An aluminium plate surface coated with a brittle Al2O3 at 420C using sputter coating techniques to...

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An aluminium plate surface coated with a brittle Al2O3 at 420°C using sputter coating techniques to protect the surface from cyclic failure. Find out the fatigue life of the coated aluminium surface at 20°C subjected to ± 200 MPa cyclic stresses. The property of Al & Al2O3 is given in the following table. [10] Property Elastic Modulus, GPa Poisson's ratio Thermal expansion coefficient, m/mK Lattice Parameter (at 420°C), nm True facture strain True fracture strength, MPa Fatigue ductility exponent Fatigue strength exponent Al 70 0.35 21 x 10-6 0.5185 1 400 - 0.5 - 0.05 Al₂O3 360 0.10 1 x 10-6 0.5145 2.86 x 10-3 1080 1 -0.1 An aluminium plate surface coated with a brittle Al2O3 at 420°C using sputter coating techniques to protect the surface from cyclic failure. Find out the fatigue life of the coated aluminium surface at 20°C subjected to ± 200 MPa cyclic stresses. The property of Al & Al2O3 is given in the following table. [10] Property Elastic Modulus, GPa Poisson's ratio Thermal expansion coefficient, m/mK Lattice Parameter (at 420°C), nm True facture strain True fracture strength, MPa Fatigue ductility exponent Fatigue strength exponent Al 70 0.35 21 x 10-6 0.5185 1 400 - 0.5 - 0.05 Al₂O3 360 0.10 1 x 10-6 0.5145 2.86 x 10-3 1080 1 -0.1