Surface modification of 17-4PH stainless steel by DC plasma nitriding and titanium nitride film duplex treatment F. Qi a , Y.X. Leng a,b, * , N. Huang a,b , B. Bai c , P.Ch. Zhang c a Key Laboratory for Advanced Technologies of Materials, Ministry of Education, Southwest Jiaotong University, Chengdu 610031, China b School of Materials Science and Engineering, Southwest Jiaotong University, Chengdu, Sichuan 610031, China c State Key Laboratory of Physical Chemistry of Surface, Jiangyou, Sichuan 621700, China Available online 19 January 2007 Abstract 17-4PH stainless steel was modified by direct current (DC) plasma nitriding and titanium nitride film duplex treatment in this study. The microstructure, wear resistance and corrosion resistance were characterized by X-ray diffraction (XRD), pin-on-disk tribological test and polarization experiment. The results revealed that the DC plasma nitriding pretreatment was in favor of improving properties of titanium nitride film. The corrosion resistance and wear resistance of duplex treatment specimen was more superior to that of only coated titanium nitride film. Ó 2007 Elsevier B.V. All rights reserved. PACS: 62.20.Qp; 68.60.Bs Keywords: Plasma nitriding; Titanium nitride film; Microstructure; Wear resistance; Corrosion resistance; Adhesion strength 1. Introduction The stainless steel is widely used in mechanical engineer- ing field because of its excellent mechanical properties. But its wear resistance and corrosion resistance were not enough in severe service condition, such as the stainless steel gear or axes in water vapor ambient. Titanium nitride (TiN) film has high hardness, good wear resistance [1], excellent corrosion resistance properties, so it has been fre- quently used to improve wear properties of mechanical engineering materials. For all films, the adhesion between the films and substrate should be considered. Because of the difference of crystal structure between films and sub- strate, an obvious interface formed between the films and substrate and the stress may exist in the interface. Nitriding prior to titanium nitride film deposition may be an efficient method to improve the adhesion of titanium nitride film for generating intergrade layer between TiN films and the sub- strate [2]. In this paper, in order to enhance the adhesion between titanium nitride film and the substrate, plasma nitriding was firstly carried out on 17-4PH stainless steel surface, and then titanium nitride films were prepared on the nitriding surface. 2. Experimental 17-4PH stainless steel was used as primary substrate material in this study. The samples had been polished and then were ultrasonically cleaned with acetone, alcohol and distill water in succession. Firstly, the DC plasma nitriding was conducted for 100 min at nitrogen partial pressure 11 Pa. The DC voltage was 850–950 V and the power was 185–285 W. The nitriding temperature, which was measured by a thermocouple imbedded in the sub- strate holder, was in a range of 280–300 °C. Then titanium nitride films were prepared on the specimens with plasma nitriding pretreatment by unbalance magnetron sputtering. 0168-583X/$ - see front matter Ó 2007 Elsevier B.V. All rights reserved. doi:10.1016/j.nimb.2007.01.087 * Corresponding author. Address: School of Materials Science and Engineering, Southwest Jiaotong University, Chengdu, Sichuan 610031, China. Tel.: +86 28 87601149; fax: +86 28 87600625. E-mail address: yxleng@263.net (Y.X. Leng). www.elsevier.com/locate/nimb Nuclear Instruments and Methods in Physics Research B 257 (2007) 416–419 NIM B Beam Interactions with Materials & Atoms