Abstract: A method of making a ceramic core for use in a casting process comprises the steps of forming a core in a mould by hot injection of a thermoplastic paste consisting of a refractory ceramic composition and an organic fraction, eliminating the organic fraction from the core by heat treatment, heat treating the core to achieve the minimum consolidation necessary to enable the core to be handled, impregnating the porous structure of the core with a solution comprising a silica or alumina based elementary oxide colloid, and eliminating the liquid from the impregnated product.

Abstract: The present invention is directed to a foundry sand additive composition, and method of casting molten metal against a foundry sand containing the additive composition. The additive composition comprises a humic acid-containing and/or a humic acid salt-containing ore (hereinafter referred to separately or in combination as "humic-containing ore") and carbon or graphite or admixtures of carbon and graphite. The combination of carbon and/or graphite and the humic-containing ore react in-situ when the foundry sand is heated by contact with molten metal, at temperatures of about 450.degree. F. to about 2300.degree. F., particularly in the range of about 600.degree. F. to about 2000.degree. F., to activate the carbon and/or graphite. The carbon and/or graphite, activated in-situ during the molding process, absorb and/or adsorb (sorb) gaseous volatile organic compounds (VOCs) within the mold, so that the VOC gases are held by the in-situ-activated carbon and/or graphite to satisfy VOC emissions requirements.

Abstract: The present invention is directed to an activated carbon and/or activated graphite foundry sand additive, and method of casting molten metal against a foundry sand containing the additive composition. In another embodiment, the activated carbon and/or activated graphite additive (or portion thereof) is formed in-situ by adding to the foundry sand a humic acid-containing and/or a humic acid salt-containing ore (hereinafter referred to separately or in combination as "humic-containing ore") and carbon or graphite or admixtures of carbon and graphite. The combination of carbon and/or graphite and the humic-containing ore react in-situ when the foundry sand is heated by contact with molten metal, at temperatures of about 450.degree. F. to about 2300.degree. F., particularly in the range of about 600.degree. F. to about 2000.degree. F., to activate the carbon and/or graphite.

Abstract: The invention relates to the use of tripotassium citrate monohydrate and other alkali metal salts of polybasic acid as bench life extenders in heat curable hot box foundry mixtures comprising sand, thermosetting binder resin, and a latent acid catalyst composition. In one embodiment, the thermosetting binder resin is a phenolic resole resin modified with urea formaldehyde resin. In another embodiment, the thermosetting binder resin is a furfuryl alcohol resin modified with urea formaldehyde resin.

Abstract: A water-dispersible mold for making a casting comprises a water-insoluble particulate material, such as foundry sand, a binder which includes polyphosphate chains and/or borate ions, and at least one fine particulate refractory material such as one selected from finely particulate silica, silicates and aluminosilicates. The incorporation of the fine particulate refractory results in improvements in the strength and related properties of the mold, when hot, prior to casting.

Abstract: A mold for metal casting contains a bonded refractory composition comprising hollow alumina-containing microspheres in which the alumina content is at least 40% by weight. The mold may be an ingot mold and the bonded refractory composition may be in the form of a sleeve or boards located in the top of the mold or in the head box thereto. The mold may be a sand mold and the bonded refractory composition may be in the form of a sleeve or boards located in a feeder cavity or in the form of a board or pad located so as to constitute a metal casting surface where it is desired to promote directional solidification in cast metal. The bonded refractory composition may also be in the form of a breaker core. In a preferred composition the microspheres contain alumina and silica and the composition may also contain one or more other particulate refractory materials, a readily oxidizable metal, an oxidizing metal, an oxidizing agent for the metal and a fluoride salt.

Abstract: In the production of castings from a melt of a reactive metal selected from the group consisting of titanium, titanium alloys, and titanium-based alloys, a reusable casting mold (20) is used; the mold, at least in the area of the surface which comes in contact with the melt, consists of at least one metal selected from the group consisting of tantalum, niobium, zirconium, and/or their alloys. The casting mold (20) preferably consists, at least in the area of the surface which comes in contact with the melt, of a tantalum based alloy containing at least 50 wt. % of tantalum. The casting molds can be made of a homogeneous metal, but it is also possible to insert shells of the metals in question into a base body to form the boundaries of the mold cavities, whereas the base body itself consists of some other metal or alloy or of a nonmetal such as graphite or silicon nitride.

