There are three different ways of relating hardness and Young modulus to the mechanical properties of the film. Matthews and Leyland proposed the study of the relationship between the tribological properties of ceramic coatings and the ratio between the hardness (H) and the Young Modulus (E) of the film. This ratio, according to the authors, is related to the elastic strain to failure of the coating [17]. On the other hand, the H3/E2 parameter proposed by Johnson [18] was associated to the coating resistance to plastic deformation [17]. This ratio can only be used for a configuration similar to a rigid-ball in contact with an elastic/plastic plate [18], provided that the hardness of the plate is three times its yield strength [19].