Provided are: a coated sand having improved fluidity and being capable of improving a filling rate of a casting mold to be obtained; and a coated sand for advantageously manufacturing a casting mold having excellent strength, which coated sand provides a casting mold with good mold-releasability and collapsibility, gives cast products a favorable casting surface, and effectively improves sand adhesion on cast products. The coated sand is formed as a dry granular material having fluidity at room temperature, in which the surface of a refractory aggregate is coated with a solid layer of a water-soluble inorganic binder, and spherical particles of silicone resin having binder-repellency exist on the surface of the binder layer, or form a layer on the surface of the binder layer, a part of the spherical particles being not covered with the water-soluble inorganic binder and being exposed.

A self-bonding refractory powder product for use in making a slurry for investment casting molds comprising a coarse refractory powder; a Nano-sized powder; and an organic polymer powder, wherein it does not require aqueous colloidal silica to produce slurries used to build investment casting molds. The Nano-sized powder comprises fumed alumina, boehmite, fumed silica, or fumed titanium oxide or combinations thereof. The coarse refractory powder comprises milled zircon, tabular alumina or fused alumina, fused silica, alumino-silicate, zirconia, and yttria or combinations thereof. The organic polymer powder comprises a cellulose-based material.

The present disclosure relates to a cement or concrete composition comprising a hydraulic binder, a water reducing plasticiser, a rheological additive, and composite spheres for lowering the density of the composition, wherein the composite spheres comprise a core having one or more coating layers thereon.

A self-bonding refractory powder product for use in making a slurry for investment casting molds comprising a coarse refractory powder; a Nano-sized powder; and an organic polymer powder, wherein it does not require aqueous colloidal silica to produce slurries used to build investment casting molds. The Nano-sized powder comprises fumed alumina, boehmite, fumed silica, or fumed titanium oxide or combinations thereof. The coarse refractory powder comprises milled zircon, tabular alumina or fused alumina, fused silica, alumino-silicate, zirconia, and yttria or combinations thereof. The organic polymer powder comprises a cellulose-based material.

The present invention provides a hydraulic composition for an additive manufacturing device having an excellent initial flexural strength development property and dimensional stability, the hydraulic composition for an additive manufacturing device including: 1.5 to 14 parts by mass of a polymer with respect to 100 parts by mass of an inorganic binder. In addition, the present invention preferably provides a hydraulic composition for an additive manufacturing device in which the inorganic binder contains 50 to 100 mass % of a calcium aluminate with respect to 100 mass % of the entire inorganic binder, and more preferably provides a hydraulic composition for an additive manufacturing device in which the inorganic binder contains 0 to 50 mass % of rapid hardening cement with respect to 100 mass % of the entire inorganic binder.

The present disclosure provides a method and device for preparing an artificial core for petroleum geological exploration. The method includes: step 1, establishing a relation curve between a median grain diameter of quartz sand and a permeability, determining a type and a usage amount of epoxy resin, and preparing a cementing agent according to a principle that the epoxy resin has a direct ratio with a specific surface; step 2, based on a method of controlling a core permeability, preparing benchmark sand with quartz sand of different grain sizes in a certain ratio, fabricating a low-permeability core by adjusting a ratio of the benchmark sand to fine sand, and fabricating a high-permeability core by adjusting a ratio of the benchmark sand to coarse sand; step 3, separately and proportionally weighing quartz sand of different grain diameters and putting them into a magnetic tray, manually mixing and agitating for later use.

A molding material in a powder-fixing lamination method includes an aggregate and a powdery precursor of a binder that binds the aggregate mutually. The aggregate is a casting sand, and the powdery precursor contains a hardening component and a hardening accelerating component. A molded product is manufactured using the molding material.

The present invention has solved the problems of conventional molding materials, and provides a hydraulic composition for additive manufacturing devices having high strength development, particularly high early strength development, and less generation of gas defect and graphite spheroidization defect. Specifically, the hydraulic composition for additive manufacturing devices of the present invention at least contains calcium aluminate. It is preferable that the hydraulic composition contain 0.5-10 parts by mass of gypsum with respect to 100 parts by mass of the calcium aluminate.

The object of the present invention is to provide a multilayer ceramic electronic component having improved highly accelerated lifetime and specific permittivity. A multilayer ceramic electronic component comprising a multilayer body in which an internal electrode layer and a dielectric layer are stacked in alternating manner, wherein the dielectric layer comprises a dielectric ceramic composition having a main component expressed by a general formula ABO.sub.3 (A is Ba and the like, and B is Ti and the like) and a rare earth component R, a segregation phase including the rare earth component R exists in the dielectric layer, an area ratio of the segregation phases in a cross section along a stacking direction is 104 ppm to 961 ppm, and 96% or more of a total area of the segregation phases contact with the internal electrode layer.

The object of the present invention is to provide a dielectric ceramic composition having even improved insulation specific resistance and highly accelerated lifetime. A dielectric ceramic composition comprising a dielectric particle having a core-shell structure including a main component expressed by a general formula ABO.sub.3 (A is Ba and the like; and B is Ti and the like) and a rare earth element component R, in which a shell part of the core-shell structure has an average rare earth element concentration C of 0.3 atom % or more, and a rare earth element concentration gradient S is 0.010 atom %/nmS0.009 atom %/nm or a rare earth element concentration variation satisfies /C0.15 (a is a standard deviation of a rare earth element concentration and C is an average rare earth element concentration).