The present disclosure relates to the manufacture of silicon nitride implants with increased surface roughness and porosity.

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.

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.

Provided are a coating structure, a turbine part having the same, and a method for manufacturing the coating structure. The coating structure is provided on a surface of a base portion including a ceramic matrix composite. The coating structure is layered on the surface of the base portion, and includes a bond coat layer formed of a rare-earth silicate and a top coat layer layered on the bond coat layer. The residual stress present in the bond coat layer is compressive residual stress. The oxygen permeability coefficient of the bond coat layer is no greater than 10.sup.−9 kg.Math.m.sup.−1.Math.s.sup.−1 at a temperature of not lower than 1200° C. and a higher oxygen partial pressure of not less than 0.02 MPa. The bond coat layer may contain carbonitride particles or carbonitride whiskers.

Provided are a coating structure, a turbine part having the same, and a method for manufacturing the coating structure. The coating structure is provided on a surface of a base portion including a ceramic matrix composite. The coating structure is layered on the surface of the base portion, and includes a bond coat layer formed of a rare-earth silicate and a top coat layer layered on the bond coat layer. The residual stress present in the bond coat layer is compressive residual stress. The oxygen permeability coefficient of the bond coat layer is no greater than 10.sup.−9 kg.Math.m.sup.−1.Math.s.sup.−1 at a temperature of not lower than 1200° C. and a higher oxygen partial pressure of not less than 0.02 MPa. The bond coat layer may contain carbonitride particles or carbonitride whiskers.

A new class of multi-component rare earth multi-silicate materials has been created for use in harsh environments such as gas turbine engines. Moreover, by combining two-or-more rare earth disilicates the properties (for example, thermal expansion, thermal conductivity, etc.) can be tailored to fit specific applications, such as having a matching thermal expansion with that of silicon-based composites and a low thermal conductivity close to that of 1 W/m K. Applications can be extended for use with other material classes such as MCrAlY, MAX-phase, and refractory metal alloys, utilizing a thermal expansion of up to about 15−10.sup.−6 /° C. By mixing of specific sets of rare earth disilicates it is possible to obtain a high entropy or entropy stabilized mixture, and utilize features such as “sluggish diffusion”, and more.

A new class of multi-component rare earth multi-silicate materials has been created for use in harsh environments such as gas turbine engines. Moreover, by combining two-or-more rare earth disilicates the properties (for example, thermal expansion, thermal conductivity, etc.) can be tailored to fit specific applications, such as having a matching thermal expansion with that of silicon-based composites and a low thermal conductivity close to that of 1 W/m K. Applications can be extended for use with other material classes such as MCrAlY, MAX-phase, and refractory metal alloys, utilizing a thermal expansion of up to about 15−10.sup.−6 /° C. By mixing of specific sets of rare earth disilicates it is possible to obtain a high entropy or entropy stabilized mixture, and utilize features such as “sluggish diffusion”, and more.

A method includes depositing a porous silicon coat on a substrate to form a bulk phase of a bond coat and introducing a reactive gas into pores of the porous silicon coat. The reactive gas reacts with silicon adjacent the pores of the porous silicon coat to form a ceramic phase of the bond coat comprising a silicon-based ceramic and reduce porosity of the porous silicon coat. A temperature of the reactive gas is greater than about 1000° C.

A method includes depositing a porous silicon coat on a substrate to form a bulk phase of a bond coat and introducing a reactive gas into pores of the porous silicon coat. The reactive gas reacts with silicon adjacent the pores of the porous silicon coat to form a ceramic phase of the bond coat comprising a silicon-based ceramic and reduce porosity of the porous silicon coat. A temperature of the reactive gas is greater than about 1000° C.

An environmental resistant coating member includes a SiC long fiber-reinforced ceramics substrate and an environmental barrier coating layer provided on the whole surface of the SiC long fiber-reinforced ceramics substrate. The environmental barrier coating layer includes a SiAlON bonding layer laminated on the SiC long fiber-reinforced ceramics substrate, a mullite layer laminated on the SiAlON bonding layer, a reaction inhibition layer laminated on the mullite layer, and a gradient layer formed on the reaction inhibition layer that gradually changes from a rare-earth disilicate to a rare-earth monosilicate. The reaction inhibition layer includes at least one of an alumina layer, a garnet layer, and a rare-earth (mono)silicate layer. When the reaction inhibition layer includes two or more of these layers, the layers are formed in the order of the alumina layer, the garnet layer, and the rare-earth (mono)silicate layer from a mullite layer side toward a gradient layer side.