Verfahren zur Verbesserung der Temperaturwechselbeständigkeit eines Überzugkörpers

摘要

Prepn. of a thermally shock resistant wash coated substrate comprises: (a) introducing a buffer soln. (I) into the microcracks and opt. into the pores of a porous sintered body having microcracks and pores of less than 5~m dia.; then (b) contacting the body with a washcoating slurry (II) comprising an oxide of no less than 50 m2/g or a precursor and a gel-forming agent to form a gel at the interface of (I) and (II) to prevent the slurry entering the microcracks; and (c) calcining the treated body at a temp. and for a time sufficient to form a wash coated substrate. (I) and (II) are at pH's which form a gel on contact.