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Luo L.,Hefei University of Technology | Liu S.,Wenzhou Cadre New Special Material Co. | Li J.,Zhejiang University | Wu Y.,Hefei University of Technology
Surface and Coatings Technology | Year: 2011

FeMnCrAl/Cr3C2 and FeMnCrAl/Cr3C2-Ni9Al coatings were deposited onto low-carbon steel substrates by high velocity arc spraying. The cross-section and interface microstructures of the coatings were analyzed by optical microscopy (OM). The thermal shock resistance of the coatings was investigated. The characteristics of the coatings after the thermal cycling test were studied by OM, field emission scanning electron microscopy, and energy dispersion spectrometry. The results show that laminated structures with pores, oxide phases, and unmelted particles were found on all the prepared coatings. The FeMnCrAl/Cr3C2 coating with a Ni9Al interlayer registered the best thermal shock resistance, which may be attributed to the interdiffusion between the low-carbon steel substrates and the Ni9Al arc-sprayed coating that converted the mechanical bond between the substrates and the coatings to a metallurgical one. © 2010 Elsevier B.V. Source


Luo L.,Hefei University of Technology | Liu S.,Wenzhou Cadre New Special Material Co. | Li J.,Zhejiang University | Yucheng W.,Hefei University of Technology
Surface and Coatings Technology | Year: 2011

FeMnCr/Cr3C2 and FeMnCrAl/Cr3C2 coatings, using Ni9Al arc-sprayed coating as an interlayer on low-carbon steel substrates, were deposited by high velocity arc spraying (HVAS) on the cored wires. The high temperature oxidation behavior of the arc-sprayed FeMnCrAl/Cr3C2-Ni9Al and FeMnCr/Cr3C2 coatings on the low-carbon steel substrates was studied during isothermal exposures to air at 800 °C. The surface and interface morphologies of the coatings after isothermal oxidation after 100 h were observed and characterized by optical microscopy, field emission scanning electron microscope, energy dispersion spectrum, and X-ray diffraction. The results showed that the oxidation weight gains of the coatings were significantly lower than that of the low-carbon steel substrate. Moreover, the FeMnCrAl/Cr3C2-Ni9Al coating registered the lowest oxidation rate. This favorable oxidation resistance is due to the Al and Cr contents of the aforementioned coating that inhibits the generation of Fe and Mn oxides. This is attributed to the interdiffusion between the substrates and the Ni9Al arc-sprayed coating, which can convert the mechanical bonding between substrates and coatings into a metallurgical one, thereby inhibiting the oxidation of interface between the low-carbon steel and the coating. © 2010 Elsevier B.V. Source


Luo L.,Zhejiang University | Liu S.,Wenzhou Cadre New Special Material Co. | Yu J.,Zhejiang University | Zhao Q.,Jiangsu University of Science and Technology | And 2 more authors.
Xiyou Jinshu Cailiao Yu Gongcheng/Rare Metal Materials and Engineering | Year: 2010

FeMnCr/Cr3C2 cored wire was developed for building up the erosion-resistant coatings of super-critical boiler pipes by means of High-Velocity Arc Spraying. The high-temperature erosion behaviors at different impact angles of FeMnCr/Cr3C2 coatings were studied and compared with those of FeCrNi/Cr3C2 coatings and 20 steel by optical microscopy, scanning electron microscopy and energy dispersion spectrum analysis. Results show that FeMnCr/Cr3C2 coatings have the maximum erosive rate when the impact angle is about 60° due to the semi-brittleness erosion mechanism for FeMnCr/Cr3C2 coatings. The erosion resistance of FeMnCr/Cr3C2 coatings is closed to that of FeCrNi/Cr3C2 coatings, and obviously better than that of 20 steel. Source


Luo L.,Zhejiang University | Yu J.,Zhejiang University | Liu S.,Wenzhou Cadre New Special Material Co. | Li J.,Zhejiang University
Journal Wuhan University of Technology, Materials Science Edition | Year: 2010

Arc spraying with the cored wires was applied to deposit FeMnCr/Cr 3C2 coatings on low carbon steel substrates, namely FM1, FM2 and FM3. Thermal shock resistances of the coatings were investigated to assess the influence of Cr3C2 content on thermal shock resistance. Characteristics of the coatings under thermal cycling test were studied by optical microscopy, field emission scanning electron microscope (FE-SEM) and energy dispersion spectrum (EDS), X-ray diffraction (XRD). The experimental results show that hardness of the coatings increases, bonding strength decreases slightly with increase of the Cr3C2 content of the coatings. As a result, FM2 coating possesses the best thermal shock resistance, attributing to its better thermal expansion matches and wettability than those of FM3 coating, less oxide rate than that of FM1 coating restraining from cracks formation and propagation in coatings. © Wuhan University of Technology and Springer-Verlag Berlin Heidelberg 2010. Source


Luo L.-M.,Hefei University of Technology | Luo L.-M.,Zhejiang University | Luo J.,Zhejiang University | Liu S.-G.,Wenzhou Cadre New Special Material Co. | And 2 more authors.
Cailiao Rechuli Xuebao/Transactions of Materials and Heat Treatment | Year: 2010

FeMnCrAl/Cr3C2 coating was deposited on AISI 20 steel substrate by high velocity arc spraying. The microstructure and high temperature oxidation resistance of FeMnCrAl/Cr3C2 coating were studied by means of optical microscopy (OM), field emission scanning electron microscopy (FE-SEM), energy dispersion spectrum (EDS) analysis and X-ray diffraction (XRD). The oxidation resistance of FeMnCrAl/Cr3C2 coating was compared with that of FeMnCr/Cr3C2 coating, 316L stainless steel coating and AISI 20 steel. The results show that the three kinds of coatings obviously have better oxidation resistance than that of AISI 20 steel substrate. FeMnCrAl/Cr3C2 coating exhibits a lower isothermal mass gain than FeMnCr/Cr3C2 coating and similar to that of 316L stainless steel coating. The formation of compact oxide film containing aluminum and iron-chromium oxide in FeMnCrAl/Cr3C2 coating is responsible for the protection of the coating from further oxidation, but the protective oxide films are not uniformly distributed due to micro-inhomogeneous composition of the as-sprayed coatings and pores in the coatings. Source

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