A method to form a machinable ceramic matrix composite comprises forming a porous ceramic multilayer on a surface of a fiber preform. In one example, the porous ceramic multilayer comprises a gradient in porosity in a direction normal to the surface. In another example, the porous ceramic multilayer includes low-wettability particles having a high contact angle with molten silicon, where an amount of the low-wettability particles in the porous ceramic multilayer varies in a direction normal to the surface. After forming the porous ceramic multilayer, the fiber preform is infiltrated with a melt, and the melt is cooled to form a ceramic matrix composite with a surface coating thereon. An outer portion of the surface coating is more readily machinable than an inner portion of the surface coating. The outer portion of the surface coating is machined to form a ceramic matrix composite having a machined surface with a predetermined surface finish and/or dimensional tolerance.

A method to form a machinable ceramic matrix composite comprises forming a porous ceramic multilayer on a surface of a fiber preform. In one example, the porous ceramic multilayer comprises a gradient in porosity in a direction normal to the surface. In another example, the porous ceramic multilayer includes low-wettability particles having a high contact angle with molten silicon, where an amount of the low-wettability particles in the porous ceramic multilayer varies in a direction normal to the surface. After forming the porous ceramic multilayer, the fiber preform is infiltrated with a melt, and the melt is cooled to form a ceramic matrix composite with a surface coating thereon. An outer portion of the surface coating is more readily machinable than an inner portion of the surface coating. The outer portion of the surface coating is machined to form a ceramic matrix composite having a machined surface with a predetermined surface finish and/or dimensional tolerance.

Hybrid composite materials including carbon nanotube sheets and flexible ceramic materials, and methods of making the same are provided herein. In one embodiment, a method of forming a hybrid composite material is provided, the method including: placing a layer of a first flexible ceramic composite on a lay-up tooling surface; applying a sheet of a pre-preg carbon fiber reinforced polymer on the flexible ceramic composite; curing the flexible ceramic composite and the pre-preg carbon fiber reinforced polymer sheet together to form a hybrid composite material; and removing the hybrid composite material from the lay-up tooling surface, wherein the first flexible ceramic composite comprises an exterior surface of the hybrid composite material.

A shell and a method for processing the shell are provided. The method includes: coating a sol prepared in advance on an inner surface of a ceramic shell prepared in advance; sintering the ceramic shell coated with the sol by using a sintering process, and forming a transition layer having nano-sized micro-pores on the inner surface of the ceramic shell.

A method to produce a protective surface layer having a predetermined topography on a ceramic matrix composite is described. The method includes applying a slurry layer to a surface of a fiber preform, and drying the slurry layer to form a particulate layer. A surface of the particulate layer is machined to improve surface smoothness and to form a machined surface. A ceramic tape is attached to the machined surface, and a tool comprising one or more features to be imprinted is placed on the ceramic tape, thereby forming a compression assembly. Heat and pressure are applied to the compression assembly to consolidate and bond the ceramic tape to the machined surface, while the one or more features of the tool are imprinted. Thus, a protective surface layer having a predetermined topography is formed.

A method to produce a protective surface layer having a predetermined topography on a ceramic matrix composite is described. The method includes applying a slurry layer to a surface of a fiber preform, and drying the slurry layer to form a particulate layer. A surface of the particulate layer is machined to improve surface smoothness and to form a machined surface. A ceramic tape is attached to the machined surface, and a tool comprising one or more features to be imprinted is placed on the ceramic tape, thereby forming a compression assembly. Heat and pressure are applied to the compression assembly to consolidate and bond the ceramic tape to the machined surface, while the one or more features of the tool are imprinted. Thus, a protective surface layer having a predetermined topography is formed.

A method for producing a decorated mineral composite body, a decorated mineral composite body and the use of a multilayer film for producing a decorated mineral composite body.

A method of producing a ceramic matrix composite including a protective ceramic coating thereon comprises applying a surface slurry onto an outer surface of an impregnated fiber preform. The surface slurry includes particulate ceramic solids dispersed in a flowable preceramic polymer comprising silicon, and the impregnated fiber preform comprises a framework of ceramic fibers loaded with particulate matter. The flowable preceramic polymer is cured, thereby forming on the outer surface a composite layer comprising a cured preceramic polymer with the particulate ceramic solids dispersed therein. The cured preceramic polymer is then pyrolyzed to form a porous ceramic layer comprising silicon carbide, and the impregnated fiber preform and the porous ceramic layer are infiltrated with a molten material comprising silicon. After infiltration, the molten material is cooled to form a ceramic matrix composite body with a protective ceramic coating thereon.

A method of producing a ceramic matrix composite including a protective ceramic coating thereon comprises applying a surface slurry onto an outer surface of an impregnated fiber preform. The surface slurry includes particulate ceramic solids dispersed in a flowable preceramic polymer comprising silicon, and the impregnated fiber preform comprises a framework of ceramic fibers loaded with particulate matter. The flowable preceramic polymer is cured, thereby forming on the outer surface a composite layer comprising a cured preceramic polymer with the particulate ceramic solids dispersed therein. The cured preceramic polymer is then pyrolyzed to form a porous ceramic layer comprising silicon carbide, and the impregnated fiber preform and the porous ceramic layer are infiltrated with a molten material comprising silicon. After infiltration, the molten material is cooled to form a ceramic matrix composite body with a protective ceramic coating thereon.

A system and a method are provided for inhibiting pyrrhotite-caused damage to concrete structures. The system includes at least one concrete structure, a quantity of migratory corrosion-inhibiting solution, a quantity of concrete reinforcing solution, and a water sealing substance. The concrete structure can be any structure where the concrete aggregate contains pyrrhotite. The quantity of migratory corrosion-inhibiting solution is applied to the concrete structure to prevent further oxidation of pyrrhotite within the concrete structure. The quantity of concrete reinforcing solution is applied to the concrete structure to lower the porosity of the concrete structure and strengthen the overall integrity of the concrete structure. The water sealing substance is applied to the concrete structure to repel water from the concrete structure preventing any further chemical reactions with the pyrrhotite.