초록 ▼

Strong, high-surface-area honeycombs of alumina or other ceramic composition are provided by compounding and shaping a moldable ceramic powder extrusion batches including a cellulosic temporary binder and a high-surface-area boehmite precursor for a permanent binder, hydrating the shaped honeycomb t

Strong, high-surface-area honeycombs of alumina or other ceramic composition are provided by compounding and shaping a moldable ceramic powder extrusion batches including a cellulosic temporary binder and a high-surface-area boehmite precursor for a permanent binder, hydrating the shaped honeycomb to develop a boehmite binding phase, and calcining the hydrated body to develop the binder and provide a ceramic honeycomb of high strength and porosity.

대표청구항 ▼

1. A method for making a ceramic honeycomb comprising the steps of: compounding a moldable ceramic powder extrusion batch comprising a ceramic powder, water, and a cellulosic temporary binder, the ceramic powder including at least one high-surface-area boehmite precursor; forming the batch into

1. A method for making a ceramic honeycomb comprising the steps of: compounding a moldable ceramic powder extrusion batch comprising a ceramic powder, water, and a cellulosic temporary binder, the ceramic powder including at least one high-surface-area boehmite precursor; forming the batch into a water-containing green honeycomb preform; heating the water-containing green honeycomb preform under moisture-retaining conditions at a temperature and for a time at least sufficient to develop a boehmite binding phase in situ in the green honeycomb preform; and drying and calcining the green honeycomb preform. 2. A method in accordance with claim 1 wherein the honeycomb has a composition consisting essentially of oxides and mixtures of oxides selected from the group consisting of silica, alumina, zirconia, titania, transition metal oxides, alkaline earth oxides, and rare earth oxides. 3. A method in accordance with claim 1 wherein the honeycomb has a composition consisting essentially of one or a combination of oxide compounds selected from the group consisting of cordierite, mullite, β-eucryptite, calcium aluminate and aluminum titanate. 4. A method in accordance with claim 1 wherein the honeycomb has a composition including at least about 50% alumina by weight. 5. A method in accordance with claim 1 wherein the boehmite precursor is a transition alumina containing less than 8% of structural water by weight. 6. A method in accordance with claim 1 wherein the boehmite precursor is a transition alumina powder having a median particle size below 20 μm. 7. A method in accordance with claim 1 wherein the boehmite precursor is a high-surface-area transition alumina selected from the group consisting of γ-, η-, δ-, χ-, θ-, ρ-, and κ-aluminas. 8. A method in accordance with claim 1 wherein the boehmite precursor is selected from the group consisting of γ-alumina and ρ-alumina. 9. A method in accordance with claim 1 wherein the boehmite precursor consists essentially of a γ-alumina powder having a median particle size not exceeding 5 μm. 10. A method in accordance with claim 1 wherein the step of forming the green honeycomb is carried out by extrusion. 11. A method in accordance with claim 1 wherein the heating step is carried out at a temperature in the range of 50-100° C. for a time in the range of 1-200 hours. 12. A method in accordance with claim 1 wherein the heating step is accompanied by slow drying of the green honeycomb. 13. A method in accordance with claim 1 wherein the cellulosic temporary binder is an ionic or non-ionic cellulose ether. 14. A method in accordance with claim 1 wherein the cellulosic temporary binder is selected from the group consisting of methylcellulose, hydroxypropyl methylcellulose, hydroxyethylcellulose, hydroxypropylcellulose, methylhydroxyethyl and methylhydroxypropyl cellulose ethers.