In an embodiment, a method of manufacturing customized ceramic labial/lingual orthodontic brackets by additive manufacturing may comprise measuring dentition data of a profile of teeth of a patient, based on the dentition data, creating a three-dimensional computer-assisted design (3D CAD) model of the patient's teeth, and saving the 3D CAD model, designing a virtual 3D CAD bracket structure model for a single labial or lingual bracket structure based upon said 3D CAD model, importing data related to the 3D CAD bracket structure model into an additive manufacturing machine, and directly producing the bracket with the additive manufacturing machine by layer manufacturing from an inorganic material including at least one of a ceramic, a polymer-derived ceramic, and a polymer-derived metal.

There is provided a ceramic substrate including: a silicon nitride crystal phase containing a plurality of silicon nitride crystals, and grain boundaries between the silicon nitride crystals; and a silicate phase containing magnesium silicate crystals and rare earth silicate crystals, respective maximum particle sizes of the magnesium silicate crystals and the rare earth silicate crystals being smaller than that of the silicon nitride crystals, the silicate phase being positioned in the grain boundaries.

A composite bond coat may include a matrix and a reinforcing component. The matrix may be formed from silicon-based particles, and the reinforcing component includes silicon-based ceramic particles. The composite bond coat may be formed by introducing a precursor composition into a plume generated by a thermal spray gun to generate a thermal spray stream. The thermal spray stream may be directed at a major surface defined by a substrate of the component to form the composite bond coat. The precursor composition includes the matrix component and the reinforcing component.

A composite bond coat may include a matrix and a reinforcing component. The matrix may be formed from silicon-based particles, and the reinforcing component includes silicon-based ceramic particles. The composite bond coat may be formed by introducing a precursor composition into a plume generated by a thermal spray gun to generate a thermal spray stream. The thermal spray stream may be directed at a major surface defined by a substrate of the component to form the composite bond coat. The precursor composition includes the matrix component and the reinforcing component.

A porous material includes aggregate particles and a binding material. In the aggregate particles, oxide films containing cristobalite are provided on surfaces of particle bodies that are silicon carbide particles or silicon nitride particles. The binding material contains cordierite and binds the aggregate particles together in a state where pores are provided therein. The mass ratio of the cordierite to the whole of the porous material is in the range of 10 to 40 mass %. The oxide films that exist between the particle bodies and the binding material have a thickness less than or equal to 0.90 m.

A porous material includes aggregate particles and a binding material. In the aggregate particles, oxide films containing cristobalite are provided on surfaces of particle bodies that are silicon carbide particles or silicon nitride particles. The binding material contains cordierite and binds the aggregate particles together in a state where pores are provided therein. The mass ratio of the cordierite to the whole of the porous material is in the range of 10 to 40 mass %. The oxide films that exist between the particle bodies and the binding material have a thickness less than or equal to 0.90 m.

A rubber mold according to an embodiment is for CIP processing of a green compact with a plate shape. The rubber mold includes one or more approximately columnar hole sections are provided on at least one or more bottom surfaces. Further, when a diameter of an opening of the hole section is denoted by a and a maximum depth of the hole section is denoted by b, a/b<2.0 is satisfied.

A ceramic substrate is formed of a polycrystalline ceramic and has a supporting main surface. The supporting main surface has a roughness of 0.01 nm or more and 3.0 nm or less in terms of Sa. The number of projections and depressions with a height of 1 nm or more in a square region with 50 m sides on the supporting main surface is less than 5 on average, and the number of projections and depressions with a height of 2 nm or more in the square region is less than 1 on average.

A ceramic substrate is formed of a polycrystalline ceramic and has a supporting main surface. The supporting main surface has a roughness of 0.01 nm or more and 3.0 nm or less in terms of Sa. The number of projections and depressions with a height of 1 nm or more in a square region with 50 m sides on the supporting main surface is less than 5 on average, and the number of projections and depressions with a height of 2 nm or more in the square region is less than 1 on average.

A silicon nitride substrate including silicon nitride crystal grains and a grain boundary phase and having a thermal conductivity of 50 W/m.Math.K or more, wherein, in a sectional structure of the silicon nitride substrate, a ratio (T2/T1) of a total length T2 of the grain boundary phase in a thickness direction with respect to a thickness T1 of the silicon nitride substrate is 0.01 to 0.30, and a variation from a dielectric strength mean value when measured by a four-terminal method in which electrodes are brought into contact with a front and a rear surfaces of the substrate is 20% or less. The dielectric strength mean value of the silicon nitride substrate can be 15 kV/mm or more. According to above structure, there can be obtained a silicon nitride substrate and a silicon nitride circuit board using the substrate in which variation in the dielectric strength is decreased.