Abstract: A method is described for improving resistance to chemical attack by aluminum or magnesium in refractory components. In one method, a slurry is formed comprising calcium silicate-containing refractory material and a barium-containing compound. This slurry is placed in a mold, then dewatered to form a component which is hydrothermally processed to form a final component. In a second procedure, a silica-containing porous refractory component is impregnated with an aqueous solution of an oxide or hydroxide of barium or strontium and thereafter dried in air.

Abstract: A composite material is rapidly melted by furnishing a pre-wetted composite material in the form of granules, placing the granules into an induction coil, and powering the induction heater to melt the metal matrix portion of the granules to form a molten mixture. High power inputs to the induction coil may be used, so that the granules are rapidly heated to their melting point and to temperatures above the melting point, from which the molten mixture may be cast. Because of the rapid heating, otherwise-reactive composite materials may be prepared by melting in air.

Abstract: A composite material mixture of free flowing reinforcement particles in a molten metal is solidified at a cooling rate greater than about 15.degree. C. per second between the liquidus and solidus temperatures of the matrix alloy. This high cooling rate imparts a homogeneous structure to the solid composite material. Care is taken to avoid the introduction of gas bubbles into the molten composite material while the mixture is stirred to prevent segregation of the particles. For viscous melts, an artificial surface layer such as a fiberglass blanket may be used to prevent entrapment of bubbles during pre-casting stirring. Additionally, gas bubbles are removed from the molten mixture by filtering and skimming.

Abstract: A method and apparatus for preparing a continuous flow of castable composite materials of nonmetallic particles in a metallic matrix, wherein particles are mixed into a molten metallic alloy to wet the molten metal to the particles, and the particles and metal are sheared past each other to promote wetting of the particles by the metal. The mixing occurs while minimizing the introduction of gas into the mixture, and while minimizing the retention of gas at the particle-liquid interface. Mixing is done at or below a maximum temperature whereat the particles do not substantially chemically degrade in the molten metal during the time required for processing, and casting is done at a temperature sufficiently high that there is no solid metal present in the melt.

Abstract: An apparatus for filtering molten material, such as a molten metal-ceramic particle mixture, includes a porous cloth filter located so that the mixture must pass through the cloth filter, and a mechanical filter shaker that prevents the accumulation of filtered solids on the porous cloth filter. Where a further degree of filtration is required, there is a second filter located so that material leaving the porous cloth filter passes through the second filter after it passes through the porous cloth filter, and a mechanism that prevents an accumulation of filtered solids on the second filter. The second filter is desirably a porous media filter.

Abstract: A composite material mixture of free flowing reinforcement particles in a molten metal is solidified at a cooling rate greater than about 15.degree. C. per second between the liquidus and solidus temperatures of the matrix alloy. This high cooling rate imparts a homogeneous structure to the solid composite material. Care is taken to avoid the introduction of gas bubbles into the molten composite material while the mixture is stirred to prevent segregation of the particles. For viscous melts, an artificial surface layer such as a fiberglass blanket may be used to prevent entrapment of bubbles during pre-casting stirring. Additionally, gas bubbles are removed from the molten mixture by filtering and skimming.

Abstract: A cast composite material is prepared from a modified aluminum-containing matrix and reinforcement particles mixed into the matrix. From about 15 to about 130, preferably from about 20 to about 50, parts per million of an element, preferably beryllium, that forms a more stable oxide than magnesium oxide is included in the matrix alloy. The stable-oxide-forming element reduces the amount and thickness of the aluminum oxide and other oxides formed at the surface of the melt, which otherwise may be mixed into the melt to cause microstructural irregularities in the matrix of the cast composite material.

Abstract: A cast composite material is prepared from a modified aluminum-containing matrix and reinforcement particles mixed into the matrix. From about 15 to about 130, preferably from about 20 to about 50, parts per million of an element, preferably beryllium, that forms a more stable oxide than magnesium oxide is included in the matrix alloy. The stable-oxide-forming element reduces the amount and thickness of the aluminum oxide and other oxides formed at the surface of the melt, which otherwise may be mixed into the melt to cause microstructural irregularities in the matrix of the cast composite material.

Abstract: Lithium feed to an aluminum-lithium alloy production system is achieved at a highly controlled rate by advancing a plunger at a predetermined volumetric rate into a body of molten lithium retained in a holding vessel to displace the lithium toward an overflow port through which it is fed into a mixing vessel where it is combined with molten aluminum. Control of the aluminum feed rate is achieved by maintaining a constant head height upstream of an orifice. The thus metered streams of molten lithium and aluminum are then combined in a vortex bowl, whose outlet is then fed to a casting station.