Patent ID: 7494613

Claim:
A method of making a cordierite structure for use in a diesel particulate filter, the method comprising: forming a mixture of cordierite-forming raw materials, a pore former and organic components, the cordierite-forming raw materials including talc, silica, and an alumina-forming source, each defining a median particle size, wherein the talc median particle size, the alumina-forming source median particle size, the amount of pore former, and the pore former median particle size satisfy the relationship R m ≦−2.64, where R m is equal to [−0.102(talc median particle diameter)+0.001466(talc median particle diameter) 2 −0.0491((weight percent super-addition of pore forming agent)/(density of pore forming agent))−0.00762(median particle diameter of pore forming agent)+0.0000760(median particle diameter of pore forming agent) 2 −0.0562(median particle diameter of the alumina-forming source)], wherein the median particle diameter is in units of micrometers; shaping the mixture into a green structure; and, firing the green structure at a temperature and for a time to produce a fired structure having a CTE (25-800° C.) of less than 13×10 −7 /° C., a bulk filter density of less than 0.60 g/cm 3 , a median pore diameter, d 50 , of less than 25 micrometers, a porosity and pore size distribution that satisfy the relationship P m ≦3.75, wherein P m is equal to 10.2474{1/[(d 50 ) 2 (% porosity/100)]}+0.0366183(d 90 )−0.00040119(d 90 ) 2 +0.468815(100/% porosity) 2 +0.0297715(d 50 )+1.61639(d 50 −d 10 )/d 50 , wherein d 10 , and d 90 are pore diameters in units of micrometers at 10% and 90% of the pore size distribution on a volumetric basis, and d 10 <d 50 <d 90 .