Abstract: Disclosed is an improved extrusion apparatus which prevents the distortion of peripheral cells in extruded honeycomb structures. The apparatus includes a die having an outward surface which is beveled to have a primary face and a surrounding face converging in the extrusion direction. An extrusion mask is provided having a central orifice and an entrance face also converging at the same angle in the extrusion direction. The use of an extrusion mask having an entrance face converging at the same angle as the beveled surface of the die body has been found to reduce peripheral cell crushing. Moreover, also disclosed are spacers situated between the die body and the mask which control the thickness of the gap between the die body and mask thus allowing for the provision of extruded honeycomb structures having skins of varying thickness.

Abstract: Honeycomb structures of brittle material having a plurality of cells extending longitudinally therethrough. When viewed in a plane perpendicular to a longitudinal axis through the structure, the plurality of cells extend thereacross and, with the exception of peripheral cells, are all of uniform size and shape. The shape is a rectangle whose length is twice its width. The cells are contiguously arranged in a repeating pattern that provides a "flexible" rectangle cellular structure wherein wall portions and joints formed by intersecting wall portions are movable to compensate for expansion/contraction stresses or forces thermally induced within the cellular structure, thereby tolerating significant strains without breaking the structure.

Abstract: Cracking of large monolithic cordierite segments and in particular monolithic honeycombed substrates having a matrix of thin walls forming a multiplicity of open ended cells extending from one end of the substrate to the other end is reduced or eliminated by limiting the amount of raw clay used in formulating the clay-talc-alumina raw material batch. The raw clay may be eliminated entirely but is preferably at least 10% of the whole batch and not more than 31% of the whole batch with the balance of the clay constituent to the raw material batch being calcined clay. The raw material batch is preferably formulated to yield at least 90% cordierite phase upon reaction during sintering.