A multilayer substrate that includes a first ceramic layer that is a dense body, a second ceramic layer that has open pores, and a resin layer adjacent the second ceramic layer, wherein a material of the resin layer is present in the open pores of the second ceramic layer.

Disclosed herein is a dual density disc comprising a dense outer tube comprising alumina having a purity of greater than 99%; and a porous core comprising alumina of a lower density than a density of the dense outer tube; wherein the porous core has an alumina purity of greater than 99%. Disclosed herein too is method comprising disposing in a dense outer tube a slurry comprising alumina powder and a pore former; heating the dense outer tube with the slurry disposed therein to a temperature of 300 to 600? C. to activate the pore former; creating a porous core in the dense outer tube; and sintering the dense outer tube with the porous core at a temperature of 800 to 2000? C. in one or more stages.

A carbon-carbon composite preform including a plurality of layers including carbon fibers or carbon-precursor fibers, the layers include a first exterior layer defining a first major surface, a second exterior layer defining a second major surface, and at least one interior layer disposed between the first exterior layer and the second exterior layer, the at least one interior layer having a peripheral region that forms a portion of an outer surface of the preform. The preform includes needled fibers, where at least some needled fibers extend through two or more layers. The preform has an exterior region and a core region, where the exterior region includes at least the peripheral region of at least one interior layer. The needled fibers define a first needled fiber number density (NFND) in the exterior region and a second greater NFND in at least a portion of the core region.

A multilayer ceramic substrate that includes a first layer positioned at a surface of the multilayer ceramic substrate, a second layer adjacent the first layer and positioned inward of the first layer, and a surface layer electrode disposed on a surface of the first layer. The first layer has a porosity of 13% or less and a maximum pore size of 10 m or less. The second layer has a porosity of 14% or less and a maximum pore size of 11 m or less.

Laminated carbon-carbon composites can be used as an ablative material, but they are often prone to delamination under thermally induced interlaminar shear and tension. Graded carbon-carbon composites with a sacrificial or ablative layer that is integral with one or more underlying layers and not fully dense can address these issues and provide other advantages. Such graded carbon-carbon composites can include a densified base layer containing a first portion of a carbonaceous matrix, and an outer ablative layer that is integral with the densified base layer and contains a second portion of the carbonaceous matrix. The carbonaceous matrix in the densified base layer has a first porosity, and the carbonaceous matrix in the outer ablative layer has a second porosity that is higher than that of the densified base layer. Methods for forming graded carbon-carbon composites can include heating a partially densified base layer and a carbonaceous matrix precursor above a carbonization temperature.

Disclosed is a ceramic matrix component having a fibrous core and a ceramic matrix composite shell surrounding at least a portion of the fibrous core. The ceramic matrix composite shell comprises a fibrous preform. The fibrous core has a greater porosity than the fibrous preform. A method of making the ceramic matrix component is also disclosed.

A method of making a ceramic matrix composite (CMC) article by combining a preceramic polymer with one or more sized nanopowders and optional surfactants and/or solvents to form a mixture suitable for 3D printing, depositing the mixture on a mandrel, curing it to form a green body, and pyrolyzing the green body such that the nanocrystalline surface of the CMC article has sufficiently the same surface roughness and figure accuracy of the mandrel to enable the CMC article to be used without further polishing. The mixture can be a paste or slurry that is self supporting and exhibit pseudoplastic rheology. The preceramic polymer is preferably a precursor to SiC, and the nanopowders preferably comprise SiC. The article can be densified by using polymer infiltration pyrolysis, with or without nanoparticles. The curing and pyrolysis of the article can be performed with microwave radiation. An example structure is a gradient density lattice with a mirror surface for use in a cryogenically cooled infrared optical system such as an orbiting space telescope.

The present invention discloses a slurry feedstock for extrusion-based three-dimensional, 3D, printing of a functionally graded article, and/or for casting an article under a low pressure at a room temperature, a method of preparing the same, a method of extrusion-based 3D printing and/or casting, and a system therefor. The slurry feedstock comprises a build material comprising a metal, a ceramic or any combinations thereof, an organic polymer binder, an additive and a volatile organic solvent. The build material mixed with the additive and the organic polymer binder dissolved with the volatile organic solvent form a first pre-mix and a second pre-mix, respectively, that are mixed to form a substantially homogeneous and flowable slurry mixture that is used for producing articles.

In some examples, a method including depositing a resin and a plurality of carbon fibers via a print head of a three-dimensional printing system to form a carbon fiber preform including a plurality of individual carbon fiber layers, wherein each individual layer of the plurality of individual carbon fiber layers includes the resin and carbon fibers, and wherein the carbon fiber preform exhibits at least one of a non-uniform composition of the resin within the preform, different types of the carbon fibers within the preform, or non-uniform fiber orientation within the preform.

An article that includes a substrate; a first layer including yttria and zirconia or hafnia, where the first layer has a columnar microstructure and includes predominately the zirconia or hafnia; a second layer on the first layer, the second layer including zirconia or hafnia, ytterbia, samaria, and at least one of lutetia, scandia, ceria, neodymia, europia, and gadolinia, where the second layer includes predominately zirconia or hafnia, and where the second layer has a columnar microstructure; and a third layer on the second layer, the third layer including zirconia or hafnia, ytterbia, samaria, and a rare earth oxide including at least one of lutetia, scandia, ceria, neodymia, europia, and gadolinia, where the third layer has a dense microstructure and has a lower porosity than the second layer.