Cavitation erosion resistance in NaCl medium of HVOF sprayed WC-based cermet coatings at various flow velocities: A comparative study on the effect of Ni and CoCr binder phases

This manuscript deals with the cavitation erosion resistance of flame-sprayed Al2O3-40%TiO2/NiMoAl cermet coatings (low-velocity oxy-fuel (LVOF)), a new functional application of cermet coatings. The aim of the study was to investigate the cavitation erosion mechanism and determine the effect of feedstock powder ratio (Al2O3-TiO2/NiMoAl) of LVOF-sprayed cermet coatings on their cavitation erosion resistance. As-sprayed coatings were investigated for roughness, porosity, hardness, and Young’s modulus. Microstructural characteristics of the cross section and the surface of as-sprayed coatings were examined by light optical microscopy (LOM), scanning electron microscopy (SEM) with energy-dispersive X-ray spectroscopy (EDS) and X-ray diffraction (XRD) methods. Coating cavitation tests were conducted in accordance with the ASTM G32 standard using an alternative stationary specimen testing method with usage of reference samples made from steel, copper, and aluminum alloys. Cavitation erosion resistance was measured by weight and volume loss, and normalised cavitation erosion resistance was calculated. Surface eroded due to cavitation was examined in successive time intervals by LOM and SEM-EDS. On the basis of coating properties and cavitation investigations, a phenomenological model of the cavitation erosion of Al2O3-40%TiO2/NiMoAl cermet coatings was elaborated. General relationships between their properties, microstructure, and cavitation wear resistance were established. The Al2O3-40%TiO2/NiMoAl composite coating containing 80% ceramic powder has a higher cavitation erosion resistance than the reference aluminium alloy.

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Comparative Study of Two Laser Coatings Used in Turbine Blades

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.711.193 ◽

2014 ◽

Vol 711 ◽

pp. 193-196

Author(s):

Wei Fu Wang ◽

Jian Zhou Xie ◽

Liu Yi Huang ◽

Fang Fang Zhang

Keyword(s):

Titanium Alloy ◽

Comparative Analysis ◽

Comparative Study ◽

Cavitation Erosion ◽

Erosion Resistance ◽

Turbine Blades ◽

Formation Mechanisms ◽

Cavitation Erosion Resistance ◽

Martensite Matrix ◽

Better Than

In order to compare the performances of two typical laser coatings used in turbine blades, the Ti-N coatings of Ti6Al4V alloy and solution-aging coatings of 17-4PH alloy were fabricated by laser treatment with optimized parameters, respectively. The formation mechanisms and performances are comparative investigated by SEM, TEM and cavitation erosion tester. The results show that the Ti-N coatings are mainly reinforced by Ti2N and α′ martensite. For 17-4PH samples, the TEM observation displays that the ε-Cu particles, which are in the size of 2-5 nm and disperse homogeneously in the martensite matrix, are the main reinforcing phases. Both the 17-4PH samples and the Ti6Al4V samples are reinforced homogeneously. Comparative Analysis indicates that the hardness of the Ti-N coatings on Ti6Al4V substrate is lower than that of solution-aging samples (on 17-4PH). However, the cavitation erosion resistance of the Ti-N coatings are better than that of solution-aging samples, which implies that the titanium alloy with Ti-N coatings are well candidate to instead of 17-4PH steel for the application in turbine blades.

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Cavitation Erosion Resistance and Wear Mechanism Model of Flame-Sprayed Al2O3–40%TiO2/NiMoAl Cermet Coatings

10.20944/preprints201806.0090.v1 ◽

2018 ◽

Author(s):

Mirosław Szala ◽

Tadeusz Hejwowski

Keyword(s):

Cavitation Erosion ◽

Erosion Resistance ◽

Ceramic Powder ◽

Low Velocity ◽

Time Intervals ◽

Cermet Coatings ◽

Mechanism Model ◽

Cavitation Wear ◽

Cavitation Erosion Resistance ◽

Sprayed Coatings

This manuscript deals with the cavitation erosion resistance of low-velocity oxy-flame (LVOF) sprayed Al2O3–40%TiO2/NiMoAl cermet coatings, a new functional application of cermet coatings. The aim of the study was to investigate the cavitation erosion mechanism and determine the effect of feedstock powder ratio (Al2O3–TiO2/NiMoAl) of LOVF cermet coatings on their cavitation erosion resistance. As-sprayed coatings were investigated for roughness, porosity, hardness, Young’s modulus. Microstructural characteristics of the cross-section and the surface of as-sprayed coatings were examined by light optical microscopy (LOM) and scanning electron microscopy (SEM) equipped with the EDS and XRD methods. Coatings cavitation tests were conducted in accordance with the ASTM G32 standard with usage of reference samples made from steel, copper and aluminum alloys. Cavitation erosion resistance was measured by weight and volume loss, and normalised cavitation erosion resistance was calculated. Surface eroded due to cavitation was examined in successive time intervals by LOM and SEM-EDS. On the basis of coating properties and cavitation investigations, a phenomenological model of the cavitation erosion of Al2O3–40%TiO2/NiMoAl cermet coatings was elaborated. General relationships between their properties, microstructure and cavitation wear resistance were established. The Al2O3–40%TiO2/NiAlMo composite coating containing 80% of ceramic powder has a higher cavitation erosion resistance than the reference aluminium alloy.

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