig te~ uel~dt~lre over 1 300~C and an ~xcessive 1 550~C viscosity. In cG""ection with the alkali and alkaline earthcontent explained below, a range of 10.5 to 12.5% B203 was det~r..,ined in order to achieve the required cher ,ical resistance.
As ex~erience shows linear thermal ex,uansiG" is greatly influenced by the alkali and alkaline earth cGntent. It was possible to det~r-"i"e that whilst ~ ~1 939~C~
accounting for the limits of alkaline earths for conductivity and ca, LGndte addition, the arguments for which are below, at least ~.4%, but at most 7.0~h alkali plus alkaline earth may be used to maintain linear II,er."al ek,uansion between 20~C and 300~C in the range of 3.9 to 4.5x10 6K '.
Furlherr"ore, it was found that the desired chemical resi~la"ce can then be achieved with utilisation of the mix alkali effect and additiGnally the mix alkaline earth effect if, in addition to 5.0 to 5.8% Na20, also 0.3 to 1.5~,6 K20 or 0.6%to 0.9% alkaline earth, or a cGi"bindtion of K20 plus alkaline earth, is added.
Since among the all~l;"e earths, BaO demo"~l~ates here the desired effect, as well as owing to the advantages explained below, it is preferred. Rec~use Li20 would increase the devitri~ication tendenc~, it is not used.
In addition to its effect of delaying melting, as is known, ZrO2 improves chemical resi~l~nce, es,~eci~'ly agai"s~ Iyes, the ",ecl,a.,ical s~a"~th, and especially the scratch hardness of the glass, which provably i"creases its service value, as well as also the e~,~,ense in the case of mechanical working.
In order that the glass can also be worked ecGno"~ic~lly, the ZrO2 content is tobe below 2.4%. Surprisingly, in the event of mass prod~ ~ction of this glass, nothreat of devitlificdLiGn could be established up to this value when Al203 is 3.7 to 4.9%. To limit the proce-~sing temperature, the Al203 contei It iS preferably4.1 to 4.5% and the ZrO2 content preferably b~tw~en 0.8 and 1.09~.
In industrial melting trials in fully electrically heated cold-top me:tirl~ fu..,aces and subsequent determination of the gas content it was furthermore found that, with a ratio of Na20 + K20 ~ CaO + MgO ~ BaO divided by SiO2 + Al203 ZrO2 + B203 of less than 0.075, the C02 and S02 contents in glass clearly declease. In order to generally maintain low introd! ~ced carbon and sulphur dioxides quar,lilies, in accordance with the invention, the use of alh~l;ne earths is limited to 0.9% and the use of carLo"at~s only per."itt~d for these alkaline earths. Other carbonates or suplhates or raw ",dt~rials contai~ ling ca~t Gna~s or sulpl ,ates may not be used bec~use of their rel~a3e of carbon and sulphur ~ioxirle. MgO increases the devitl ific~lion tendel ,cy and is thus ruled out asraw material component. In cGm~arison to CaO, BaO increases the ref.d..ti~e index and pro,l,otes the brilliance of the glass, as desired in use as housecr-dfl glass. Owing to this property and its favourable influence upon the acid class, exclusively BaO is used as the alkaline earth con,ponent. This is u"der~tood to mean that only CaO and MgO impurities are permitted, which despite all arrangements may enter the glass by up to 0.1%. To fully avoid reboil susceptibility, the glass preferred accorJil~g to the invention is free of alkaline earth, except for the tolerated impurities.
If the glass must be stablised, the introduction of a d~ned quantity of ceriu IV oxide has proven advant~geous for lime-soda glass, as it oxidises polyvalent impurity ions. It was found that the lelease of oxygen from the cerium IV oxide ~es not destroy the laterally or bottom installed molybdenum rod elec~odes, ~ ! 93q~9 since me r~le-~,ed oxygen no longer comes into CG~ Ct with these. Moreover, it was established that the known cGr,osh,e influence ~F~ct~d by As203 or Sb203 does not occur in the case of the quantity of cerium oxide used acco, ~Jiny to the invention, des~ r~ the prevailing high ".elti"y te,~rdt~re for sulphate-free bGro~ 'v glass. At the same time, tne desi,~d redox condition is ~dj!,~s~le and co,lb~l'able U,er~ l,. 1 Io~/e~er, the CeO collh~.lt in tne glass does not exceecl 196, as ~Jthe/ ~ise, in addition to an incr~ase in molybdenum wear, negative ;"~ ent of the cl,en,ical resi~ance would occur.
