Gas, Pressure and Salt Bath Nitrinding Techniques
This type of nitriding is carried out in normal furnaces with nitriding atmospheres at atmospheric pressure and at temperatures between 470 and 550°C.
The delivery of nitrides is effected by the molecular breakdown of ammonia.
Noteworthy is the long processing time required as well as the fragility of the combination layer obtained.
Currently, a new technique is entering practice using VACUUM OVENS, called HIGH PRESSURE NITRIDING, because its application is carried out at between 2 and 20 bars of pressure.
This system has the advantage of working with new clean technologies, meaning the surface quality of the parts treated with VACUUM techniques is excellent.
Besides the cleanliness provided by this technique applied in VACUUM FURNACES, of note is the reduction of the time required for the process, the possibility of nitriding small parts and in bulk as well as the elimination of problems with nitriding any holes the parts may have that need to be treated against wear.
SALT BATH NITRIDING
In this process the parts are placed into a liquid medium, known as a salt bath, which is composed of cyanides and cyanates in a melted state.
The most advantageous aspect of this technique is the good toughness properties of the combination layer, for a relatively short processing time.
The system is not very versatile, given the temperature is pre-established at 570°C.
The salt compound in itself also causes difficulties in the subsequent cleaning of the parts, especially with regard to small openings. Moreover, polished surfaces lose this condition.