THE INFLUENCE OF HEAT TREATMENT MODES ON THE STRUCTURE OF PROTECTIVE COATINGS

Purpose. Increasing the durability of ГTK-10I hollow working blades due to double-sided protection of their profile part. Research methods. Microstructure studies were carried out on microsections under a “Neophot-2” microscope and a “Stereoscan” microscope-analyzer. Microhardness was measured with a ПMT-5 device. Short-term strength tests (GOST 1497-61, GOST 9651-61, GOST 1497-84) were carried out on standard cylindrical samples (diameter of the working part 5 mm, length 25 mm) at temperatures of 200, 800, 900 and 1000 °C on a УME-10TM brand tensile machine. Long-term strength tests (GOST 10145-81) were performed on standard cylindrical samples at temperatures of 800, 900, 10000 °C and corresponding loads of 600, 400, 180 MPa on the AIMA-5-2 machine by uniaxial stretching of samples under constant load. Comparative experimental studies of high-temperature corrosion of alloys were carried out in synthetic ash using a method widely used in the industry. For corrosion tests, standard cylindrical samples (diameter Æ 10 mm, length l = 12 mm) were used, on which, after preliminary degreasing, measurement and weighing on an analytical balance with an accuracy of (± 0.0005 g), synthetic ash in an amount of 12 mg / cm2 was applied to their surface, simulating the combustion products of gas turbine fuel, which were placed and kept in a furnace on a platform made of refractory material in an air atmosphere. Results. The influence of double-sided protection of the profile part of the working hollow blades of ГTK-10I was studied. It was shown that the formation of the coating is most effectively carried out at a temperature equal to or higher than the peritectic reaction temperature (»1130°С). It was established that the strength characteristics of superalloys when using the complex protection technology at temperatures of 800 and 850°С do not decrease. It was shown that at relatively lower coating formation temperatures (1080°С, 4 hours), the structure of the slip coating is significantly different from similar ones with a heterogeneous structure and fully corresponds to the classical RT-22A type. It was established that the predicted service life of the working blades increases by 10 thousand hours when using their double-sided protection using the complex technology. Scientific novelty. The obtained results make it possible to evaluate the processes occurring during coating application and blade operation and to establish the relationships between the thickness, kinetics and type of coating and the corrosion rate. Practical value. The obtained results allow us to recommend developed coatings and application technologies to increase the strength characteristics and durability of products.