Sol-gel process using porous mold
AssigneeYazaki Corporation
InventorsRahul Ganguli, Fikret Kirkbir, Douglas Meyers
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Abstract
A sol-gel process for producing dry porous gel monoliths, e.g., silica glass monoliths, in which the successive process steps of gelling, aging and drying all occur within a mold formed of a porous material, e.g., graphite. The mold is inert to the gel solution and it has sufficient strength to withstand the temperatures and pressures encountered during the process, yet it has sufficient porosity to facilitate the escape of liquid from the gel pores directly through the mold, itself. The mold and gel thereby can remain within a sealed autoclave during these process steps, and mechanical handling of the mold and the gel are minimized. This substantially enhances the process' efficiency. Alternatively, the mold can have a non-porous inner skin.
Claims31
A process for producing a dry, porous, silica gel monolith comprising the steps of:
- placing a solution into a mold formed of a porous material that is inert to the solution and that is formed principally of a material selected from the group consisting of graphite, carbides and mixtures thereof, wherein the solution consists essentially of the following components, in prescribed relative proportions
- tetraethyl orthosilicate or tetramethyl orthosilicate,
- an alcohol,
- deionized water, and
- an acid catalyst and/or a base catalyst;
- allowing the solution to gel within the mold;
- drying the gel within the mold;
- and
- removing the dried gel from the mold to produce a dry, porous, silica gel monolith.
A process for producing a monolithic article of high-purity silica, comprising the steps of:
- mixing an alkoxide solution that consists essentially of the following components, in prescribed relative proportions
- tetraethyl orthosilicate or tetramethyl orthosilicate,
- an alcohol,
- deionized water, and
- an acid catalyst and/or a base catalyst;
- placing the alkoxide solution into a mold formed of a porous graphite material having a porosity in the range of about 10 to 15% and having a substantially uniform thickness in the range of 3 to 5 mm;
- allowing the alkoxide solution to gel within the porous graphite mold;
- aging the gel within the porous graphite mold;
- drying the gel within the porous graphite mold;
- removing the dried gel from the porous graphite mold;
- and
- sintering the dried gel to produce a monolithic article of high-purity silica glass.
A process for producing a dry, porous, silica gel monolith comprising the steps of:
- placing a solution into a mold formed of a material that is inert to the solution and that is formed principally of a material selected from the group consisting of graphite, carbides, and mixtures thereof, wherein the mold has a porous body and a non-porous inner skin, and wherein the solution used in the step of placing consists essentially of the following components, in prescribed relative proportions
- tetraethyl orthosilicate or tetramethyl orthosilicate,
- an alcohol,
- deionized water, and
- an acid catalyst and/or a base catalyst;
- allowing the solution to gel within the mold;
- drying the gel within the mold;
- and
- removing the dried gel from the mold to produce a dry, porous, silica gel monolith.
Dependencies are inferred from the claim text.