Numerical and Experimental Study of the Mechanical Properties of Cobalt-Doped Tin Oxide Coatings

Tin oxide coatings doped with cobalt are produced on a glass substrate at 450 ℃ using the spray pyrolysis technique. The influence of cobalt doping on SnO2 coatings was investigated. Analysis of the SnO2:Co thin films by XRD shows that they have a crystalline structure. The XRD diagram shows four peaks in the directions (110), (111), (211) and (130). The mechanical and tribological characteristics of pure and cobalt-doped SnO2 coatings have been investigated by means of nanoindentation and scratch tests. The shapes of the load-depth curves show that pristine and cobalt-doped SnO2 coatings have elastic-plastic behavior. Nanoindentation results show that doping SnO2 with cobalt improves Young's modulus, hardness and yield strength. Furthermore, the study of the wear resistance is ensured by a scratch test called “wear mode”. The results show that doping SnO2 with cobalt decreases the coatings’ coefficient of friction and wear energy, thus improving the adhesion to the glass substrate. The Abaqus finite element simulation reproduces the experimentally tested load-depth curves of the indentation with good accuracy and demonstrates that the numerical model is valid. In addition, the residual indentation in terms of stress, strain and displacement was computed and appears to be dependent on Co doping.