| 摘要 |
1440492 Lining moulds OFFICE NATIONAL D'ETUDES ET DE RECHERCHES AEROSPATIALES 5 Oct 1973 [6 Oct 1972] 46646/73 Heading B3F A mould for casting directionally solidified articles comprises a body of heat conducting refractory material, e.g. W, Mo, Ta or graphite, having on its surface a layer of alumina, the said layer having a purity of at least 99À5% and having been deposited by blowpipe projection, e.g. by using an oxyacetylene or plasma blowpipe. The mould may consist of two parts (21) and (22) pressed against one another by a jacket (40) surrounding the parts. The abutting surfaces (33) and (34), (35) and (36) of the parts as well as the surfaces defining the mould cavity are provided with a layer of alumina. In use, the metal may be either melted in the mould cavity or introduced into the cavity in a liquid state and is solidified at a rate between 0À6 and 5 cm./hr. while maintaining a temperature gradient at the solidification front of between 100‹ and 200‹ C./cm. |
