Analysis and development of methods for eliminating production defects of thermal barrier coatings formed by electron beam physical vapor deposition in the vacuum

The purposes. The process of forming a heat-protective coating on the surface of turbine blades of gas turbine engines involves a complex of complicated technological equipment. The purpose of this work is to systematize, identify the causes and possible ways to eliminate manufacturing defects of thermal barrier coatings produced by electron beam evaporation in vacuum. Methods. To achieve this goal, of thermal barrier coating formed on the turbine blades from a single-crystal nickel superalloy ZHS32-VI were analyzed. The metal sublayer in the thermal barrier coating system was deposited by the ion-plasma method on the MAP1-M equipment. The ceramic thermal insulation layer was formed by electron beam evaporation with condensation from the vapor phase on the L-8 installation. Optical and electron microscopy and metallography were used to study defects in the ceramic coating. The chemical composition of the phase components in the surface layer and thermal barrier coatings of the blades was performed using an energy dispersive analyzer included in an electron microscope. Results. The causes of coating defects at different stages of production have been identified. The classification of defects and measures for their elimination and prevention of their occurrence are carried out. Conclusion. After analyzing the experience of serial technology, it can be concluded that defects of thermal barrier coatings can be divided into two groups: defects formed during deposition as well as defects formed during auxiliary coating manufacturing operations. Defects detected by visual inspection can be eliminated, despite the increase in the production time at the same time as its price increase. However, the greatest danger is hidden defects, which cannot be detected at the manufacturing and control stage. Such defects appear only during testing or operation, endangering the performance of the entire engine as a whole.