The invention discloses micron-nano pore gradient oxide ceramic films with biological activity, which are prepared by the following methods: The surface structures are biomedical engineering materials; Inorganic precursor coating solutions or the organic precursor coating solutions are prepared with or without micron and nanopore additives; The surface structures of the substrate are treated in the following steps: (1) The surfaces of the substrate are coated by the inorganic precursor coating solutions or the organic precursor coating solutions with or without micron and nanopore additives; (2) The substrate with coatings are dried, sintered, naturally cooled, and cleaned. (3) The biomedical engineering materials with the micron-nanopore gradient oxide ceramic films, especially biomimetic micro-nanoporous gradient alumina film, yttrium partially stabilized zirconia film, and alumina doped yttrium partially stabilized zirconia films in this invention greatly improve biocompatibility and biological activity.

An article may include a substrate defining at least one at least partially obstructed surface. The substrate includes at least one of a ceramic or a ceramic matrix composite. The article also may include a multilayer, multi-microstructure environmental barrier coating on the at least partially obstructed substrate. The multilayer, multi-microstructure environmental barrier coating includes a first layer comprising a rare earth disilicate and a substantially dense microstructure; and a second layer on the first layer. The second layer includes a columnar microstructure and at least one of a rare earth monosilicate or a thermal barrier coating composition comprising a base oxide comprising zirconia or hafnia; a primary dopant comprising ytterbia; a first co-dopant comprising samaria; and a second co-dopant comprising at least one of lutetia, scandia, ceria, gadolinia, neodymia, or europia.

An article may include a substrate defining at least one at least partially obstructed surface. The substrate includes at least one of a ceramic or a ceramic matrix composite. The article also may include a multilayer, multi-microstructure environmental barrier coating on the at least partially obstructed substrate. The multilayer, multi-microstructure environmental barrier coating includes a first layer comprising a rare earth disilicate and a substantially dense microstructure; and a second layer on the first layer. The second layer includes a columnar microstructure and at least one of a rare earth monosilicate or a thermal barrier coating composition comprising a base oxide comprising zirconia or hafnia; a primary dopant comprising ytterbia; a first co-dopant comprising samaria; and a second co-dopant comprising at least one of lutetia, scandia, ceria, gadolinia, neodymia, or europia.

An article may include a substrate defining at least one at least partially obstructed surface. The substrate includes at least one of a ceramic or a ceramic matrix composite. The article also may include a multilayer, multi-microstructure environmental barrier coating on the at least partially obstructed substrate. The multilayer, multi-microstructure environmental barrier coating includes a first layer comprising a rare earth disilicate and a substantially dense microstructure; and a second layer on the first layer. The second layer includes a columnar microstructure and at least one of a rare earth monosilicate or a thermal barrier coating composition comprising a base oxide comprising zirconia or hafnia; a primary dopant comprising ytterbia; a first co-dopant comprising samaria; and a second co-dopant comprising at least one of lutetia, scandia, ceria, gadolinia, neodymia, or europia.

An article may include a substrate defining at least one at least partially obstructed surface. The substrate includes at least one of a ceramic or a ceramic matrix composite. The article also may include a multilayer, multi-microstructure environmental barrier coating on the at least partially obstructed substrate. The multilayer, multi-microstructure environmental barrier coating includes a first layer comprising a rare earth disilicate and a substantially dense microstructure; and a second layer on the first layer. The second layer includes a columnar microstructure and at least one of a rare earth monosilicate or a thermal barrier coating composition comprising a base oxide comprising zirconia or hafnia; a primary dopant comprising ytterbia; a first co-dopant comprising samaria; and a second co-dopant comprising at least one of lutetia, scandia, ceria, gadolinia, neodymia, or europia.

The disclosure describes a method for forming a surface layer of a ceramic matrix composite (CMC) article. The technique includes depositing a slurry on a surface of an infiltrated CMC. The slurry includes a carrier material, a binder, a plasticizer, and solid particles. The solid particles include a plurality of fine ceramic particles defining a fine particle average size less than about 5 micrometers. The method further includes drying the slurry to form an article having an outer surface layer that includes the solid particles on the infiltrated CMC. The method further includes machining at least a portion of the outer surface layer of the article. The method further includes infiltrating the article with a molten infiltrant to form a composite article.

A part includes a substrate, having, adjacent to a surface of the substrate, at least a portion that is made from a material that contains silicon, and an environmental barrier formed on the surface of the substrate, the environmental barrier including at least a first layer including a rare earth disilicate of formula RE.sup.a.sub.2Si.sub.2O.sub.7 present at a molar content lying in the range 70% to 99.9%, where RE.sup.a is a rare earth element; and at least one rare earth oxide of formula RE.sup.b.sub.2O.sub.3 present at a molar content lying in the range 0.1% to 30%, where RE.sup.b is a rare earth element different from RE.sup.a.

A part includes a substrate, having, adjacent to a surface of the substrate, at least a portion that is made from a material that contains silicon, and an environmental barrier formed on the surface of the substrate, the environmental barrier including at least a first layer including a rare earth disilicate of formula RE.sup.a.sub.2Si.sub.2O.sub.7 present at a molar content lying in the range 70% to 99.9%, where RE.sup.a is a rare earth element; and at least one rare earth oxide of formula RE.sup.b.sub.2O.sub.3 present at a molar content lying in the range 0.1% to 30%, where RE.sup.b is a rare earth element different from RE.sup.a.

A coating according to an exemplary embodiment of this disclosure, among other possible things includes a bond coat including gettering particles and diffusive particles dispersed in a matrix; a top coat disposed over the bond coat, the top coat includes metal silicate particles; and an intermediate layer between the bond coat and the top coat. The intermediate layer includes hafnium silicate particles and matrix. A concentration of metal silicate in the intermediate layer is less than a concentration of metal silicate in the top coat. An article is also disclosed.

An example article includes a substrate and a barrier coating on the substrate extending from an inner interface facing the substrate to an outer surface opposite the inner interface. The barrier coating includes a bulk matrix and a plurality of discrete plugs inset within the bulk matrix and dispersed across the outer surface of the barrier coating. An example technique includes forming the barrier coating on the substrate of a component.