The Effects of Substrate Temperature and Bias on the Structural, Mechanical and Tribological Properties of TiC films dep
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The Effects of Substrate Temperature and Bias on the Structural, Mechanical and Tribological Properties of TiC films deposited by Magnetron Assisted Pulsed Laser Deposition
A.R.Phani, J.E.Krzanowski* and J.J.Nainaparampil# Department of Mechanical Engineering, University of New Hampshire, Durham, NH # Systron Inc, Dayton, Ohio
ABSTRACT Titanium carbide films have been deposited using a hybrid magnetron sputtering/ pulsed laser deposition technique. One set of films was deposited at substrate temperatures ranging from room temperature to 600oC with no substrate bias, and a second set was deposited at 400oC bias voltages up to –150V. X-ray diffraction, X-ray photoelectron spectroscopy, and electron microscopy were employed for structural and compositional characterization of the films, and nano-indentation hardness testing and pin-on-disc wear tests were used to evaluate the mechanical and tribological properties. All the TiC films deposited without substrate bias were highly crystalline. The films deposited with bias had significantly reduced crystallinity and non-stoichiometric film compositions. The hardness of the TiC films increased with substrate temperature from 8 GPa at room temperature to 18 GPa at 600oC, whereas the biased films had a maximum hardness of 12 GPa. The wear test data showed significantly lower friction and longer wear life for the –150V biased film. INTRODUCTION Transitional metal carbides can exhibit exceptionally high hardness levels, low friction coefficients, and excellent wear resistance making them candidates for hard coatings materials. As a result, these carbides have received considerable attention as potential materials in a number of applications including high-energy nuclear reactor walls, passivating coatings in semiconductor devices, and protective antiwear coatings on tribological surfaces. Transitional metal carbide coatings have been successfully deposited by both chemical and physical vapor deposition methods. While most work on the deposition of carbide coatings has employed traditional CVD and sputtering techniques, magnetron sputtering assisted pulsed laser deposition has been recently introduced [1,2] and has the potential to provide a low temperature deposition method for carbide films. In the conventional PLD process, a high energy pulsed laser is focused onto a target, such as TiC, and an energetic vapor is produced and collected onto a nearby substrate. In the MSPLD process for TiC, the carbon is ablated by PLD and titanium is sputtered simultaneously to get the desired stoichiometric composition of TiC in the film. In our previous investigations [3,4] TiC films were deposited by PLD from TiC targets. The films were highly crystalline, and exhibited high hardness (~30-40 GPa), good wear behavior and a low friction coefficients (0.2-0.3). However, the deposition rate was relatively low (~0.06 nm/sec) limiting practical applications of the process. Ablation of carbon from a graphite target generally results in P9.6.1
Table II: X-ray Photoelectron Spectroscopy Data on
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