A borosilicate glass accor~.ny to the invention with a linear thermal expansion L_hr~en 20~C and 300~C of 3.9to 4.5x10 ~K ', a ll_.l;.f~rrlldtiGn te,n~ erdture of 540 to 57~~C, a ~,rocessi. ~y t~ per~h~re at 10 4 dPa s of 1200 to 1 270~C, and a 1 550~C viscosity of 1 02~5dPa s, which has a s~ecif~c ~31e t- iC resi~Lnce at 1 550~C of 20 to 33 Ohm cm, and an elecl.ic conductivity at 1550~C of 3.0 to 5.0 S/m, and at the same time fulfils the first hydrolytic class as per DIN 12111, tne first acid class as per DIN 121 16, and the second Iye class as per DIN
52322, has the f~llo~i.~y cGn.,ssition:
-21 93~9c~
SiO2 76.6 to 78.0 weight %
B203 10.5 to 12.5 weight %
Al203 3.7 to 4.9 weight %
Na20 5.0 to 5.8 weight %
K20 0.3 to 1.5 weight %
CaO andJor MgO (impurity) less than 0.1 weight BaO 0.0 to 0.9 weight %
ZrC)2 0.6 to 2.4 weight 9'o Cl 0.0~ to 0.4 weight %
Only NaCI or KCI is used as a r~ning agent, As203 or Sb203 is ruled out.
The use of raw materials conatining CaO, MgO, sulphate, or fluoride, is ,~en..iU.ad only with the ~ ,Ai~l~ of the smallest impurities.
The bor ~ c-~ glass accor~ g to the invenffon requires no all~line earth (apartfrom unavoidable impurities) and lllel~re fully P~lu~ies ff~e use of c~. bGn~t~s. This lowers the reboil s~lsce~l,ility. The alkalis are introduc~
only as borates, aluminates, or silicat~s. This glass, which is pr~f~l,6d according to the invenff~n, is cl,a.._ct~liaed by the following cG~ osit;on:
21 939q9 SiO2 76.6 to 77.7 weight %
B203 11.0 to 12.0 weight%
Al203 4.1 to 4.5 weight %
Na20 5.1 to ~.6 weight %
K20 0.8 to 1.2 weight %
CeO 0.0 to 0.5 weight %
ZrC)2 0.8 to 1.~ weight %
Cl 0.05 to 0.2 weight %
Es,uecially advantageous is that the borosili~te glass accordir,g to the invention with its ch6"~ical colnpGsitiGn and its physical properties can be manufactured using the full electric cold-top mellin!J process which is ecclcgi~lly er,erg~ically, and operationally highly efficient. In such a glass melting furnace the glass accordin.J to the invention with a linear thermal expansion bet r/a0n 20~C and 300~C of 4.0 to 4.4x10 ~ a l,~nsfo",.aUGn temperature of 550 to 575~C and a processi"y temperature at 104 dPa s of 1215 to 1 260~C tne first hydrolytic class according to DIN 121 1 1 tne first acid class accorcling to DIN 12116 and the second Iye class accor.li.,y to DIN
52322 is melted and processed in good quality whereby telllpGr..rily and reversibly re~,lacement by borosi' cate glass 3.3 is possible, rapidly and without problem.
In the follo-:;.,g the invention is explained in greater detail by means of an embodiment.
Glass nos. 5 to 19 shown in the table represent examples of continuou~ly working, fully electrically heated cold-top melting f ",aces.
"- 21 93999 Glass nos. 9 to 11 were melted with 20 to 30% refuse glass.
Glass nos. 1 to 4 serve as a co,..parison and are m~ le fully electrically according to the cold-top pr~cess.
Glass 1 concerns a t~orosilic~e glass 3.3 according to DIN ISO 3585.
~lass 20 serves as a comparison and cannot be man~ ~ured bubble-free with the fully electric cold-top process (alkali plus alkaline earth too high specific electric resistance too low, basicity module too high).
Remarks on the table:
Glass oxides in per( entages per weight.
Alpha: Linear mermal e~ . ,sion be~Nee" 20 and 300~C in 10 L'IK.
Tg: Tr~nsf~Jrrllatiol) tei~"~er~re in ~C.
Ep: Sinking point or processing temperature at 104dPa s in ~C.
Ew: Fusion point 10~ ~dPa s in ~C.
R: Specific electric resistance at 1550~C in Ohm cm.
v: Melting rate in mm/min.
Visk.: LogariU"" of the viscosity at 15~0~C in dPa s.
