Mat material, exhaust gas treating apparatus, and method of manufacturing mat material

摘要

A mat material includes a plurality of inorganic fibers. At least some of the inorganic fibers include a core portion and a surface layer surrounding the core portion, the surface layer containing more silica (SiO 2 ) than the core portion does. An exhaust gas treating apparatus employs such a mat material as a retain/seal material wound around an exhaust gas treating body. A method of manufacturing such a mat material includes (A) forming inorganic fibers having a core portion and a surface layer surrounding the core portion; (B) preparing a laminated sheet from the inorganic fibers formed in step (A); and (C) forming a mat material from the laminated sheet by a needling process.