A method for joining an optical part made of quartz glass and a supporting part made of ceramic includes forming a metal layer on a surface of the supporting part by electroless plating, polishing the formed metal layer with a polishing pad to form a first smoothed face on the supporting part surface, polishing a surface of the optical part with the polishing pad to form a second smoothed face, cleaning the first smoothed face and the second smoothed face with ultrasonic cleaning water, forming a first metal film on the first smoothed face by vapor deposition and forming a second metal film on the second smoothed face by vapor deposition, and joining the first metal film and the second metal film to each other by interatomic joining by atomic diffusion between the faces at which the first metal film and the second metal film contact with each other.

Provided is a method for producing a silicon nitride sintered body including: a step of molding and firing a raw material powder containing silicon nitride, in which an α-conversion rate of the silicon nitride contained in the raw material powder is less than or equal to 30 mass %. A thermal conductivity (at 20° C.) of the silicon nitride sintered body exceeds 100 W/m.Math.K and a fracture toughness (K.sub.IC) is greater than or equal to 7.4 MPa.Math.m.sup.1/2.

A soldering material (1) for active soldering, in particular for active soldering of a metallization (3) to a carrier layer (2) comprising ceramics, wherein the soldering material comprises copper and is substantially silver-free.

A joint body of the present disclosure includes a substrate including a base member having insulating properties and a metal layer positioned on a first main surface of the base member, a metal joint layer, and a metal member. The metal joint layer is positioned between the metal layer and the metal member of the substrate. The metal joint layer includes a nickel layer, a solder layer, and a composite layer containing a mix of nickel and solder. The nickel layer, the composite layer, and the solder layer are positioned in this order from the metal layer side to the metal member side. The nickel in the composite layer extends from the nickel layer in the thickness direction and forms protrusions and recesses.

Various embodiments include a method for producing a ceramic insulator for a high-voltage or medium-voltage switching system comprising: attaching a base material for an equipotential layer between two axially symmetrical ceramic structural elements; disposing the electrically conductive equipotential layer between the two ceramic structural elements; and joining the two ceramic structural elements to form a unitary body along a symmetry axis of a first of the two elements.

A heater includes a base body, terminal and joining layer. The base body is made of ceramic. The joining layer contains metal as a principal ingredient and is located between the base body and the terminal. The base body includes a first surface and second surface. The first surface faces an outer side of the base body and includes at least one of a region which is superimposed on the terminal and a region which is located on a periphery of the terminal. The second surface intersects with the first surface and is located on the side closer to an internal portion of the base body on the side away from the first surface. The joining layer extends from the terminal and first surface up to the second surface.

The present invention provides a gallium nitride sintered body and a gallium nitride molded article which have high density and low oxygen content without using a special apparatus. According to the first embodiment, a gallium nitride sintered body, which is characterized by having density of 2.5 g/cm.sup.3 to less than 5.0 g/cm.sup.3 and an intensity ratio of the gallium oxide peak of the (002) plane to the gallium nitride peak of the (002) plane of less than 3%, which is determined by X-ray diffraction analysis, can be obtained. According to the second embodiment, a metal gallium-impregnated gallium nitride molded article, which is characterized by comprising a gallium nitride phase and a metal gallium phase that exist as separate phases and having a molar ratio, Ga/(Ga+N), of 55% to 80%, can be obtained.

A joining layer of a joined body includes a joining material which contains, as a main component, a metal having a surface tension of 1000 mN/m or less at its melting point, and a metal layer which has a plurality of pores formed therein and in which at least some of the pores are impregnated with the joining material.

A base plate containing a having a top and a bottom and comprising a beryllium oxide composition containing at least 95 wt % beryllium oxide and optionally fluorine/fluoride ion. The base plate demonstrates a clamping pressure of at least 133 kPa at a temperature of at least 600° C. and a bulk resistivity greater than 1×10.sup.5 ohm-m at 800° C.

Provided are a heat dissipating substrate and a preparation method thereof, which can form a precise pattern in a thick electrode metal plate and improve insulating strength and peel strength. heat dissipating substrate for semiconductor may include: an electrode metal plate having a plurality of electrode patterns which are electrically insulated from each other by a pattern space formed therebetween; a metal base disposed under the electrode metal plate, and configured to diffuse heat conducted from the electrode metal plate; an insulating layer formed between the electrode metal plate and the metal base; and an insulating material filled portion configured to fill the pattern space and a peripheral portion outside an electrode pattern group composed of the plurality of electrode patterns, and support the electrode patterns while brought in direct contact with side surfaces of the plurality of electrode patterns.