| 摘要 |
<p>PURPOSE:To obtain the title general-purpose structure ca. 1OMEGA.cm in electrical resistivity, usable at <=ca. 300 deg.C, by applying a specified amount of carbonaceous film on the entire inner surface of three-dimensional open holes of a porous ceramic calcined form with specified content of iron. CONSTITUTION:Firstly, granules <=ca. 1mm in size, containing 10-70wt.%, on a metallic iron basis, of an iron component, consisting of iron oxide or a ceramic mixture predominant in iron oxide is incorporated with an inorganic binder such as clay followed by forming. Thence, the resultant form is calcined at a maximum temperature of ca. 1,000-1,300 deg.C in an oxidizing flame atmosphere to produce a porous calcined form. During the cooling process after the calcination, or another process, said calcined form is put to smoldering treatment at <ca. 1,000 deg.C but >=600 deg.C to attach 0.05-0.5wt.% of carbon to the entire inner surface of the holes in said calcined form. Greater amount of said iron component will reduce the electrical resistance of said calcined form, but excessive amount thereof will result in harder calcination and smoldering leading to being liable to develop cracks. The amount of said carbon attached is closely associated with the electrical resistivity of the calcined structure, hence, being specified within the above-mentioned range.</p> |
