Method of making composite borosilicate glass articles
First Claim
1. A method for producing a glass article which comprises melting a composition in the phase separable regions of the alkali-borosilicate or alkali-boro-germania-silicate systems and forming a preshaped glass article, inducing the preshaped article to phase separate into a silica-rich phase and a silica-poor phase by heat-treating it at 480°
- C. to 550°
C. for 0.5 to 200 hours, leaching out the silica-poor phase only from the surface layers of the article so as to form a structure having porous surface layers surrounding an unleached region of substantially the original glass composition, washing this structure with an organic media which contains less than 50% by weight water to dissolve and remove oxides of boron and other leaching reaction products without substantially attacking the silica-poor phase which remains in the structure, said organic media including a member selected from the group consisting of lower aliphatic alcohols containing from one to five carbon atoms, acetone, or mixtures thereof, drying and heating the washed glass article to collapse the outer porous surface layers to form a glass having a silica-rich surface layer surrounding said unleached region of substantially the original glass composition.
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Abstract
A method for producing a glass article which comprises melting and forming a preshaped glass article having a composition in the phase separable regions of the alkali-boro-silicate or alkali-boro-germania-silicate systems, inducing the article to phase separate, leaching out a silica-poor phase from the surface layers only to form a structure having porous surface layers surrounding a solid region of substantially the original glass composition, washing this structure with an organic media which dissolves oxides of boron and other leaching reaction products, drying and heating to collapse the outer porous structure to form a glass having a silica-rich surface layer surrounding a solid region having substantially the original glass composition.
48 Citations
13 Claims
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1. A method for producing a glass article which comprises melting a composition in the phase separable regions of the alkali-borosilicate or alkali-boro-germania-silicate systems and forming a preshaped glass article, inducing the preshaped article to phase separate into a silica-rich phase and a silica-poor phase by heat-treating it at 480°
- C. to 550°
C. for 0.5 to 200 hours, leaching out the silica-poor phase only from the surface layers of the article so as to form a structure having porous surface layers surrounding an unleached region of substantially the original glass composition, washing this structure with an organic media which contains less than 50% by weight water to dissolve and remove oxides of boron and other leaching reaction products without substantially attacking the silica-poor phase which remains in the structure, said organic media including a member selected from the group consisting of lower aliphatic alcohols containing from one to five carbon atoms, acetone, or mixtures thereof, drying and heating the washed glass article to collapse the outer porous surface layers to form a glass having a silica-rich surface layer surrounding said unleached region of substantially the original glass composition. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
- C. to 550°
Specification
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- Resources
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Current AssigneeDe Macedo; Pedro Buarque, Theodore A. Litovitz
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Original AssigneeDe Macedo; Pedro Buarque, Theodore A. Litovitz
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InventorsGupta, Prabhat K., de Macedo, Pedro B., Drexhage, Martin G.
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Primary Examiner(s)Schor, Kenneth M.
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Application NumberUS06/008,158Time in Patent Office713 DaysField of Search65/31, 65/60 R, 65/30 R, 65/111, 65/60 D, 65/117, 65/60 B, 428/428, 428/427, 427/309, 156/663, 106/52, 106/54US Class Current65/31CPC Class CodesC03C 23/008 comprising a lixiviation stepC03C 3/089 containing boronC03C 3/091 containing aluminium
