Nanoindentation Fracture Behaviors of Diamond-Like Carbon Film on Aluminum Alloy with Different Interface Toughnesses
Fracture behaviors of a diamond-like carbon (DLC) film on an aluminum alloy (AA2017) were analyzed by a nanoindentation test under conditions of deep and full penetrations of an indenter tip through the DLC film. The interface structure between the DLC and AA2017 was modified by using the substrate...
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| Published in | Japanese Journal of Applied Physics Vol. 51; no. 9; pp. 090127 - 090127-4 |
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| Main Authors | , , , |
| Format | Journal Article |
| Language | English |
| Published |
The Japan Society of Applied Physics
01.09.2012
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| Online Access | Get full text |
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| Summary: | Fracture behaviors of a diamond-like carbon (DLC) film on an aluminum alloy (AA2017) were analyzed by a nanoindentation test under conditions of deep and full penetrations of an indenter tip through the DLC film. The interface structure between the DLC and AA2017 was modified by using the substrate sputtering and redeposition (SSRD) method. The films deposited with a shorter (30 min) SSRD duration showed weak adhesion to the substrate and often resulted in wide delamination from the impressions. At the same time, films deposited with a longer (120 min) SSRD duration showed no such delamination. Obvious brittle fractures were detected in the load-displacement curves mainly in the film with the short SSRD duration. These results suggest that a long SSRD inhibited the delamination of the DLC film from AA2017 under local and strong stress conditions because of the improved interface toughness. |
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| Bibliography: | Time-sequence diagram of the substrate bias and target power in the SSRD method. The durations of the substrate sputtering are (A) 30 and (B) 120 min. Maximum indentation depth ($h_{\text{max}}$) in indentation test plotted against the maximum load ($L_{\text{max}}$). The SSRD durations of (A, circle) 30 and (B, cross) 120 min are compared. The film thickness (1 μm) is shown as a dotted line. The inset shows the definition of $h_{\text{max}}$ and $L_{\text{max}}$ in a load-displacement curve. Apparent hardness of DLC/AA2017 components plotted against the maximum load in indentation test. The SSRD durations of (A, circle) 30 and (B, cross) 120 min are compared. The original hardness of the AA2017 substrate (2.6 GPa) is shown as a dotted line. SEM images of impressions. SSRD duration of (a1--a3) 30 and (b1--b3) 120 min. Large delamination areas are encircled in (a1). Small delamination from the indentation is indicated by arrows in (b1). DLC films are delaminated in the vicinity of the impressions in (a2) and (a3) in sample (A). No delamination was observed in the SSRD duration of 120 min, which was sample (B). Auger electron spectra of (a) C \text{KLL , (b) O \text{KLL , and (c) Al \text{KLL of sample (A) as a function of Ar + ion cleaning time just before measurement. An electron beam was scanned in a $5\times 5$ μm 2 rectangular region on the delaminated area shown in the SEM image (d). Wide delamination was observed in the vicinity of the impressions only in sample (A), which had an SSRD duration of 30 min. Peaks at 210 eV in (a) are due to residual Ar in the ion cleaning process. Load-displacement curves for SSRD duration (A) 30 and (B) 120 min. The inset of (a) schematically shows the brittle deformation depth in a load-displacement curve. Distribution of the maximum brittle deformation from 64 indentation tests with $L_{\text{max}} = 40$ mN. The SSRD duration is (A, closed red) 30 and (B, open blue) 120 min. |
| ISSN: | 0021-4922 1347-4065 |
| DOI: | 10.1143/JJAP.51.090127 |