Na20 + K20 + CaO + MgO + BaO
Basicity module =
B203 + SiO2 + A1203 + ZrO2 21 939q9 E"~L)~li.,~ents (Nos. 1 to 4 and 20 for tG~ , ison) No. SiO2 B203 A203 Na20 K~ CaO MgO BaO Z~2 Cl SK~2 8203 Z~02 R20 + RO
1 80.40 13.0 2.25 3.7Q 0.55 0.02 0.01 0.03 0.05 80.43 17.28 2 79.80 12.40 3.00 4.20 0.~6 0.01 0.05 0.55 80.35 17.323 79.00 11.00 3.75 4.g5 0.80 0.01 0.05 0.85 0.05 78.85 16.81 4 78.90 10.65 4.10 4.45 1.40 0.01 0.05 0.85 0.05 79.75 16.56 77.50 11.93 3.77 5.06 0.83 0.05 0.86 0.06 78.36 17.87 6 77.?0 11.00 4.10 5.20 0.90 0.01 0.05 0.90 0.08 78.60 17.16 7 77.60 11.00 4.25 5.20 0.091 0.01 0.05 0.90 0.09 78.50 17.17 8 76.~0 11.30 4.37 5.45 0.92 0.02 0.01 0.92 0.10 77.82 17.70 3 76.60 11.3g 4.40 5.58 0.95 0.02 0.02 0.93 0.07 77.53 17.90 76.~0 11.44 4.25 5.25 1.05 0.02 0.05 0.91 0.10 77.81 17.81 11 76.90 11.58 4.15 5.22 1.06 0.05 0.01 0.89 0.09 77.79 17.79 12 76.60 11.00 4.25 5.20 0.91 0.01 0.05 1.90 0.10 78.50 17.17 13 77.10 11.~4 4.15 5.30 0.30 0.05 0.05 0.80 0.~3 0.10 77.73 18.11 14 77.00 11.89 4.21 5.45 0.40 0.01 0.01 0.63 0.10 77.63 17.7B
79.~3 12.00 4.25 5.45 0.83 0.02 0.02 0.80 0.10 77.43 18.32 16 77.46 10.eO 4.80 5.25 0.75 0.02 0.02 090 0.1C 78.36 16.8417 76.65 12.20 4.30 5.70 0.40 0.Q2 0.02 0.70 0.10 77.36 18.34 18 76.69 11.90 4.25 5.t2 1.40 0.02 0.02 0.50 0.10 77.29 18.46 1~ 76.~0 11.20 4.15 5.06 0.95 0.02 0.02 2.00 0.10 78.B0 17.25 75.32 12.20 3.68 5.~8 0.01 0.07 0.01 1.01 1.10 0.12 76.42 19.28 l~lo. 14 ~ nally 0.40% CeO No. 20 ~1- Iiti~nally 0.33% CeO.
No. R20 RO RO Ba~ ~lpha Tg Ew Ep R \~sk. v + RO Z~3 ~y mod~
ule 1 4.28 0.03 1.00 0.045 3.30 535 815 1245 32.0 2.7 0.42 2 4.92 0.06 0.11 0.061 3.63 559 825 1234 3 5.81 0.06 0.07 0.062 3.90 557 1233 26.2 0.36 4 5.91 0.06 0.07 0.063 3.85 559 1245 5.94 0.05 0.06 0.063 4.07 567 815 1231 25.8 2.65 0.36 6 6.16 0.06 0.07 0.066 4.18 570 818 1228 25.0 2.65 7 6.17 0.06 0.07 0.066 4.18 56g 820 1228 25.0 2.65 0.39 8 6.40 0.03 0.03 0.068 4.30 566 809 1222 23.6 2.65 0.38 9 6.57 0.04 0.04 0.070 4.33 807 1219 23.2 2.65 0.47 6.37 0.07 0.08 0.068 4.26 571 813 1227 24.0 2.65 0.44 11 6.34 0.06 0.07 0.068 4.27 1227 24.0 2.65 0.43 12 6.17 0.06 0.03 0.066 4.12 554 1228 13 6.50 0.90 1.43 0.070 4.00 553 1226 14 5.87 0.02 0.03 0.063 4.05 552 1222 6.32 0.04 0.05 0.067 4.1g 552 1222 16 6.04 0.04 0.04 0.064 4.07 555 1227 17 6.14 0.04 0.06 0.065 4.16 551 1217 18 6.56 0.04 0.07 0.070 4.22 553 1230 19 6.05 0.04 0.02 0.064 4.06 555 1218 7.08 1.09 0.99 0.077 4.25 540 799 1176 13.6 2.45 0.54
- ~,rocessi"~ t ."perdture at 10~ dPa s:
1200 to 1270~C
- viscosity at 1550~C: 10Z ~to 10Z-YdPa s - sp~cific elect~ic ~ t~nce at 1550~C:
20 to 33 Ohrn cm - melting r~te of the batch without refuse glass:
0.35 to 0.45 mm/min.
By means of trial melts it was shown that the process linked high processi"
t~,l.per,Jt.lre speci~ed and the 1550~C vixosity could be achieved ~nth a conbnt of SiO2 plus ZrO2 of more than 77% and a content of A1203 of 3.5 to 5.096. ~t above 81% SiO2 plus ZrO2 ~e processi".J t~r",~rature and the VistG_ ~.y at 1 550~C incr~asa, but not to u..co, d.ollably high values and relicts of these difficultto melt cG~IlpGllel~ts must be recl~n~ with. Under 77% SiO2 plus ZrO2, the linear thermal ~A~U&. ,sicn i- ,clec.ses over 4.5x10 ~' wffl the Al203 cont~nt according to the inv~ . ~'bGI 1.
Furtl,e".,Gre it was ascell~;"6d that the process linked conductivity and the s~c;fic ~le_b ic re~ 3nce specifiv~l fix the ratio of the sum of alkalis plus alkaline earths to the sum from SiO2 ~ B203 + A1203 + ZrO2 at 0.060 to 0.075. Above that an ~ essive ele_t~ ic conductivity at 1 550~C over 5 S/m leads to a high current density below that under 3 Slm too much current 2~ 939~9 flows through the stone material.
