Compositions: ceramic – Ceramic compositions – Glass compositions – compositions containing glass other than...
Patent
1985-06-07
1987-03-10
McCarthy, Helen M.
Compositions: ceramic
Ceramic compositions
Glass compositions, compositions containing glass other than...
204420, 204421, 501 49, C03C 323
Patent
active
046491260
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to halide-containing glass and, more specifically, it relates to glasses with anionic conductivity for fluorine.
DESCRIPTION OF PRIOR ART
The majority of halide-containing glasses developed hitherto for processes of electric current transfer are characterized by the presence of anions, in particular fluorine ions, and contain, as the glass-forming agent, phosphoric anhydride (P.sub.2 O.sub.5). Their basic disadvantage resides in the complexity of the glass melting process conditions which requires the use of special crucibles, e.g. made from vitreous carbon and creating a strictly controlled melting atmosphere, e.g. atmosphere of dried argon with the content of oxygen of not more than 0.003% when melting in vitreous carbon crucibles. The melting process can be carried out in platinum crucibles as well, but the latter are destroyed after 2-5 melting cycles.
It is somewhat easier to produce halide-containing glasses in systems containing, as the glass-forming agents, SiO.sub.2 and B.sub.2 O.sub.3. Thus, the synthesis of sodium-boron silicate and sodium borate halide-containing glasses necessitates the use of crucibles of transparent quartz in the atmosphere of nitrogen (gauge pressure 0.3-0.5 atm) or platinum vessels respectively. However, in these systems the predominantly anionic conductivity cannot be ensured due to the presence of alkali ions and high volatility of halogen ions.
Known in the art is alkali-free lead-containing glass incorporating, as the glass-forming oxide, SiO.sub.2 which features anionic conductivity for fluorine.
However, this composition has high values of thermal expansion (about 200.times.10.sup.-7 .degree. C..sup.-1) which hinders the glass manufacture owing to a high cracking liability of articles during solidification of the melt.
Finally, known in the art are compositions of glasses with anionic conductivity for fluorine, containing PbO, F and, as the glass-forming agent, SiO.sub.2. These compositions are melted in corundum crucibles following the conventional process in the glass-making industry.
The compositions contain, percent by mass:
They feature good melting properties (melting temperature 750.degree. to 850.degree. C.) and do not crack during solidification of the glass mass, since they have a heat expansion coefficient not exceeding 150.times.10.sup.-7 .degree. C..sup.-1). However, variation of volume resistivity of these types of glass by two orders of magnitude simultaneously causes variation of the thermal expansion by 40.times.10.sup.-7 .degree. C..sup.-1, thus making impossible the production of matched junctions as a result of their sintering, which hinders, in particular, the manufacture of electric signal dividers with sintered glass blocks.
DESCRIPTION OF THE INVENTION
The present invention is directed to glasses with anionic conductivity for fluorine, which have such a composition that ensures, upon variation of volume resistivity by two orders of magnitude, a difference in the value of the thermal expansion not more than 5.times.10.sup.-7 .degree. C..sup.-1.
The object of the present invention is accomplished by providing a glass with anionic conduction for fluorine containing PbO, F and a glass-forming agent. As the glass-forming agent boron oxide is used (B.sub.2 O.sub.3), with the following proportions of the components, percent by mass:
The advantage of the compositions according to the present invention resides in variation of the value of the heat expansion coefficient by not more than 5.times.10.sup.-7 .degree. C..sup.-1 upon variation of the volume resistivity by two orders of magnitude.
PREFERRED EMBODIMENTS
The compositions according to the present invention with anionic conduction for fluorine feature constant (within the range of 5.times.10.sup.-7 .degree. C..sup.-1) values of the thermal expansion upon variation of the volume electric resistivity by two orders of magnitude; they contain, percent by mass:
Deviation from the above-specified limits of the content of the components resul
REFERENCES:
patent: 2530217 (1950-11-01), Bain
Hagenmuller, P., Solid Electrolytes (1978), Academic Press, NYC, pp. 279-280 and 324-325, 327.
Bakuradze Georgy V.
Evstropiev, deceased Konstantin K.
Gaprindashvili Khanzerifa I.
Kekelia Dzhemal I.
Kogan Vadim E.
Institut Kibernetiki Akademii Nauk Gruzinskoi SSR
McCarthy Helen M.
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