Materials Science Forum Vol. 844

Abstract: In present article the influence of Low Pressure Plasma Spraying (LPPS) process parameters on microstructure of MCrAlY coatings was studied. Nowadays the Atmospheric Plasma Spray (APS) is the most widely used process to obtain MCrAlY-type coatings. The LPPS process may be consider as an alternative technology for deposition of this type coatings which have less porosity and smaller amount of oxides compared to APS coatings. This features are important to obtain coatings with better hot corrosion and oxidation resistance. In order to determine and optimize the process parameters the microscopic investigations were carried out. Assessment of microstructure, thickness of coating and porosity level was conducted as well. Correlation between LPPS parameters and obtained microstructure have been found. It has significant meaning for deposition of MCrAlY coatings which could be applied as a bond coat in thermal barrier coating (TBC).

Abstract: The PS-PVD method is a promising technique for production of ceramic coatings from the vapor phase on gas turbine components. The resulting layers combine benefits of coatings made by the plasma spray method and other methods of Physical Vapor Deposition. The plasma spray process is carried out under reduced pressure (~ 200 Pa) and with the use of a gun applied in the method (the LPPS torch 0C3P). The PS-PVD enjoys many of the benefits of plasma spray methods combined with relatively low production costs and overall better properties. One of the significant costs of coating manufacturing by this method is the use of helium as process gas to generate plasma. The authors attempted to form a ceramic coating from ZrO₂, where a mixture of argon and nitrogen in various proportions was used. The resulting layers were analyzed by XRD, LFA, SEM-EDS.

Abstract: In the paper the formation of Thermally Grown Oxides on newly developed Thermal Barrier Coatings were described. The CMSX-4 Single Crystal nickel superalloy was used as a base material. The bondcoat was produced by overaluminizing of an MeCrAlY–type coating deposited by low pressure plasma spraying method (LPPS). The outer ceramic layer of yttria oxide stabilized zirconia oxide (Metco 6700) was deposited by plasma spray physical vapour deposition (PS-PVD). The isothermal oxidation test at 1100oC for 1000h shown that thickness of the TGO layer in overaluminized bondcoat was significantly thicker in comparison with conventional LPPS-sprayed MeCrAlY bondcoats in the same type of TBCs.