Mechanical Testing in Electroless Ni Modified TiN Coating
- PDF / 407,167 Bytes
- 6 Pages / 414.72 x 648 pts Page_size
- 104 Downloads / 222 Views
MECHANICAL TESTING IN ELECTROLESS Ni MODIFIED TiN COATING
J. G. Duh, J. C. Doong and C. T. Huang Department of Materials Science and Engineering National Tsing Hua University Hsinchu, Taiwan
ABSTRACT TiN films are prepared by reactive rf magnetron sputtering on carbon steel substrates which are widely applied as structural materials. The electroless Ni-P plating is introduced as an interlayer in the surface modification of TiN coating. The electroless Ni-P deposit crystallizes during rf sputtering due to the elevated sputtering temperature and thus a TiN/Ni3P/Fe coating assembly is formed. The employment of electroless Ni-P deposit results in an increase in the surface microhardness and adhesion strength. The surface hardness as high as 2266HK1 close to the hardness of bulk TiN can be achieved in the Ni 3P interlayer modified TiN coating. With respect to the wear-resistance, the adhesion of the TiN coating plays an important role for the sliding wear-resistance and the interlayer Ni 3 P acts as a hard barrier instead of the soft carbon steel substrate. INTRODUCTION The improvement for the durability of tool surfaces is very important for tool lifetime and application, and it is implemented by the use of coating film technology such as electroless Ni-P [1] and transition metal nitrides [2]. Electroless Ni-P plating and titanium nitride are commercialized today, because of their many advantages in application. They exhibit good mechanical and corrosion-resistance properties [2,3, and are iswidely applied as coatings of tool surfaces. The process of electroless Ni-P p3lating an auto-catalytic process and can be well controlled with uniform thickness [3]. TiN films possess gold-like color and can be deposited either by chemical vapor deposition (CVD)[2,4] or physical vapor deposition (PVD)[2,5] depending on the application. The substrate employed in this study is carbon steel. Carbon steel is widely applied as a structural material because of its lower cost, yet its hardness, wear-resistance and corrosion-resistance are poor. The deposition of TiN coatings on stainless steels with excellent adhesion has been shown to be successful in the improvement of stainless steel surface properties such as hardness, wear-resistance' [6,7] and corrosion-resistance [8]. However, the adhesion of TiN coating on carbon steel is poor [7]. Moreover, the TiN/Fe or TiN/Ti/Fe coating assembly degrades since the coated layers are not perfect and might have some defects [8]. Consequently the corrosion of Fe is accelerated in spite of the presence of TiN. In this study, the electroless Ni-P plating is introduced as an interlayer between carbon steel and TiN coating. The purpose of this study is to investigate the role of electroless Ni-P plating interlayer in TiN coating. A TiN/Ni3P/Fe coating assembly is formed, since Ni 3 P precipitates during sputtering of TiN films. Different phosphorus composition of electroless Ni-P interlayer are employed and TiN films are prepared byi reactive rf planar magnetron sputtering. The effects of processing
Data Loading...