The sum of all oxides effective as fluxes ~alkali + alkaline earth + B203) accelerates the melting behaviour. In order that the desired cold-top con.litiGns prevail at melt;ng temperatures over 1 ~0~C required for ~ri"i.~g i.e. the batchsur~ace required for insulation does not melt this flux quantity may not exceed 18.5%. In orderto acl,ieve a batch surface cG,n,uarable to bor~silicate glass 3.3 up to this value at least 0.6~h of the required SiO2 is repl~ed by ZrO2 which greater delays melting. Below 16~,6 flux the glass melts more slowly than borosilic~te glass 3.3 this would require e~(cessively high temperatures and the danger of the occurrence of residllal quarlz relicts. In dependei ,ce upon the variable alkaline earth content ex~lained below the melting behaviour is stabilised by a d~ined increase in ZrO2 in that the ratio of alkaline earth to ZrO2 is maintained below 1.5.
As is known the B203 CG ntent influences the chemical resia~ance and is limited downwardly by an ex&essive proceâsil Ig te~ uel~dt~lre over 1 300~C and an ~xcessive 1 550~C viscosity. In cG""ection with the alkali and alkaline earthcontent explained below, a range of 10.5 to 12.5% B203 was det~r..,ined in order to achieve the required cher ,ical resistance.
As ex~erience shows linear thermal ex,uansiG" is greatly influenced by the alkali and alkaline earth cGntent. It was possible to det~r-"i"e that whilst ~ ~1 939~C~
accounting for the limits of alkaline earths for conductivity and ca, LGndte addition, the arguments for which are below, at least ~.4%, but at most 7.0~h alkali plus alkaline earth may be used to maintain linear II,er."al ek,uansion between 20~C and 300~C in the range of 3.9 to 4.5x10 6K '.
Furlherr"ore, it was found that the desired chemical resi~la"ce can then be achieved with utilisation of the mix alkali effect and additiGnally the mix alkaline earth effect if, in addition to 5.0 to 5.8% Na20, also 0.3 to 1.5~,6 K20 or 0.6%to 0.9% alkaline earth, or a cGi"bindtion of K20 plus alkaline earth, is added.
Since among the all~l;"e earths, BaO demo"~l~ates here the desired effect, as well as owing to the advantages explained below, it is preferred. Rec~use Li20 would increase the devitri~ication tendenc~, it is not used.
In addition to its effect of delaying melting, as is known, ZrO2 improves chemical resi~l~nce, es,~eci~'ly agai"s~ Iyes, the ",ecl,a.,ical s~a"~th, and especially the scratch hardness of the glass, which provably i"creases its service value, as well as also the e~,~,ense in the case of mechanical working.
In order that the glass can also be worked ecGno"~ic~lly, the ZrO2 content is tobe below 2.4%. Surprisingly, in the event of mass prod~ ~ction of this glass, nothreat of devitlificdLiGn could be established up to this value when Al203 is 3.7 to 4.9%. To limit the proce-~sing temperature, the Al203 contei It iS preferably4.1 to 4.5% and the ZrO2 content preferably b~tw~en 0.8 and 1.09~.
In industrial melting trials in fully electrically heated cold-top me:tirl~ fu..,aces and subsequent determination of the gas content it was furthermore found that, with a ratio of Na20 + K20 ~ CaO + MgO ~ BaO divided by SiO2 + Al203 ZrO2 + B203 of less than 0.075, the C02 and S02 contents in glass clearly declease. In order to generally maintain low introd! ~ced carbon and sulphur dioxides quar,lilies, in accordance with the invention, the use of alh~l;ne earths is limited to 0.9% and the use of carLo"at~s only per."itt~d for these alkaline earths. Other carbonates or suplhates or raw ",dt~rials contai~ ling ca~t Gna~s or sulpl ,ates may not be used bec~use of their rel~a3e of carbon and sulphur ~ioxirle. MgO increases the devitl ific~lion tendel ,cy and is thus ruled out asraw material component. In cGm~arison to CaO, BaO increases the ref.d..ti~e index and pro,l,otes the brilliance of the glass, as desired in use as housecr-dfl glass. Owing to this property and its favourable influence upon the acid class, exclusively BaO is used as the alkaline earth con,ponent. This is u"der~tood to mean that only CaO and MgO impurities are permitted, which despite all arrangements may enter the glass by up to 0.1%. To fully avoid reboil susceptibility, the glass preferred accorJil~g to the invention is free of alkaline earth, except for the tolerated impurities.
If the glass must be stablised, the introduction of a d~ned quantity of ceriu IV oxide has proven advant~geous for lime-soda glass, as it oxidises polyvalent impurity ions. It was found that the lelease of oxygen from the cerium IV oxide ~es not destroy the laterally or bottom installed molybdenum rod elec~odes, ~ ! 93q~9 since me r~le-~,ed oxygen no longer comes into CG~ Ct with these. Moreover, it was established that the known cGr,osh,e influence ~F~ct~d by As203 or Sb203 does not occur in the case of the quantity of cerium oxide used acco, ~Jiny to the invention, des~ r~ the prevailing high ".elti"y te,~rdt~re for sulphate-free bGro~ 'v glass. At the same time, tne desi,~d redox condition is ~dj!,~s~le and co,lb~l'able U,er~ l,. 1 Io~/e~er, the CeO collh~.lt in tne glass does not exceecl 196, as ~Jthe/ ~ise, in addition to an incr~ase in molybdenum wear, negative ;"~ ent of the cl,en,ical resi~ance would occur.
