Abstract: Ceramic structural body having improved material properties of a sealing member, such as adhesion properties at room temperature and high temperature, and having an improved durability. The ceramic structural body comprises an assembly of plural united ceramic members each having a plurality of through-holes arranged side by side along a longitudinal direction, in which end faces at either side of these through-holes are closed in a checkered pattern so as to have a reverse relation of open and close between gas inlet side and gas outlet side and adjacent through-holes are permeable to each other through porous partition walls. A plurality of the ceramic members are integrally adhered by interposing a sealing member of an elastic material comprising at least inorganic fibers, an inorganic binder, an organic binder and inorganic particles and mutually bonded three-dimensionally intersected organic fibers and inorganic particles through the inorganic binder and organic binder between the mutual ceramic members.

Abstract: The cavitation prevention system according to the present invention is provided with an air introducing passageway for introducing an air within means for storing air, such as a water tank, into a cooling water passageway at a suction portion of a water pump. The means for storing air is provided with an air metering means for controlling an amount of air to be supplied to the cooling water circulating passageway, thereby to maintain an air mixture ratio at the desirable valve for effectively preventing cavitation erosion. An air flow control valve means mounted to the air introducing passageway is controlled by output signals from means for detecting various conditions of an engine in which cavitation occurs or cavitation teuds to occur accurately, wherein the air is introduced into the cooling water only when the engine condition requires it to prevent cavitation, but at other conditions of the engine the air introduction is not effected so as to improve the engine cooling performance.