In the following expression, it is assumed that a thickness of a coating agent applied to a foam pattern [2] is t (mm), a diameter of a hole part [3] is D (mm), and a normal-temperature transverse strength of the dried coating agent is σc (MPa). At the time of producing a casting provided with a hole having a diameter of 18 mm or smaller and a length of 1 (mm), a coating agent that satisfies the following expression is used when a solidification end time te (sec) at which solidification of a melt ends on a periphery of the hole part [3] is within a time t0 (sec) at which thermal decomposition of the coating agent ends.

σc≧{t0/(t0−te)}×(1.5×10.sup.−4×1.sup.2/t.sup.2+160/D.sup.2)

A hollow metal article can be fabricated by casting a molten metal alloy around a core, solidifying the molten metal alloy to form a metal article, and chemically removing the core from the metal article to form a hollow cavity in the metal article. The core includes a ceramic core body and an x-ray radiopaque coating disposed on the ceramic core body. A method for testing the hollow metal article includes submitting the hollow metal article to x-ray imaging and determining based upon the x-ray imaging whether any of the x-ray radiopaque coating of the core remains in the hollow metal article.

A hollow metal article can be fabricated by casting a molten metal alloy around a core, solidifying the molten metal alloy to form a metal article, and chemically removing the core from the metal article to form a hollow cavity in the metal article. The core includes a ceramic core body and an x-ray radiopaque coating disposed on the ceramic core body. A method for testing the hollow metal article includes submitting the hollow metal article to x-ray imaging and determining based upon the x-ray imaging whether any of the x-ray radiopaque coating of the core remains in the hollow metal article.

Disclosed herein are refractory coating compositions with improved drying times, defect prevention, and gas permeability and methods for using such refractory coating compositions.

Disclosed herein are refractory coating compositions with improved drying times, defect prevention, and gas permeability and methods for using such refractory coating compositions.

Methods and systems in which a shapable mass, which is processed according to the method or in the system, has a lubricant applied thereto. As it is processed in the system, the shapable mass having the lubricant applied thereto is used to transfer lubricant to a part or parts of the system.

Methods and systems in which a shapable mass, which is processed according to the method or in the system, has a lubricant applied thereto. As it is processed in the system, the shapable mass having the lubricant applied thereto is used to transfer lubricant to a part or parts of the system.

A method to form a displacement, the method including disposing a powder blend comprising a plurality of ground ceramic particles and a plurality of ground resin particles into a mold, densifying the powder blend while in the mold, heating the mold to form a first displacement, impregnating said first displacement with a polymer precursor compound to form a second displacement, and heating the second displacement to form a third displacement.

Provided is a casting method using lost foam capable of forming a small highly-finished hole with a diameter of 18 mm or less and a length of 50 mm or more by casting. A casting method using lost foam of the present embodiment includes the steps of embedding, in foundry sand, a casting pattern formed by applying a mold wash with a thickness of 1 mm or more to a surface of the foam pattern, the foam pattern having a hole with a diameter of D (mm); replacing the foam pattern with molten metal by pouring the molten metal into the casting pattern and losing the foam pattern; and forming a casting having a small hole with a diameter of 18 mm or less and a length of 50 mm or more by cooling the molten metal, and the method satisfies the following formulas (0) and (1):

2<D≦19.7   Formula (0)

σc≧−0.36+140/D.sup.2   Formula (1) where σc (MPa) is transverse rupture strength (bending strength) of the mold wash that is heated to decompose resin constituting the mold wash and then returned to room temperature.

Provided is a casting method using lost foam capable of forming a small highly-finished hole with a diameter of 18 mm or less and a length of 50 mm or more by casting. A casting method using lost foam of the present embodiment includes the steps of embedding, in foundry sand, a casting pattern formed by applying a mold wash with a thickness of 1 mm or more to a surface of the foam pattern, the foam pattern having a hole with a diameter of D (mm); replacing the foam pattern with molten metal by pouring the molten metal into the casting pattern and losing the foam pattern; and forming a casting having a small hole with a diameter of 18 mm or less and a length of 50 mm or more by cooling the molten metal, and the method satisfies the following formulas (0) and (1):

2<D≦19.7   Formula (0)

σc≧−0.36+140/D.sup.2   Formula (1) where σc (MPa) is transverse rupture strength (bending strength) of the mold wash that is heated to decompose resin constituting the mold wash and then returned to room temperature.