A method and apparatus (1) for treating a filter (2) for filtering particulate matter from exhaust gas. A reservoir (3) containing a dry powder (4) is provided. A vacuum generator (6) establishes a primary gas flow through a porous structure of the filter (2) by applying a pressure reduction to an outlet face of the filter (2). A spray device (7) receives the dry powder (4) from a transport device (8) and sprays the dry powder (4) towards the inlet face of the filter (2). A controller (9) is configured to control operation of at least the vacuum generator (6) and the spray device (7).

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 infiltrating a porous preform for a gas turbine engine is provided, which comprises providing a chamber for infiltrating a porous preform. The porous preform is positioned within a slurry confinement fixture within the chamber. A vacuum is created in the chamber. A solvent is added to the slurry confinement fixture until a pressure in the chamber is substantially equal to an equilibrium partial pressure of the solvent. A slurry is added to the slurry confinement fixture. The slurry includes the solvent and a particulate. The pressure in the chamber is increased, and the slurry is urged into the porous preform.

Systems and methods for infiltrating porous ceramic matrix composite (CMC) preforms to form CMC articles are disclosed. One method may include positioning the porous CMC preform in an opening of a die set for an infiltration system, and flowing a molten densifier over the porous CMC preform in a first flow direction to infiltrate a plurality of voids formed between each of a plurality of ply stacks of the CMC preform. The method may also include flowing the molten densifier over the porous CMC preform in a second flow direction, distinct from the first flow direction, to infiltrate the plurality of voids formed between each of the plurality of ply stacks of the CMC preform. The second flow direction may be substantially parallel to a predetermined, unidirectional material orientation of at least one ply stack of the plurality of ply stacks of the CMC preform.

A resistance temperature detector (RTD) that uses a ceramic matrix composite (CMC), such as a silicon carbide fiber-reinforced silicon carbide matrix, as an active temperature sensing element, which can operate at temperatures greater than 1000 C. or even 1600 C. Conductive indium tin oxide or a single elemental metal such as platinum is deposited on a dielectric or insulating layer such as mullite or an environmental barrier coating (EBC) on the substrate. Openings in the layer allow etching of the CMC surface in order to make high quality ohmic contacts with the conductive material, either directly or through a silicide diffusion barrier such as ITO. The RTD can measure both temperature and strain of the CMC. The use of an EBC, which typically is deposited on the CMC by the manufacturer, as the insulating or dielectric layer can be extended to other devices such as strain gages and thermocouples that use the CMC as a sensing element. The EBC can be masked and etched to form the openings. A conductive EBC can be used as the silicide diffusion barrier.

A process for treating a substrate made of stone material, preferably in the form of slabs, is provided which process improves the mechanical, thermal and catalytic properties of the substrate. The process includes applying a protective coating to the outer surface of the substrate made of stone material and, to improve adhesion of the protective coating to the outer surface of the substrate, preliminarily subjecting the substrate to one or more pre-treatment steps that eliminate or reduce the presence of pollutants and porosity on the surface of the substrate. The pre-treatment of the substrate made of stone material comprises at least one step of treatment under vacuum conditions inside an autoclave, preferably under pressure conditions lower than 10.sup.2 mbar. Then, after having brought the substrate back to ambient pressure, it is possible to apply and effectively adhere the protective coating to the surface of the stone material.

A process for treating a substrate made of stone material, preferably in the form of slabs, is provided which process improves the mechanical, thermal and catalytic properties of the substrate. The process includes applying a protective coating to the outer surface of the substrate made of stone material and, to improve adhesion of the protective coating to the outer surface of the substrate, preliminarily subjecting the substrate to one or more pre-treatment steps that eliminate or reduce the presence of pollutants and porosity on the surface of the substrate. The pre-treatment of the substrate made of stone material comprises at least one step of treatment under vacuum conditions inside an autoclave, preferably under pressure conditions lower than 10.sup.2 mbar. Then, after having brought the substrate back to ambient pressure, it is possible to apply and effectively adhere the protective coating to the surface of the stone material.

A method of forming a ceramic-metal composite part is described herein. The method includes maintaining molten metal in an interior of a housing in a liquefied state, the interior including a first chamber, a second chamber, and a port defined therebetween. The method further includes sealing the port such that the molten metal in the first chamber is maintained at a first liquid level, suspending a part at a height within the first chamber above the first liquid level, forming a pressure differential between the first chamber and the second chamber, unsealing the port such that molten metal from the second chamber flows into the first chamber, and resealing the port when the molten metal in the first chamber reaches a second liquid level such that the ceramic part is submerged in the molten metal.

A method of forming a ceramic-metal composite part is described herein. The method includes maintaining molten metal in an interior of a housing in a liquefied state, the interior including a first chamber, a second chamber, and a port defined therebetween. The method further includes sealing the port such that the molten metal in the first chamber is maintained at a first liquid level, suspending a part at a height within the first chamber above the first liquid level, forming a pressure differential between the first chamber and the second chamber, unsealing the port such that molten metal from the second chamber flows into the first chamber, and resealing the port when the molten metal in the first chamber reaches a second liquid level such that the ceramic part is submerged in the molten metal.

A ceramic heat shield for a gas turbine. The ceramic heat shield has a ceramic body containing aluminium oxide and has a surface layer of the ceramic body which contains yttrium aluminium garnet as reaction coating material. A gas turbine includes such a ceramic heat shield and a method produces such a ceramic heat shield.