A borosilicate glass accor~.ny to the invention with a linear thermal expansion L_hr~en 20~C and 300~C of 3.9to 4.5x10 ~K ', a ll_.l;.f~rrlldtiGn te,n~ erdture of 540 to 57~~C, a ~,rocessi. ~y t~ per~h~re at 10 4 dPa s of 1200 to 1 270~C, and a 1 550~C viscosity of 1 02~5dPa s, which has a s~ecif~c ~31e t- iC resi~Lnce at 1 550~C of 20 to 33 Ohm cm, and an elecl.ic conductivity at 1550~C of 3.0 to 5.0 S/m, and at the same time fulfils the first hydrolytic class as per DIN 12111, tne first acid class as per DIN 121 16, and the second Iye class as per DIN
52322, has the f~llo~i.~y cGn.,ssition:
-21 93~9c~
SiO2 76.6 to 78.0 weight %
B203 10.5 to 12.5 weight %
Al203 3.7 to 4.9 weight %
Na20 5.0 to 5.8 weight %
K20 0.3 to 1.5 weight %
CaO andJor MgO (impurity) less than 0.1 weight BaO 0.0 to 0.9 weight %
ZrC)2 0.6 to 2.4 weight 9'o Cl 0.0~ to 0.4 weight %
Only NaCI or KCI is used as a r~ning agent, As203 or Sb203 is ruled out.
The use of raw materials conatining CaO, MgO, sulphate, or fluoride, is ,~en..iU.ad only with the ~ ,Ai~l~ of the smallest impurities.
The bor ~ c-~ glass accor~ g to the invenffon requires no all~line earth (apartfrom unavoidable impurities) and lllel~re fully P~lu~ies ff~e use of c~. bGn~t~s. This lowers the reboil s~lsce~l,ility. The alkalis are introduc~
only as borates, aluminates, or silicat~s. This glass, which is pr~f~l,6d according to the invenff~n, is cl,a.._ct~liaed by the following cG~ osit;on:
21 939q9 SiO2 76.6 to 77.7 weight %
B203 11.0 to 12.0 weight%
Al203 4.1 to 4.5 weight %
Na20 5.1 to ~.6 weight %
K20 0.8 to 1.2 weight %
CeO 0.0 to 0.5 weight %
ZrC)2 0.8 to 1.~ weight %
Cl 0.05 to 0.2 weight %
Es,uecially advantageous is that the borosili~te glass accordir,g to the invention with its ch6"~ical colnpGsitiGn and its physical properties can be manufactured using the full electric cold-top mellin!J process which is ecclcgi~lly er,erg~ically, and operationally highly efficient. In such a glass melting furnace the glass accordin.J to the invention with a linear thermal expansion bet r/a0n 20~C and 300~C of 4.0 to 4.4x10 ~ a l,~nsfo",.aUGn temperature of 550 to 575~C and a processi"y temperature at 104 dPa s of 1215 to 1 260~C tne first hydrolytic class according to DIN 121 1 1 tne first acid class accorcling to DIN 12116 and the second Iye class accor.li.,y to DIN
52322 is melted and processed in good quality whereby telllpGr..rily and reversibly re~,lacement by borosi' cate glass 3.3 is possible, rapidly and without problem.
In the follo-:;.,g the invention is explained in greater detail by means of an embodiment.
Glass nos. 5 to 19 shown in the table represent examples of continuou~ly working, fully electrically heated cold-top melting f ",aces.
"- 21 93999 Glass nos. 9 to 11 were melted with 20 to 30% refuse glass.
Glass nos. 1 to 4 serve as a co,..parison and are m~ le fully electrically according to the cold-top pr~cess.
Glass 1 concerns a t~orosilic~e glass 3.3 according to DIN ISO 3585.
~lass 20 serves as a comparison and cannot be man~ ~ured bubble-free with the fully electric cold-top process (alkali plus alkaline earth too high specific electric resistance too low, basicity module too high).
Remarks on the table:
Glass oxides in per( entages per weight.
Alpha: Linear mermal e~ . ,sion be~Nee" 20 and 300~C in 10 L'IK.
Tg: Tr~nsf~Jrrllatiol) tei~"~er~re in ~C.
Ep: Sinking point or processing temperature at 104dPa s in ~C.
Ew: Fusion point 10~ ~dPa s in ~C.
R: Specific electric resistance at 1550~C in Ohm cm.
v: Melting rate in mm/min.
Visk.: LogariU"" of the viscosity at 15~0~C in dPa s.
