Investigation on surface properties of NbN/NbCN coated steels

Keywords: Thermo-chemically-coating, NbN, NbCN, Wear, Mechanical properties, Structural properties In this study, nitro-niobizing treatment was realized on the surfaces of the AISI 1010, AISI 4140, AISI D2 and AISI M2 steels. Steel samples are gas nitrided before the coating treatment for production of nitride base coatings (in the temperature of 530-570°C for an hour). After than, niobium is to diffused on the surface of pre-nitrided steel samples by thermo reactive diffusion method in the powder mixture consisting of ferro-niobium, ammonium chloride, naphthalene and alumina in the temperature of 900-1100°C for niobium nitride, and niobium carbo-nitride coatings. Niobium is to diffused at the temperature of 900°C,1000°C and 1100°C for 1, 2, 3, 4 hours periods. Structural characterization and phase analysis of the coated samples were realized using optical microscopy, scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (SEM-EDS), X-ray difractometer. Wear tests and microhardness measurements were realized for mechanical behaviours. Wear tests were realized against alumina and AISI M2 stell balls of the sliding speeds of 0.1 m/s and under the loads of 2.5N, 5N and 10N so, the wear behaviours of coatings for a coating paramerter were invertigaled. Worn tracks and scans of disk and ball metarials were analyzed using optical microscopy and scannig electron microscopy (SEM). Microhardness measurements were realized using Vickers inderter tester at 10g load.