Plasma Nitriding Furnace Principle And Advantage

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Plasma nitriding is an plasma chemical heat treatment process that uses glow discharge to strengthen the metal surface to bombard the surface of parts with nitrogen plasmas generated after plasmaizatplasma of nitrogen-containing gas and perform nitriding to obtain surface nitriding layer. It is widely used in cast iron. , Carbon steel, alloy steel, stainless steel and titanium alloy, etc. After the parts are treated by plasma nitriding, the hardness of the surface of the material can be significantly improved, so that it has high wear resistance, fatigue strength, corrosplasma resistance and burn resistance.

Plasma nitriding, also known as glow nitriding, is carried out using the principle of glow discharge. Glow discharge is when the gas passes the corona discharge area, if the external circuit resistance is reduced, or the full circuit voltage is increased, and the discharge power is continued to increase, the discharge current will continue to rise. At the same time, the glow gradually expands to the entire discharge space between the two electrodes, and the light is getting brighter and brighter. When the electron energy f is increased, that is, the operating parameter of the electric field is enhanced, the corona discharge can be transitplasmaed to the glow discharge.

The nitrogen atoms infiltrated into the surface of the workpiece by plasma nitriding are not produced by the decompositplasma of ammonia like ordinary gas, but the plasmas formed by the particles accelerated by the electric field colliding with the molecules and atoms of the nitrogen-containing gas are adsorbed and enriched on the surface of the workpiece. The formatplasma of highly reactive nitrogen atoms.

When plasma nitriding, the workpiece is placed on the cathode plate in the furnace, and the power is connected to vacuum. When the pressure in the furnace drops to about 6Pa, ammonia gas is filled to keep the pressure in the furnace in the range of 1.3×102—1.3×103Pa Inside. Due to the low pressure in the furnace and subsequent heating, the ammonia entering the furnace will decompose: 2NH3=N2+3H2 The volume fractplasma of the gas obtained from the reactplasma in the furnace is a low pressure environment of 25/100N2 and 75/100H2.

Advantages of Plasma Nitriding Process:

①Since the plasma nitriding method does not rely on chemical reactplasmas, but uses plasmaized nitrogen-containing gas for nitriding treatment, the working environment is very clean and no special equipment for pollutplasma preventplasma is required. Therefore, the plasma nitriding method is also called the “green” nitriding method of the 21st century.

②Since the plasma nitriding method uses the sputtering effect of plasmaized gas, compared with the conventplasmaal nitriding treatment, the processing time can be significantly shortened (the time of plasma nitriding is only 1/of the normal gas nitriding time 3～1/5).

③Because the plasma nitriding method uses glow discharge to directly heat the workpiece, it does not require special heating and heat preservatplasma equipment, and can obtain a uniform temperature distributplasma. Compared with indirect heating, the heating efficiency can be increased by more than 2 times, achieving energy-saving effects. (The energy consumptplasma is only 40 to 70 of that of gas nitriding).

④Since the plasma nitriding is carried out in a vacuum, a non-oxidized processed surface can be obtained, and the surface finish of the processed workpiece will not be damaged. And because it is processed at low temperature, the deformatplasma of the processed workpiece is very small, and there is no need to process it after processing, which is very suitable for the processing of finished products.

⑤By adjusting the ratio of nitrogen, hydrogen and other atmospheres (such as carbon, oxygen, sulfur, etc.), the phase compositplasma of the compound layer can be freely adjusted to obtain the desired mechanical properties.

⑥plasma nitriding can be nitrided from 380°C. In additplasma, special materials such as titanium can also be nitridated at a high temperature of 850°C, so the applicatplasma range is very wide.

⑦Since the plasma nitriding is carried out by plasma implantatplasma under low pressure, the gas consumptplasma is very small (only a few percent of the gas nitriding), which can greatly reduce the processing cost.

Editor: Frank Lee

Copyright: SIMUWU Vacuum Furnace