The effects of Si incorporation on the thermal and tribological properties of DLC films deposited by PBII&D with bipolar pulses

https://doi.org/10.1016/j.surfcoat.2006.02.084Get rights and content

Abstract

In the present study, the thermal stability and tribological properties of silicon-incorporated diamond-like carbon (DLC) films were investigated. The DLC films were deposited using a bipolar-type plasma based ion implantation and deposition (PBII&D) technique, and the Si contents in the films were varied from 0 to 29 at.%. The deposited DLC films were annealed at 500 °C for 30 min in ambient air.

The structure and mechanical properties of the Si-DLC films with a high Si content (≥ 21 at.%) were not affected by the thermal annealing. The 21 at.% Si-DLC film annealed at 500 °C shows low wear as well as low friction, whereas the 29 at.% Si-DLC film exhibited a high friction due to the creation of cracks on the worn surface related to the SiC-like nature. The 11 at.% Si-DLC film annealed at 500 °C shows the lowest friction coefficient at the cost of significant wear in the graphitized film. The formation of a thick silicon oxide layer on the Si-DLC film could be favorable for low friction and wear.

Introduction

The thermal degradation of diamond-like carbon (DLC) films is a major problem in achieving high temperature applications. It has been reported that DLC films maintain stable properties up to about 400 °C while the graphitization of the films starts above this temperature [1]. It is required that DLC films should endure at least up to 500 °C in ambient air to achieve high temperature applications such as coating materials for molds. Though many studies have been carried out to understand the high temperature behavior of DLC films, most of the studies have dealt with their thermal stability in a vacuum or inert gas conditions [2], [3], [4].

In the present study, the thermal and tribological properties of silicon-incorporated DLC films in ambient air were investigated. The DLC films were deposited using a bipolar-type plasma based ion implantation and deposition (PBII&D) technique, and the effect of the Si content on the thermal stability of the DLC films was investigated.

Section snippets

Experiments

A bipolar-type PBII&D system [5] was used for the deposition of DLC films on steel and Si substrates. The steel substrates were used for the friction measurements. The deposition conditions of the DLC films are shown in Table 1. The deposited DLC films were annealed at 500 °C for 30 min in ambient air. The composition and microstructure of the DLC films were investigated using X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy. The hardness of the films was measured by

Structure and composition of the DLC films

Raman spectra of the DLC films before and after annealing are shown in Fig. 1. The as-deposited DLC film without Si (pure DLC) shows a typical diamond-like structure with peaks centered at 1539 (G band) and 1373 cm 1 (D band). With the increasing Si content, the G peak becomes more pronounced relative to the D peak, and the peak for the 29 at.% Si-DLC film can be fitted by a single Gaussian, which has also been reported by Camargo et al [2]. Also, the intensity ratio, Id/Ig, decreases from 0.81

Conclusions

The silicon-incorporated DLC films were deposited using a bipolar-type plasma based ion implantation and deposition (PBII&D) technique, and the thermal stability and tribological properties of the films with respect to the Si content were investigated. The major results obtained are as follows.

  • (1)

    Raman spectral analysis and the hardness measurements revealed that the structure and mechanical properties of the Si-DLC films with a Si content greater than 21 at.% are not affected by thermal annealing

References (11)

  • S.S. Camargo et al.

    Diamond Relat. Mater.

    (1998)
  • L.G. Jacobsohn et al.

    Diamond Relat. Mater.

    (2000)
  • V. Kulikovsky et al.

    Diamond Relat. Mater.

    (2003)
  • S. Miyagawa et al.

    Surf. Coat. Technol.

    (2002)
  • S.C. Ray et al.

    Thin Solid Films

    (2005)
There are more references available in the full text version of this article.

Cited by (0)

View full text