Designed Experiment to Evaluate the Canning Strength of Various High Cell Density / Ultra Thin Wall Ceramic Monoliths 2001-01-3663
High cell density (HCD) (≥ 600 cpsi) and /or ultra thin wall (UTW) (≤ 4 mil) extruded ceramic monolith substrates are being used in many new automotive catalyst applications because they offer (1) increased geometric surface area, (2) lower thermal mass, (3) increased open frontal area and (4) higher heat and mass transfer rates. Delphi has shown in previous papers how to use the effectiveness, NTU theory, to optimize the various benefits of these HCD / UTW catalysts.
A primary disadvantage of these low solid fraction substrates is their reduced structural strength, as measured by a 3-D hydrostatic (isostatic) test. The weakest of these new substrates is only 10 to 20% as strong as standard 400 × 6.5 substrates. Improved converter assembly methods with lower, more uniform forces will likely be required to successfully assemble converters with such weak substrates in production.
To investigate this issue, Delphi arranged with NGK, Corning and ASEC to undertake a cooperative study based on a designed experiment using robust engineering principles. Nominally 400 × 3.5, 600 × 3.5, 900 × 2.5, and 1200 × 2.5 substrates were washcoated with high and low loadings of a ceria- or a non-ceria-containing washcoat. The bricks were tested to destruction using either a stuffing apparatus or a tourniquet apparatus using Tekscan film to measure failure pressures and their uniformity. This initial report describes the sample details and the preliminary results from the twenty-eight stuffed parts.