Department of Material Science, Faculty of Mechanical Engineering and Aeronautics, Rzeszow University of Technology, Powstancow Warszawy 12, 35-959 Rzeszow, Poland
Prof. Marek Goral
Department of Material Science, Faculty of Mechanical Engineering and Aeronautics, Rzeszow University of Technology, Powstancow Warszawy 12, 35-959 Rzeszow, Poland
The article presents a new technology of thermal barrier coating deposition called Plasma Spray – Physical Vapour Deposition (PS-PVD). The key feature of the process is the option of evaporating ceramic powder, which enables the deposition of a columnar ceramic coating. The essential properties of the PS-PVD process have been outlined, as well as recent literature references. In addition, the influence of a set of process conditions on the properties of the deposited coatings has been described. The new plasma-spraying PS-PVD method is a promising technology for the deposition of modern thermal barrier coatings on aircraft engine turbine blades.
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.
1 January 2023 in Advances in Mechanical and Materials Engineering
This article assesses the tribological performance of new composite tool sets for stamping dies. Four sets of composite countersamples were tested. These consisted of polyurethane resin with mineral filler (base variant) and modified with aluminium powder (10wt%) and roving fabric (5wt%). Strip samples for the strip drawing tests were cut from AMS5599 (Inconel 625) corrosion-resistant nickel alloy, AMS5510 (321) corrosion and heat-resistant steel and AMS6061-T4 heat treatable aluminium alloy sheet metals. The influence of the type of sample material on the coefficient of friction (COF) was observed. The smallest values of the COF over the entire range of clamping force values used on AMS5599 and AMS5510 sheets were observed during tests with countersamples made of the base variant of composite. When testing the AMS6061-T4 aluminium alloy sheet, the countersamples modified with roving fabric provided the lowest value of COF, which stabilised at a value of about 0.197 as pressure was increased.
The paper presents the preliminary results of technological tests of aluminizing using a new BPX Pro 325 S CVD equipment. Nickel based cast superalloys: IN 738 and MAR M200+Hf were used as a substrate material. The aluminizing processes with different parameters - pressure, HCl flow and time - were conducted. Microstructure analysis showed coatings whose thickness didn't exceed 20 µm. The authors showed that the changes of parameters values in the analyzed range weakly influenced the coating thickness (about 1-2 µm). It was proven, that it was necessary to decrease the flow of hydrogen chloride and perform the thermodynamic analysis.
In the article, the new concept of plasma-sprayed coatings for the cylinder liner was presented. The new type of powder containing WC-CrC-Ni with a 5 and 10 wt. % addition of nano-YSZ powder was plasma-sprayed on aluminum 2017 alloy samples. The selection of optimal plasma-spraying parameters was made taking into account the thickness, porosity, and hardness of the coatings. For the coatings obtained according to the developed parameters, the analysis of their microstructure, chemical, and phase composition was performed. At the next stage, the friction coefficient of the developed coatings was tested and compared with the properties of a classic cast-iron cylinder liner. The obtained results suggest that the developed type of coating might be used for cylinder liner applications after a deeper friction analysis.
Ceramic topcoats of thermal barrier coatings (TBCs) make it possible to increase the working temperature of the hot sections of jet engines. Yttria-stabilized zirconia oxide (YSZ) is usually used to protect the turbine blades and vanes against high temperature and oxidation. It is necessary to develop new materials which can operate at higher temperatures in a highly oxidizing gas atmosphere. Re2Zr2O7-type pyrochlores are promising YSZ replacements. Usually, they are produced by mixing pure oxides in the calcination process at higher temperatures. In a recent article, the new concept of pyrochlore synthesis during the deposition process was presented. The new technology, called reactive plasma spray physical vapor deposition (reactive PS-PVD), was developed and a Gd2Zr2O7 (GZO) coating was achieved. The reactive PS-PVD process allowed for the use of a mixture of untreated ZrO2 and Gd2O3 powders as reactants, instead of the commercially available gadolinium zirconate powders used in other types of processes. The results of microstructure observations revealed a columnar microstructure in the produced ceramic layer. The phase composition indicated the presence of gadolinium zirconate. Thermal analysis showed a decrease in the thermal conductivity in the range of 700 to 1200 °C of the produced layers, as compared to the layer made of the currently used conventional YSZ.