Abstract: A method for producing a thermally shock resistant washcoated substrate involves introducing a buffer solution into the microcracks, and optionally the micropores of a porous sintered body, the pH of the buffer solution being at a predetermined value to result in the formation of a gel on contact of the buffer solution with the slurry which is to be subsequently applied, contacting the body with a washcoating slurry to form a gel at the interface of the buffer solution and slurry. Formation of the gel prevents the slurry from entering the microcracks. The body is then calcined at a temperature and for a time sufficient to form the washcoated substrate.

Abstract: A porous catalyst support which may be used in a catalytic converter for treating automotive exhaust gases. The support comprises a substrate having a multichannel structure of generally thin walls and washcoat particles of colloidal particle size mainly or wholly within the pores of the walls so as to increase open frontal area and reduce back pressure. Substrate is either ceramic or metal. In a ceramic substrate with microcracks in the walls, the washcoat colloidal dispersion is free of soluble inorganic constituents and the particles do not fill the microcracks so as to prevent undesirable increase in thermal expansion and corresponding decrease in thermal shock resistance.