Abstract: The present invention pertains to a process for preparing ceramic shells as casting molds, wherein a) a pattern of a part to be cast, which pattern can be melted or dissolved out, is prepared, b) the pattern is dipped into a dip-coating composition of a slurry of a refractory material and a binder in order to form a wet coating on the pattern, c) a coarse refractory powder is sprinkled onto the coating, d) the coating is dried, and e) steps b), c) and d) are repeated until the mold shell has reached the desired thickness. A ceramic protective material is added to the dip-coating composition and/or to the coarse refractory powder. Carbon is introduced into the ceramic protective material during the preparation in the molten state. The carbon is able to chemically bind oxygen at the time of the cooling of the casting essentially at mold temperatures above the firing temperature of the casting mold and is thus able to prevent skin decarburization and surface defects in carbon-containing steels.

Abstract: A method of constructing a fully dense metal part or a metal mold half for mating with another mold half to form a mold for casting multiple parts. Steps include placing a pattern in a tubular mold base, casting a ceramic member onto critical surfaces of the pattern, removing the pattern from the mold base, covering the critical surfaces transferred to the ceramic member with a powdered metal having a melting temperature greater than that of an infiltration metal, placing a quantity of an infiltration metal over the powdered metal, placing the tubular mold base in a furnace at a temperature sufficient to melt the infiltration metal without melting the powdered metal, and removing the ceramic member from the first open end of the tubular mold base to expose the critical surfaces. The quantity of the infiltration metal is sufficient to fill voids between the particles of the powdered metal when the infiltration metal is melted, thereby generating a fully dense metal part.

Abstract: A core for casting titanium or an alloy thereof consists essentially of a sintered formed substrate of a powder having as its main component either mullite powder alone or a combination of mullite powder and at least one member selected from among quartz glass, alumina, zircon, magnesia, and cristobalite and a surface layer formed of at least one member selected from among yttria, zirconia, hafnia, alumina, neodymium oxide, and samarium oxide and deposited as a coating layer on the surface of the formed substrate.

Abstract: A composite core for a hollow gas turbine engine blade is constructed by forming a first core part determinative of the cavity size of the trailing edge blade portion from a first ceramic material and joined to a second core part determinative of the blade cavity for the blade body portion which is formed from a second ceramic material. The first and second ceramic materials can be chosen to have appropriate characteristics grain sizes, flowability, leachability, and/or reactivity characteristics taking into consideration the different dimensional restrictions imposed by the desired blade product. A tongue is formed on the adjoining edge surface of the trailing edge core part, and the trailing edge core part is then inserted into a second die and the body core part is formed, including a complementary groove member which is formed around the tongue member on the trailing edge core part. The joined trailing edge and body core parts can then be sintered to form a composite casting core.

Abstract: A mold comprising a cavity for defining the shape of a casting and a mold body for forming said cavity, comprising: a mold body formed of an ordinary temperature setting resin or thermosetting resin and casting sand, said mold body having a surface layer portion on the surfaces thereof including depressions, said depressions in the surface layer portion being filled up with at least one porous powdered material selected from the group consisting of hydrous magnesium silicate clay mineral, activated carbon and activated alumina, thereby providing the mold body with smooth surfaces whereby said mold generates less amount of material such as gums which cause defective castings during casting since molten metal is restrained from intruding into the walls of said mold.

Abstract: A method of producing a casting utilizing an expendable polymeric foam pattern along with unbonded sand having specific thermal properties. The pattern, formed of a material such as polystyrene, has a configuration corresponding to that of the article to be cast. The pattern is placed with an outer flask and unbonded sand surrounds the pattern as well as filling the cavities in the pattern. The sand has a heat diffusivity greater than 1500 J/m.sup.2 /.degree.K./s1/2. The molten hypereutectic aluminum silicon alloy is fed into the flask in contact with the pattern causing the pattern to vaporize with the vapor being entrapped within the interstices of the sand while the molten metal fills the space initially occupied by the foam pattern to produce a cast article. The thermal properties of the sand reduces the particle size of the precipitated primary silicon particles in the casting, thereby increasing the machinability of the casting.

Abstract: A method of producing dimensionally predictable metal castings utilizing an expendable polymeric foam pattern along with unbonded sand having specific thermal properties. The pattern, formed of a material such as polystyrene, has a configuration corresponding to that of the article to be cast. The pattern is placed with an outer flask and unbonded sand surrounds the pattern as well as filling the cavities in the pattern. The sand has a linear expansion of less than 1% from 0.degree. C. to 1600.degree. C., a heat diffusivity greater than 1500 J/m.sup.2 /.degree.K/S1/2, an AFS grain fineness number of 25 to 33, and an AFS base permeability number of 450 to 500. A molten metal, such as an aluminum alloy or a ferrous alloy, is fed into the mold in contact with the pattern causing the pattern to vaporize with the vapor being entrapped within the interstices of the sand while the molten metal fills the space initially occupied by the foam pattern to produce a cast article.

