Abstract: The invention concerns a method for the preparation of moulds and cores used in the casting of metals. In the method the moulds and cores are prepared out of a granular moulding material as well as out of a binder agent that binds the moulding-material granules together. The binder agent used for the moulding mix is an anorganic salt, sodium aluminate, soluble in water and having a high melting point, as a rule higher than the casting temperature, which said salt is mixed with the granular moulding material as binder-agent solution dissolved in water. In the moulding process the binder agent is crystallized out of its water solution by microwave energy so that the binder agent forms a solid bridge between the granules of moulding material, said bridge binding the granules of moulding material together.

Abstract: An additive for green moulding sands for use in foundry industry comprising a "stabilized" and polyhydroxylated carbohydrate, in particular as aqueous solution, and preferably consisting of a monosaccharidic and/or oligosaccharidic derivatives where any of the aldehydic and ketonic functions have been selectively reduced or oxidated. The additive improves the flowability and plasticity of the moulding said with a reduced moisture demand and a better surface finishing of the castings.

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: For the fabrication of a disintegratable sand core, refractory particles such as silica sand are mixed with two binders, one consisting of an inorganic substance such as a silicate and the other consisting of a starch, and, preferably, with water. The two binders function to cancel the disadvantages arising from the use of only either. The mixture is introduced into a core box molded essentially of materials pervious to microwave energy. Exposed to microwave energy through the core box, the mixture hardens in the shape of the core box cavity. For the production of cores having greater surface stability at room temperature, the starch and water are first mixed together into a paste, and this paste is added to the refractory particles together with the inorganic binder, thereby assuring uniform dispersion of the starch throughout the mixture.

Abstract: Foundry moulds and, more especially, cores are made by the use of a binder comprising ammonium polyacrylate and zinc oxide or a metal salt to form a complex ammonium metal polyacrylate which is mixed with the sand and after the core or mould has been formed in a warm box warm air is passed through it to drive off the ammonia and form a water-insoluble metal polyacrylate which bonds the grains of sand together. The resulting core or mould has a good shelf life combined with excellent knock-out behavior.

Abstract: An investment shell mold of a texture having a stucco material dispersed in mullite useful for grain-oriented casting of a Ni-base super alloy is produced by preparing a slurry having alumina powder or a mixture of alumina powder with at least one ceramic powder selected from among zircon powder, mullite powder, and spinel powder blended with a silicate binder such as silica sol, applying the slurry to the surface of an expendable pattern made typically of wax for the production of the mold, then applying thereon a stucco material, thereafter repetitively applying substantially equal slurry and stucco material alternately thereon until the applied layers assume a prescribed thickness, allowing the applied layers to solidify, then heating the hardened layers to a temperature exceeding 1,400.degree. C. thereby enabling SiO.sub.2 produced from the binder and the alumina powder in the slurry to react with each other and produce mullite.

Abstract: A foundry binder of the water-soluble alkali metal polyacrylate type having additives that include lime is cured by the use of the vapour of a low-boiling point organic ester having not more than three carbon atoms, primarily methyl formate, entrained in a carrier gas, e.g. carbon dioxide or nitrogen.

Abstract: An investment material for dental casting comprises 100 parts by weight of a mixture of hemihydrate gypsum, quartz and/or cristobalite and 2 to 5 parts by weight of natural starch optionally with 0.1 to 1.0 part by weight of soluble starch.

Abstract: Binder, filler, and refractory compositions and methods of using and making these compositions are disclosed. The binder composition comprises colloidal silica, a liquid material containing Si--OH groups, a solvent which is capable of solubilizing the liquid material and the colloidal silica, and at least one aprotic, non-ionic, non-metallic, organic compound which contains at least one element selected from phosphorus, sulfur, boron and nitrogen and which stabilizes the binder composition against self-gelling. The liquid material and the colloidal silica are present in a ratio by weight of from about 10:1 to about 1:10 respectively. The liquid material has at least about 20% by weight SiO.sub.2. The colloidal silica contains at least about 15% by weight SiO.sub.2.

Abstract: A die material particularly suitable for the making of castings or the like, comprises 50 to 80 parts of magnesium oxide, 10-40 parts of alumina, 2 to 6 parts of monohydrated ammonium phosphate, and 1 to 4 parts of dihydrated ammonium phosphate. The dry blend thus formed, when mixed with a chilled liquid binder containing a collodial silica sol of about 40 weight percent solids content in the ratio of one portion of the liquid binder and from 2 to 5 portions of the dry blend, forms a ceramic slurry which can be readily set in hot water within 4 to 10 minutes. The set ceramic casting is then dry heated to about 250.degree. F. for one to two hours. Molten metal is then applied on the casting for forming a metal jacket to use in dental prostheses.

Abstract: A binder for a foundry core or mould consists of an alkali metal salt of a polybasic organic acid or of a polymerized monobasic organic acid, for example sodium polyacrylate, an alkaline earth metal hydroxide such as calcium hydroxide, one or more polyvalent metal oxides, preferably magnesium oxide, and calcium citrate, together with water. The mixture may also include another polyvalent metal oxide, for example zinc oxide. The inclusion of calcium citrate in the binder composition, particularly in the presence of magnesium oxide, has been found to reduce the problem of `softening back` in which the strength of the core or mould interior deteriorates over storage periods of a few days due to the continued absorption of carbon dioxide from the atmosphere in damp conditions.

