Abstract: A method for producing a ceramic honeycomb structure comprising a ceramic honeycomb body comprising large numbers of axially extending cells defined by cell walls, and an outer peripheral wall formed on an outer peripheral surface of the ceramic honeycomb body, comprising the steps of applying a coating material comprising elongated colloidal silica particles to the outer peripheral surface, and drying the coating material to form the outer peripheral wall.

Abstract: A radio wave absorption material is characterized to be obtained by firing a ferrite material that is formed by adding an accessory component, 0.1 to 2 wt % of CoO, to an oxide magnetic material containing main components, 30 to 49.5 mol % of Fe2O3, 0.5 to 20 mol % of Mn2O3, 5 to 35 mol % of ZnO, 0.2 to 15 mol % of (Li0.5Fe0.5)O and MnO as the rest. In the above-mentioned composition, part of ZnO may be replaced with 20 mol % or less of CuO. This radio wave absorption material has high strength and humidity stability and has excellent radio wave absorption performance although low in cost.