(180ao) Nitriding of Metal Powder

Nitriding of metal is an interesting part of surface treatment for increasing physical properties like corrosion resistance, hardness and chemical resistance.

Atomisation of liquid metal with nitrogen leads to an instable condition. Because of this fact the reaction with a nitriding gas shows other behaviour than not atomised metal powder.

Ammonia is an important nitriding gas because of the lower dissociation temperature than nitrogen. The sintering temperature of metal powder is lower than the dissociation temperature of molecular nitrogen.

A common nitriding temperature of atomised metal powder is between 350°C to 600°C, wherefore ammonia is used for the favour nitriding gas.

For analysing the kinetic nitriding process measurements are made with a thermo gravimetric analyser (TGA).

Therefore measurements with several gas additions (CO, N2, O2, air), gassing rates, pre-treatments and different temperatures are investigated. Thereby the increasing of the mass is relevant for the kinetic analyses.

Further the content of alloying elements shows the influences to the nitriding process.

Aims of this work are the optimal nitriding conditions to decrease the nitriding duration and increase the product quality and reproducibility of nitration.