Abstract: A hollow cast product such as a gas-cooled gas turbine engine blade is formed using a composite core constructed by forming a first core part determinative of the cavity size of the trailing edge blade portion from a first ceramic material and joined to a second core part determinative of the blade cavity for the blade body portion which is formed from a second ceramic material. The first and second ceramic materials can be chosen to have appropriate characteristics grain sizes, flowability, leachability, and/or reactivity characteristics taking into consideration the different dimensional restrictions imposed by the desired blade product. A tongue is formed on the adjoining edge surface of the trailing edge core part, and the trailing edge core part is then inserted into a second die and the body core part is formed, including a complementary groove member which is formed around the tongue member on the trailing edge core part.

Abstract: A composite core for a hollow gas turbine engine blade is constructed by forming a first core part determinative of the cavity size of the trailing edge blade portion from a first ceramic material and joined to a second core part determinative of the blade cavity for the blade body portion which is formed from a second ceramic material. The first and second ceramic materials can be chosen to have appropriate characteristics grain sizes, flowability, leachability, and/or reactivity characteristics taking into consideration the different dimensional restrictions imposed by the desired blade product. A tongue is formed on the adjoining edge surface of the trailing edge core part, and the trailing edge core part is then inserted into a second die and the body core part is formed, including a complementary groove member which is formed around the tongue member on the trailing edge core part. The joined trailing edge and body core parts can then be sintered to form a composite casting core.

Abstract: Cores for use in the casting of hollow metal parts by directional solidification from temperatures which may exceed 2700.degree. F., in which the strength, dimensional stability and shape of the core is maintained at such high temperatures by formulating the core to contain Cristobalite in an amount of at least 2.5% by weight.