NH3 Process Gas Analyzer Nitriding / Nitrocarburizing

At present, an H2 sensor is used to monitor the nitriding atmosphere. The degree of cracking of the NH3 is calculated theoretically from the known fresh gas quantities and the hydrogen value of the furnace atmosphere. An equilibrium reaction of the NH3 is assumed for the calculation.

Possible reactions of the free hydrogen with impurities in the batch and the furnace system, as well as measurement errors in the fresh gas quantities, are not taken into account when calculating the degree of splitting of the NH3.

With this analysis device, the actual residual NH3 content in the exhaust gas is determined. When calculating the nitriding potential, the reaction of NH3 and H2 can thus be taken into account.

The nitriding potential is in equilibrium with the γ' and ε nitride at the nitriding temperature. The nitriding potential thus describes which structure can primarily occur at a given temperature. The NH3 content in the reaction gas is measured with this sensor system according to the well-known physical principle of the different thermal conductivities of reaction and additional gases from the nitriding process.

A direct comparison of the calculations of the nitriding potential from the H2 and NH3 content of the nitriding atmosphere can thus be carried out for the quality assurance of the heat treatment.