Oxidation‐Resistant Environmental Barrier Coatings for Mo‐Based Alloys: A Review

Gatzen, Caren; Smokovych, Iryna; Scheffler, Michael; Krüger, Manja

doi:10.1002/adem.202001016

Cited by 23 publications

(6 citation statements)

References 114 publications

(261 reference statements)

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“…Additionally, it was observed that the HVOF coatings of Al0.3CrFeCoNiNb0.5 (see Figure 1d) and Al0.3CrFeCoNiMo0.75 (see Figure 1f) are characterized by a higher proportion of oxidized particles (gray lamellae in Figure 1d,f). It is well known from the literature that the elements Nb and Mo are susceptible to atmospheric oxidation [42,43]. Given this, the higher proportion of oxide lamellae in the Al0.3CrFeCo-NiNb0.5 and Al0.3CrFeCoNiMo0.75 HVOF coatings can be explained.…”

Section: Characterization Of the Initial Microstructurementioning

confidence: 94%

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: Characterization Of the Initial Microstructurementioning

confidence: 94%

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

2022

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“…[40], and a specific overview dealing with poly(silazane)-based coatings for refractory metal-oxidation protection is given in ref. [41].…”

Section: Coatingsmentioning

confidence: 99%

Processing of Ceramics from Polysil(sesquioxane)‐Type Precursors: Coatings, Tapes, Tailored Surfaces, and Porosity Control

Scheffler

2023

Adv Eng Mater

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Poly(silsesquioxane)‐based polymer‐derived ceramics (PDCs), may be manufactured by a great variety of processes and process combinations leading to ceramic parts seven with high functionality. Advantage of the use of poly(silsesquioxane)s as starting materials with a defined amount of oxygen is that low‐temperature‐processing steps such as shaping and cross‐linking may be carried out in air, and a disadvantage often discussed is a maximum service temperature below 1200 °C. In this article, the focus is set to PDC tapes, coatings, tailored surfaces, and tailored porosity. And, a rough distinction is made between materials pyrolyzed below 1200 °C and far above 1200 °C. The later provides porosity formed by high‐temperature reactions between particulate fillers and the ceramic residue from pyrolysis.

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“…Research on alloys based on refractory metals, such as molybdenum, is of active interest due to the possibility of manufacturing parts from them that operate at temperatures above 1300 • C. However, molybdenum undergoes severe destruction at temperatures above 730 • C [1]. The problem of increasing heat resistance is solved in several ways: by alloying alloys with elements that can form stable, protective films during oxidation [1][2][3][4], by applying protective coatings [5][6][7], or by a combined method. The most promising and realistic way to solve the heat resistance problem is using coatings.…”

Section: Introductionmentioning

confidence: 99%

“…The most promising and realistic way to solve the heat resistance problem is using coatings. The most common type of high-temperature protective coatings are coatings with the participation of silicon, the high heat resistance of which is explained by the ability to form a surface oxide film based on SiO 2 [1,[5][6][7].…”

Section: Introductionmentioning

confidence: 99%

Physicochemical Conditions of Boron–Siliconizing of Molybdenum-Based Alloys in Chlorine and Fluorine Medium

Loskutova,

Scheffler,

Ivanov

et al. 2024

Metals

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The physicochemical conditions of the siliconizing and boron–siliconizing processes of molybdenum-based alloys in a closed reaction space in an environment of chlorine and fluorine at reduced pressure were studied. Theoretical calculations of the equilibrium composition of systems with the participation of silicon, boron, molybdenum, nitrogen, oxygen, chlorine, and fluorine were carried out, which made it possible to determine the influence of process parameters (temperature, composition of the reaction medium) on the probable phase composition of the obtained coatings. Based on thermodynamic calculations, the composition and rational consumption of the initial powders and the temperature intervals of the chemical heat treatment (CHT) during the complex saturation of molybdenum-based alloys with silicon and boron were modeled. It was established that it is advisable to use chlorine as an activator, which leads to the formation of molybdenum chlorides MoCl4 and MoCl3 in the composition of the gas phase and can indicate the flow of exchange reactions between chlorides and the matrix of the processed material in the reaction space. The rational saturation temperature of alloys based on molybdenum with silicon and boron is determined—1100–1250 °C. The possibility of the existence of condensed phases MoSi2, MoB2.15, B6Si, MoB1.65, and MoB is shown.

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Oxidation‐Resistant Environmental Barrier Coatings for Mo‐Based Alloys: A Review

Cited by 23 publications

References 114 publications

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

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

Processing of Ceramics from Polysil(sesquioxane)‐Type Precursors: Coatings, Tapes, Tailored Surfaces, and Porosity Control

Physicochemical Conditions of Boron–Siliconizing of Molybdenum-Based Alloys in Chlorine and Fluorine Medium

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