Patent ID: 6838026
Filing Date: 2005-01-04
Classification: B01D,C04B

Abstract:
1. A method for producing a silicon nitride filter, which comprises: heat-treating, in an atmosphere consisting essentially of nitrogen or consisting essentially of a combination of an inert gas and nitrogen in which the partial pressure of nitrogen is at least 50 kPa, a green body comprising: from 35 to 90 wt % of silicon nitride particles having an average particle diameter of from 1 to 3 μm, from 5 to 60 wt % of a pore-forming agent of spherical organic polymer particles selected from the group consisting of a polyvinyl alcohol, an acrylic resin, a vinyl acetate resin or cellulose ranging in size from 20 to 100 μm and from 0.1 to 5 wt % of metal oxide solid particles, provided that the total amount of the silicon nitride particles, the pore-forming agent and the metal oxide particles is at least 90 wt %, to form a product having a porosity ranging from 30 to 80% and an average pore diameter as measured by a mercury immersion method ranging from 5 to 40 μm that effectively filters particulate matter from diesel fuel.