AVS 47th International Symposium
    Surface Engineering Tuesday Sessions
       Session SE-TuP

Paper SE-TuP8
Characterization of Plasma-nitrided Iron by SEM, XRD and XPS

Tuesday, October 3, 2000, 5:30 pm, Room Exhibit Hall C & D

Session: Poster Session
Presenter: P.A.P. Nascente, Universidade Federal de Sao Carlos, Brazil
Authors: L.C. Gontijo, Centro Federal de Educacao Tecnologica do Espirito Santo, Brazil
P.A.P. Nascente, Universidade Federal de Sao Carlos, Brazil
R. Machado, Universidade Federal de Sao Carlos, Brazil
E.J. Miola, Universidade de Sao Paulo, Brazil
L.C. Casteletti, Universidade de Sao Paulo, Brazil
Correspondent: Click to Email
Plasma nitriding technique has been used to improve the tribological and mechanical properties of materials, specially iron-based alloys. In this work, the Pulsed Glow Discharge (PGD) technique was used for nitriding pure iron. Four samples were nitrided in a gas mixture of 80 % H@sub 2@ and 20 % N@sub 2@ under a pressure of 400 Pa, discharge frequency of 9 kHz, and temperature of 853 K. Samples 1, 2 and 3 were nitrided for 30, 60 and 90 minutes, and then quenched in situ. The fourth sample was nitrided for 90 minutes and then quenched in air. The nitrided iron samples were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). SEM micrographs showed differences in the surface morphologies for the samples which were quenched inside the chamber. However, when the results for samples 3 and 4 were compared, it was noticed an even more significant change in the surface morphology, which demonstrates the importance of the cooling rate on the formed layer. XRD identified the Fe@sub 4@N phase in all samples. Besides this phase, also the Fe@sub 3@N, Fe@sub 2@O@sub 3@ and Fe@sub 3@O@sub 4@ phases were detected in the sample quenched in air. XPS was employed to obtain chemical-state and quantitative information of the plasma-nitrided iron surfaces.