Design and Durability of Standard and Advanced Ceramic Substrates

The stringent emissions regulations in North America, Europe and Japan have necessitated the development of advanced ceramic substrates*. This paper focuses on the design and durability of advanced ceramic substrates which promote fast light-off, improve conversion efficiency, reduce back pressure and meet physical durability requirements. The advances in ceramic substrates are made possible through judicious choice of cell shape and size, wall porosity and microstructure of parent material, namely cordierite. The paper compares the attributes of both square and nonsquare cell geometries for a given cell density and wall thickness which helps select the optimum cell structure. Following a brief review of design process for selecting the optimum cell shape and size from performance point of view, the paper addresses mechanical and thermal durability of advanced ceramic substrates which call for certain trade-offs. The paper shows that, on balance, the square cell offers the best compromise from the point of view of manufacturability, coatability and physical durability. It concludes with recent examples of successful application of advanced ceramic substrates.