Abstract
In this paper, analyzed are the effects of the plasma spray distance on the microstructure and mechanical properties of the NiCrAlCoY2O3 coating layers deposited at atmospheric pressure. The microstructure and mechanical properties of the coating layers are under the influence of the interaction of plasma particles (ions and electrons) with powder particles, providing the transfer of velocity and temperature of the plasma particles onto the powder particles. The effect of the interaction is directly dependent on the time the powder particles were present in the plasma which is defined by distance of the plasma gun from the substrate, depending on the granulation of the powder, the melting point and specific gravity. In order to obtain homogeneous and denser coating layers with high adhesion, in the experiment three distances from the substrate were used: 95 mm, 105 mm and 115 mm. The layers were deposited on thin sheets of AlMg1 aluminum thickness of 0.6 mm. Evaluation of mechanical properties of the layers was carried out by examining microhardness using the HV0.1 method and the bond strength by tensile testing. The morphology of the powder particles was examined on the SEM, while the microstructure of the layers was evaluated under a light microscope in accordance with the Pratt Whitney standard. The results of the experiment showed that the distance from the substrate substantially influenced the structure and mechanical properties of the coating layers. The best deposited layers were examined in the system with the ZrO224%MgO ceramic coating, which have proved to be reliable protectionfrom high temperature and abrasive rocket jet fuel.
Highlights
To protect substrates from the effects of gas corrosion and high temperature oxidation developed were nickel and cobalt based powders, type MeCrAlX (Me = Ni or Co, and X = Y or Hf) which were alloyed with metal components or as a composite - coated nickel-chrome powder with other metals or ceramics
The microhardness and tensile bond strength values of the deposited coating layers made of the composite NiCr/Al/Co/Y2O3 powder, depending on the plasma spray distance, are shown in Figures 4 and 5
The higher microhardness values indicate that the powder particles in thedeposition process fully melted and that in the plasma jet the components of the NiCr/Al/Co/Y2O3 coating powder completely reacted, forming complex oxides, which was confirmed by metallographic examinationof the coating layers
Summary
To protect substrates from the effects of gas corrosion and high temperature oxidation developed were nickel and cobalt based powders, type MeCrAlX (Me = Ni or Co, and X = Y or Hf) which were alloyed with metal components or as a composite - coated nickel-chrome powder with other metals or ceramics. Paper is available on the website: www.idk.org.rs/casopis particles of Al, Co and Y2O3 powders in the form of sheaths. The powders are deposited using plasma spray systems, as protective coatings or as bond coatings in combination with ceramic coatings (TBC thermal barrier coatings). When administered as bond layers they have a critical role in the performances of thermal barrier coatings for providing adhesion to the ceramic layers and resistance to oxidation and corrosion. The deposited layers must be harmonized with the stress caused by sudden changes in temperature and substrate creep
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