The bonded ceramic assembly of the present disclosure includes a first substrate made of ceramic, a second substrate made of ceramic, and a bonding layer positioned between the first substrate and the second substrate. The bonding layer contains aluminum, at least one of calcium and magnesium, a rare earth element, silicon, and oxygen. Out of a total 100 mass % of all of the components making up the bonding layer, the bonding layer contains from 33 mass % to 65 mass % aluminum in terms of oxide, a total of from 27 mass % to 60 mass % calcium and magnesium in terms of oxide, and from 2 mass % to 12 mass % rare earth element in terms of oxide. The silicon content, in terms of oxide, of the surface of the bonding layer is greater than the silicon content, in terms of oxide, of the interior of the bonding layer.

The bonded ceramic assembly of the present disclosure includes a first substrate made of ceramic, a second substrate made of ceramic, and a bonding layer positioned between the first substrate and the second substrate. The bonding layer contains aluminum, at least one of calcium and magnesium, a rare earth element, silicon, and oxygen. Out of a total 100 mass % of all of the components making up the bonding layer, the bonding layer contains from 33 mass % to 65 mass % aluminum in terms of oxide, a total of from 27 mass % to 60 mass % calcium and magnesium in terms of oxide, and from 2 mass % to 12 mass % rare earth element in terms of oxide. The silicon content, in terms of oxide, of the surface of the bonding layer is greater than the silicon content, in terms of oxide, of the interior of the bonding layer.

Disclosed herein are embodiments of low temperature co-fireable dielectric materials which can be used in conjunction with high dielectric materials to form composite structures, in particular for isolators and circulators for radiofrequency components. Embodiments of the low temperature co-fireable dielectric materials can be scheelite or garnet structures, for example, bismuth vanadate. Adhesives and/or glue is not necessary for the formation of the isolators and circulators.

A method to produce a ceramic matrix composite with controlled surface characteristics includes: applying a scrim ply to a surface of a fiber preform, where the fiber preform includes silicon carbide fibers coated with boron nitride; infiltrating the fiber preform and the scrim ply with a slurry, thereby forming an impregnated ply on an impregnated fiber preform; infiltrating the impregnated fiber preform and the impregnated ply with a melt comprising silicon, and then cooling, thereby forming a ceramic matrix composite having a ceramic surface layer thereon, where the ceramic surface layer has a predetermined thickness and is devoid of boron; machining or grit blasting the ceramic surface layer to form an intermediate layer suitable for coating; and depositing an environmental barrier coating on the intermediate layer. Thus, a ceramic matrix composite coated with the environmental barrier coating is formed with the intermediate layer in between.

Disclosed is a joined ceramic body comprising a first ceramic portion comprising a first ceramic, a second ceramic portion comprising a second ceramic, and a joining layer formed between the first ceramic portion and the second ceramic portion. The joining layer has a bond thickness of from 0.5 to 20 um and comprises silicon dioxide having a total impurity content of 20 ppm and less. A method of making the joined ceramic body and a joining material are also disclosed.

Provided is a polycrystalline ceramic substrate to be bonded to a compound semiconductor substrate with a bonding layer interposed therebetween, wherein at least one of relational expression (1) 0.7<α.sub.1/α.sub.2<0.9 and relational expression (2) 0.7<α.sub.3/α.sub.4<0.9 holds, where α.sub.1 represents a linear expansion coefficient of the polycrystalline ceramic substrate at 30° C. to 300° C. and α.sub.2 represents a linear expansion coefficient of the compound semiconductor substrate at 30° C. to 300° C., and α.sub.3 represents a linear expansion coefficient of the polycrystalline ceramic substrate at 30° C. to 1000° C. and α.sub.4 represents a linear expansion coefficient of the compound semiconductor substrate at 30° C. to 1000° C.

Provided is a polycrystalline ceramic substrate to be bonded to a compound semiconductor substrate with a bonding layer interposed therebetween, wherein at least one of relational expression (1) 0.7<α.sub.1/α.sub.2<0.9 and relational expression (2) 0.7<α.sub.3/α.sub.4<0.9 holds, where α.sub.1 represents a linear expansion coefficient of the polycrystalline ceramic substrate at 30° C. to 300° C. and α.sub.2 represents a linear expansion coefficient of the compound semiconductor substrate at 30° C. to 300° C., and α.sub.3 represents a linear expansion coefficient of the polycrystalline ceramic substrate at 30° C. to 1000° C. and α.sub.4 represents a linear expansion coefficient of the compound semiconductor substrate at 30° C. to 1000° C.

A method for manufacturing a sensor element that includes: a pair of electrodes; a ceramic layer having a hollow space that is to be an air introduction hole; and a first layer and a second layer stacked at both surfaces of the ceramic layer, One of the electrodes is in communication with the hollow space, The method includes: preparing an unsintered ceramic sheet, and a burn-out material sheet having a thickness different from that of the unsintered ceramic sheet, the burn-out material sheet having, in a plane orthogonal to the direction of an axial line O, a cross-sectional area substantially identical to a cross-sectional area of the pre-sintering hollow space; placing the burn-out material sheet in the pre-sintering hollow space; pressing the sheets so as to have an identical thickness; and burning out the burn-out material sheet.

A heater includes a base, a resistive heating body, and a terminal portion. The base is formed of ceramic and has a plate shape. The resistive heating body is located in the base. The terminal portion is electrically connected to the resistive heating body. The base includes a protruding portion surrounding the terminal portion, on a lower surface side. The protruding portion is formed of a ceramic member, and the terminal portion passes through a through hole formed in the ceramic member. The ceramic member is bonded to at least one of the lower surface of the base or the terminal portion.

A ceramic joined body (1) includes: a pair of ceramic plates (2,3) that include a conductive material; and a conductive layer (4) and an insulating layer (5) that are interposed between the pair of ceramic plates (2, 3), a porosity at an interface between the pair of ceramic plates (2, 3) and the insulating layer (5) is 4% or less, and a ratio of an average primary particle diameter of an insulating material which forms the insulating layer (5) to an average primary particle diameter of an insulating material which forms the ceramic plates (2, 3) is more than 1.