Also known as the glow ion nitriding nitriding, is using the principle of glow discharge. Ion nitriding is in low vacuum filling with nitrogen gas inside the furnace body metal workpiece as the anode and cathode furnace for medium nitrogen hydrogen atoms in the high voltage direct current field after the power supply by ionization, between Yin and Yang very in the formation of plasma. Under the effect of plasma strong electric field, the nitrogen and hydrogen ions to the surface at high speed bombardment. Ion high kinetic energy into heat energy, heating surface to the required temperature. Due to ion bombardment, the workpiece surface sputtering atom, purified and, at the same time due to the adsorption and diffusion, nitrogen into the workpiece surface.
Ion nitriding method (or glow discharge nitriding) is by the German B.B erghaus invented in 1932. The law is in 0.1 ~ 10 Torr (Torr = 133.3 Pa) nitrogen atmosphere, furnace body as anode, the processed workpiece as the cathode, the electrode of Yin and Yang of hundreds of volts dc voltage, because the glow discharge phenomenon will produce a soft light like strobe lights covering on the surface of the workpiece are processed. At this point, the ionized gas composition are accelerated electric field, the impact is processed workpiece surface and the heating. At the same time rely on nitriding processing such as sputtering and ionization effect.
Some ion nitriding method has the following advantages:
(1) due to the effect of ion nitriding method is not dependent on chemical reaction, but the use of ionization of the nitrogen gas nitriding processing, so the working environment is very clean without special equipment to prevent pollution. Therefore, ion nitriding method is also known as the 21st century "green" method of nitride.
(2) by ion nitriding method using the ionization of gas spraying effect, and compared with the previous nitriding treatment, can significantly shorten the processing time (ion nitriding time only for ordinary gas nitriding time 1/3 ~ 1/5).
(3) due to the ion nitriding method using the glow discharge the workpiece heated directly, also need not special heating and heat preservation equipment, and can obtain uniform temperature distribution, compared with the indirect heating mode heating efficiency can be increased by more than 2 times, to achieve energy saving effect (energy consumption of gas nitriding only 40 ~ 70%).
(4) due to the ion nitriding was conducted in a vacuum, and thus can be obtained without oxidation processing surface, also won't damage is processed workpiece surface finish. And for processing, because it is in the low temperature processed workpiece deformation small, after processing without any processing, very suitable for the processing of finished products.
(5) by adjusting the nitrogen, hydrogen and other (such as carbon, oxygen, sulfur, etc.) the proportion of the atmosphere, can freely adjust the phase composition of the compound layer, to obtain the desired mechanical properties.
(6)ion nitriding since 380 ℃ can be nitriding treatment, in addition, the titanium and other special materials can also be used in nitriding treatment under the high temperature of 850 ℃, thus the range is very wide.
(7)Cruelly by ion nitriding was conducted under low pressure in the form of ion implantation, so little gas consumption (only a few percent of gas nitriding), can greatly reduce the processing cost.
Ion nitriding in dilute ammonia or a mixture of hydrogen and nitrogen in the atmosphere. Like ordinary atmosphere nitriding method, can also be used to the atmosphere to hydrocarbon gas in the mixture, it is in the white layer formation epsilon - carbide. That the process can also be used to make surface decarburization controlled method, and reduces the brittleness of the surface.