Abstract: A method and ceramic mold structure for use in producing articles having a predetermined crystalline orientation such as single crystals. The technique involves the use of a ceramic mold mounted on a chill plate with the mold defining a cavity tilted at an angle between about 5.degree. and 75.degree. relative to the vertical. One or more seed crystals are supported adjacent the chill plate and the orientation of the crystal is selected to provide a desired orientation in the resulting casting. The method results in improved solidification control, particularly with reference to avoiding defects caused by shrinkage.

Abstract: An improved method of casting an article decreases the time required to cast the article without affecting the quality of the article. When a directionally solidified (DS) casting is made, molten metal is poured into a mold cavity. One end of the mold cavity is exposed to a chill plate which initiates solidification of the molten metal. As the metal solidifies, a dendritic structure grows upwardly into the mold cavity. Molten metal is disposed in the interstices of the uppermost portions of dendritic structure. As the metal in the mold cavity cools, the molten metal in the interstices solidifies and the dendritic structure, including a region containing some molten metal in the interstices, continues to grow upwardly toward the upper end of the mold cavity. The directional solidification of the metal in the mold cavity is promoted by slowly withdrawing the mold from a furnace as the molten metal solidifies.

Abstract: A lost foam metal casting process employs a chill member to reduce porosity within a region of a product casting. The chill is adhesively bonded to a fugitive pattern prior to jointly embedding within a particulate sand mold by fluidization, thereby conveniently and reliably arranging the chill and the pattern within the mold for casting.

Abstract: Disclosed is a method for directional solidification of large single crystal metal alloy castings using multiple seed crystals. Solidification interfaces emanate from the separate seeds, and merge to form a unitary solidification interface which is caused to move through the article. The crystallographic orientation of the seeds is controlled, to avoid unacceptable mismatch of crystal structure orientation where the separate interfaces merge.

Abstract: An improved method of casting an article includes using the same starter element during the casting of a plurality of metal articles. In one specific instance the starter element consisted of a single metal crystal. The single crystal starter element was used to initiate the solidification of molten metal in a mold to form a single crystal cast article. This was done without significant bonding between the solidified metal and the single crystal starter element. Therefore, the starter element could be separated from the solidified body of metal and subsequently used in the casting of another article. In order to tend to maximize the rate of heat transfer from the starter element and to tend to minimize bonding of the molten metal with the starter element, the starter element is advantageously located in a recess in a chill block with an upper surface of the starter element even with an upper surface of the chill block.

Abstract: A seed and method for epitaxial solidification of materials, a preferred seed having at least a portion with a melting point 20.degree.-45.degree. C. depressed from that of the alloy being solidified into an article. Boron and silicon are preferably added to nickel superalloys seeds when directionally solidified columnar grain and single crystal articles are formed. Improved seeds also have surface compositions which promote the dissolution of surface contamination films that interfere with epitaxy.

Abstract: Foundry moulds are preheated throughout their surface areas, inclusive of bottom portions thereof, prior to being fed to the crystallization zone. Extending through heating, crystallization and cooling zones is a bottom plate formed as a single guide intended for the movement of foundary moulds therealong. The bottom plate is made up of a heated graphite section and of a cooled metallic section with the point of their joining being disposed at the entry to the crystallization zone wherein are arranged heaters movable over the height relative to the bottom plate and interlocked in a manner to permit stepwise control of heating lengthwise of the bottom plate.

Abstract: A cast metal turbine wheel is made comprising a cylindrical disc with equiaxed grains and integral blades with columnar grains oriented substantially parallel to the leading and trailing blade edges. The blades are solidified unidirectionally by withdrawing heat through chill means located adjacent the mold at the blade tips. Cooling is inhibited from other blade surfaces by retaining cast metal in mold portions located above and below the blades. The disc portion of the mold is insulated so that it cools slowly to promote grain nucleation throughout the metal therein and equiaxed grain growth.

Abstract: In a directionally solidified alloy casting operation the retractor is securely attached to the ingot mold by means also enabling easy separation of the resulting ingot from the retractor.

Abstract: The invention relates to a process and apparatus for manufacturing silicon astings or moldings, having a columnar structure of single-crystal regions of crystal with a preferential crystallographic orientation, and which can be manufactured cheaply and in large numbers in a semi-continuous mode of production. Liquid silicon is cast in a casting station, under an inert gas and preferably under reduced pressure, preferably in graphite molds which are exposed to a temperature gradient of 200.degree. to 1,000.degree. C. After cooling, the silicon is withdrawn automatically via a transport chamber connected to the casting station into special cooling stations, while the casting station is reloaded with an empty mold for repeating the process. The silicon blocks which have preferably been produced by this procedure are use as basic material for inexpensive solar cells having efficiencies of more than 10%, after they have been sawn into individual small wafers and have been doped and lead-bonded.

Abstract: A friction stressed machine part of cast iron with a ledeburitic-containing bearing surface contains 0.1 to 10 area percent of predominantly nodular-shaped graphite in the ledeburitic-containing bearing surface. A number of methods for producing such a machine part are provided, including, casting the machine part against a quenching plate so that it hardens in a mottled manner in the region of the bearing surface.

Abstract: A porous high-silica core is disclosed for use in directional solidification casting processes having exceptional thermal stability at temperatures above 1650.degree. C. and containing mineralizers which promote the formation of cristobalite. The cores may be made by mixing at least 75 parts of essentially pure fused silica particles with 1 to 25 parts of activating particles containing a mineralizer, such as an alkali metal or alkaline earth metal compound, may be fired at a temperature of 1000.degree. to 1300.degree. C. until they contain 35 percent or more of cristobalite and may then be cooled to room temperature. They may thereafter be incorporated in a shell mold in accordance with the "lost-wax" process and preheated with the shell mold at a temperature of 1300.degree. to 1600.degree. C. to provide a cristobalite content of 60 to 85 percent or more within a short period of time, such as 10 to 30 minutes, and before a molten superalloy is allowed to flow into the mold.

Abstract: The mold is preheated to a temperature above the maximum local casting temperature prior to casting of the melt and is also cooled to obtain a variation of temperatures throughout the mold. The resulting temperature gradient of the mold is intended to maintain the heat content per unit volume in the unsolidified melt portions greater than in the adjacent solidified melt portions to compensate for the latent heat of solidification in the melt and thus avoid shrinkholes and blowholes.

Abstract: In making columnar grained castings the shell mold is spaced from the chill plate by a ceramic ring on which the mold is positioned, the ring being made thicker and/or of a different ceramic from the mold to withstand the thermal stress developing while the mold is being heated for pouring, so that the mold, not being subjected to such stresses at the base, may be made thinner for producing better castings. In this way the best mold material for the purpose may be selected, as, for example, a material to have no reaction with the alloy and, by lowering the thermal gradient decrease the likelihood of mold failure.

Abstract: In the manufacture of hollow turbine blades or vanes especially those having a columnar crystalline growth in the alloy, the blade is cast in two opposed halves against a central mold element, the latter being rigid enough to avoid deformation during heating of the mold prior to pouring and during solidification. This central element has on opposite surfaces the configurations of the inner surfaces of the hollow blade. Cooperating with this inner element are outer elements having cooperating inner surface configurations of the convex and concave sides of the blade respectively. After the blade halves are cast simultaneously in the assembled mold and removed therefrom they are bonded together to form a complete blade.

Abstract: The invention relates to a method of casting superalloy articles and more particularly to directionally solidifying eutectic superalloy compositions to produce a composite structure of a superalloy matrix reinforced with aligned carbide fibers.