Abstract: The bonding apparatus has a holding device, a pressing device for pressure welding substances to be bonded to each other, and a superhigh vacuum bonding chamber provided with the holding device and the pressing device. A superhigh vacuum bonding preparatory chamber is connected with the superhigh vacuum bonding chamber through a gate valve and a conveyor is arranged for conveying the substances to be bonded between the superhigh vacuum bonding preparatory chamber and the superhigh vacuum bonding chamber. The preparatory chamber is provided with a rotary preparatory table having a plurality of stages for releasably supporting holders for holding the substances to be bonded, the preparatory table being moved to successive positions to register with the conveyor.

Abstract: Less dispersion and more homogenized ceramics are produced by sintering ceramic materials, in particular, containing silicon nitride or silicon carbide as a predominant component with other assistants or additives, machining the surface of the resulting sintered compact and then subjecting the sintered compact to a heat treatment for homogenizing in a non-oxidizing atmosphere such as nitrogen or argon gas at a temperature of from the mass-transfer temperature at which the mass-transfer takes place in the interior of the ceramics to blunt the fine point of a crack to the sintering temperature of the ceramics.