Title: Activity modification of a new type of carbamide-based non-polluting solid powdery medium used in the sulphonitrocarburising process

Authors: Mihai Ovidiu Cojocaru; Mihai Branzei; Mariana Ion; 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, 006042 Bucharest, Romania ' Department of Metallic Materials, Physical Metallurgy, Faculty of Materials Science and Engineering, University POLITEHNICA of Bucharest, 313 Spl. Independentei, Sector 6, 006042 Bucharest, Romania ' Department of Metallic Materials, Physical Metallurgy, Faculty of Materials Science and Engineering, University POLITEHNICA of Bucharest, 313 Spl. Independentei, Sector 6, 006042 Bucharest, Romania ' Technical Sciences Academy of Romania, Bulevardul Dacia 26, 030167 Bucharest, Romania

Abstract: Carbamide (technical grade urea) is frequently used as a highly efficient active component in the mediums used for ferritic or austenitic nitrocarburising processes, and across a wide range of temperature values, ranging from values below 590°C required for achieving the ferritic nitrocarburising process, to values above 800°C required for the austenitic nitrocarburising process. The carbamide activity generates a particularly intense layer of growth kinetics. This paper studies the ability of carbamide to supply nitrogen and carbon, in the temperature range 550-950°C. It was concluded that this process varies by temperature, and for a composition of the solid powdery medium (35% carbamide, 50% carbon, 10% sulphur and 5% ammonium chloride) at 820°C the carbon potential level is higher compared to the nitrogen one.

Keywords: carbamide; sulphonitrocarburising; non-polluting medium; element potential; solid powdery medium.

DOI: 10.1504/IJSURFSE.2020.112284

International Journal of Surface Science and Engineering, 2020 Vol.14 No.4, pp.307 - 319

Received: 19 Apr 2020
Accepted: 11 Jun 2020
Published online: 06 Jan 2021 *

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