Michalski Jerzy, Frączek Tadeusz, Prusak Rafał, Dudek Agata, Kowalewska-Groszkowska Magdalena, Major Maciej
Łukasiewicz Research Network-Warsaw Institute of Technology, 01-796 Warszawa, Poland.
Department of Materials Engineering, Faculty of Production Engineering and Materials Technology, Czestochowa University of Technology, 42-201 Czestochowa, Poland.
Materials (Basel). 2025 Jun 26;18(13):3041. doi: 10.3390/ma18133041.
This paper proposes a mathematical description of nitriding atmospheres obtained from a one-component ammonia ingoing atmosphere and a two-component ammonia inlet nitrogen-diluted atmosphere. The Fe-N phase equilibrium diagrams of the nitriding atmosphere in the hydrogen content-temperature (Q-T) system for selected NH/N atmosphere compositions are presented. The nitriding atmosphere obtained with different degrees of nitrogen dilution of the ingoing atmosphere was characterized. It has been shown that in processes carried out in nitriding atmospheres obtained from a two-component atmosphere with nitrogen, there is no direct relationship between the value of the nitrogen potential and the degree of dilution of the ingoing atmosphere with nitrogen. It has been shown analytically and confirmed experimentally that with changes in the degree of dilution of ammonia with nitrogen, the hydrogen content of the nitriding atmosphere and, consequently, the nitrogen availability of the nitriding atmosphere change. Using the example of nitriding AISI 52100 steel, it has been experimentally demonstrated that the change in nitrogen availability, caused by a change in the degree of dilution of the ingoing atmosphere with nitrogen, is not accompanied by a change in the value of the nitrogen potential. It has also been shown that the change in the nitrogen availability of the nitriding atmosphere, induced by the change in the composition of the NH/N ingoing atmosphere, affects the kinetics of nitrogen mass gain in the nitrided layer and the distribution of nitrogen mass between the iron nitride layer and the solution zone. It has also been shown that with the change in nitrogen availability, what changes in addition to the thickness of the iron nitride layer is also the phase composition of the layer. Using gravimetric tests, the mass of nitrogen in the iron nitride layer and the solution zone has been determined. To describe the equilibrium between the NH/H atmosphere and nitrogen in the different iron phases, a modified Lehrer diagram in the coordinate system of temperature and hydrogen content in the nitriding atmospheres (T-Q) has been proposed.
本文提出了一种对由单一组分的氨进气气氛和双组分的氨进气氮气稀释气氛所获得的渗氮气氛的数学描述。给出了选定的NH₃/N₂气氛组成下，渗氮气氛在氢含量-温度（Q-T）系统中的Fe-N相平衡图。对由进气气氛不同程度的氮气稀释所获得的渗氮气氛进行了表征。结果表明，在由含氮双组分气氛获得的渗氮气氛中进行的过程中，氮势值与进气气氛的氮气稀释程度之间没有直接关系。通过分析表明并经实验证实，随着氨被氮气稀释程度的变化，渗氮气氛中的氢含量以及渗氮气氛的氮有效性会发生变化。以AISI 52100钢的渗氮为例，通过实验证明，由进气气氛的氮气稀释程度变化引起的氮有效性变化，并未伴随氮势值的变化。还表明，由进气NH₃/N₂气氛组成变化引起的渗氮气氛氮有效性变化，会影响渗氮层中氮质量增加的动力学以及氮化铁层与固溶区之间氮质量的分布。还表明，随着氮有效性的变化，除了氮化铁层的厚度变化外，该层的相组成也会发生变化。通过重量测试，确定了氮化铁层和固溶区中氮的质量。为了描述NH₃/H₂气氛与不同铁相中的氮之间的平衡，提出了一种在渗氮气氛温度和氢含量坐标系（T-Q）中的修正勒雷尔图。