Abstract: The invention concerns a new material for molding elements as well as the molds produced in this manner. This material contains more than 30% vitreous fused silica and various adjuvants and binders and presents the advantage of the possibility of modulating the thermal conductivity of the molds. Application to all types of industries utilizing shaping by molding of liquid or paste-like materials, or by the hot deformation of flat products.

Abstract: An improved refractory investment material for use in making refractory molds is provided. The material comprises an investment powder including a binder, a refractory selected from calcined mullite and pyrophyllite, additives for controlling setting and about 0.01 to about 0.04% by weight of a sulfate salt. The investment powder is formed into a slurry with a solution of a water based colloidal silica in an amount providing about 3% to about 6% by weight colloidal silica based on the weight of the water and a chloride salt in an amount of at least about 0.5% by weight based on the weight of said investment powder.

Abstract: Casting cores particularly useful in the investment casting industry are described. The cores are characterized by the presence of hollow ceramic particles, which facilitate the removal of the core from the casting they are used to form. In a preferred embodiment of the invention, the core is characterized by solid and hollow ceramic particles sintered to each other to form a core matrix, and such particles have the same composition. In an even further preferred embodiment, high temperature stable fibers are distributed uniformly throughout the matrix.

Abstract: The present invention is a process for forming net shape parts by matching mold and component CTE and having the mold heated near the liquidus such that the mold and the component go through the same thermal and dimensional changes during cool down of the component. The present invention also pertains to a method of producing the matched CTE mold. The method includes the step of providing the first material in porous form. Next, there is the step of melting the second material. Then, there is the step of infiltrating the first porous material with the second melted material in proportion such that their combined CTE essentially matches that of the composite component. The composite mold and composite component can be formed at the same time. In an alternative method for forming the mold having a specific CTE, there is the step of providing the first material and the second material.

Abstract: A hollow metal article can be made by casting a metal article around a ceramic core and leaching the core from inside the article. These steps form a hollow space in the shape of the ceramic core. An x-ray detectable agent that has a higher x-ray density than the ceramic core is introduced into the core. Any core remaining inside the article after the leaching step is detected by making and analyzing an x-ray radiograph of the article.

Abstract: Expendable mandrels and methods of using such mandrels for forming voids within materials or surfaces on materials deposited onto the mandrels are described. The mandrels have a coefficient of thermal expansion that substantially matches that of the material to be deposited on the mandrel. Matching coefficients of thermal expansion reduces the likelihood of cracking of the base material when the mandrel and base material are cooled.

Abstract: A new and improved, non-porous carbon foundry sand and a method of treating a fluid coke, having a spherical or ovoid particle shape and a size suitable for a coating surface, or a core or mold surface in the foundry industry, wherein the carbon sand is processed by heating the carbon particles at a controlled rate to a temperature in the range of about 1900.degree. F. to about 2300.degree. F. during a period of time preferably of more than about 30 minutes, and preferably for a period of about 1 to 2 hours, particularly to about 2000.degree. F. to about 2200.degree. F., and a method of casting molten metal against the heat treated carbon particles wherein the non-porous carbon foundry sand is combined with a suitable binder with which mixture a mold is formed to cast metal parts. The non-porous carbon sand also is useful in forming molds, cores, shell molds and shell cores and otherwise in using the carbon sand to replace other molding an core-making sands used in the foundry industry.

Abstract: In forming an aluminothermic weld between adjoining rail ends, a sand mold is arranged around the rail ends disposed in spaced relation. The sand mold is formed at least in part of silica sand. The surface of the mold in contact with the rail ends and enclosing the space between the rail ends is formed of one of a combination of silica sand and zircon sand, a layer of zircon sand inwardly from a layer of silica sand, or a thin layer of a zircon mold wash on a surface formed of silica sand.

Abstract: A high permeability metal casting plaster is used for production of high accuracy simulated castings for prototypes and any other plastermold castings. Methods are provided that create the high permeability metal casting plaster and mold. Also, a high permeability metal casting plaster is disclosed that uses control ground and screened alpha-hemihydrate gypsum, control ground and screened beta-hemihydrate gypsum, sucrose for protection against thermal shock, and a foaming agent.