Abstract: Aqueous alkali metal silicate solutions are made by dissolving an alkali silica powder that includes insoluble impurities and putting the impurities into stable suspension with a suspending agent such as a cellulose derivative. When used as a foundry binder the solutions give improved early strength and improved breakdown properties.

Abstract: Aqueous alkali metal silicate bonding compositions having a molar ratio of SiO.sub.2 :Me.sub.2 O of 2.4:1 to 3.4:1, wherein Me is sodium and/or potassium, a solids content of about 35 to 50 percent by weight, and containing triethanolamine. The bonding compositions can be mixed with fillers such as quartz sand and used for the manufacture of molded forms for the casting of metals.

Abstract: A combination of foundry aggregate, binder and hardener for the foundry aggregate wherein a linear metal polyphosphate or ammonium polyphosphate is used as the binder, and the hardener is phosphoric acid or a mixture of phosphoric acid and a source of polyvalent metal cations.

Abstract: A binder for a foundry mould or core comprises an alkali metal salt of a polyvalent organic acid or a polymerized monovalent organic acid, for example sodium polyacrylate, and an alkaline earth hydroxide such as calcium hydroxide, together with a suitable solvent. Up to 80% of the calcium hydroxide may be replaced by a polyvalent metal oxide or hydroxide. The mixture may include small proportions of other materials, such as aluminum sulphate. It is important that the pH of the organic acid salt solution before mixing with the alkaline earth hydroxide should not be too high and it should preferably be between 5 and 8, in particular between 5.7 and 6.6.

Abstract: A combination binder and hardener therefor for a foundry aggregate wherein a linear metal polyphosphate or ammonium polyphosphate is used as the binder, the hardener is a mixture of phosphoric acid and a source of polyvalent metal cations.

Abstract: A water soluble core comprises a mold product prepared by a mixture of sand, potassium carbonate as a first binder and at least one of barium carbonate and alkali silicate as a second binder. This water soluble core is utilized for a method of manufacturing a cast rotor for forming ventilation ducts of an induction motor.

Abstract: Aggregate-containing products bonded by an aluminosilicate hydrogel are disclosed. A system of two-part mixing and blending of binder components with various granular-like aggregates, modifiers and/or fillers is described in which the resulting compositions are temporarily fluid and formable for short, controllable periods of time but which thereafter become strong, rigid, adherent, erosion resistant composites, requiring little or no external heat supply to achieve full set. The compositions can be formulated for molding on suitable forms or patterns, and may also be prepared in slurry form suitable for spray coating or sealing applications. A wide variety of products can be manufactured of the compositions, including investment molds and cores for foundry use, as well as non-foundry products such as heat and electrical insulators, construction blocks, panels, coating slurries, etc. which may be of essentially solid or foamed (cellular) construction.

Abstract: An improved binder for a foundry aggregate comprising aluminum dihydrogen phosphate in combination with ammonium polyphosphate, potassium polyphosphate, potassium olivine phosphate, volcanic ash, sodium silicate, phosphoric acid or mixtures thereof.

Abstract: An inorganic cement binder for a foundry aggregate comprising, in combination, potassium olivine phosphate and as a hardener therefor, water, aqueous sodium silicate, or aqueous phosphoric acid.

Abstract: In a method for producing a mold for metal casting capable of being easily disintegrated by water which comprises the steps of kneading alumina sand with hydrous sodium aluminate as a binder, forming the kneaded mixture into the desired mold shape and then passing carbon dioxide gas through the mold to decompose sodium aluminate and harden it; the improvement wherein the kneading of alumina sand with the binder before mold formation is carried out in an atmosphere of carbon dioxide gas to decompose 50 to 80% of the sodium aluminate in advance.

Abstract: A binder and a hardener therefor for a foundry aggregate. The binder is a resin obtained by reacting phosphoric acid with a mineral silicate. The hardener is a linear alkali metal polyphosphate, ammonium polyphosphate, a source of polyvalent cations, potassium olivine phosphate and other metal silico-phosphates or aluminum dihydrogen phosphate or mixtures thereof. A process for manufacturing molds and cores from a mixture of said binder and hardener and foundry aggregate.

Abstract: A hydrogel binder for a foundry aggregate comprising, in combination, a metal silico-phosphate and as a hardener therefor a mixture of aluminum dihydrogen phosphate, water and phosphoric acid and a process for manufacturing molds and cores from same.

Abstract: Foundry mold and core compositions containing sand, an alkali metal silicate and a hardening agent therefor include, and are characterized by, a demolding agent comprising a finely divided inorganic metal compound, together with from 1 to 99% by weight thereof, of a hydrated alumina having an average grain size ranging from 0.2 to 5.mu..

Abstract: A method for binding particulate materials which involves mixing the particulate material with a solution containing lithiumions, blending sodium silicate into the mixture and subsequently shaping the mixture to the desired form and curing same by microwave radiation.

Abstract: A rapid method for dehydrating a water-sand mixture containing sodium or potassium silicate to produce a strongly bonded sand core is disclosed. The silicate is mixed in a water/silicate ratio of 1.45-3.22:1 and is limited to 0.25-3% of the weight of the mixture. The core box is semi-foraminous and partially transparent to micro-wave energy whereby generated vapor is reduced due to the heated inner surface of the core box (some degree of lossiness) and due to some escape through limited core-box openings. The controlled supersaturated environment about the core serves to prevent micro-porosity and surface defects when controlled micro-wave energy is used to heat cure the mixture. To promote resistance to humidity after curing, the mixture may contain 0.5% zinc oxide, chromic oxide, or aminoaldehyde.