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Streszczenie:
This paper presents the results of the investigation of NiCrRe coating deposited by plasma spray process at the atmospheric pressure on boiler steel substrate. These coatings were characterized by means of a scanning electron microscopy, and Energy-dispersive X-ray spectroscopy. The wear resistance of plasma sprayed NiCrRe coatings has been investigated under dry sliding conditions at applied load of 10 N in air. The continuous stiffness measurement (CSM) method was used for the investigation of nanohardness using Agilent G200 Nano-indenter in order to determine the mechanical properties of the coatings. Microstructural observations pointed out that the NiCr layer with white isles of rhenium possessed porosity, oxidized, un-melted and semimelted particles, and inclusions. According to the results the thickness of the layer is 450 μm, the indentation modulus 158 ± 24.4 GPa, hardness 3.74 ± 0.76 GPa and the coefficient of friction is 0.45.

Słowa kluczowe:
coating, plasma, tribology

Streszczenie:
The high-velocity oxy-fuel technique (HVOF) was used to produce dense NiCrRe coating on boiler steel substrate with a minimal amount of oxide impurities and low porosity. Microstructure analysis, tribology and nano-hardness measurement have been realized with the aim to characterize the systems. The microstructure was studied using scanning electron microscopy and Energy-dispersive X-ray spectroscopy. Tribological characteristics have been studied under the dry sliding condition at applied loads of 5, 10 and 20 N using the ball-on-flat technique with SiC ball at room temperature. Nano-hardness was investigated in continuous stiffness measurement (CSM) mode, the indentation depth limit was 1500 nm. Microstructure analyses proved that the HVOF sprayed layer, with a thickness approximately 870 µm, contains a relatively low volume fraction of porosity with a chemical composition based on Nickel, Chromium, with white areas of Rhenium. The wear rate of the coating is significantly lower than the wear rate of 16Mo3 steel. The average values of indentation modulus and hardness were EIT = 237.6 GPa and HIT = 6.3 GPa, respectively.

Słowa kluczowe:
HVOF, mechanical properties of NiCrRe, NiCrRe coating