New functions for nitriding potential control

Theisen Frank - STANGE Elektronik GmbH (Germany)

With the dynamic gas amount control our mission is to increase the adjustment range before soaking phase clearly and to decrease the NH3 consumption at controlled nitriding. The reaction of the ammonia molecules is determined significantly by the temperature at the active surfaces (retort wall and batch). With heating up phase the activity of the ammonia at the retort wall is very high based on the temperature difference between batch and heating. After equalization between heating and retort the activity moves to the batch. With the creation of nitrides on the batch surface the reaction of NH3 decreases. Based on the diffusion law Kn will increase and in result the H2 content in the furnace atmosphere will decrease. If this effects the nitrogen could be decreased. So the ratio of ammonia is getting larger and the flow speed will be lower. This dynamic nitriding potential control with new functions shall be discussed by our presentation.

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