Abstract: A new and improved carbon sand and a method of treating a petroleum fluid coke, having a spherical or ovoid particle shape and a size suitable for a core or mold surface in the foundry industry, by heating or roasting the carbon particles at a temperature in the range of about 1000.degree. F. to about 1500.degree. F., particularly about 1200.degree. F. to about 1400.degree. F., for a time sufficient to volatilize from the carbon particles substantially all of the organic contaminants volatilizable at the roasting temperature, and a method of casting molten metal against the heat treated carbon particles, combined with a suitable binder, to form cast metal parts. The carbon sand also is useful in forming shell molds and shell cores and otherwise using the carbon sand to replace other molding and coremaking sands used in any of the various molding and coremaking processes with any of the various binder systems practiced by the foundry industry.

Abstract: A novel method of making a ceramic core for use in casting a metal component includes freezing a ceramic slurry comprising a ceramic powder filler, a freezable liquid and a gelling agent in a mold to form a frozen core shaped body. The frozen core shaped body is removed from the mold and thawed to room temperature. A high viscosity gel is provided in the core shaped body at room temperature that is strong enough to retain the core shape until the body can be fired to form a porous, sintered ceramic core. The gel present at room temperature may be formed as the ceramic slurry is cooled in the mold cavity to form the frozen article shaped body and/or as the frozen core shaped body is thawed to room temperature.

Abstract: A molding medium and process for making it, preferably for use in the evaporative pattern casting process, is disclosed. The molding medium comprises, in one embodiment, a base granular molding material having spherically shaped grains wherein the individual grains of the material are coated with a refractory material. Preferably the grains are coated first with a binding agent and then mixed with a refractory material, which may be zirconium oxide. After coating, the material is fired at a high temperature, crushed and screened to size, according to one method. Alternatively, the base molding material may itself be a refractory material, in which case the refractory material is mixed with a binding agent to agglomerate the base material into substantially spherical particles and a refractory coating need not be applied. In either embodiment, substantially spherical free-flowing particles are produced having a low angle of repose.

Abstract: A metal casting mold formed of a ceramic material. The mold is reusable and is formed of a crystalline ceramic whose coefficient of thermal expansion (in the range 0.degree. to 1000.degree. C.) is between about 0 and 15.times.10.sup.-7 /.degree.C./ The mold interior surface includes at least one projection extending towards the mold cavity. The projection is provided with a release (draft) angle of about 6.degree., tapering away from the base of the projection. Upon pouring, the molten metal surrounds at least a portion of the projection. Upon cooling within the mold, shrinkage of the metal casting against the tapered sides of the projection forces the casting along the projection, toward the latter's tapered end and away from the mold interior surface and thus partially out of the mold cavity. A method of making the ceramic mold of this invention is also disclosed.

Abstract: An asbestos-free insulating material suitable for use as a header in molten metal casting. The material is made from a dry mixture comprising lime, siliceous component, delaminated vermiculite or spodumene or lithium aluminate or mixtures thereof, and optionally, wollastonite and organic fiber. The dry mixture is mixed with water to form a slurry, shaped, heated in the presence of steam, and dried to remove free water.

Abstract: An aqueous bath or slurry for use in forming a shell mould, comprising from 20 to 40 wt. % of colloidal silica, from 20 to 40 wt. % of finely ground zircon, from 15 to 25 wt. % of silica sand, from 15 to 35 wt. % of finely ground fused silica, and from 1 to 5 wt. % of finely ground cristobalite. The shell-mould is made by repeatedly dipping a wax model into the bath or slurry to form a coating of the desired thickness, and then thermally treating the shell-mould so formed by placing the mould into an oven, heating the oven to a temperature between 1050.degree. C. and 1200.degree. C., maintaining the temperature for a period of between 1 and 2 hours, and then allowing the oven and mould to cool to ambient temperature. The mould obtained contains from 10 to 30 wt. % of cristobalite at ambient temperature.

Abstract: Casting cores are fabricated from a mixture comprising a molten salt having dispersed therein a particulate material which includes a first refractory material having a mesh size of 60-120 and a second refractory material having a mesh size of at least 200. The salts are preferably halides, carbonates, sulfates, sulfites, nitrates or nitrites of Group Ia and Group IIa metals and the refractory material may be selected so as to be non-reactive with the molten salt. Some preferred refractory materials include alumina and magnesium silicate.

