Abstract: A method of preparing a ceramic matrix composite (CMC) component that includes a protective ceramic layer comprises adhering at least one flexible ceramic tape to a ceramic fiber preform, where the at least one flexible ceramic tape comprises ceramic particles dispersed in an organic binder phase. After the adhering, the at least one flexible ceramic tape is heated to a temperature sufficient to volatilize the organic binder phase, thereby forming a porous ceramic layer on at least a portion of the ceramic fiber preform. After the heating and volatilizing, the ceramic fiber preform and the porous ceramic layer are infiltrated with a molten material, thereby forming a CMC component including, on at least a portion thereof, a protective ceramic layer.

Abstract: An improved method of preparing ceramic matrix composites includes blending one or more ceramic powders with one or more paraffinic binders to form a slurry; introducing a ceramic fiber preform into a die or mold; heating the slurry to a temperature above the melting point of the one or more paraffinic binders to form a heated slurry; introducing the heated slurry into the die or mold, the heated slurry infiltrating the ceramic fiber preform to form a slurry infiltrated preform; cooling the die or mold below the solidification temperature of the paraffinic binder, thereby forming a solid component from the slurry infiltrated preform; removing the solid component from the die or mold; heating the solid component to a temperature whereby the paraffinic binder is removed; and densifying the solid component after removing the paraffinic binder, thereby forming the ceramic matrix composite.

Abstract: End mills are disclosed which may be made monolithically of ceramic or other materials. The cutting portions of the end mills have lengths of cut that are no more than twice their cutting diameters and cores which are at least 0.7 times their cutting diameters. Their axial blades have cutting edges with negative radial rake and are separated by helical flutes. Their cutting ends have negative axial rake and are gashed ahead of center and have radial cutting edges with negative rake. Such end mills also have radiused corners and gashes transitioning from radial to axial at a flute. Methods of milling materials using such ceramic end mills are also disclosed.

Abstract: An improved method of preparing ceramic matrix composites includes blending one or more ceramic powders with one or more paraffinic binders to form a slurry; introducing a ceramic fiber preform into a die or mold; heating the slurry to a temperature above the melting point of the one or more paraffinic binders to form a heated slurry; introducing the heated slurry into the die or mold, the heated slurry infiltrating the ceramic fiber preform to form a slurry infiltrated preform; cooling the die or mold below the solidification temperature of the paraffinic binder, thereby forming a solid component from the slurry infiltrated preform; removing the solid component from the die or mold; heating the solid component to a temperature whereby the paraffinic binder is removed; and densifying the solid component after removing the paraffinic binder, thereby forming the ceramic matrix composite.

Abstract: A method of preparing a ceramic matrix composite (CMC) component that includes a protective ceramic layer comprises adhering at least one flexible ceramic tape to a ceramic fiber preform, where the at least one flexible ceramic tape comprises ceramic particles dispersed in an organic binder phase. After the adhering, the at least one flexible ceramic tape is heated to a temperature sufficient to volatilize the organic binder phase, thereby forming a porous ceramic layer on at least a portion of the ceramic fiber preform. After the heating and volatilizing, the ceramic fiber preform and the porous ceramic layer are infiltrated with a molten material, thereby forming a CMC component including, on at least a portion thereof, a protective ceramic layer.

Abstract: End mills are disclosed which may be made monolithically of ceramic or other materials. The cutting portions of the end mills have lengths of cut that are no more than twice their cutting diameters and cores which are at least 0.7 times their cutting diameters. Their axial blades have cutting edges with negative radial rake and are separated by helical flutes. Their cutting ends have negative axial rake and are gashed ahead of center and have radial cutting edges with negative rake. Such end mills also have radiused corners and gashes transitioning from radial to axial at a flute. Methods of milling materials using such ceramic end mills are also disclosed.

Abstract: Composite materials comprising titanium diboride, silicon carbide and carbon-containing scavenger additions are useful in electrolytic aluminum production cells. The carbon-containing scavenger additions may include tungsten carbide, boron carbide and/or carbon. The amounts of titanium diboride, silicon carbide and carbon-containing scavenger are controlled in order to provide optimum performance. The titanium diboride/silicon carbide composite materials may be used as cathodes in electrolytic aluminum production cells and are electrically conductive, exhibit desirable aluminum wetting behavior, and are capable of withstanding exposure to molten cryolite, molten aluminum and oxygen at elevated temperatures during operation of such cells.

Abstract: Composite materials comprising titanium diboride, silicon carbide and carbon-containing scavenger additions are useful in electrolytic aluminum production cells. The carbon-containing scavenger additions may include tungsten carbide, boron carbide and/or carbon. The amounts of titanium diboride, silicon carbide and carbon-containing scavenger are controlled in order to provide optimum perfonnance. The titanium diboride/silicon carbide composite materials may be used as cathodes in electrolytic aluminum production cells and are electrically conductive, exhibit desirable aluminum wetting behavior, and are capable of withstanding exposure to molten cryolite, molten aluminum and oxygen at elevated temperatures during operation of such cells.

Abstract: Composite materials comprising titanium diboride and boron nitride that are used to line electrolytic aluminum production cells are disclosed. The composite materials may be used to line the side walls and/or bottom wall of the cell. The ratio of titanium diboride to boron nitride may be controlled in order to provide the desired level of electrical conductivity depending upon the particular region of the cell in which the liner plate is installed. The titanium diboride/boron nitride composite materials exhibit desirable aluminum wetting behavior, and are capable of withstanding exposure to molten cryolite, molten aluminum and oxygen at elevated temperatures during operation of the electrolytic aluminum production cells.