Alkali resistant glass compositions
First Claim
1. An alkali resistant glass, comprising:
- a silicate based glass body;
a passivity layer formed on an exterior surface of the silicate based glass body, wherein the passivity layer has a composition that is different than the composition of the glass body, said passivity layer comprises a substance that is native to the silicate based glass body, wherein the substance in combination with other substances in the passivity layer results in the passivity layer being substantially chemically inert in an alkaline environment.
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Abstract
An alkali resistant glass composition having improved durability to withstand highly alkali environments at elevated temperatures, such as curing of cementitious products in an autoclave, is conveniently formed from economical and abundant materials. The glass composition includes increased levels of calcium and iron, and relatively low levels of alkali metals, as compared to many other alkali resistant glass products, and comprises essentially of, by weight, >35% Si2O3, 1-25% CaO, 1-15% Fe2O3, 1-10% R2O, and an amount of Al2O3 such that the ratio of Si2O3:Al2O3 is greater than or equal to 1. Alkali resistance can be improved by forming a passivity layer on the surface of glass articles by treating the articles hydrothermally in a basic environment. Optionally zirconia and/or titania may be added to the composition to further improve alkali resistance.
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Citations
33 Claims
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1. An alkali resistant glass, comprising:
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a silicate based glass body;
a passivity layer formed on an exterior surface of the silicate based glass body, wherein the passivity layer has a composition that is different than the composition of the glass body, said passivity layer comprises a substance that is native to the silicate based glass body, wherein the substance in combination with other substances in the passivity layer results in the passivity layer being substantially chemically inert in an alkaline environment. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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- 8. An alkali resistant glass, which consists essentially of, by weight percent:
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21. A method of increasing the alkali resistance properties of glass, comprising:
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providing a glass article consisting essentially of, by weight percent;
SiO2
>
35%,CaO 1-25%, Fe2O3 1-15%, R2O 1-10%, wherein R is selected from the group consisting of Na, K, and Li; and
treating the glass articles by exposing the glass articles to a basic environment to form a passivity layer over the surface of the glass articles thereby improving the alkali resistance of the glass articles. - View Dependent Claims (22, 23, 24)
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25. A synthetic microsphere, comprising:
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a synthetic, hollow, substantially spherical wall, the wall having an inner surface and an outer surface and a thickness therebetween; and
a passivity layer on the outer surface of the spherical wall. - View Dependent Claims (26, 27, 28, 29, 30)
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31. A cementitious composite article comprising:
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a cementitious material;
a glass additive material, the glass comprising, by weight percent;
SiO2
>
35%CaO 1-25% Fe2O3 1-15% R2O 1-10%, and an amount of Al2O3 such that SiO2;
Al2O3≧
1. - View Dependent Claims (32, 33)
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Specification