ANALYSIS OF THE QUALITY OF COATINGS MADE BY PLASMA SPRAYING FOR NODES AND PARTS OF GAS TURBINES ENGINES AND INSTALLATIONS

An analysis of the available methods for assessing the quality of protective coatings applied by plasma spraying for strengthening and restoring assemblies and parts of gas turbine engines and installations has been carried out.The degree of influence of the structure of the coatings on their main quality indicators has been established.An assessment of the effectiveness of the methods for studying these indicators is given.It is noted that for assessing the quality indicators of coatings applied by plasma spraying, physical methods of instrumental research prevail among the methods of their analysis.However, recently, mathematical modeling methods have also been used.Such methods for analyzing the behavior of coatings significantly simplify the development and selection of technological processes.Using calculation methods and numerical modeling, it is possible to predict their behavior under different conditions with a sufficient degree of accuracy, depending on the selected operating mode of the plasma installation and the order of application of sprayed layers with different components.These calculations relate to descriptions of the stress state of plasma coatings.The possibility of such a forecast is confirmed by the obtained coincidence of the results of studies of estimates of numerical values of quality indicators of protective coatings properties, performed by mathematical and experimental methods.Along with the modes and materials of spraying, the operating conditions of the coating, the dependence obtained analytically proves the importance of choosing its thickness to ensure its given strength.It is concluded that in the case of uneven coating thicknesses due to deformation of parts from the thermal effect of the plasma flow, it is not possible to obtain an adequate assessment of the stress state of the coatings using already known methods of analytical calculation and modeling.The analysis showed that most methods of analysis and evaluation of coatings are not perfect and require both additions and new solutions, including using other physical phenomena and means.