CoCrMo alloy treated by floating potential plasma assisted nitriding and plasma based ion implantation: Influence of the hydrogen content and of the ion energy on the nitrogen incorporation

SURFACE & COATINGS TECHNOLOGY

卷:204

Article; Proceedings Paper

Pichon, L.¹  Okur, S.²  Ozturk, O.²  Riviere, J. P.¹  Drouet, M.¹ 

[1] Univ Poitiers, Lab Phys Mat PhyMat, CNRS, UMR 6630,SP2MI, F-86962 Futuroscope, France

[2] Izmir Inst Technol, Dept Phys, TR-35430 Izmir, Turkey

关键词: Cobalt-chromium-molybdenum alloy;    Expanded austenite structure;    RF plasma nitriding;    Plasma based ion implantation;   

DOI  :  10.1016/j.surfcoat.2010.01.050

来源: Elsevier

【 摘 要 】

Nitriding was performed on a medical grade CoCrMo alloy at 400 degrees C in N-2 or N-2-H-2 atmosphere at a working pressure of 0.84 Pa for 2 h. Various surface treatment techniques were used to incorporate nitrogen into the CoCrMo alloy: without any plasma assistance, by floating potential radio-frequency plasma assisted nitriding (FPPAN), by plasma based ion implantation (PBII) with several high voltage accelerations (up to 20 kV). Without plasma activation, no nitrogen is incorporated in the CoCrMo. On the contrary, all the plasma or PBII treated samples show the formation of a nitrogen-rich f.c.c. gamma(N) phase. The layer nitrided over few microns has a nitrogen composition ranging from 30 at.% to about 20 at.% near the nitrided layer-substrate interface, with an enhanced surface microhardness. Hydrogen is found to enhance the nitriding efficiency. Without hydrogen, a high voltage polarization provides a supplementary amount of implanted nitrogen available for further diffusion and the sputtering of the surface passive oxide. So, with limited high voltages, thicker layers with higher amounts of nitrogen can be achieved by PBII compared to plasma nitriding. However, with higher voltages, the sputtering becomes too important and the nitride layer is thinner. (C) 2010 Elsevier B.V. All rights reserved.

【 授权许可】

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