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Highlights • Formation of TEL is in situ monitored by EIS, ATR-FTIR and video observation. • Thickening and thinning of TEL could be monitored by comb-like copper sensor. • Dewing could be monitored sensitively in the high-low temperature cyclic tests. Abstract A novel dewing sensor consisting of two interlacing (comb-like) copper electrodes was fabricated by photolithography to monitor the formation and evaporation process of thin electrolyte layer (TEL), as well as atmospheric corrosion of copper during wetting-drying and high-low temperature cyclic tests. Thanks to the ultra-narrow space between the comb-like electrodes, the sensor can probe earlier dew condensation on Cu even at low relative humidity. Moreover, the thickness of TEL can be easily calculated based on high-frequency impedance during the drying process of TEL. [ABSTRACT FROM AUTHOR]

To improve the density and hydrogen barrier performance of the anodic oxide layer on the surface of ZrH 1.8 , anodization of the ZrH 1.8 substrate was performed under a constant current mode. In an alkaline electrolyte environment, the film growth process was investigated under varying current densities (233, 280, 326, and 373 A/m2). The morphology, phase structure, thickness, and adhesion of the film were analyzed. The hydrogen barrier properties of the films at different current densities were evaluated through dehydrogenation experiments. The barrier properties of the film were further analyzed via electrochemical tests. The results indicate that zirconia hydrogen barrier coatings with thicknesses of 12.77, 18.74, 23.16 and 22.26 µm can be fabricated on the surface of ZrH 1.8 at different current densities. The coatings contain both monoclinic zirconia (M-ZrO 2) and tetragonal zirconia (T-ZrO 2) phases, among which M-ZrO 2 prevails. The current density has no substantial effect on the phase composition of the coatings. At a current density of 280 A/m2, a more homogeneous and compact film with superior dense adhesion and the thickness of 18.74 µm was fabricated on the ZrH 1.8 surface. The hydrogen permeation temperature reached 660 °C, demonstrating a relatively good hydrogen barrier performance. • A dense oxide film is generated via anodic oxidation on the surface of ZrH 1.8. • This film significantly enhances the hydrogen desorption temperature of ZrH 1.8. • The influence of varying current density on the properties of the anodic oxide film was explored. • The microscopic and mesoscopic hydrogen resistance mechanisms of the zirconia film were studied. • New possibilities for the use of ZrH 1.8 in high-temperature environments are opened up, promoting the application of the material in nuclear engineering fields. [ABSTRACT FROM AUTHOR]

The cyclic oxidation behavior of fourth-generation nickel-based single crystal superalloys with 2–4 wt% Mo content were studied at 900 ℃ and 1100 ℃. At 900 ℃, with the increase of Mo content, the oxide layer accumulates more growth stress, resulting in the interface between the outer oxide layer and the inner oxide layer more prone to crack initiation. At 1100 ℃, the oxidation layer accumulates more growth stress and thermal stress, so the oxidation layer occurs large scale spalling, which is more severe in 4Mo alloy. The results show that the increase of Mo content of alloy promotes the oxidation of containing W-Re alloy, which promotes the volatilization of oxides and the spalling of oxide, decreases the protection of oxide layer, and deteriorates the oxidation resistance of the alloy. • The increase of Mo content of alloy promotes the oxidation of containing W-Re alloy. • With the increase of Mo content, the volatilization of oxides and the spalling of oxide of alloy was promoted. • Mo has more severe harm to the oxidation resistance of the alloy at higher temperature. • The alloy with 2 wt% Mo addition has the highest oxidation resistance. [ABSTRACT FROM AUTHOR]

