1, the laser welding
    
     The high energy density of the laser used in ceramic sealing (welding) then known as laser welding.
     Ceramic laser welding, first consider how to avoid the heating and cooling rate and the temperature gradient caused by thermal cracking. Its solution would have pre-heating of the ceramic workpiece with a dual laser guns and adjust the laser beam and other measures.
     Laser welding apparatus for ceramics shown in Figure 1. The carbon dioxide laser power 1.2kw. The laser reflector and condenser lens focused on the sample surface. Preheating furnace for preheating the sample irradiated with laser light in order to avoid sudden localized heat cracks. High alumina ceramic preheating temperature 1200 ℃, to prevent cracks. Preheat temperature and welding speed greater impact on the quality of welding.
     Mullite laser welding specimen (Al2O359%, SiO238%), after 100 times of repeated heating and cooling thermal fatigue test. Welded samples no significant decrease in bending strength. Has now emerged with a carbon dioxide laser welding device alumina ceramic, mullite and forsterite ceramics and other new ceramic.
   
    2, sintered metal powder method
    
     Sintered metal powder is a method of high-temperature reducing atmosphere, the metal powder is sintered on the surface of the porcelain to the metal film, and then the Ceramic metallization sealing a method.
     With this sealing process should follow the following principles:
     (1) melting point of the metal member to be higher than the metalization temperature above 200 ℃, and the welding, the metal member and the metal of the component is no longer formed of a metal alloy.
     (2) between the metal member and the ceramic member should be close to the coefficient of expansion.
     Molybdenum - manganese ceramic-metal sealing method is the most widely used method, the process is roughly: the ceramic surface coating of molybdenum-manganese alloy pastes, under the protection of the hydrogen gas (containing 0.25% to 1% oxygen), at low the sintering temperature of 100 ~ 200 ℃ temperature ceramic metal sintering, and then plating layer of nickel at about 1000 ℃ sintered in dry hydrogen, the nickel layer and a molybdenum-manganese alloy layer is firmly bonded, and finally the ceramic member and the metal member solder join between the hydrogen gas or vacuum brazing.
     Metallized alumina ceramic and metal sealing the process diagram shown on the following page. Hermetic seals porcelain ceramic pieces 70 and 95 porcelain.
     Kovar metal welding with pure silver solder feed (such as the use of relatively low temperature can also be silver-copper solder), can only be used when welding with oxygen-free copper-silver-copper eutectic alloy.
3, the glass solder sealing method
     Ceramics and glass solder is suitable for sealing various metal alloys, especially strength and air tightness requirements of the occasion.
     And calcium oxide in the alumina-based glass solder, when adding various oxides, the different performance of the solder,
4, the solid-phase method of sealing
     Carbides, nitrides and other non-oxide ceramic sealing multi-use solid-phase method, the solid phase in contact with the ceramic by the pressure, heating to expand the contact area, so that the diffusion of the components, until the completion of the volume diffusion bonding. Solid phase diffusion bonding process, three stages are:
     First stage: first surface contact, and then expand the surface area of ​​contact changes.
     Second stage: the interface moves and voids gradually disappear.
     Phase III: volume diffusion caused by the interface moves and empty completely disappear.
     A sealing material for the same, because the interface moves, sealing surface may disappear. For the sealing of different materials, there is often the interface. At this time, the sealing surface engaging and forming the diffusion layer to form a reaction layer bonded.
     In addition to temperature, pressure, time, the pre-sealing sealing surface state and the atmosphere is also important. Usually sealed in an oxidizing atmosphere, due to the metal oxide film formed on the surface sealing hindered.
     Parameters affecting the inner seal, mainly for the combination of ceramic and metal thermal expansion coefficient difference, reactivity,
    Parameters affecting the inner seal, mainly for the combination of ceramic and metal thermal expansion coefficient difference, reactivity, speed difference between the diffusion of elements, atoms form the joint interface and so on.