| 摘要 |
<p>An appts. for making monocrystallie metal products incorporates a ceramic mould and a cooling unit. The mould has a housing in its base for a crystal primer. The cooling unit has a flat plat which is mounted below the mould and can be moved vertically. It has an axial hole through which a tube passes. The interior of the tube is divided into two sections by a partition. The upper section fits over the primer housing. The lower section can be supplied with a cooling liq. The upper part of the tube is made of a metal such as tungsten or molybdenum, with a thermal conductivity giving the max. temp. gradient along the primer. The lower part is made of stainless steel, the junction being in the cooling unit, where the temp. is low. Device is used for mfr. of mono-crystalline prodts. from metals and alloys, having a predetermined crystal structure, e.g. in fins for turbines and in permanent magnets. The service life of monocrystalline turbine fins is 4 times greater at max. operating temp. and 6 to 8 times greater at moderate temps., than that of polycrystalline fins. The strength of monocrystalline permanent magnets is 2.5-3 times that if polycrystalline ones.</p> |
