Physicomechanical properties and failure of detonation coatings

Conclusions The effect of the complex of external factors such as plastic deformation, temperature, chemical interaction causes structural and phase changes of powder materials in detonation coatings leading to relatively low ductility of the coating. The bend strength of the coatings up to 0.25 mm thick is similar to that of the dense materials. To produce high-quality detonation coatings, it is necessary to avoid hard temperature and kinetic parameters of the spraying process, and the extent of deformation of the particles should be limited to minimize formation, in the coatings, of internal stresses and a defective structure. Coatings made of alloyed steels with a large amount of the hardening phase are especially sensitive to defects.The physicochetnical and mechanical properties of the coatings on the substrates showed the strong mutual effect in the process of formation of the coatings and combined deformation under loading. This fact must be taken into account in selecting coating-substrate pairs for service in the conditions specified in advance.The mechanism of failure of detonation of coatings up to 0.25 mm thick produced by optimum technology in three-point bend loading does not differ from the mechanism of failure of the dense materials. With increasing thickness of the coatings their strength and ductility properties rapidly decrease and the failure mechanism also changes.Translated from Poroshkovaya Metallurgiya, No. 11(299), pp. 88–94, November, 1987.