Abstract: The present invention relates to a mold material for casting pure titanium or a titanium alloy which comprises one or more chief materials selected from among silica-alumina mixtures, mullite and spinel and a hardening agent comprising a phosphate and a basic metal oxide and a process for casting pure titanium or a titanium alloy by the use of said mold material. This mold material forms a refractory structure having a melting point higher than that of pure titanium or a titanium alloy therein to enable pure titanium which is unstable in a molten state to be cast stably.

Abstract: An improved composition and process for preparing plaster molds used in casting nonferrous metals is provided wherein plaster molds are prepared from particulate calcium sulfate molding plaster admixed with insoluble calcium sulfate anhydrite whisker fibers.

Abstract: Y.sub.2 O.sub.3 is recovered from investment casting shell molds by introducing used mold materials into a dissolution reactor preferably consisting of a rotating vessel having an interior lining of acid and abrasion resistant material. An acid is combined with the materials in the reactor and agitated for a selected time period. Thereafter, the liquid remaining in the reactor is separated from the residual solids and removed. The liquid contains dissolved Y.sub.2 O.sub.3 which is precipitated, preferably using oxalic acid to produce yttrium oxalate [Y.sub.2 (C.sub.2 O.sub.4).sub.3.9H.sub.2 O]. The Y.sub.2 (C.sub.2 O.sub.4).sub.3.9H.sub.2 O is ultimately removed from the solution and calcined to produce high purity Y.sub.2 O.sub.3.

Abstract: This invention concerns an improvement in a molding die for use in casting in which a metal article is molded by charging a molten metal to the inside of a molding die comprising paired male and female dies, and then cooling the temperature of the molten metal to a solidification region and a solidification range where the solid phase and the liquid phase are present together, wherein one or both of paired male and female dies constituting the molding die equipped retractably with a pressurizing insert for applying the pressure to the molten metal charged to the molding die is made of ceramics thereby obtaining a molding die that can facilitate the control for the temperature distribution over the entire molding die, particularly, within the molding die upon cooling to solidify the molten metal, as well as having sufficient strength such as thermal shock resistance, shock resistance and durability enabling to mold a high temperature metal article by solidifying the high temperature molten metal of about 600.

Abstract: A process for continuous direct chill casting of aluminum alloys, particularly aluminum-lithium alloys. The molten alloy is cast in a mold containing a header comprising delaminated vermiculite or spodumene or lithium aluminate. The header preferably comprises delaminated vermiculite blended with wollastonite, lime, silica, and wood fiber. The mixture is slurried with water, molded into shape, compressed to expel water, steam cured, and dried. The header forms ingots of good quality and has excellent resistance to attack by molten aluminum-lithium alloys.

Abstract: A mold and method for producing, or casting a high-melting metal article from a high-melting metal having a melting point of about 900.degree. to 1600.degree. C.

Abstract: The present invention relates to a mold material for casting pure titanium or a titanium alloy which comprises one or more chief materials selected from among silica-alumina mixtures, mullite and spinel and a hardening agent comprising a phosphate and a basic metal oxide and a process for casting pure titanium or a titanium alloy by the use of said mold material. This mold material forms a refractory structure having a melting point higher than that of pure titanium or a titanium alloy therein to enable pure titanium which is unstable in a molten state to be cast stably.

Abstract: An yttria-based slurry comprising a dense grain yttria powder and a non-aqueous-based binder is used as a mold facecoat and corecoat for investment casting of reactive metals such as titanium and titanium alloys.

Abstract: A foundry mold for casting to size a material-forming die of a zinc-base alloy is formed by compacting and sintering a particulate mixture composed predominantly of alumina particles and containing raw kyanite particles. During sintering, the raw kyanite particles react to expand the mold by an amount sufficient to compensate for shrinkage of the solidified alloy during cool down.

Abstract: Molding material composed of casting sand coated with a thermosetting resin and hydrous magnesium silicate clay mineral which may be impregnated with an acid and/or coated with a thermosetting resin, and a shell mold produced from the molding material. This material and mold minimize generation of smoke and irritating gases at the time of mold making and casting.

Abstract: A high temperature mold assembly particularly adapted for thermit reaction welding, and mold components and mold compositions therefor, based on a mined aggregate containing carbon and silica and thermosetting, non-hygroscopic resinous binder.