Na20 + K20 + CaO + MgO + BaO
Basicity module =
B203 + SiO2 + A1203 + ZrO2 21 939q9 E"~L)~li.,~ents (Nos. 1 to 4 and 20 for tG~ , ison) No. SiO2 B203 A203 Na20 K~ CaO MgO BaO Z~2 Cl SK~2 8203 Z~02 R20 + RO
1 80.40 13.0 2.25 3.7Q 0.55 0.02 0.01 0.03 0.05 80.43 17.28 2 79.80 12.40 3.00 4.20 0.~6 0.01 0.05 0.55 80.35 17.323 79.00 11.00 3.75 4.g5 0.80 0.01 0.05 0.85 0.05 78.85 16.81 4 78.90 10.65 4.10 4.45 1.40 0.01 0.05 0.85 0.05 79.75 16.56 77.50 11.93 3.77 5.06 0.83 0.05 0.86 0.06 78.36 17.87 6 77.?0 11.00 4.10 5.20 0.90 0.01 0.05 0.90 0.08 78.60 17.16 7 77.60 11.00 4.25 5.20 0.091 0.01 0.05 0.90 0.09 78.50 17.17 8 76.~0 11.30 4.37 5.45 0.92 0.02 0.01 0.92 0.10 77.82 17.70 3 76.60 11.3g 4.40 5.58 0.95 0.02 0.02 0.93 0.07 77.53 17.90 76.~0 11.44 4.25 5.25 1.05 0.02 0.05 0.91 0.10 77.81 17.81 11 76.90 11.58 4.15 5.22 1.06 0.05 0.01 0.89 0.09 77.79 17.79 12 76.60 11.00 4.25 5.20 0.91 0.01 0.05 1.90 0.10 78.50 17.17 13 77.10 11.~4 4.15 5.30 0.30 0.05 0.05 0.80 0.~3 0.10 77.73 18.11 14 77.00 11.89 4.21 5.45 0.40 0.01 0.01 0.63 0.10 77.63 17.7B
79.~3 12.00 4.25 5.45 0.83 0.02 0.02 0.80 0.10 77.43 18.32 16 77.46 10.eO 4.80 5.25 0.75 0.02 0.02 090 0.1C 78.36 16.8417 76.65 12.20 4.30 5.70 0.40 0.Q2 0.02 0.70 0.10 77.36 18.34 18 76.69 11.90 4.25 5.t2 1.40 0.02 0.02 0.50 0.10 77.29 18.46 1~ 76.~0 11.20 4.15 5.06 0.95 0.02 0.02 2.00 0.10 78.B0 17.25 75.32 12.20 3.68 5.~8 0.01 0.07 0.01 1.01 1.10 0.12 76.42 19.28 l~lo. 14 ~ nally 0.40% CeO No. 20 ~1- Iiti~nally 0.33% CeO.
No. R20 RO RO Ba~ ~lpha Tg Ew Ep R \~sk. v + RO Z~3 ~y mod~
ule 1 4.28 0.03 1.00 0.045 3.30 535 815 1245 32.0 2.7 0.42 2 4.92 0.06 0.11 0.061 3.63 559 825 1234 3 5.81 0.06 0.07 0.062 3.90 557 1233 26.2 0.36 4 5.91 0.06 0.07 0.063 3.85 559 1245 5.94 0.05 0.06 0.063 4.07 567 815 1231 25.8 2.65 0.36 6 6.16 0.06 0.07 0.066 4.18 570 818 1228 25.0 2.65 7 6.17 0.06 0.07 0.066 4.18 56g 820 1228 25.0 2.65 0.39 8 6.40 0.03 0.03 0.068 4.30 566 809 1222 23.6 2.65 0.38 9 6.57 0.04 0.04 0.070 4.33 807 1219 23.2 2.65 0.47 6.37 0.07 0.08 0.068 4.26 571 813 1227 24.0 2.65 0.44 11 6.34 0.06 0.07 0.068 4.27 1227 24.0 2.65 0.43 12 6.17 0.06 0.03 0.066 4.12 554 1228 13 6.50 0.90 1.43 0.070 4.00 553 1226 14 5.87 0.02 0.03 0.063 4.05 552 1222 6.32 0.04 0.05 0.067 4.1g 552 1222 16 6.04 0.04 0.04 0.064 4.07 555 1227 17 6.14 0.04 0.06 0.065 4.16 551 1217 18 6.56 0.04 0.07 0.070 4.22 553 1230 19 6.05 0.04 0.02 0.064 4.06 555 1218 7.08 1.09 0.99 0.077 4.25 540 799 1176 13.6 2.45 0.54
Claims (6)
1. Borosilicate glass having a linear thermal expansion between 20°C and 300°C of 3.9 to 4.5 x 10 -6 K-1, wherein it has a processing temperature at 10 4 dPas of 1200 to 1270°C, a viscosity at 1550°C of 10 2-6 to 10 2-8 dPas, a specific electric resistance at 1550°C of 20 to 33 Ohm cm, and an electric conductivity at 1550°C of 3.0 to 5.0 S/m, melts under cold-top conditions at approx. 1600°C
with 0.3 to 0.5 mm/min, and has the following composition:
SiO2 + ZrO2 77.0 to 81.0 weight %
B203 + Na2O + K2O + CaO + MgO + BaO 16.0 to 18.5 weight %
of which Na2O + K2O + CaO + MgO + BaO 5.4 to 7.0 weight %
of which CaO + MgO + BaO to 0.9 weight %
Al2O3 3.7 to 4.9 weight %
Cl- 0.05 to 0.4 weight %
with the relations:
Ratio 0.0 to 1.5 Ratio 0.060 to 0.075
with 0.3 to 0.5 mm/min, and has the following composition:
SiO2 + ZrO2 77.0 to 81.0 weight %
B203 + Na2O + K2O + CaO + MgO + BaO 16.0 to 18.5 weight %
of which Na2O + K2O + CaO + MgO + BaO 5.4 to 7.0 weight %
of which CaO + MgO + BaO to 0.9 weight %
Al2O3 3.7 to 4.9 weight %
Cl- 0.05 to 0.4 weight %
with the relations:
Ratio 0.0 to 1.5 Ratio 0.060 to 0.075
2. Borosilicate glass according to claim 1, wherein it has a transformation temperature of 540 to 575°C, corresponds to the first hydrolytic class according to DIN 12111, the first acid class according to DIN 12116, and the second lye class according to DIN 52322, and has the composition SiO2 76.6 to 78.0 weight %
B2O3 10.5 to 12.5 weight %
Al2O3 3.7 to 4.9 weight %
Na2O 5.0 to 5.8 weight %
K2O 0.3 to 1.5 weight %
CaO and/or MgO (impurity) less than 0.1 weight %
BaO 0.0 to 0.9 weight %
ZrO2 0.6 to 2.4 weight %
Cl- 0.05 to 0.4 weight %
