Diamond-like coating (DLC) of 2.5 micron thick coated on the aluminum alloy samples, were subjected to rotating bending fatigue test in methanol and air environments respectively. DLC coating is X-ray amorphous in nature as revealed by grazing incidence X-ray diffraction studies. Residual stresses generated due in the coatings were measured using Raman peak shift analysis of G band of carbon. Fractographic analysis of uncoated fatigue tested samples in methanol revealed severe damage in contrast to coated samples in methanol. Diamond polished and DLC coated samples revealed better coating adherence and fatigue performance than 1200 grit polished and fatigue tested samples. © 2017 Trans Tech Publications, Switzerland.

Nedunchezhian Srinivasan

Aluminum

Aluminum alloys

carbon

Coatings

Diamonds

Fatigue damage

Fatigue testing

Fracture

Methanol

Residual stresses

X ray diffraction

7075-T6 ALUMINUM ALLOY

DIAMOND LIKE COATINGS

Fatigue performance

Fractographic analysis

GRAZING INCIDENCE X-RAY DIFFRACTION STUDIES

INFLUENCE OF ENVIRONMENTS

RAMAN SHIFT

ROTATING BENDING FATIGUE TESTS

Aluminum coatings

IIT Madras is a public technical and research university located in Chennai, Tamil Nadu. Founded in 1959, it is recognised as an Institute of National Importance.

IIT Madras has been ranked as the top engineering institute in India for four years in a row by the National Institutional Ranking Framework of the MHRD

It currently offers undergraduate, postgraduate and research degrees across 16 disciplines in Engineering, Sciences, Humanities and Management. About 596 faculty belonging to science and engineering departments and centres of the Institute are engaged in teaching, research and industrial consultancy.

IIT Madras

Key Engineering Materials

Amorphous diamond-like carbon coating (DLC) of 2 μm in thickness was deposited over the aluminum alloy substrate using magnetron sputtering deposition technique. In order to understand the efficacy of coating deposition, coated specimens were subjected to rotating bending fatigue in air and methanol environments respectively. Raman spectroscopy was used in conjunction with grazing incidence X-diffraction technique to obtain depth-resolved residual stress gradients of coated-aluminum substrate. The residual stress generated due to coating deposition was calculated using Raman spectroscopy and it was −1.13 ± 0.16 GPa (compressive in nature). Furthermore, Raman spectroscopy was utilized for the quantification of stress relaxation upon fatigue loading in air and methanol environments. It was observed that the irrespective of the testing environment, good correlation exists between the stress relaxation magnitude and number of cycles endured before failure. © 2018 Elsevier Ltd

Fulltext

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Residual stress gradient and relaxation upon fatigue deformation of diamond-like carbon coated aluminum alloy in air and methanol environments

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Journal	Key Engineering Materials
Publisher	Trans Tech Publications Ltd
ISSN	10139826
Open Access	No