Abstract: To prevent the deterioration of catalyst or the damage of a particulate filter caused by the rapid temperature rise of the particulate filter when the abrupt deceleration of an engine occurs, and avoid the deterioration of fuel consumption by depositing a large PM in the particulate filter and regenerating the same at once. A heat-absorbing area 4 is provided by forming a deeply clogged structure at the exhaust gas flowing-out side end of the particular filter 1 disposed in an exhaust pipe 2 of an internal combustion engine E. As the heat-absorbing area has a heat capacity larger than that in the other portions, the combustion heat is absorbed and dispersed even if the rapid chain reaction of PM combustion occurs, whereby it is possible to suppress the temperature rise of the downstream portion of the particulate filter liable to be high in temperature.

Abstract: To prevent the deterioration of catalyst or the damage of a particulate filter caused by the rapid temperature rise of the particulate filter when the abrupt deceleration of an engine occurs, and avoid the deterioration of fuel consumption by depositing a large PM in the particulate filter and regenerating the same at once. A heat-absorbing area 4 is provided by forming a deeply clogged structure at the exhaust gas flowing-out side end of the particular filter 1 disposed in an exhaust pipe 2 of an internal combustion engine E. As the heat-absorbing area has a heat capacity larger than that in the other portions, the combustion heat is absorbed and dispersed even if the rapid chain reaction of PM combustion occurs, whereby it is possible to suppress the temperature rise of the downstream portion of the particulate filter liable to be high in temperature.

Abstract: A cordierite honeycomb body is produced by forming a cordierite material including kaoline into a honeycomb shape and sintering it. The kaoline included in the cordierite material is at least partly composed of kaolinite having a Hinckley crystallinity index of 0.5 or more thereby having a less amorphous phase portion in a kaolinite particle. Therefore, when the cordierite material is sintered, the number of micropores generated in the cordierite is decreased due to the less amorphous phase portion in the kaolinite particles. As a result, density of the cordierite is increased without increasing a C.T.E. thereof. Thus, the cordierite honeycomb body has sufficient strength even when thickness of a cell wall thereof is decreased.

Abstract: A cordierite honeycomb structure having a coefficient of thermal conductivity of not less than 0.035 J/cm..degree.K.sec, a porosity of not more than 16%, and a coefficient of thermal expansion of not more than 1.0.times.10.sup.-6 /.degree.C. at 40 to 800.degree.0 C. is described. A process for producing a cordierite honeycomb structures, involves at least the steps of: mixing powders of kaolin, talc, and other starting materials for cordierite together so as to provide a chemical composition of cordierite; extruding the mixture; and firing the extrudate, wherein the kaolin has an average particle diameter of not more than 5 .mu.m and such a particle size distribution that the proportion of particles with diameters of less than 1 .mu.m is 10% by weight and the talc has an average particle diameter of not more than 10 .mu.m and such a particle size distribution that the proportion of particles with diameters of less than 1 .mu.m is not more than 5%.

Abstract: There are provided thin-walled honeycomb structural bodies with high strength and excellent thermal shock resistance by using as the starting material for cordierite honeycomb structural bodies a combination of talc with a median particle diameter exceeding 7 .mu.m and not greater than 20 .mu.m and with a CaO content of 0.2 wt % or less and another cordierite material such as kaolin with a median particle diameter of not greater than 1 .mu.m, molding the starting material into a honeycomb shape with a cell wall thickness of 130 .mu.m or less, and firing the mold.

Abstract: A cordierite honeycomb structure having a coefficient of thermal conductivity of not less than 0.035 J/cm.multidot..degree.K..multidot.sec, a porosity of not more than 16%, and a coefficient of thermal expansion of not more than 1.0.times.10.sup.-6 /.degree.C. at 40.degree. to 800.degree. C. A process for producing a cordierite honeycomb structures, involves at least the steps of: mixing powders of kaolin, talc, and other starting materials for cordierite together so as to provide a chemical composition of cordierite; and extruding the mixture; and firing the extrudate, wherein the kaolin has an average particle diameter of not more than 5 .mu.m and such a particle size distribution that the proportion of particles with diameters of less than 1 .mu.m is 10% by weight and the talc has an average particle diameter of not more than 10 .mu.m and such a particle size distribution that the proportion of particles with diameters of less than 1 .mu.m is not more than 5%.

Abstract: A method for cutting an extruding honeycomb structure by a jet of high pressure water. The jet is controlled in position to assure a smooth, straight cut perpendicular to the extruding direction.