Title: Nitriding in ammonia-nitrogen gaseous mixtures, after the simultaneous saturation with Ti and Al

Authors: Mihai Ovidiu Cojocaru; Mihai Branzei; Andrei Mihai Ghinea; Cosmin Mihai Cotrut; Leontin Nicolae Druga

Addresses: Department of Metallic Materials, Physical Metallurgy, Faculty of Materials Science and Engineering, University Politehnica of Bucharest, 313 Spl. Independentei, Sector 6, 060042 Bucharest, Romania ' Department of Metallic Materials, Physical Metallurgy, Faculty of Materials Science and Engineering, University Politehnica of Bucharest, 313 Spl. Independentei, Sector 6, 060042 Bucharest, Romania ' Department of Metallic Materials, Physical Metallurgy, Faculty of Materials Science and Engineering, University Politehnica of Bucharest, 313 Spl. Independentei, Sector 6, 060042 Bucharest, Romania ' Department of Metallic Materials, Physical Metallurgy, Faculty of Materials Science and Engineering, University Politehnica of Bucharest, 313 Spl. Independentei, Sector 6, 060042 Bucharest, Romania ' Technical Sciences Academy of Romania, Bulevardul Dacia 26, 030167 Bucharest, Romania

Abstract: The paper addresses aspects of nitriding in ammonia-nitrogen gaseous mixtures, after simultaneous saturation with Ti and Al using solid powdery media. The effects quantification of the nitriding conditions variation, i.e., temperature, the ammonia dissociation degree and dilution degree with nitrogen, on the layer's growth kinetics, simultaneous saturated with Ti and Al and subsequently nitrided, in the case of two metallic materials, Fe-ARMCO and 34CrAlMo5 steel, could be ensured using the second-order non-compositional experimental programming method. It was concluded that, in the case of ammonia dilution with nitrogen, the variation of the ammonia dissociation degree in the range 20÷70%, in the context of simultaneous dilution of ammonia with nitrogen, statistically significantly influences the layers growth kinetics with increasing nitriding temperature. On the other hand, for a dilution degree of ammonia with about 30% nitrogen and an ammonia dissociation degree of about 45%, the most intense layers growth kinetics was highlighted if the nitrided layer has been previously saturated simultaneously with Ti and Al.

Keywords: nitriding; ammonia; nitrogen; saturation; programming; potential; kinetics; titanium; aluminium; phase.

DOI: 10.1504/IJSURFSE.2022.122186

International Journal of Surface Science and Engineering, 2022 Vol.16 No.1, pp.17 - 38

Received: 29 May 2021
Accepted: 08 Sep 2021
Published online: 11 Apr 2022 *

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