发明授权
US6024163A Investment casting brittle, reactive materials 失效
投资铸造脆性,反应性材料

Investment casting brittle, reactive materials
摘要:
Investment casting shells, methods for their manufacture and methods for casting metals and alloys using such shells are disclosed. One feature of the shells is that the facecoat plus interior backup layers are purposefully designed to have substantially similar coefficients of thermal expansion to the seal dip layers. This helps reduce the occurrence of dimensional casting defects caused by differential thermal expansions of the layers comprising the shell. One embodiment of such a shell comprises a facecoat, plural interior backup layers and plural intermediate backup layers wherein at least one of the plural intermediate backup layers comprises a material capable of undergoing a volumetric transformation during cool down, and wherein the seal-dip layers have a coefficient of thermal expansion that varies from the coefficient of thermal expansion of the facecoat and interior backup layers by less than about 10 percent. A particular embodiment of the method is useful for investment casting aluminides, particularly TiAl, using a shell having an alumina facecoat.
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