A composition which comprises a soluble or partially soluble phosphate, a refractory material and less than 1% of an oxide or hydroxide of magnesium or calcium. The composition may be mixed with water to form an investment casting slurry into which a wax pattern may be dipped. Slurry coated onto the pattern may be set by applying a stucco composition which comprises an oxide or hydroxide of magnesium or calcium. Coats of set slurry may be built up on the pattern to form an investment casting shell.

A mullite shell mold for casting includes a facecoat layer containing ceramic flour. The mullite shell mold also includes a first layer disposed on the facecoat layer. The first layer can contain sintered ceramic media. The facecoat layer and the first layer can each contain less than 1 wt % crystalline silica.

The present disclosure belongs to the technical field of casting, and specifically relates to a high-inertia mold shell for casting, a preparation method thereof, and a method for improving precision of a magnesium alloy cast. The high-inertia mold shell for casting includes a surface layer, which is configured to contact a magnesium alloy pouring liquid, wherein the surface layer contains an inorganic compound, and the inorganic compound is at least one selected from the group consisting of boric anhydride, borax, potassium fluoride, and sodium fluoride; and in the above, based on a total amount of raw materials of the surface layer, a content of the inorganic compound accounts for 10-40 wt %.

There is provided an electronic device including a terminal configured to receive power and be provided on a back surface side of the electronic device, the terminal including a hole portion configured to be concaved from the back surface side to a front surface side of the electronic device and include a first connection portion configured to be provided on the back surface side of the electronic device and include an inner circumferential surface having a female screw groove shape, and a second connection portion configured to be provided on an inner side of the first connection portion, and include an inner diameter smaller than an inner diameter of the first connection portion and an inner circumferential surface smoother than the inner circumferential surface of the first connection portion.

A method of manufacturing precision cast parts for vehicle exhaust systems includes fabricating a model of a product to be manufactured using a substance selected from the group consisting of a wax and a plastic, forming a first coating layer on a surface of the model using a first slurry, forming a second coating layer on the surface of the model coated with the first coating layer using a second slurry, drying the first and second coating layers to form a mold and heating the mold to remove the model, pre-heating the mold, placing the mold in a ceramic box with a top portion open, and filling an inner part of the ceramic box with ceramic balls, and producing a product by injecting a molten metal into the mold to cast the product.

Provided are slurry compositions and methods for producing investment casting molds. These compositions include a refractory material, a binder, a solvent, and a thixotropic agent comprising a polymer emulsion. Implementation of these slurry compositions enables a reduction in the number of backup layers in an investment casting shell, while retaining similar viscosity characteristics and similar or greater strength characteristics in the finished investment mold.

The present disclosure belongs to the technical field of casting, and specifically relates to a high-inertia mold shell for casting, a preparation method thereof, and a method for improving precision of a magnesium alloy cast. The high-inertia mold shell for casting includes a surface layer, which is configured to contact a magnesium alloy pouring liquid, wherein the surface layer contains an inorganic compound, and the inorganic compound is at least one selected from the group consisting of boric anhydride, borax, potassium fluoride, and sodium fluoride; and in the above, based on a total amount of raw materials of the surface layer, a content of the inorganic compound accounts for 10-40 wt %.