Amorphous Al 2 O 3 coating was prepared on Ni-based single crystal superalloy via atomic layer deposition (ALD) for high temperature oxidation protection. The oxygen inward transport and outward-cation diffusion were hindered by amorphous Al 2 O 3 coating, and the coated alloy showed high oxidation resistance. The low oxygen partial pressure at the alloy/coating interface altered the alloy oxidation behavior, allowing the priority oxidation of protective Al and Cr elements. The oxidation process was controlled by the growth of Cr 2 O 3 and Al 2 O 3. The coating exhibited high spallation resistance. Degradation of the coating, the formation of NiAl 2 O 4 phase in amorphous Al 2 O 3 layer, was observed. • Amorphous Al 2 O 3 coating was proposed and prepared on Ni-based single crystal superalloy. • The amorphous Al 2 O 3 coating improved oxidation resistance and exhibited high adhesion. • The amorphous Al 2 O 3 coating altered the oxidation behavior of the alloy. • The effect mechanism of amorphous Al 2 O 3 coating on the alloy oxidation was discussed. [ABSTRACT FROM AUTHOR]

LaB 6 powders with uniform distribution were successfully in-situ grown in the substrate of C/C felt. ZrC and SiC were subsequently introduced to fabricate four kinds of LaB 6 modified C/C-SiC-ZrC composites. The ablation property of composites was codetermined by fiber structure and ablation-resistant ability of oxide scale, which were all lied on the relative fraction of in-situ growth LaB 6. Doping with 22.12 wt%LaB 6 , the composites showed decent mechanical and the best ablation properties among all fabricated composites. After plasma ablation for 120 s, the mass and linear ablation rates of composites were 1.541 mg/s and 1.924 µm/s, respectively. • LaB 6 powders with uniform distribution were successfully in-situ grown in the substrate of C/C felt. • The in-situ growth of LaB 6 was stepwise conducted. • The fraction of in-situ growth LaB 6 determined the ablation property of prepared LaB 6 modified C/C-SiC-ZrC composites. [ABSTRACT FROM AUTHOR]

A fully dense Mg-modified ZrC-SiC composite was prepared by spark plasma sintering. The microstructure, phase evolution and ablation behaviour of the composite were investigated. Results show that the formation of a viscous Mg-Si-O liquid phase, as MgSiO 3 and Mg 2 SiO 4 were incorporated into molten SiO 2 , significantly improved the ablation resistance of composite whose mass ablation rate (−5.26 μg/s) and linear ablation rate (0.03 µm/s) were both lower than those of the monolithic ZrC-SiC composite (8.21 μg/s and 2.54 µm/s, respectively). Furthermore, the introduction of Mg effectively restrained the martensitic transformation from t-ZrO 2 to m-ZrO 2 , strengthening the integrity of the oxide layer. • A full densify Mg modified ZrC-SiC composite with 100% relative density is developed by spark plasma sintering. • Mg in amorphous Mg-Si-O optimises ceramic particle distribution in the matrix, promoting densification of composite. • The Mg-Si-O suppresses SiO 2 volatilisation by reacting with SiO 2 to create MgSiO 3 and Mg 2 SiO 4. • The transformation of MgSiO 3 and Mg 2 SiO 4 into a high viscosity liquid improves the anti-ablation property of the composite. • The doping of Mg prevents the martensitic transformation from t-ZrO 2 to m-ZrO 2 , preserving the integrity of the oxide layer. [ABSTRACT FROM AUTHOR]

• LaB 6 offers the reactive sintering by reacting with HfC or TaC to establish a compact ceramic structure. • La 2 O 3 can react with other oxides to generate several ternary phases of La 2 Si 2 O 7 , La 2 Hf 2 O 7 and LaTaO 4 , resulting in the reconciled layer at the ablation center of composites. HfC, TaC and SiC with different proportions were introduced into C f /LaB 6 preform to fabricate four kinds of UHTC doped C/C composites. Results show that LaB 6 could react with HfC or TaC to establish a compact ceramic structure. After ablation for 120 s, the composites doped with LaB 6 -HfC-TaC-SiC possessed the best ablation property, and the ablation rates were 1.129 mg/s and 3.133 μm/s. A layer with La 2 Si 2 O 7 , La 2 Hf 2 O 7 and LaTaO 4 is observed due to the reactions between La 2 O 3 and other binary oxides. Further ablation was suppressed and stability of the multi-phase layer is therefore confirmed, indicating good coordination among the oxides. [ABSTRACT FROM AUTHOR]