Abstract: A molding medium and process for making it, preferably for use in the evaporative pattern casting process, is disclosed. The molding medium comprises, in one embodiment, a base granular molding material having spherically shaped grains wherein the individual grains of the material are coated with a refractory material. Preferably the grains are coated first with a binding agent and then mixed with a refractory material, which may be zirconium oxide. After coating, the material is fired at a high temperature, crushed and screened to size, according to one method. Alternatively, the base molding material may itself be a refractory material, in which case the refractory material is mixed with a binding agent to agglomerate the base material into substantially spherical particles and a refractory coating need not be applied. In either embodiment, substantially spherical free-flowing particles are produced having a low angle of repose.

Abstract: A core or insert primarily for the production of metal and alloy castings, e.g. of complicated internal shape, is a refractory body comprising essentially a water-soluble salt and a calcium silicate, the calcium silicate being present in amount of at least 45%, by weight, based on the total weight of calcium silicate and water-soluble salt, and the water-soluble salt and the calcium silicate having a particular particle size distribution. The calcium silicate is preferably a wollastonite.The core may be removed from the cast or moulded article by dissolution in water.

Abstract: An alumina-carbon shape is manufactured from a composition comprising 1-8 weight percent fine silicon, 1-16 weight percent reactive alumina, 1-30 weight percent calcined fluidized bed coke, 1-30 weight percent of a spalling inhibiting additive, and the balance of the mix synthetic alumina, plus the additions of 5-10 weight percent of a high carbon yielding resin as a molding vehicle and 0.5-4 weight percent solvent, and up to 2 weight percent of a low temperature curing agent, such as, paraformaldehyde or hydrochloric acid. The mix is formed at ambient temperature into a shape through an injection molding process. Solidification is accomplished by curing in the mold at a temperature less than 100.degree. C. After stripping the shape from the mold, the solvents are removed from the shape by drying at a temperature above 100.degree. C. The shapes are then heated to a temperature above 550.degree. C. to coke the resin.

Abstract: A mold for casting particularly a core, is produced by mixing refractory particles with colloidal alumina to give a slurry, filling said slurry in a pattern having water absorption properties, solidifying the slurry, followed by drying and firing. The resulting mold, particularly core, has high dimensional accuracy with no cracks.

Abstract: An improved core material is used in an improved method of forming cores for investment casting of articles. The core material comprises fused silica, synthetic amorphous silica, a refractory material, and a binder. The synthetic amorphous silica has a surface area of at least 200 square meters per gram. Even though the synthetic amorphous silica has a relatively large surface area, it has a particle size of less than 10 microns and is 5% or less by weight of the total weight of the solid constituents of the core material slurry. After a green core has been formed in a core mold it is fired to set the core material. During firing, the green core shrinks in size. To compensate for deviations in the size of a finished core from a desired size, the percentage of synthetic amorphous silica in the core material slurry is varied.

Abstract: Magnesium and magnesium alloy castings are produced using porous, calcined plaster of Paris molds by filling the mold cavity and the pores communicating therewith with a pressurized inhibitor gas comprising sulfur hexafluoride and monitoring temperature conditions during cooling of the cast metal using a thermocouple placed in the mold close to the sprue whereby, in the event of an exotherm as indicated by non-decreasing temperature, the mold may be broken to prevent an explosion.

Abstract: A method of making a dental prosthesis includes providing an upper or a lower impression of the oral cavity of a patient; and filling such impression with a castable mixture comprising (1) a ceramic composition containing a major proportion of magnesia and a significant minor proportion of alumina and (2) an aqueous composition containing silica as the essential ingredient, the ratio of the aqueous silica composition to the ceramic composition being such as to render the latter flowable. The mixture is then permitted to harden in the impression, and the resulting hardened model is removed from the impression. Thereafter, a liquefied metal composition is spray-coated on to a selected portion of the model to form a metallic prosthetic base, which is separated from the selected portion of the model and provided with a porcelain coating on its exterior surface.

Abstract: The invention provides an improved method for the preparation of a porous ongy body of a metal or alloy having an open cell structure. The basic principle of the method is the pressurized casting of a melt of the metal or alloy with a preheated powder compact of an inorganic compound soluble in a solvent to fill up the pores and dissolving away the inorganic compound with a solvent after solidification of the melt.

Abstract: A casting process is described, the process embodying the use of cores made from material comprising dicalcium silicate. Dicalcium silicate undergoes various phase changes during heating and cooling one of which, the .beta. to .gamma. transformation, is accompanied by a large volume increase. By using this feature casting cores may be produced which disintegrate during cooling of the solidified metal.