AVS 51st International Symposium
    Advanced Surface Engineering Tuesday Sessions
       Session SE-TuM

Paper SE-TuM11
Microstructure and Properties of Ti-Al-Si-N Coatings Prepared by r.f.-Reactive Sputtering in Facing Targets-type Sputtering (FTS) System

Tuesday, November 16, 2004, 11:40 am, Room 303D

Session: Hard and Low Friction Coatings with Advanced Designs
Presenter: M. Nose, Takaoka National College, Japan
Authors: M. Nose, Takaoka National College, Japan
W.A. Chiou, Univ. of California at Irvine
H. Suzuki, Toyama Univ., Japan
E. Honbo, Toyama Industrial Research Center, Japan
S. Ikeno, Toyama Univ., Japan
H. Anada, Toyama Univ., Japan
S. Nogi, Osaka Univ., Japan
Correspondent: Click to Email
Ti-Al-N films have been widely used in the coating industry as a superior wear protection material in comparison with its predecessor, TiN; however, the discovery of Ti-Si-N nano-composite film (by Veprek et. al. in 1995) has sparked recent interest in the study of quaternary system coatings such as Ti-Al-Si-N. Research on the influence of Si content on the mechanical properties of the quaternary system has been reported, however, the studies of microstructure and properties of Ti-Al-Si-N films containing high Al content are scarce. The effect of Si concentration on the microstructure and on high aluminum-content systems (such as (Ti@sub0.5@A1@sub0.5@)@sub50@-N@sub50@ film), remain unclear. Thin Ti-Al-Si-N films were synthesized by r.f. reactive sputtering in a facing target-type sputter (FTS) system on the hight speed steel substrates. A pair of composite targets consisting of a Ti@sub50@-Al@sub50@ plate and Si chips was used. During the deposition the substrate was heated from room temperature up to 300° C. The crystallite size of the deposited film without bias voltage decreased from 14 nm to 7 nm with the increase of Si content up to about 7 at. %. XRD patterns of Ti-Al-Si-N films suggested two phases, the cubic B1 NaCl type structure and an amorphous phase, were presented in the film. XPS analysis exhibited a peak that corresponded to the Si@sub3@N@sub4@ phase. TEM investigation of (Ti@sub48@-Al@sub0.48@-Si@sub0.04@)@sub50@-N@sub50@ films revealed a nano-column structure. The nano-column structure has a long aspect ratio ranging from 3 to 10 with an average around 7 to 9. Without applying substrate bias, the hardness of the films increased from 35 GPa for Ti-Al-N films, reaching a maximum of 38GPa for Ti-Al-Si-N films containing approx. 4 at. % Si. Based on thermal-gravity measurement by oxidation of films at 900° C in the air, the oxidation ratio of the Ti-Al-Si-N films was only a quarter of that in Ti-Al-N films. These special characteristics of the Ti-Al-Si-N films are potential results from the formation of an amorphous Si@sub3@N@sub4@ phase.