EFFECT OF NETS OF MICROCRACKS ON ELASTIC PROPERTIES OF MATERIALS

Low elastic stiffness of coatings and of free-standing parts prepared by thermal spraying is explained as an effect of microcracks between a nd inside the splats. Two theoretical models are used for estimates of the elastic constants: imperfect bonding between the ''bricks'' and r epresentation of the microcracks by hollow flat rotational ellipsoids. Both models describe the elastic anisotropy of the material (the so-c alled transverse isotropy with five independent elastic constants), th e decrease of Young moduli in comparison with bulk material without mi crocracks and different behaviour in tension and in compression.