NIST Standard Reference Database 30
Last Update to Data Content: 2002
"Tribology of Diamond-Like Carbon Sliding Against Itself, Silicon Nitride, and Steel," K. Jia, Y.Q. Li, T.E. Fischer, and B. Gallois, Journal of Materials Research, Vol. 10 [6], pp. 1403-1410 (1995), published by Materials Research Society.Language: English
"An RF plasma-assisted chemical vapor deposition system was used to deposit the DLC films. Two parallel plate-electrodes were capacitively coupled to generate a glow discharge at a frequency of 13.56 MHz. Micro-polished (100) silicon wafers and silicon nitride balls with a diameter of 6.35 mm were ultrasonically degreased in acetone, then methanol, and rinsed with distilled water. They were placed on the cathode and cleaned in an argon glow discharge for 60 min before introducing the reactant gases, methane and hydrogen, for the deposition of the DLC films under the following conditions: CH4 flow rate of 20 sccm, H2 flow rate of 5 sccm, pressure of (93 Pa = 700 mTorr), and RF powder density of 0.13 W/cm2. The measured substrate temperature and bias voltage were 360 K and 150 V. The growth rate of the DLC film was 1.5 µm/h. The thickness of the films used in this study was typically 2 µm."
"The hardness of the DLC film was measured with a Vickers indenter at a load of 5 g and a contact time of 25 s, and the hardness of the steel and silicon nitride balls at a load of 50 g. The penetration depth into the DLC film under the load of 5 g is about 0.4 µm, compared with the thickness of 2 µm of the film; thus, the effect of the substrate can be neglected."Wear test (ball on flat)
"The tribology experiment was performed with the geometry of sliding a ball against a disk, and the friction force was continuously monitored with a load cell. The tests were conducted with 9.8 N normal load (a Hertzian pressure of 1300 MPa with a silicon nitride ball) and 1.6 cm/s sliding speed (0.6 cm diameter track at 50 rpm). After sliding a distance of 1200 m, the surface morphology of both ball and disk were examined with an optical microscope and a profilometer. Quantitative wear rates were determined by calculating the volume removed from the surface profiles of the wear scars and the wear tracks."
| Counterface Material | Relative Humdity ( % ) | Friction Coefficient ( no unit ) |
|---|---|---|
| Si3N4 | 0 | 0.04 |
| Si3N4 | 40 | 0.05 |
| Steel | 0 | 0.04 |
| Steel | 40 | 0.06 |
| DLC | 0 | 0.05 |
| DLC | 40 | 0.07 |
"...the friction cofficient decreases gradually from around 0.15 to about 0.05 with an increasing number of sliding passes, then reaches a constant value until the DLC films are worn through..."
| Temperature ( °C ) | Hardness ( GPa ) |
|---|---|
| 23 | 18 ± 2 |
| Counterface Material | Counterface Wear Rate Log ( mm3/N·m ) | Relative Humidity ( % ) | Log Wear Rate ( mm3 m-1 N-1 ) |
|---|---|---|---|
| Si3N4 | -7.6 | 0 | -10.7 |
| Si3N4 | -6.7 | 40 | -7.3 |
| Steel | -8.2 | 0 | -10.4 |
| Steel | -8.0 | 40 | -9.2 |
| DLC | -8.2 | 0 | -8.3 |
| DLC | -10.0 | 40 | -9.7 |