A ferrite sintered magnet 100 comprises M-type ferrite crystal grains 4 having a hexagonal structure, two-crystal grain boundaries 6a formed between two of the M-type ferrite crystal grains 4, and multiple-crystal grain boundaries 6b surrounded by three or more of the M-type ferrite crystal grains 4. This ferrite sintered magnet 100 contains at least Fe, Ca, B, and Si, and contains B in an amount of 0.005 to 0.9 mass % in terms of B.sub.2O.sub.3, the two-crystal grain boundaries 6a and the multiple-crystal grain boundaries 6b contain Si and Ca, and in a cross-section parallel to a c-axis of the ferrite sintered magnet, when the number of multiple-crystal grain boundaries 6b having a maximum length of 0.49 to 5 m per cross-sectional area of 76 m.sup.2 is N, N is 7 or less.

The present disclosure provides a method for preparing a dielectric which can provide a low-dielectric loss dielectric not variable to frequency, wherein the dielectric shows a narrow variation in dielectric characteristics depending on temperature, undergoes no change in dielectric characteristics depending on frequency and thus has a low dielectric loss. The present disclosure also provides a dielectric prepared by the method.

The invention relates to a batch composition for producing a refractory product, a method for producing a refractory product, a refractory product, and to the use of a synthetic raw material.

A method for welding together at least two parts of green material, referred to as green parts, by means of co-sintering, comprising the following steps:assembling the at least two green parts at a junction zone of said parts so as to form a green one-piece assembly,de-binding the green one-piece assembly, andsintering the one-piece assembly so as to obtain a dense one-piece assembly forming a final part, characterised in that the two green parts (10, 12) each have a composition of different powder, so as to produce a final part (1) having at least two parts with different grain sizes.

A novel composite diamond film comprising of a relatively thick layer of UNCD (Ultrananocrystalline Diamond) with a Young's modulus of less than 900 GPa and a relatively thin MCD (microcrystalline diamond) outermost layer with a Young's modulus of greater than 900 GPa, has been shown to exhibit superior delamination resistance under extreme shear stress. It is hypothesized that this improvement is due to a combination of stress relief by the composite film with a slightly softer UNCD layer, a disruption of the fracture mechanism through the composite layer(s), and the near ideal chemical and thermal expansion coefficient match between the two diamond layers. The combination of a thick but softer underlying UNCD layer with a thin but harder overlying MCD layer provides an excellent compromise between the low deposition cost and smoothness of UNCD with the extreme hardness and unparalleled chemical, electrochemical and immunological inertness of even a thin layer of MCD. The MCD layer's roughness is minimized and its adhesion maximized by the use of a thin layer of MCD and its deposition on the smooth surface of the chemically nearly identical underlying UNCD layer. The composite film can be applied to any application currently utilizing a diamond or a similar hard film, including cutting tools, abrasive surfaces, electrochemistry, biomedical applications such as human implants or thermally conductive films and the like, requiring superior durability, chemical resistance and/or immunological inertness.

A measuring method for measuring a concentration of a donor element which is solid-solved in ceramic grains of a plurality of ceramic dielectric layers, includes measuring (a current value at 10 V/m when a direct voltage is applied to a plurality of ceramic dielectric layers at 125 degrees C.)/(a current value at 10 V/m when a direct voltage is applied to the plurality of the ceramic dielectric layers at 85 degrees C.), with respect to a multilayer ceramic capacitor having a multilayer structure in which each of the plurality of ceramic dielectric layers and each of a plurality of internal electrode layers are alternately stacked.

A bone substitute material is disclosed consisting of a zirconium dioxide ceramic having preferably an open porosity. The bone substitute material can be used in particle form or in block form.

The invention relates generally to uranium fuel in a nuclear reactor and, more particularly, the inclusion of a fuel additive component to the bulk fuel material. The fuel additive component is selected and provided in an amount such that it is effective to improve one or more properties of the bulk fuel material. The fuel additive component has a grain size that is less than the grain size of the bulk fuel material. The granular fuel additive component coats or covers the granular bulk fuel material.

The present invention relates to a light-transmitting ceramic sintered body which contains air voids having pore diameters of 1 m or more but less than 5 m at a density within the range of from 10 voids/mm.sup.3 to 4,000 voids/mm.sup.3 (inclusive), while having a closed porosity of from 0.01% by volume to 1.05% by volume (inclusive). With respect to this light-transmitting ceramic sintered body, a test piece having a thickness of 1.90 mm has an average transmittance of 70% or more in the visible spectrum wavelength range of 500-900 nm, and the test piece having a thickness of 1.90 mm has a sharpness of 60% or more at a comb width of 0.5 mm.

A two-step synthesis of SiC including initial exposure of carbon surfaces to Si vapor, followed by Si melt infiltration, is described herein. Interrupted differential thermal analysis (DTA) of amorphous C and Si powder mixtures and microstructure characterization are used to identify the stages of the reaction. Exposure to Si vapor yields a SiC layer with nanoscale porosity driven by the volume change associated with the reaction. This forms a continuous pore network that promotes subsequent melt access to the reaction front with the C. While the pores remain open, the vapor phase reaction proceeds at a nearly-constant rate and exhibits a strong temperature sensitivity, the latter due largely to the temperature sensitivity of the Si vapor pressure. The implications for enhancing the reactive melt infiltration process and fabrication of SiC matrices for ceramic composites are discussed.