Exhaust gas treatment device and method for making the same

A method for making a mounting mat structure comprising:nproviding inorganic fibers;heat treating said inorganic fibers wherein heat treating comprises heating the leached glass fibers at a temperature of at least about 300° C. or at least about 900° C. for an effective period of time to provide a minimum holding pressure for holding the fragile structure within the housing of one of (i) at least 50 kPa after 1000 cycles of testing at a hot face temperature of 300° C., a gap bulk density of between 0.3 and 0.5 g/cm3, and a percent gap expansion of 2 percent, and (ii) at least 10 kPa after 1000 cycles of testing at a hot face temperature of 900° C., a gap bulk density of between 0.3 and 0.5 g/cm3, and a percent gap expansion of 5 percent;applying a holding pressure performance increasing surface treatment comprising an inorganic particulate material to at least a portion of the exterior surfaces of at least a portion of the inorganic fibers; andincorporating the surface treated inorganic fibers into a mat structure for holding a fragile catalyst support structure within the housing of an exhaust gas treatment device, wherein the holding pressure performance of the mounting mat containing the surface treated inorganic fibers is greater than a mounting mat containing the same inorganic fibers without the surface treatment.

A method for making a mounting mat structure comprising:nproviding leached glass fibers containing at least 67 weight percent silica;heat treating the leached glass fibers at a temperature of at least about 300° C. or at least about 900° C. for an effective period of time to provide a minimum holding pressure for holding the fragile structure within the housing of one of (i) at least 50 kPa after 1000 cycles of testing at a hot face temperature of 300° C., a gap bulk density of between 0.3 and 0.5 g/cm3, and a percent gap expansion of 2 percent, and (ii) at least 10 kPa after 1000 cycles of testing at a hot face temperature of 900° C., a gap bulk density of between 0.3 and 0.5 g/cm3, and a percent gap expansion of 5 percent:applying a holding pressure performance increasing surface treatment to at least a portion of the exterior surfaces of at least a portion of the inorganic fibers; andincorporating the surface treated inorganic fibers into a mat structure for holding a fragile catalyst support structure within the housing of an exhaust gas treatment device, wherein the holding pressure performance of the mounting mat containing the surface treated inorganic fibers is greater than a mounting mat containing the same inorganic fibers without the surface treatment.

A method for making a mounting mat structure comprising:nproviding inorganic fibers;heat treating said inorganic fibers at a temperature of at least about 900° C. for an effective period of time;applying a holding pressure performance increasing surface treatment comprising an inorganic particulate material to at least a portion of the exterior surfaces of at least a portion of the inorganic fibers; andincorporating the surface treated inorganic fibers into a mat structure for holding a fragile catalyst support structure within the housing of an exhaust gas treatment device,wherein said mounting mat has a minimum holding pressure for holding the fragile structure within the housing of one of (i) at least 50 kPa after 1000 cycles of testing at a hot face temperature of 300° C., a gap bulk density of between 0.3 and 0.5 g/cm3, and a percent gap expansion of 2 percent, and (ii) at least 10 kPa after 1000 cycles of testing at a hot face temperature of 900° C., a gap bulk density of between 0.3 and 0.5 g/cm3, and a percent gap expansion of 5 percent.