IUVSTA 15th International Vacuum Congress (IVC-15), AVS 48th International Symposium (AVS-48), 11th International Conference on Solid Surfaces (ICSS-11)
    Surface Engineering Monday Sessions
       Session SE-MoP

Paper SE-MoP12
A Study of Nitrided Layers of SAE 303 Stainless Steel using a Magnetized Plasma Process

Monday, October 29, 2001, 5:30 pm, Room 134/135

Session: Poster Session
Presenter: H.S. Maciel, Instituto Tecnologico de Aeronautica - ITA - Brazil
Authors: G.A. Lacerda, Instituto Tecnologico de Aeronautica - ITA - Brazil
C. Otani, Instituto Tecnologico de Aeronautica - ITA - Brazil
H.S. Maciel, Instituto Tecnologico de Aeronautica - ITA - Brazil
C. Alves Jr., Universidade Federal do Rio Grande do Norte, Brazil
Correspondent: Click to Email
Iron nitride is an important material in metallurgy, especially as constituent of the so-called compound layers generated on the surface of workpieces made of steel and hardened by nitriding and carbonitriding. More recently the iron nitrides reappeared in the literature but now as thin films and as potencial candidates for magnetic recording heads or eventually recording media. Dealing with an investigation of this subject, a series of plasma nitriding experiments has been conducted on SAE 303 austenitic stainless steel samples, using an experimental system based on an ordinary dc glow discharge which was located between the magnetic poles of an electromagnet. In this system the sample is placed on the cathode and the magnetic field (B), which is uniform and perpendicular to the sample surface, can be varied from zero to 1440 Gauss. The nitriding processes were carried out under constant substrate temperature of 430 °C and gas pressure of 5.0 Torr, whereas different N@sub 2@-H@sub 2@ gas mixtures were used. The nitrided layers were characterized by micro-hardness testings, X-ray diffraction, conversion electron Mössbauer spectroscopy and scanning electron microscopy. The results showed a strong influence of the applied magnetic field upon the mechanical properties of the samples surface as consequence of different nitride phase growing. A decrease in the surface hardness with the increase of the magnetic field strengh was observed for all the conditions tested. For certain gas mixtures, as for example 50%N@sub 2@-50%H@sub 2@, a noticeable effect occurred, i.e., at low and high B field, in the range provided by the electromagnet, the prevalent structure of the nitrided layer is dominated by the Fe@sub 3@N, but it changes to Fe@sub 4@N based structure for B field in the middle range of (260-770) Gauss.