Are there any correlations (direct/ indirect/ emperical/ physical) between the flexural strength and residual stresses in coatings/claddings? How does one aspect influence the other one?
First, it should be mentioned that if there is residual stresses in a coating then, for satisfying equilibrium conditions, there is also residual stresses in the substrate. So, depending on the coating process and on the materials involved, if compressive residual stresses take place in the coating, tensile residual stresses appear in the substrate just below the coating and conversely, if tensile residual stresses take place in the coating, compressive residual stresses appear in the substrate.
These residual stresses in both the coating and the substrate will be added to the bending stresses during a flexural test and of course can change the flexural behavior inducing plastic deformation or even cracks in the zone near the coating.
There is a relationship between modulus of elasticity of the layer and the residual stress therein, the higher the modulus, the greater the residual stresses. For this reason, materials with a low modulus of elasticity are better suited for thermal spraying and for cladding.
Hi,
There are a number of emperical relationships/ mathematical models defining flexural strength and residual stresses in coatings. For the Basic understanding you can check bending tests/ nanoindentation of coatings performed for highly stressed coatings. PVD coatings generally have compressive stresses and the relationship with flexural stresses are generally determined through bending tests. Therefore, I would recommend to investigate in this direction
Hi,
There are a number of emperical relationships/ mathematical models defining flexural strength and residual stresses in coatings. For the Basic understanding you can check bending tests/ nanoindentation of coatings performed for highly stressed coatings. PVD coatings generally have compressive stresses and the relationship with flexural stresses are generally determined through bending tests. Therefore, I would recommend to investigate in this direction. I hope it helps
Dr. Bergheau, Dr. Verlotski and Dr. Mahammad Naveed thanks alot for your valuable suggestions.
Dr. Naveed can you send me a few links of the papers published on emperical relationships/ mathematical models defining flexural strength and residual stresses in coatings. I would be grateful to you.
Thanks
Hi,
I just went quickly through literature and found some of the related links. I am attaching these links here. I studied the effect of mechanical properties due to residual stresses for my research work and found that this can be studied through nanoindentation and bending tests. I hope that these links work for you.
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