Kvasnytska I. Increase of operational characteristics of Nickel-based superalloys and development of technology for producing GTE blades

According to the results of the analysis of modern scientific bases of the processes of structure formation in castings and obtaining blades for gas turbine engines, the directions for improving of the production and increase of operational characteristics of cast metal from superalloys were determined. The temperature-time dependences of the formation of fragiled phases in superalloys, as well as effective methods of alloying them with refractory metals (chromium, tungsten, molybdenum, niobium, rhenium and tantalum) were determined. The influence of alloying elements on phase-structural stability, corrosion resistance the physical and mechanical properties of turbine blades was studied and a new corrosion-resistant nickel-based superalloy was created for their production. To improve the strength properties and purity with gases and non-metallic inclusions of cast metal, obtaining a dispersed structure of a given orientation in castings, reducing the burn and increasing the geometric accuracy of the blades, compositions of refractory materials have been developed, which are modified with aluminum, silicon and boron, for the produce of ceramic crucibles, molds and rods, filters. The influence of modifying additives and their quantity in refractories on the strength, thermo mechanical properties of ceramic products are investigated. The interfacial interaction of ceramics in contact with a high-temperature melt of superalloys is studied. The expediency of using of ceramic filters in flood-feeding systems of castings has been substantiated. This solution allowed filling the forms with the metal by the rain method, to reduce the thermal impact of the melt on the rods and to reduce the content of gases, non-metallic inclusions in the castings. Experimental trials at Ukrainian enterprises have shown that using of ceramic mixtures for crucibles, shapes, rods and filters with modified ceramics can reduce the defect of cast products and increase the geometric accuracy of the turbine blades. The optimal technological parameters of the process of obtaining from nickel-based superalloy the turbine blades with a directed structure (cooling rate and solidification of castings, temperature gradient at the front of their crystallization etc.) were determined. The technology is realized in production conditions on a vacuum-induction plant, which installed an additional cooling system of the mold with regulate intensity. The results of the research and the created technological process allowed to get the blades of turbines for energy and ship assignment from a new superalloy with operational characteristics corresponding to world analogues and exceeding their level by 15-20% in cast products made of CM88Y alloy.