Abstract: The oxidation resistance of a superalloy casting such as an equiaxed, directionally solidified, or single crystal casting, is improved by melting, pouring, or casting the alloy so as to react with a magnesium or calcium-bearing ceramic material. Magnesium or calcium is introduced into the alloy through a controlled reaction between the alloy and the magnesium or calcium-bearing ceramic material.

Abstract: A high melting point and/or low ductility metal or alloy is investment cast in a refractory mold including a facecoat layer and a plurality of back-up layers wherein at least one back-up layer is a relatively weak, sacrificial layer. This latter layer is crushed as necessary as the casting cools below its ductile-to-brittle transition temperature to avoid hot tearing or cracking of the solidified metal or alloy during cooling in the mold.

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: A technique of preparing graphite molds for growing single crystals of active metals and alloys. The inner surfaces of the graphite molds in contact with the growing up single crystals are of passive graphite. Various types of single crystal selectors are available in the graphite molds.

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 ceramic shell mold and method of making the same. The ceramic shell mold includes a facecoat layer comprised of a first ceramic material. A plurality of alternating layers are formed overlaying the facecoat layer. The alternating layers are comprised of a second ceramic material and a third ceramic material, the third ceramic material having thermophysical properties different than the second ceramic material. The second ceramic material and the third ceramic material are preferably a zircon-based material and an alumina-based material, respectively. The resultant ceramic shell mold has a greater high temperature creep resistance than a shell mold formed solely from the second ceramic material or solely from the third ceramic material.

Abstract: An investment compound for use in a precision casting mold comprises MgO powder and Al.sub.2 O.sub.3 powder as main constituents in such a manner that the MgO powder and/or the Al.sub.2 O.sub.3 powder are or is in the range of 100 .mu.m or less in grain size and of 10% or more in weight precent, whereby even when a high-temperature active casting material such as titanium is used, the material provides a casting having a very beautiful surface with no bubbles formed therein and can positively compensate for shrinkage due to the solidification of cast material in a lost-wax process and can advantageously provide the casting at lower prices.

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: An alloy having the following composition limits by weight:Chromium 13-15%, silicon 3.4-4.2%, boron 1.7-2.3% and the balance nickel, is cast in a mold that is made by the lost wax process from CaCO.sub.3, so that when the molten metal alloy is cast in the preheated mold at 2300.degree. F., held in a furnace at 1750.degree. F. for an hour, and then rapidly cooled to room temperature. The casting will have a fairly low hardness of R.sub.c 30.+-.3 so that it can be machined. After machining, the casting is heated to a temperature of 1150.degree. F. for at least three hours before cooling, resulting in a casting that is hardened to R.sub.c 45 to R.sub.c 50.

Abstract: The invention concerns a composition for making a coating consisting essentially of a refractory material selected from the group consisting of yttrium oxide, zirconium oxide, fused yttrium oxide, fused zirconium oxide, fused stabilized zirconium oxide, and fused mixtures of zirconium oxide and yttrium oxide; and a sufficient amount of an yttria sol binder. The composition can be used to prepare refractory materials, casting and core molds.

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: 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 method of making an investment shell mold in such a way that the shell is protected from cracking on simultaneous firing and removal of the pattern. The method includes application of conventional molding materials in the first slurry and stucco coats. By conventional molding materials is meant molding materials that are transparent to microwaves and microwave energy. In the second slurry and/or stucco coats, and in later coats if necessary, a certain amount of microwave susceptible material, such as graphite or certain metal oxides including Fe.sub.2 O.sub.4, MnO.sub.2, NiO and cobalt oxide, is added. Then, if necessary to achieve sufficient mold strength, additional coats of conventional molding materials are applied. After drying is complete, the pattern and mold are exposed to microwave radiation. This radiation interacts with the microwave susceptible material to heat the pattern adjacent to the mold surface, while avoiding generalized heating of the pattern.

Abstract: A process is disclosed for providing a refractory composition on a surface. In the process an acidic hybrid binder composition and a basic colloidal silica sol composition are provided. The surface is coated with the acidic hybrid binder composition and the colloidal silica sol composition so that each colloidal silica sol composition coat contacts an acidic hybrid binder composition coat to form alternating layers of the acidic hybrid binder composition and the colloidal silica sol composition. Each acidic hybrid binder composition layer and each colloidal silica sol layer are dried prior to coating with the alternating layer to a sufficient hardness such that lift-off of the applied coatings from the surface is inhibited when a subsequent coating step is performed. A refractory laminate composition is also disclosed which comprises a plurality of layers of hardened acidic hybrid binder composition alternating with a plurality of layers of hardened basic colloidal silica sol composition.

Abstract: Process for the production of precision castings with well-defined reproduction of detail and a great accuracy of measurement, by which the pattern to be reproduced is equipped with a drainage apparatus, having at least one duct extending outside the molding box, and the molding material containing phosphate as the bonding agent is poured in the molding box and solidified. After the pattern is removed from the solidified mold, by the introduction of compressed gas, the water of the solidified material is pressed out, and after calcining at a temperature of at least 250.degree. C., the mold is connected to a vacuum line and evacuated. The molten metal mass is then poured into the mold while the vacuum is maintained and solidified.

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: A method for the manufacture of an investment shell mold is disclosed which comprises applying to the surface of a wax pattern at least one layer of slurry formed by dissolving in an organic solvent a soluble organic cellulose derivative containing a dispersed metallic oxide, subsequenty applying to the first layer at least one layer of slurry formed by mixing a refractory powder with a cellulose binder, and thereafter causing the applied slurry layers to set and removing the pattern by the ordinary method.

Abstract: Method for investment casting of metal matrix composites by vacuum infiltration using a ceramic mold formed directly on the pattern.

Abstract: A ceramic shell mold having the properties of being easily removed from the metal castings, high permeability, and a fired strength that can be controlled at levels lower than conventional molds, characterized in that the refractory used to make the mold is at least in part hydrated alumina.