Thermal Stability and Tribological Performance of DLC-Si–O Films

Nutthanun Moolsradoo,Shuichi Watanabe,Shinya Abe

doi:10.1155/2011/483437

Nutthanun Moolsradoo, Shuichi Watanabe + Show 1 more

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https://doi.org/10.1155/2011/483437

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Abstract

The thermal stability and tribological performance of silicon- and oxygen-incorporated diamond-like carbon films were investigated. The DLC-Si-O films were deposited using plasma-based ion implantation (PBII) method. The deposited films were annealed at 400°C, 600°C, and 750°C for 1 hour in vacuum, in argon, and in air atmospheres. Film properties were investigated using the Fourier transforms infrared spectroscopy, Raman spectroscopy, energy dispersive X-ray spectroscopy, and a ball-on-disk friction tester. The structures of the DLC-Si-O films with a low Si content (25 at.%Si, 1 at.%O) and high Si content (25 at.%Si, 1 at.%O) were not affected by the thermal annealing in vacuum at 400°C and 600°C, respectively, while they were affected by thermal annealing in argon and in air at 400°C. Film with 34 at.%Si and 9 at.%O after annealing demonstrated almost constant atomic contents until annealing at 600°C in vacuum. The friction coefficient of DLC-Si–O films with 34 at.%Si and 9 at.%O was shown to be relatively stable, with a friction coefficient of 0.04 before annealing and 0.05 after annealing at 600°C in vacuum. Moreover, the low friction coefficient of film annealed at 600°C in vacuum with 34 at.%Si and 9 at.%O was corresponded with low wear rate of 1.85 10−7 mm3/Nm.

Highlights

Diamond-like carbon (DLC) coatings are metastable amorphous films that exhibit unique combinations of properties such as high hardness and elastic modulus, low friction coefficients, optical transparency, good wear resistance, and excellent corrosion resistance
It has been reported that DLC films maintain stable properties up to approximately 400◦C; the graphitization process of the samples starts at this temperature, as revealed by the increasing ratio of D and G peaks of the Raman spectra [8]
Film properties were investigated by the Fourier transforms infrared (FT-IR) spectroscopy, the Raman spectroscopy, energy dispersive X-ray spectroscopy, and a ball-on-disk friction tester

Summary

Introduction

Diamond-like carbon (DLC) coatings are metastable amorphous films that exhibit unique combinations of properties such as high hardness and elastic modulus, low friction coefficients, optical transparency, good wear resistance, and excellent corrosion resistance. Silicon incorporation into DLC has been proven to overcome some of the stated drawbacks, including low intrinsic compressive stress, good adhesion, and mechanical resistance [9] When both silicon and oxygen are incorporated into DLC films, substantial structural modifications occur. The unique advantages of PBII include a low working temperature of less than 100◦C This low working temperature avoids film quality degradation, such as loose and rough surface structure, and avoids DLC graphitization caused by normal chemical vapor deposition and plasma laser deposition, which are performed at higher working temperatures [17]. Film properties were investigated by the Fourier transforms infrared (FT-IR) spectroscopy, the Raman spectroscopy, energy dispersive X-ray spectroscopy, and a ball-on-disk friction tester

Experimental Details

Results and Discussion

Conclusions