Abstract: Complex shapes, e.g. for ceramic cores, can be produced by bonding components with simpler shapes together without the use of glue or cement, thus permitting high precision and avoiding problems caused by excess of cement. The components are formed of curable binder (preferably thermosetting) and a filler (generally a ceramic powder). At least one of the components to be bonded is not completely cured. It is placed in close contact with another component. Heating to cure the uncured component(s) gives a bonded assembly which is then fired.

Abstract: A shell mould comprising an inner layer of ceramic material which has a predetermined co-efficient of thermal expansion at a predetermined temperature and an outer ceramic layer of lower thermal co-efficient than the inner layer. The outer layer subjects the inner layer to compression on firing and during casting.

Abstract: A reinforced tubular core for casting gas turbine engine blades with cooling air passages therein is disclosed. A method of casting is also disclosed in which the blades are directionally solidified to produce columnar grained or single crystal blades and in which non-linear passages can be produced. The problem in producing such articles is that the moulds and cores used in the casting process are held at temperatures in excess of 1500.degree. for long periods and presently used Silica cores deform during the process. Stronger cores of Alumina or Silicon Nitride cannot be easily bent were believed to be non-leachable from the casting. The present invention provides a core having a tubular silica sheath with a solid alumina rod inside it for support. The sheath can be bent and the straight alumina rods can be inserted from opposite ends of the sheath.

Abstract: A method for moulding multiple castings in which each mould is fed from a source of molten metal through a thin slit the width of which lies in the range 1.25 mm down to 0.25 mm. The cast articles can easily be removed from the runner and riser system after casting without a machining operation so that the casting moulds can be packed closer together and more castings can be produced from each mould assembly. The thin slit also acts as a filter. A particular mould assembly seen in FIG. 2 is cylindrical and comprises a plurality of wedge-shaped mould segments 2 having mould cavities 4 in abutting faces. A central runner passage 6 is formed when the mould segments are assembled and the metal flows into the mould cavities through narrow slits 10 in one edge of each mould. After casting and removal of the mould the narrow flashing formed in the slits can easily be broken to remove the cast articles from the metal formed in the central runner passage.

Abstract: A method of removing refractory material from a component comprises contacting the refractory material with a chemically active agent whereby to convert the refractory material to a more easily removable substance, and removing the more easily removable substance. The method enables alumina cores defining cooling passages in cast blades for use in gas turbine engines to be removed at practically useful rates.

Abstract: A reinforced tubular core for casting gas turbine engine blades with cooling air passages therein is disclosed. A method of casting is also disclosed in which the blades are directionally solidified to produce columnar grained or single crystal blades and in which non-linear passages can be produced. The problem in producing such articles is that the moulds and cores used in the casting process are held at temperatures in excess of 1500.degree. for long periods and presently used silica cores deform during the process. Stronger cores of alumina or silicon nitride cannot be easily bent were believed to be non-leachable from the casting. The present invention provides a core having a tubular silica sheath with a solid alumina rod inside it for support. The sheath can be bent and the straight alumina rods can be inserted from opposite ends of the sheath.

Abstract: In a process for making refractory articles, such as cores and moulds for use in casting metals, the articles are formed from dies using a refractory material mixed with a thermosetting resin. The articles are formed with the mixture heated to a softened state and the resin is cured. Thereafter the article has to be fired and problems have arisen with deformation of the articles during the firing process.With the present invention, the articles, 8, which as can be seen in FIG. 2 are mould segments, are bound into an assembly with a flexible refractory tape (15) which shrinks on firing to a greater extent than the articles, and thus pulls the assembly tightly together whereby each article provides support for the adjacent article and prevents distortion. The joint faces between the mould segments are thus held in tight abutment and for pouring metal into the mould, the firing cup is fitted and a coating of refractory slurry is brushed on without removing the tape to seal the assembly.

Abstract: In a mould assembly for multiple castings each mould is fed from a source of molten metal through a thin slit the width of which lies in the range 1.25 mm to 0.25 mm. The cast articles can be easily removed from the runner and riser system after casting without a machining operation so that the casting moulds can be packed closer together and more castings can be produced from each mould assembly. The thin slit also acts as a filter. A particular mould assembly seen in FIG. 2 is cylindrical and comprises a plurality of wedge-shaped mould segments 2 having mould cavities 4 in abutting faces. A central runner passage 6 is formed when the mould segments are assembled and the metal flows into the mould cavities through narrow slits 10 in one edge of each mould. After casting and removal of the mould the narrow flashing formed in the slits can be easily broken to remove the cast articles from the metal formed in the central runner passage.