An extruded porous substrate having inorganic bonds

Abstract

A method is provided for producing a highly porous substrate. More particularly, the present invention enables fibers, such as organic, inorganic, glass, ceramic, polymer, or metal fibers, to be combined with binders and additives, and extruded, to form a porous substrate. Depending on the selection of the constituents used to form an extrudable mixture, the present invention enables substrate porosities of about 60% to about 90%, and enables process advantages at other porosities, as well. The extrudable mixture may use a wide variety of fibers and additives, and is adaptable to a wide variety of operating environments and applications. Additives can be selected that form inorganic bonds between overlapping fibers in the extruded substrate that provide enhanced strength and performance of the porous substrate in a variety of applications, such as, for example, filtration and as a host for catalytic processes, such as catalytic converters.

Description

technical field [0001] The present invention relates generally to extrusion processes for extruding porous substrates, and in one implementation, to extrusion processes for extruding porous ceramic substrates. Background technique [0002] Many processes require a rigid substrate to assist and support the various processes. For example, substrates are used in filtration applications to filter particulate matter, separate different substances, or remove airborne bacteria or microorganisms. These substrates can be configured to operate in air, exhaust gas or liquid waste, and can be fabricated to withstand greater environmental or chemical stress. In another example, catalytic materials are deposited on a substrate to facilitate chemical reactions. For example, noble metals can be deposited on suitable substrates, which can then catalyze the conversion of hazardous exhaust gases into less toxic gases. In general, these rigid substrates operate more efficiently when they hav...

AI Technical Summary

Problems solved by technology

However, in situ growth of these crystals requires careful and accurate control of the solidification process, making the process difficult to scale, relatively expensive and prone to rejects

Furthermore, this difficult process only improves porosity by a few percent

Finally, the process can only grow mullite-type whiskers, which limits the scope of the substrate

For example, mullite is known to have a large coefficient of thermal expansion, which makes mullite whiskers undesirable in a variety of applications that require a wide range of operating temperature bands and transition processes with sudden temperature changes

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