The prospect of using nickel-based sealing coatings in the hot tract of gas turbine engines

Abstract

In work the analysis of the possibility of raising the operating temperature sealing thermal coatings on Nickel-based alloying by rare-earth metals. The literature review indicates that the operating temperature of the thermal sealing to Nickel-based that are easy to work reaches about 900 ° C, and its increase is possible by alloying the material of the coatings of rare earth metals (REM). Therefore, there is a positive effect of doping rare-earth metals, especially yttrium, the performance properties of high-temperature Nickel-based alloys. First of all it is known that the introduction of heat-resistant alloy is: 0.01...0.05% of Y improves thermal stability, retards coagulation γʹ the main strengthening phase and formation of a double carbide М₆С unfavorable morphology. The introduction of yttrium promotes the formation on the surface of the protective alloy oxide, Ni(Cr,Al,Y)₂O₄ and  (Сr, Y),₂O₃. Also stated that the microalloying of Hf, La, Ce, Zr, Y, Yb, Th, Er increases the adhesion of the oxide film, and the introduction of lanthanum in the alloy of VKNA type allows to form in the alloys modified structure, which is stabilized by nanometer-sized precipitates of lanthanide Nickel and aluminum and nano-size precipitates of the phases formed by refractory elements. However, it is established that the works devoted to the study of the influence of doping on thermal spray coatings is not sufficient.
The study examines the effect of doping the sealing cover type kPa aristarain ligatures. To determine the distribution of chemical elements carried out microprobe studies. There is a positive effect of alloying yttrium on improvement of dispersion and uniformity of distribution of elements, as evidenced by the fact that the most uniform distribution of elements is observed in the doped coatings with monolateral Y and complex alloys Co-Ni-Cr-Al-Y.