Oxidation of Metals and Alloys

Hou, P.Y.

doi:10.1016/b978-044452787-5.00013-5

Cited by 13 publications

(3 citation statements)

References 332 publications

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“…In contrast to the HVOF-sprayed Al 0.3 CrFeCoNi coating, the interface between the HVOF-sprayed Al 0.3 CrFeCoNiNb 0.5 coating and the oxide layer is convoluted. This was also observed by Hou et al [60]. In addition to the enrichment of Cr, a higher concentration of Fe was found in the oxide layer.…”

Section: Microstructural Characterization Of the Wear Trackssupporting

confidence: 84%

Nb and Mo Influencing the High-Temperature Wear Behavior of HVOF-Sprayed High-Entropy Alloy Coatings

2022

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To qualify high-entropy alloys (HEAs) as resource-saving and high-temperature wear-resistant coating materials, high-velocity oxygen fuel (HVOF) coatings produced from the inert gas-atomized powder of Al0.3CrFeCoNi, Al0.3CrFeCoNiNb0.5 and Al0.3CrFeCoNiMo0.75 were investigated in reciprocating wear tests at temperatures at 25, 500, 700 and 900 °C. In addition to the high-temperature wear tests, the microstructure and chemical composition of the three HEAs were analyzed using scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD). In particular, HVOF coatings are characterized by high hardness (Vickers hardness HV0.1) and low porosity, which were also determined. After high-temperature wear tests, the wear depth was measured using laser scanning microscopy (LSM). It was found that adding Nb and Mo to Al0.3CrFeCoNi significantly reduces the wear depth with increasing temperature. The wear mechanisms change from abrasive wear and delamination (25 °C and 500 °C) to a combination of (abrasion), delamination, adhesion and oxidative wear. Thereby, oxidative wear will be the primary mechanism at 900 °C for all the HVOF coatings investigated. The most important finding is that the adhesion of the oxide layer formed is improved by adding Nb and Mo, resulting in significantly reduced wear depth at 900 °C.

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Section: Microstructural Characterization Of the Wear Trackssupporting

confidence: 84%

Nb and Mo Influencing the High-Temperature Wear Behavior of HVOF-Sprayed High-Entropy Alloy Coatings

2022

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“…The activation energy of Ni oxidation is reported to be 180–240 kJ/mol, which is similar to Ni lattice diffusion at 154–254 kJ/mol 39 . At temperature below 1000°C, NiO growth is dominated by the diffusion of Ni through the grain boundaries of growing NiO and above 1000°C, by lattice diffusion.…”

Section: Discussionmentioning

confidence: 63%

“…The activation energy of Ni oxidation is reported to be 180-240 kJ/mol, which is similar to Ni lattice diffusion at 154-254 kJ/mol. 39 At temperature below 1000 • C, NiO growth is dominated by the diffusion of Ni through the grain boundaries of growing NiO and above 1000 • C, by lattice diffusion. We observed that Ni particles oxidized when sintered in air, independent if done by conventional sintering or flash sintering.…”

Section: Discussionmentioning

confidence: 99%

Sintering behavior of 8YSZ‐Ni cermet: Comparison between conventional, FST/SPS, and flash sintering

Mundra

Mishra

Bram

et al. 2023

Int J Applied Ceramic Tech

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Cermets are ceramic metal composites. The metallic phase in the cermet typically undergoes oxidation during sintering in air. Electric field‐assisted sintering processes such as field‐assisted sintering technology/spark plasma sintering (FAST/SPS) and flash involves very high heating rates, short processing time and low processing temperature. The main aim of this work was to see if field‐assisted sintering techniques can prevent the oxidation of the metallic phase in the cermet. Sintering behavior of 8YSZ‐5 wt.% Ni cermet was studied by three different techniques namely; conventional sintering, FAST/SPS and flash sintering. Phases and microstructure were analyzed through X‐ray diffraction and scanning electron microscopy, respectively. Temperature and time required for sintering the samples via FAST/SPS and flash sintering was significantly lower than that during conventional sintering. In addition, we found limited grain growth during FAST/SPS and flash sintering. During conventional sintering in reducing atmosphere (Ar and vacuum), Ni particles retained their elemental state, however the extent of densification was poor in the cermet. FAST/SPS in argon and vacuum resulted in almost complete densification (relative density > 97%) and Ni particles were retained in their elemental state in the cermet. During flash sintering in air, the samples sintered to a high densification (relative density ∼98%), however, Ni particles were completely oxidized.

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