Methods for forming a sintered bond coat (64) on a silicon-based substrate (14) and articles (50) formed by the methods are disclosed. The methods include applying a bond coat slurry on the silicon-based substrate (14), drying the bond coat slurry on the silicon-based substrate to form a dried bond coat (44), and sintering the dried bond coat (44) in an oxidizing atmosphere to form a sintered bond coat (64) on the silicon-based substrate (14). The bond coat slurry includes a bond coat patching material in a bond coat fluid carrier. The articles (50) include a silicon-based substrate (14), a sintered bond coat (64) formed on the silicon-based substrate (14), and a sintered environmental barrier coating (EBC) (66) formed on the sintered bond coat (64). The sintered bond coat (64) includes a silicon-based phase and an oxide of the silicon-based phase.

Methods for forming a sintered bond coat (64) on a silicon-based substrate (14) and articles (50) formed by the methods are disclosed. The methods include applying a bond coat slurry on the silicon-based substrate (14), drying the bond coat slurry on the silicon-based substrate to form a dried bond coat (44), and sintering the dried bond coat (44) in an oxidizing atmosphere to form a sintered bond coat (64) on the silicon-based substrate (14). The bond coat slurry includes a bond coat patching material in a bond coat fluid carrier. The articles (50) include a silicon-based substrate (14), a sintered bond coat (64) formed on the silicon-based substrate (14), and a sintered environmental barrier coating (EBC) (66) formed on the sintered bond coat (64). The sintered bond coat (64) includes a silicon-based phase and an oxide of the silicon-based phase.

Methods for improving the wear performance of silicon nitride and/or other ceramic materials, particularly to make them more suitable for use in manufacturing biomedical implants.

Methods for improving the wear performance of silicon nitride and/or other ceramic materials, particularly to make them more suitable for use in manufacturing biomedical implants.

A honeycomb structure according to at least one embodiment of the present invention includes: partition walls defining cells each extending from a first end surface of the honeycomb structure to a second end surface thereof to form a fluid flow path; and an outer peripheral wall. The partition walls and the outer peripheral wall are each formed of ceramics containing silicon carbide and silicon. A surface of the silicon has formed thereon an oxide film having a thickness of from 0.1 ?m to 5.0 ?m.

A honeycomb structure according to at least one embodiment of the present invention includes: partition walls defining cells each extending from a first end surface of the honeycomb structure to a second end surface thereof to form a fluid flow path; and an outer peripheral wall. The partition walls and the outer peripheral wall are each formed of ceramics containing silicon carbide and silicon. A surface of the silicon has formed thereon an oxide film having a thickness of from 0.1 ?m to 5.0 ?m.

Methods for forming ceramic cores are disclosed. A ceramic core formed using the method of the present application includes a silica depletion zone encapsulating an inner zone. The inner zone includes mullite and the silica depletion zone includes alumina. The method includes heat-treating a ceramic body in a non-oxidizing atmospheric condition for an effective temperature and time combination at a pressure less than 10.sup.2 atmosphere to form the silica depletion zone at a surface of the ceramic core.

Methods for forming ceramic cores are disclosed. A ceramic core formed using the method of the present application includes a silica depletion zone encapsulating an inner zone. The inner zone includes mullite and the silica depletion zone includes alumina. The method includes heat-treating a ceramic body in a non-oxidizing atmospheric condition for an effective temperature and time combination at a pressure less than 10.sup.2 atmosphere to form the silica depletion zone at a surface of the ceramic core.

The present invention concerns a method for obtaining a finished or semi-finished zirconia-based article (1), the article having a metallic external appearance and non-zero surface electrical conductivity, characterized in that the method includes the steps consisting in: taking at least one zirconia article, pre-shaped in its finished or semi-finished form; placing said article inside a chamber (10) in which a gaseous mixture is arranged, this gaseous mixture including at least a first hydrogen and carbon based gas compound in a first concentration (C1) and a second hydrogen and nitrogen based gas compound in a second concentration (C2); heating the gaseous mixture until the molecules of the first and second compounds dissociate and keeping said article in the reactive atmosphere thereby created to obtain diffusion of the carbon and nitrogen atoms in the external surface (2) of said article and to form stoichiometric carbonitride (ZrC.sub.xN.sub.y) at the surface, and prior to the step of heating the process gases contained in the chamber, a reduction step consisting in placing said article inside a chamber into which dihydrogen is injected and in heating the dihydrogen allowing diffusion towards the surface and release of the oxygen contained in said zirconia article.

The present invention concerns a method for obtaining a finished or semi-finished zirconia-based article (1), the article having a metallic external appearance and non-zero surface electrical conductivity, characterized in that the method includes the steps consisting in: taking at least one zirconia article, pre-shaped in its finished or semi-finished form; placing said article inside a chamber (10) in which a gaseous mixture is arranged, this gaseous mixture including at least a first hydrogen and carbon based gas compound in a first concentration (C1) and a second hydrogen and nitrogen based gas compound in a second concentration (C2); heating the gaseous mixture until the molecules of the first and second compounds dissociate and keeping said article in the reactive atmosphere thereby created to obtain diffusion of the carbon and nitrogen atoms in the external surface (2) of said article and to form stoichiometric carbonitride (ZrC.sub.xN.sub.y) at the surface, and prior to the step of heating the process gases contained in the chamber, a reduction step consisting in placing said article inside a chamber into which dihydrogen is injected and in heating the dihydrogen allowing diffusion towards the surface and release of the oxygen contained in said zirconia article.