Durable honeycomb structures
A method for manufacturing an inorganic honeycomb structure that resists water damage after drying comprises compounding a base batch mixture including inorganic powders, a batch cross-link agent, an aqueous vehicle, and a cross-linkable batch constituent, and forming the batch mixture into a honeycomb core or skin component while reacting the cross-link agent with cross-linkable batch constituent.
1. A method for manufacturing a ceramic honeycomb structure comprising the steps of:
(a) compounding a powder batch mixture for a ceramic core or skin component for a ceramic honeycomb structure comprising at least one inorganic powder, an aqueous vehicle, at least one cross-linkable batch constituent, and at least one batch cross-link agent for the at least one cross-linkable batch constituent;
(b) forming the batch mixture into a green cellular core or skin component for a honeycomb structure, said structure being a unitary ceramic structure of honeycomb configuration,
(c) drying the green core or skin component to remove aqueous vehicle therefrom,
(d) reacting the at least one batch cross-link agent with the at least one cross-linkable batch constituent to produce a cross-linked, unfired core or skin component, and
(e) subjecting the cross-linked, unfired core or skin component to supplemental processing with an aqueous medium.
2. The method of claim 1 wherein the at least one cross-linkable batch constituent is a water-active organic compound, and wherein supplemental processing comprises contacting the core or skin component with an aqueous catalyst, washcoating or passivating solution.
3. The method of claim 1 wherein the at least one cross-linkable batch constituent is a cellulosic binder and wherein the forming step comprises forming the batch mixture into a ceramic honeycomb skin component on a unitary ceramic core structure of honeycomb configuration.
4. The method of claim 3 wherein the at least one batch cross-link agent is selected from the group consisting of formaldehyde, dialdehyde, acrylic anhydride, diisocyanate, epihalohydrin, polyamide, polyacrolein, polyimine and cyclic amide cross-linking compounds.
5. The method of claim 3 wherein the step of reacting the at least one batch cross-link agent with the at least one cross-linkable batch constituent comprises a reaction with a hydroxyl group via at least one of a condensation mechanism and a ring open mechanism.
6. The method of claim 3 wherein the step of reacting the at least one batch cross-link agent with the at least one cross-linkable batch constituent is accelerated through the application of thermal or electromagnetic energy to the honeycomb skin component.
7. The method of claim 1 wherein the powder batch mixture further comprises at least one optional batch constituent selected from the group consisting of colloidal oxide additions, inorganic reinforcing fibers, and emulsifying surfactants.
8. The method of claim 1 wherein the forming step comprises extruding batch mixture into a honeycomb core component.
9. The method of claim 1 wherein the inorganic powder is selected from the group consisting of oxides, nitrides, carbides, silicates, titanates, aluminates, and mixtures thereof.
10. The method of claim 9 wherein the inorganic powder is of a composition that sinters or reaction-sinters to a stable ceramic of silicate, aluminate, titanate, nitride or carbide structure.
11. A method for manufacturing a ceramic honeycomb structure comprising the steps of:
(a) compounding a powder batch mixture for a ceramic honeycomb component comprising at least one inorganic powder, an aqueous vehicle, at least one cross-linkable batch constituent selected from the group consisting of binders, lubricants and surfactants, and at least one batch cross-link agent for the cross-linkable batch constituent; the at least one cross-linkable batch constituent comprising a cellulosic binder and the at least one batch cross-link agent being selected from the group consisting of formaldehyde, dialdehyde, acrylic anhydride, diisocyanate, epihalohydrin, polyamides, polyacrolein, cyclic amides, and polyimines;
(b) forming the batch mixture into a green skin component on a unitary ceramic core component of honeycomb configuration;
(c) drying the green skin component to remove aqueous vehicle therefrom,
(d) reacting the at least one batch cross-link agent with the at least one cross-linkable batch constituent to produce a cross-linked, dried, unfired skin component, and
(e) subjecting the unfired skin component and core component to use as a honeycomb catalyst support, particulate filter, or heat exchanger.