① evaporable getter, also known as diffusion or the flash type:
The need for heating after getter metal getter film is formed out of evapotranspiration. Barium, strontium, magnesium, calcium as the main material, typically evaporable getter commonly used aluminum, nickel and barium getter and a nitrogen-doped getter. Aluminum, nickel and barium getter widely used in various power transmitting tubes, oscillating tube, camera tube, tube, tube solar collectors and other devices. Some CRT is used in nitriding of aluminum, barium getter, which emit large amounts of nitrogen in evapotranspiration exothermic reaction, a large number of barium evapotranspiration due to the collision with the nitrogen molecule, barium getter film without adhering screen or mask above but gather around the neck, only good suction performance, but also increases the brightness of the screen.
② non-evaporable getter:
It does not require the getter metal evapotranspiration out by activation of the getter metal surface so as to have the ability to inhale it. Now often zirconium as the main body. Is the volume-type getter (coating type), it is divided into elemental volume type, the volume of alloy type, large specific surface area of the three. They are suitable for use in the film can not be used suction occasions. For example: the device are small, no suitable membrane surface evapotranspiration Shen, fear and fear the introduction of the leakage device parasitic capacitance and high working temperature of the device can not be used etc. NEG. Usually it into a sheet or strip, widely used in power tubes, magnetrons, vacuum relay, gas lasers, suction pump, vacuum thermos flasks, X-ray tubes, image converters, camera tube, magnetron electrostatic suspended gyroscope, pacemakers and other devices. Typical non-evaporable getter commonly used are: aluminum zirconium 16, zirconium, vanadium, zirconium and iron and graphite.
③ composite getter: from evaporable mixed with non-evaporable getter. As mercury releasing getter, which both mercury releasing metal getter can, which is called a getter composite getter. Typical composite getter release agents as well as alkali metal (alkaline source).
Suction mechanism getter
NEG getter process has three main contributing factor: ET breathing, internal surface adsorption and diffusion, the relationship between the three: First, the suction evapotranspiration, surface adsorption breeds diffusion factors, internal diffusion must be adsorbed to the surface as a precondition. The absorption of non-bulk type getter process: surface adsorption, internal diffusion.
① ET inspiration:
When heated evapotranspiration, splashing out of the gas molecules and atoms of barium tube space collide on a collision course some barium atoms only change its direction evapotranspiration, some chemical reaction with gas molecules to produce the corresponding compound, and the deposition on the envelope surface. Results pipe gas concentration within the space is reduced, most of the residual gas is absorbed.
When gas molecules collide solid surface, it may be bounced back, may also be adsorbed, the adsorbed molecules can be adsorbed very firmly, it can only be bound by a very weak force.
(A) van der Waals forces: physical adsorption
(2) the remaining valence forces: chemical absorption
③ Internal diffusion:
Gas adsorbed on the surface, has a large surface mobility, it can quickly spread to the entire surface. As the surface diffusion, under certain conditions, the gas adsorbed on the surface will be further getter metal inside diffusion. Diffusion of the form:
(1) metal surface of the deep depression or lesion;
Between (2) was immersed in the grain boundary;
(3) into the crystalline defects among themselves;
(4) Synthesis of metal and intermetallic compounds;
(5) and the metal form a solid solution.