Method of fabricating a multiple flow path body

An improved method of fabricating a multiple flow path body having a plurality of contiguous flow paths extending therethrough for separate fluid flow, from an extruded ceramic honeycombed body having a matrix of thin walls defining a multiplicity of open-ended cells extending from one face end thereof to another face end thereof and being bounded on sides generally parallel to cell axes by generally opposed upper and lower boundary surfaces connected by first and second side boundary surfaces, the cells being grouped into a plurality of columns of cells, each column being separated from adjacent columns of cells by a fluid barrier wall surface consisting of the thin cell walls which extend continuously from the upper boundary surface to the lower boundary surface and from the one face end of the honeycombed body to the other face end thereof, wherein the improvement comprises:

• a. filling the open-ended cells on both face ends of the honeycombed body to a predetermined depth from each face end with a heatsoftened thermoplastic resist material,
• b. cooling the resist material below its softening termperature,
• c. forming channels of a predetermined depth in selected columns of cells from both face ends of the honeycombed body and removing substantially all of the resist material from selected columns of cells by cutting portions of cell walls and portions of at least one of the upper boundary surface and the lower boundary surface, all between adjacent fluid barrier wall surfaces in the selected columns of cells,
• d. applying a ceramic cement to the channels and transforming the channels in the selected columns of cells into conduits having at least one open-end by filling the channels from face ends with the ceramic cement to a depth less than the depth of the channels and
• e. heating the honeycombed body to temperatures at which the resist material is removed and the ceramic cement is sintered.

An improved method of fabricating a multiple flow path body having a plurality of contiguous flow paths extending therethrough for separate fluid flow, from a honeycombed body having a matrix of thin walls defining a multiplicity of open-ended cells extending from one face end thereof to anoher face end thereof and being bounded on sides generally parallel to cell axes by generally opposed upper and lower boundary surfaces connected by first and second side boundary surfaces, the cells being grouped into a plurality of columns of cells, each column being seperated from adjacent columns of cells by a fluid barrier wall surface extending continuously from the upper boundary surface to the lower boundary surface and from the one face end of the honeycombed body to the other face end thereof, wherein the improvement comprises

• a. forming channels of a predetermined depth in selected columns of cells from both face ends of the honeycombed body by removing portions of the cell walls and portions of at least one of the upper boundary surface and the lower boundary surface, all between adjacent fluid barrier wall surfaces in the selected columns of cells, thereafter
• b. sealing the open-ended cells in unselected columns of cells and enclosing the channels on both face ends of the honeycombed body with a resist material which enters the cells and channels to a predetermined depth,
• c. selectively removing the resist material from the channels in the selected column of cells, d. stiffening the remaining resist material in unselected columns of cells,
• e. applying a final sealant material to the channels and transforming the channels in the selected columns of cells into conduits having at least one open-end by filling the channels from face ends with the final sealant material to a depth less than the depth of the channels, and
• f. removing the remaining resist material.

An improved method of fabricating a multiple flow path body having a plurality of contiguous flow paths extending therethrough of separate fluid flow, from a honeycombed body having a matrix of thin walls defining a multiplicity of open-ended cells extending from one face end thereof to another face end thereof an being bounded on sides generally parallel to cell axes by generally opposed upper and lower boundary surfaces connected by first and second side boundary surfaces, the cells being grouped into a plurality of columns of cells, each cell column being separated from adjacent columns of cells by a fluid barrier wall surface extending continuously from the upper boundary surface to the lower boundary surface and from the one face end of the honeycombed body to the other face end thereof, and each column being designated a member of a first group or a second group of cell columns, wherein the improvement comprises

• a. sealing the open-ended cells on both face ends of the honecombed body with a resist material which enters the cells to a predetermined depth, and thereafter becomes removably stiff,
• b. forming channels of a predetermined depth in the cell columns of at least one of the first and second groups of cell columns from the one face end of the honeycombed body by removing portions of the cell walls and portions of at least one of the upper boundary surface and the lower boundary surface, all between adjacent fluid barrier wall surfaces in the columns of cells near the one face end,
• c. forming channels of a predetermined depth in the cell columns of at least one of the first and second groups of cell columns from the other face end of the honeycombed body by removing portions of the cell walls and portions of at least one of the upper boundary surface and the lower boundary surface, all between adjacent fluid barrier wall surfaces in the columns of cells near the other face end,
• d. applying a final sealant material to the channels and transforming the channels in the columns of cells into conduits having at least one open-end by filling the channels from both face ends with the final sealant material to a depth less than the depth of the channels, and
• removing the remaining resist material.