INFLUENCE OF STRUCTURE ON THE CRACK RESISTANCE OF DETONATION SPRAYED CERMET COATINGS

Haracteristics are determined by the properties of their working surfaces. One of the most promising ways to improve the operational properties and durability of products is the cladding of functional coatings on their surface using a variety of spraying technologies. Treatment of different metal surface by the use of multi-chamber detonation sprayer allows obtaining composite surface layers with high mechanical properties. The purpose of this work was to study the structural and phase features and to evaluate their effect on the crack resistance of cermet coatings obtained by the multi-chamber detonation spray method. Techniques. The investigations were carried out on coatings obtained with the use of zirconium ceramics ZrSiO4 and alumina powders Al2O3 (Amperit 740.0) with additives of pure Al and Ti. Structural-phase and concentration changes in chemical elements in the sprayed and substrate materials were studied by methods of optical microscopy (Versamet-2, Neophot-32), scanning electron microscopy (Philips SEM-515) and transmission electron microscopy (JEOL JEM-200CX). Results. Based on obtained experimental data on different structural levels, analytical estimates were made that show the effect of the concrete structural parameters (phase composition, grain and subgrain structure) on the mechanical properties and the crack resistance of the sprayed coatings. Scientific novelty. Structural factors influencing the character and distribution of local internal stresses, which are potential sources of crack initiation, are determined. Practical significance. The obtained results showed the prospects of using multi-chamber detonation sprayer, which ensures the necessary complex of mechanical properties of coatings by forming the most favorable structure.