B2O3 10.5 to 12.5 weight %
Al2O3 3.7 to 4.9 weight %
Na2O 5.0 to 5.8 weight %
K2O 0.3 to 1.5 weight %
CaO and/or MgO (impurity) less than 0.1 weight %
BaO 0.0 to 0.9 weight %
ZrO2 0.6 to 2.4 weight %
Cl- 0.05 to 0.4 weight %
3. Borosilicate glass according to claim 1 or 2, wherein Cerium IV oxide is added to the batch as decolouring agent and stabiliser of the redox condition and up to 1.0 per cent CeO2 by weight is present in the glass.
4. Borosilic glass according to one of claims 1 to 3, wherein it is manufactured only with use of NaCl or KCl as refining agent, As2O3 or Sb2O3 are excluded, and if NaCl or KCl is added, the specified quantity of Cl- in the glass is set accounting for any chloride impurity in raw materials and refuse glass.
5. Borosilicate glass according to one of claims 1 to 4, wherein it has the following composition:
SiO2 76.6 to 77.7 weight %
B2O3 11.0 to 12.0 weight %
Al2O3 4.1 to 4.5 weight %
Na2O 5.1 to 5.6 weight %
K2O 0.8 to 1.2 weight %
CeO 0.0 to 0.5 weight %
ZrO2 0.8 to 1.0 weight %
Cl- 0.05 to 0.2 weight %
SiO2 76.6 to 77.7 weight %
B2O3 11.0 to 12.0 weight %
Al2O3 4.1 to 4.5 weight %
Na2O 5.1 to 5.6 weight %
K2O 0.8 to 1.2 weight %
CeO 0.0 to 0.5 weight %
ZrO2 0.8 to 1.0 weight %
Cl- 0.05 to 0.2 weight %
6. Use of the borosilicate glass according to one of claims 1 to 5 for manufacturing laboratory glass, housecraft glass, pharmaceutical receptacle glass, lamp glass, flat glass, as well as other industrial and optical high quality glass products.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE19515608.0 | 1995-04-28 | ||
| DE1995115608 DE19515608C1 (en) | 1995-04-28 | 1995-04-28 | Borosilicate glass with linear thermal expansion |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2193999A1 true CA2193999A1 (en) | 1996-10-31 |
Family
ID=7760566
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA 2193999 Abandoned CA2193999A1 (en) | 1995-04-28 | 1996-04-06 | Borosilicate glass |
Country Status (5)
| Country | Link |
|---|---|
| EP (1) | EP0767763A2 (en) |
| CA (1) | CA2193999A1 (en) |
| DE (1) | DE19515608C1 (en) |
| MX (1) | MX9700022A (en) |
| WO (1) | WO1996033954A2 (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2017014066A1 (en) * | 2015-07-17 | 2017-01-26 | 日本電気硝子株式会社 | Borosilicate glass for medical container |
| US10442723B2 (en) | 2014-12-23 | 2019-10-15 | Schott Ag | Borosilicate glass with low brittleness and high intrinsic strength, the production thereof, and the use thereof |
| US10662107B2 (en) | 2016-05-03 | 2020-05-26 | Lg Chem, Ltd. | Borosilicate glass, light guide plate comprising the same and fabricating methods thereof |
Families Citing this family (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE19913227C1 (en) * | 1999-03-23 | 2000-07-27 | Schott Glas | Borosilicate glass of specified composition is used for production of thermal cycling resistant beverage containers, especially coffee machine jugs, tea-pots and baby milk bottles |
| DE10150884A1 (en) * | 2001-10-16 | 2003-05-08 | Schott Glas | Alkali borosilicate glass used in the production of flat glass comprises oxides of silicon, boron, aluminum, sodium and potassium, and optionally calcium |
| JP2014088293A (en) * | 2012-10-31 | 2014-05-15 | Nippon Electric Glass Co Ltd | Medical glass and medical glass tube |
| DE102017102485A1 (en) | 2017-02-08 | 2018-08-09 | Schott Ag | Glasses with improved hydrolytic and alkali resistance |
| EP4444665A1 (en) * | 2021-12-06 | 2024-10-16 | Corning Incorporated | Chemically durable borosilicate glass compositions for storing pharmaceutical compositions and articles formed therefrom |
| CN114349336B (en) * | 2022-01-13 | 2022-09-27 | 浙江大学 | Low-expansion borosilicate transparent colored glaze and preparation method and application thereof |
Family Cites Families (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE3722130A1 (en) * | 1987-07-02 | 1989-01-12 | Schott Glaswerke | BOROSILICATE GLASS |
| DD301821A7 (en) * | 1990-03-23 | 1994-04-07 | Jenaer Glaswerk Gmbh | ZIRKONHALTIGES BOROSILICATE GLASS |
| DE4012288C1 (en) * | 1990-04-17 | 1991-07-18 | Schott Glaswerke, 6500 Mainz, De | |
