Abstract: A composition of a multiple-layered ceramic fiber filter paper and method for manufacturing for use in a filter apparatus removes particulate from high temperature gas streams. In this application, ceramic fibers of varying diameters and lengths are combined in such a manner to yield different specific average pore sizes in segregated locations in the filter paper. The fiber combinations are formed into a paper sheet using a method that produces two or three porosity zones with different average pore sizes in each layer or porosity zone. The porosity gradient from large at gas stream entry to fine at gas stream exit increases particle-holding capacity while reducing the filtered gas backpressure experienced in single sized porosity layer media.

Abstract: A process for the production of ceramic fibrils comprising the steps of subjecting a quantity of a catalyst for the conversion of silicon and carbon to silicon carbide under conditions of elevated temperature and the presence of a gaseous precursor for silicon and carbon, in a reaction vessel, to heating by microwave energy to a temperature not in excess of about 1300° C. for a time sufficient to disassociate said precursor into at least silicon and carbon, saturation of the catalyst with the disassociated components of the gaseous precursor and resultant growth of silicon carbide fibrils on the reaction vessel.