Yttria-stabilized zirconia (YSZ) is one of the most common materials used for a ceramic top coat in the thermal barrier coating (TBC). The high operating temperature used in the gas turbine engines causes the stress between the top coat and the bond coat. The stress relaxation can be assured by modifications of YSZ. Hence, studies on how to modify the chemical and phase composition of these coatings are still conducted. The laser flash analysis was used to determine the thermal diffusivity of composite mixture of 8 mol% yttria-stabilized zirconia with α-Al₂O₃ in the range of temperatures between 20 and 1100 °C. The powders were prepared with 5 and 25 mass% Al₂O₃ addition to 8YSZ. The particle size distribution was done for each powder to analyse the grain size after milling of the α-Al₂O₃ with 8YSZ in the ball mill. The density of each powder was measured in the helium pycnometer. The disc-shaped samples were produced by pressing using an isostatic press and then sintered at various temperatures: 1000, 1200, 1400 and 1600 °C.

In the present article the doping of aluminide coatings by Pt/Pd as well as Hf or Pd using industrial processes was developed. The different combinations of doping elements were tested as well as their influence on chemical composition of coatings was initially investigated. The Pt and Pd and both Pt + Pd was electroplated on the surface of the MAR M247 nickel superalloy. The Zr or Hf was doped during low activity CVD aluminizing process using industrial Bernex BPX Pro 325S system. The conducted research showed that Pt and Pd formed the (Ni, Pd, Pt) Al solid solution in the outer additive layer. The higher concentration of palladium in the near surface and in the whole additive layer was detected. The platinum was presented below the surface of aluminide coating. The Zr or Hf was detected mainly in the diffusion zone. The low concentration of Zr (about 0.1 wt.%) in the outer zone was observed. The hafnium was detected mainly in the diffusion zone but in the outer additive layer a small concentration of this element was measured. The obtained results showed that formation of three elements (Pd, Pt) + Zr or Hf modified aluminide coating using proposed technology is possible. The structure of all obtained aluminide coatings was typical for a low-activity, high temperature (LAHT) formation process mainly by outward diffusion of Ni from base material.

The oxidation behavior of the nickel superalloy Inconel 740H was studied at 750 °C for 100, 250, 500, 1000, and 2000 h in a steam atmosphere. Microstructure observations were performed using scanning electron microscopes and scanning-transmission electron microscope. The phase identification of existing oxidation products was conducted by electron diffraction in transmission electron microscope. The obtained results showed that the microstructure of Inconel 740H was stable during the oxidation process. The kinetic data showed that the superalloy has the ability to form protective oxide layers that are characterized by good adhesion and no tendency to spallation during the test. The oxidation products were mainly composed of external and internal oxides mainly at grain boundaries. The oxides in the external layer were Cr₂O₃, MnTiO_3,, and α-Al₂O₃ after 2000 h of oxidation. Internal oxides were α-Al₂O₃ and TiO₂. The occurrence of discontinuities in the internal oxidation zone was also observed after 500 h of test. It was found that the thickness of the internal oxidation zone was greater than the thickness of the external oxide layer, which proves the strong tendency of the superalloy to form internal oxides after oxidation in the steam atmosphere.

The development of the aviation industry is related to the production of new materials that can operate at high temperatures and corrosive atmospheres. The paper presents new material for application in high temperature obtained by pressing and sintering a composite made from SiC–Al₂O₃–Ni. Analysis of the microstructure showed high porosity, which is caused by used manufacturing technique. Studies of thermal expansion do not show any phase transition and keeps linearity in thermal expansion in wide range (from 550 to 1450 K). X-ray diffraction showed the presence of all components of phase with those used, the phase associated with the components and silicon oxide, which was formed during the sintering of the samples.