| DE4230607C1 (en) * | 1992-09-12 | 1994-01-05 | Schott Glaswerke | Chemically and thermally highly durable, can be fused with tungsten borosilicate glass and its use |
| DE4313217C1 (en) * | 1993-04-22 | 1994-09-01 | Jenaer Schmelztechnik Jodeit G | Method and device for completely electric melting of neutral glass |
| DE4325656C2 (en) * | 1993-07-30 | 1996-08-29 | Schott Glaswerke | Use of a glass body for producing a tempered glass body suitable as a fire protection safety glass on a conventional air pretensioning system |
-
1995
- 1995-04-28 DE DE1995115608 patent/DE19515608C1/en not_active Expired - Fee Related
-
1996
- 1996-04-06 EP EP96909020A patent/EP0767763A2/en not_active Withdrawn
- 1996-04-06 MX MX9700022A patent/MX9700022A/en unknown
- 1996-04-06 CA CA 2193999 patent/CA2193999A1/en not_active Abandoned
- 1996-04-06 WO PCT/DE1996/000610 patent/WO1996033954A2/en not_active Application Discontinuation
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US10442723B2 (en) | 2014-12-23 | 2019-10-15 | Schott Ag | Borosilicate glass with low brittleness and high intrinsic strength, the production thereof, and the use thereof |
| WO2017014066A1 (en) * | 2015-07-17 | 2017-01-26 | 日本電気硝子株式会社 | Borosilicate glass for medical container |
| JPWO2017014066A1 (en) * | 2015-07-17 | 2018-04-26 | 日本電気硝子株式会社 | Borosilicate glass for pharmaceutical containers |
| US10710925B2 (en) | 2015-07-17 | 2020-07-14 | Nippon Electric Glass Co., Ltd. | Borosilicate glass for pharmaceutical container |
| US10662107B2 (en) | 2016-05-03 | 2020-05-26 | Lg Chem, Ltd. | Borosilicate glass, light guide plate comprising the same and fabricating methods thereof |
Also Published As
| Publication number | Publication date |
|---|---|
| DE19515608C1 (en) | 1996-08-08 |
| WO1996033954A2 (en) | 1996-10-31 |
| EP0767763A2 (en) | 1997-04-16 |
| WO1996033954A3 (en) | 1996-12-12 |
| MX9700022A (en) | 1997-12-31 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US7490486B2 (en) | Method for producing borosilicate glasses | |
| JP5336455B2 (en) | Boron free glass | |
| JP4454266B2 (en) | Borosilicate glass and use thereof | |
| KR100404028B1 (en) | Glass sheet for manufacturing substrates or thermally stable plates, and methods for manufacturing substrates or heat resistant window glass for emitting screens therefrom | |
| EP0822169B1 (en) | Glass composition | |
| KR100406021B1 (en) | Alkali-free glass and method for producing the same | |
| CA1078412A (en) | Low pollution glass fiber compositions | |
| JP5798195B2 (en) | Boron-free general purpose glass | |
| US6686304B1 (en) | Glass fiber composition | |
| Kim et al. | LCD waste glass as a substitute for feldspar in the porcelain sanitary ware production | |
| WO2002020419A1 (en) | Glass fiber forming compositions | |
| JPH09118541A (en) | Highly chemical-resistant and lowly viscous borosilicate glass containing zirconium oxide and lithium oxide | |
| JP2007529402A (en) | Glass strand capable of strengthening organic and / or inorganic materials | |
| CA2375719C (en) | Glass fiber composition | |
| CA2193999A1 (en) | Borosilicate glass | |
| NO178493B (en) | Process for making a glass intended for conversion into continuous or staple fibers | |
| JP4306044B2 (en) | Alkali-free glass and method for producing the same | |
| KR980001880A (en) | Water-enhanced sulfate refining process to reduce toxic emissions from glass melting furnaces | |
| AU2013213481A1 (en) | Method for producing mineral wool | |
| US11377385B2 (en) | Glass tube for metal sealing and glass for metal sealing | |
| JPH1143350A (en) | Non-alkali glass and its production | |
| CN1155876A (en) | Borosilicate glass | |
| JP3666609B2 (en) | Glass composition for electric lamp | |
| KR100699572B1 (en) | Use of sintered refractory materials based on tin oxide for producing glass furnace throats | |
| Kim et al. | Recycling of waste glass generated from end-of-life LCD devices: A feasibility study using simulated waste glass |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| EEER | Examination request | ||
| FZDE | Dead |