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Ceramic to metal seal

Font Size: [Big][Mid][Small] 2012-9-19  Views: 843
In recent 20 years , Soon the research and application progress of engineering ceramics by countries all over the world. Compared to ceramics and alloys and engineering plastics , In wear, High temperature oxidation, Has excellent properties of corrosion resistance and dielectric properties. But as a structural material , Ceramic has plastic is not good, Difficult machining, Strength of dispersion, Fatigue resistance and thermal shock resistance difference, Not easy to welding defects , Alone is not too ideal. For this , Scientists are developing a variety of metal / Ceramic composite materials, composite materials for both metal and ceramic superiority to expectations.
Now, Metal or ceramic matrix composites generally exist in the high cost of production, High energy consumption, The scale of production problems. For the complex component shapes and large component ( Such as aviation engine combustion chamber, Turbine blade ) Speaking , Using a single metal / Ceramic composite materials to the manufacturing cost is high. But if the connection of ceramic and metal composite components to use. , It can reduce the cost and energy consumption , And easy for engineering. For the manufacturing requirements of high reliability such as aviation engine products , Selection of suitable ceramic / Technology of metal connection, can increase the reliability of the ceramic materials.
1 ceramic / metal connection method
Ceramic and metal is two kinds of different materials, different engagement exists at the interface of chemistry and physics properties. The two different connection method , Characteristics of the new interface formed by different. Use of mechanical connection and bonding connection technology Limited , These two kinds of process of joint use can further increase the joint strength and tightness of the joint , But the conditions of use is limited. Once the need to consider the complex load conditions, Higher temperature and reliability factors , You can only select ceramic / welding technology for metal. The main method of welding connection:
(1) glaze sealing -- in the air to the ceramic sintering silicate glass material, Then in reducing atmosphere and metal welding, but the glaze layer crack and stress joints seriously. This method may be gradually eliminated.
(2) sintered metal powder method -- coating formed on ceramic surface coated metal powder and sintering, Then use the solder of ceramic and metal welding, multi element for ceramic metal electronic sealing and connection.
(3) is the main welding -- Fusion welding and electron beam welding laser, To be able to manufacture high temperature joint stability under the , But it is difficult to form surface 2 Surface is connected, the equipment investment is expensive.
(4) friction welding -- to make the two welding relative rotation friction and pressure, When the metal surface is heated to a plastic state stopped Applying larger, upsetting force makes the welding connection. The joints with both mechanical and chemical bonding. But this method is limited to the welding rod, pipe fittings and so on.
(5) solid phase diffusion welding -- at high temperature and under the action of external force, The ceramic - Close contact with the metal surface , Base metal plastic deformation occurs in certain , For atomic diffusion, the two materials together.
(6) ceramic / Metal brazing -- the use of ceramic / Between the base metal solder melts at high temperature , The active component and ceramic chemical reaction , Formation of gradient layer stability, two kinds of materials together.
(7) the self-propagating high-temperature synthesis (SHS - Self-propagating High-temperature Synthesis) Welding -- in ceramics / Metal interface preset between high-energy solder , Lit solder produce short-time high temperature combustion wave , The solder and ceramics / Metal interface rapidly fusion , And fast cooling to form joint. This method is of high efficiency , Low energy consumption , In the fabrication of metal matrix, Is of great significance in ceramic matrix composites. Considering the various methods of forming properties, process characteristics of welded joints, The mechanism and process of cost factors , We believe that the solid phase diffusion welding, Brazing and SHS Welding has a certain research foundation and good application prospect, should research and development focus.
Connect the theory and related technology of ceramic / metal , The development of ceramics / Metal composite component , Especially for high temperature structural composite materials is very important. , On the first Century energy and power industry with the economic and social benefits of potential. The present study is almost around the ceramic / Metal interface bonding mechanism, To solve the interface stress, Connection technology to carry out the. Considering the connection theory, Process etc. , We think , Active metal brazing, SHS Welding technology is the most promising to become ceramic / metal connecting key development project process.

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