Process for manufacturing a component for a catalytic converter
In a process for manufacturing a catalytic converter component, a ceramic unit is used that has been prepared by extruding green ceramic product through a die to form an extrusion having a honeycomb substrate structure in which tubular passages extend along the extrusion, the passages bounded by walls dividing adjacent passages from one another. The unit is obtained by cutting off a length of the extrusion and curing and firing it. The process further comprises flowing insulation material from one end of the unit into selected ones of the elongate passages, the insulating material then being cured. The passages are selected so that the cured insulation material forms an internal thermal insulating barrier between a core zone and a radially outer zone of the unit. Passages in the inner and outer zones are free of insulation material and the honeycomb structure walls include walls crossing the insulating barrier.
1. A process for manufacturing a component for a catalytic converter, comprising taking a ceramic unit prepared by extruding green ceramic product through a die to form an extrusion having a honeycomb substrate structure having a regular array of parallel, linear tubular passages extending along the length of the extrusion, the passages bounded by walls dividing adjacent passages from one another, the ceramic unit being obtained by cutting off a length of the extrusion and curing and firing the cut off length of extrusion, the process further comprising, following the firing, injecting low viscosity insulation material from an end of the ceramic unit into selected ones of the elongate passages so as to block the selected passages over at least a part of the lengths thereof while maintaining all of the walls of the ceramic unit, and curing the injected insulation material to form a thermally insulating barrier, extending over at least a part of the length of the ceramic unit and extending continuously around a central axis of the ceramic unit between a radially inner zone and a radially outer zone thereof, wherein, passages in the inner and outer zones are free of such insulation material, wherein the maintained walls include walls crossing the insulating barrier, and wherein the insulation material in at least some of the passages is injected from said one end to fill the selected passages to the other end of the ceramic unit.
2. The process as claimed in claim 1 , wherein the injected insulation material includes components of glass fibres, ceramic slurry and polymer binder.
3. The process as claimed in claim 2 , wherein the insulation material is in the form of a low viscosity paste which is injected into the selected passages, the insulation material further including water.
4. The process as claimed in claim 1 , wherein the curing of the insulation material is effected by microwave irradiation.
5. The process as claimed in claim 4 , wherein the curing is such as to have microwave radiation penetrate from both sides of the insulating barrier.
6. The process as claimed in claim 1 , further comprising using a gasket layer on an input end of the ceramic unit, the gasket layer having a first aperture shaped and positioned to limit incursion of the insulation material into passages other than the selected passages.
7. The process as claimed in claim 6 , further comprising incrementally relatively moving the die and the ceramic unit to optimize registration of the annular aperture to entrance openings of the selected passages.
8. The process as claimed in claim 1 , wherein, following curing, at least a part of the cured insulation material is a matrix of silica.
9. A process for manufacturing a component for a catalytic converter, comprising taking a ceramic unit prepared by extruding green ceramic product through a die to form an extrusion having a honeycomb substrate structure having a regular array of parallel, linear tubular passages extending along the length of the extrusion, the passages bounded by walls dividing adjacent passages from one another, the ceramic unit being obtained by cutting off a length of the extrusion and curing and firing the length of extrusion, the process further comprising, following the firing, injecting a low viscosity material from an end of the ceramic unit into selected ones of the elongate passages so as to block the selected passages over at least a part of the lengths thereof while maintaining all of the walls of the ceramic unit, and curing the injected material, wherein the material has a viscosity that would enable the material to flow 6 inches length along one of the selected passages at an injection pressure of the order of 650 psi.
10. The process as claimed in claim 9 , further comprising using a gasket layer on an input end of the ceramic unit, the gasket layer having a first aperture shaped and positioned to limit incursion of the material into passages other than the selected passages.
11. The process as claimed in claim 9 , wherein through a combination of surface tension, viscosity, adhesion properties of the material, and porosity and surface roughness properties of the ceramic unit, the material does not flow out of the passages into which it is injected before curing.