Introduction: produced between the coating and the substrate [1,2,18,19,25] in order to facilitate adhesion. In Hard and brittle coatings are mainly used to some cases, an interlayer is deposited separately to improve the wear resistance of soft metallic act as a bond coat between the coating and the substrates and can also serve to resist metallic substrate [17,26-29]. The thickness of this corrosion [3,4]. The adhesion, deformation and interlayer should be kept as minimum as possible to fracture mechanism of these coatings has been control the adhesion of the coating [3,20,30]. explained by many researchers [1-18] but it still needs more work to develop better understanding. An important technique to analyze the deformation The adhesion of these coatings is affected by the and damaging behavior of hard-film/ductile- residual stresses [1-4,11,19-23] as well as by the substrate system is the uniaxial tensile testing. In- interfaci al strengt h [4-7,24] . If a coati ng is situ tensile testing in scanning electron microscope synthesized at high temperature (e.g. using CVD (SEM) has shown its worth to understand fracture process) then an intermediate compound layer is and delamination behavior of diamond like carbon Stress evolution in diamond thin film bonded to ductile substrate analyzed by Finite element modeling and micro-Raman spectroscopy * 1 1 1 1 F. Ahmed , K. Nur , M. Zubair , M. A. Rafiq , L. Ali Abstract In this work, finite element analysis (FEA) has been used to study the effects of hard film thickness, interlayer and its thickness, and residual stresses in the ‘film and interlayer’ on the stress transfer to the film from the substrate under uniaxial tensile loading. Moreover, the successive stress development/evolution in the film, and the deformation mechanism of the hard-film/ductile-substrate system have been comprehended. Using FEA, the results of stress evolution in diamond film, acquired from in-situ tensile testing in μ-Raman spectroscope [1,2], have been validated. The present results show that thicker films need higher amount of stress transfer from the substrate as compared to thinner films to acquire the same stress level under uniaxial tensile loading. An interlayer reduces the amount of stress transfer to the film. Moreover, the thinner the interlayer the higher will be the stress transfer to the film per unit substrate strain. The presence of residual stress in the interlayer also increases the amount of stress transfer to the film from the substrate. Further, the stress evolution results produced with FEA are consistent with the experimental data of in-situ tensile testing in μ-Raman spectroscope [1,2]. Keywords: Finite element modeling; stress transfer; stress evolution; film thickness; interlayer Submitted: 21/01/2015, Accepted: 08/04/2015, Online: 20/04/2015 1 Department of Metallurgical and Materials Engineering, University of Engineering and Technology, Lahore- Pakistan *Corresponding Author: F urqan Ahmed (furqan.ahmed@uet.edu.pk) JPIChE 43 (1) 2015: 147-157 journal homepage: www.piche.org.pk/journal Journal of Pakistan Institute of Chemical Engineers 147 Journal of The Pakistan Institute of Chemical Engineers