Optical investigation of surface morphology of the WC tool-plate subjected to nitriding preprosessing
|Łukasz Zięba 2, Janusz Jaglarz 2, Jan Cisowski 1,2, Marek Dąbrowski 3|
1. Polish Academy of Sciences, Centre of Polymer Chemistry, M. Sklodowskiej-Curie 34, Zabrze 41-819, Poland
The performance of tribological coatings depends greatly on the adhesion strength between coating and substrate and the substrate morphology strongly affects the mechanical properties of coatings. It has been recently shown that a comparatively low-energy nitrogen ion beam (1-2 kV) with a much higher beam current density can increase the hardness of some high-speed tools. When the nitrogen ion implantation is used as a preliminary process, it can lead to increase of the surface roughness. Before covering, the tools are cleaned by glow discharge in nitrogen atmosphere (nitriding preprocessing). After cleaning, a short-time titanium bombardment is used (titanizing preprocessing). The bias voltage in both cases is of the order of 1 kV and the final coverage is made after these preliminary processes.
In this work, we have investigated the influence of the implantation with low-energy N- and Ti-ions on the surface roughness of wolfram carbide (WC) high speed tool-plate. We have also studied the surface topography of TiN layers deposited on the WC high speed tool-plate as a function of time of nitriding and titanizing preprocessing. TiN coatings have been prepared by the ARC physical vapour deposition (PVD) technique in a commercial equipment PUSK 83. We have carried out complex optical, atomic force microscopy (AFM) and scanning electron microscopy (SEM) investigations. The optical studies include X-Y optical profilometer measurements and bidirectional reflection distribution function (BRDF) measurements, being complementary to AFM and SEM methods. The mean initial value of srms (root-mean square) roughness of WC substrates is equal to 255 nm and after 20 min of nitrogen cleaning process srms rises to about 550 nm. For short deposition time of the subsequent TiN layer, its surface roughness reflects the substrate roughness, while with longer deposition time the TiN surface becomes more and more smooth.
Keywords: TiN, nitrogen implantation, surface roughness
Presentation: Poster at E-MRS Fall Meeting 2007, Symposium J, by Łukasz Zięba
See On-line Journal of E-MRS Fall Meeting 2007
Submitted: 2007-05-10 10:11 Revised: 2009-06-07 00:44