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A series of 16 mol% CeO 2 -2 mol% Re 2 O 3 co-stabilised zirconia (ZrO 2) (16Ce4ReSZ, Re Eu, Gd, Dy, Y, Er, Yb) ceramic materials were synthesised using a chemical coprecipitation– high-temperature roasting method. Their phase structure, high-temperature phase stability, mechanical properties, thermal conductivity and coefficient of thermal expansion (CTE) were investigated. The results show that the ZrO 2 tetragonal phase co-stabilised by CeO 2 and Re3+ with a smaller radius has better stability. The 16Ce4ReSZ (Re Dy, Y, Er, Yb) materials have high fracture toughnesses, low thermal conductivities, and high CTE values. As the radius of the Re3+ ions decreases, the lattice energy increased, while the lattice distortion decreases, the CTE decreases slightly and the thermal conductivity of the material increases slightly. Owing to the high phase stability of 16Ce4YbSZ, its mechanical properties are best after 100 h of sintering at 1400 °C. [ABSTRACT FROM AUTHOR]

CeO 2 and Sc 2 O 3 co-stabilized ZrO 2 ceramics have attracted much attention as potential thermal barrier coatings (TBCs) materials for applications above 1300 °C. In this study, a series of Sc 0.04 Ce x Zr 0.96-x O 1.98 (SCZ, x = 0.08, 0.10, 0.12, 0.16) ceramic materials were synthesized with the solid-state method and their phase stability, microstructures and thermo-physical properties were systemically investigated by x-ray diffraction (XRD), Raman spectra, field emission scanning electron microscopy (SEM), thermal dilatometer, laser flash apparatus (LFA), and Vickers hardness tester. The results showed that Sc 0.04 Ce 0.12 Zr 0.84 O 1.98 (4S12CZ) and Sc 0.04 Ce 0.16 Zr 0.80 O 1.98 (4S16CZ) ceramic materials still maintained stable tetragonal phase structure after 100 h high temperature treatment at 1500 °C. SCZ had a high thermal expansion coefficient (TEC), low thermal conductivity, and high fracture toughness. The TEC of the ceramics increased with CeO 2 addition because lattice energy reduced with increasing substitution of Zr4+ by bigger Ce4+ while thermal conductivity decreased due to the increase of lattice distortion. Compared with 4S12CZ, 4S16CZ exhibited a higher fracture toughness of 6.48 ± 0.04 MPa m1/2 and showed the better anti-sintering property. Besides, the thermal conductivity, TEC and thermal cycling lifetime of 4S16CZ were optimal. The comprehensive performance of 4S16CZ suggested it could be explored as a promising TBC material for high-temperature application. [ABSTRACT FROM AUTHOR]

In this study, the corrosion behaviors of Sc 0.04 Ce 0.16 Zr 0.80 O 1.98 (SCZ) and YSZ (4 mol% Y 2 O 3 -stabilized ZrO 2) in CMAS (Ca-Mg-Al-Si) at 1250 °C were investigated systematically by X-ray diffraction (XRD), Raman spectroscopy, field emission scanning electron microscope (FE-SEM), and field emission transmission electron microscope (FE-TEM). The results showed that Y3+can be easily precipitated from YSZ and diffused into the CMAS molten salt due to high solubility in the CMAS corrosion environment, prompting the transition from the tetragonal (t) phase to the monoclinic (m) phase. During the corrosion of YSZ powder, the reverse migration of Mg and Ca into the lattice increased the stabilizer content in part of the YSZ crystal lattice, resulting in the generation of a small amount of cubic (c) phase. For SCZ materials, the stabilizer CeO 2 was chemically inert in the CMAS environment. Sc3+ had low solubility and poor affinity with Ca2+, and can only be readily precipitated from the surface layer of the ceramic bulk with high CMAS concentrations, which led to the generation of the m phase. The SCZ material had better resistance to CMAS corrosion and t phase stability than the YSZ material. • The SCZ material has better resistance to CMAS corrosion and better t phase stability than the YSZ material. • Compared with Y3+, Sc3+ has lower solubility and poorer affinity with Ca2+ in the CMAS environment. • The stabilizer CeO 2 is chemically inert in the CMAS and stably present in the ZrO 2 crystal lattice. [ABSTRACT FROM AUTHOR]

High-temperature degradation of the plasma sprayed 16 mol% TaO 2.5 + 16 mol% YO 1.5 co-stabilized ZrO 2 (YTZ) and YSZ (7.6 wt% Y 2 O 3 -stabilized ZrO 2) coatings under calcium-magnesium-aluminon-silicate (CMAS) attack at 1200 °C and 1250 °C were comparatively investigated. Results indicated that the coatings were insensitive to the infiltration of CMAS after 10 h corrosion at 1200 °C. At 1250 °C, the entire YSZ cross-section completely failed and also underwent serious chemical corrosion after 3 h hot corrosion. Even after 10 h corrosion, the penetration depth of CMAS into the YTZ was only about 80 µm. For YTZ coating, the YTaO 4 stabilizer could not easily dissolve in CMAS and precipitated out of the YTZ crystal lattice owing to the strong chemical interaction between Ta5+ and Y3+. The wettability of CMAS on YTZ coating was worse than that on YSZ coating. Compared with YSZ coating, the YTZ coating showed better resistance to CMAS corrosion. [ABSTRACT FROM AUTHOR]

In this study, (Ce 0.15 Ti 0.05)Zr 0.80 O 2 (CTZ) with the tetragonal (t) phase was fabricated by solid-state reaction, and the destabilization resistance of CTZ ceramic was investigated in V 2 O 5 , and Na 2 SO 4 + V 2 O 5 molten salts, respectively. After CTZ was corroded in V 2 O 5 molten salt at 700 °C for 2 h, ZrV 2 O 7 and CeVO 4 were formed, and the t phase was the main crystalline phase on the CTZ surface. After CTZ was corroded in V 2 O 5 molten salt at 800 °C or 900 °C for 2 h, the amount of CeVO 4 increased significantly, and CTZ surface underwent a more corrosion degradation than at 700 °C. After CTZ was corroded in Na 2 SO 4 + V 2 O 5 molten salts at 700 °C or 800 °C for 2 h, the hot corroded products were m-ZrO 2 and CeVO 4. However, after CTZ was corroded in Na 2 SO 4 + V 2 O 5 molten salts at 800 °C for 10 h or 900 °C for 2 h or 10 h, a new phase of CeO 2 was formed due to the mineralization effect. The destabilization of CTZ ceramic under hot corrosion was mainly caused by the chemical interaction and phase transformation. • The destabilization of CTZ ceramic was mainly caused by the chemical interaction and phase transformation. • Corrosion products and corrosion degree are closely related to the type of corrosion salts, the corrosion temperature and heat duration. • The morphologies of CeVO 4 exhibited significant difference. It evolved from the V 2 O 5 corrosion environment is polyhedral, while it was rod-like in the Na 2 SO 4 +V 2 O 5 corrosion environment. [ABSTRACT FROM AUTHOR]

In this study, 16 mol% CeO 2 –2 mol% Sc 2 O 3 co-stabilized ZrO 2 (4S16CZ) coating was prepared by atmospheric plasma spraying (APS) technology. Parameters related to the application of 4S16CZ as a thermal barrier coatings (TBCs) were studied, including high-temperature stability, thermal insulation performance, coefficient of thermal expansion (CTE), thermal shock behavior and CaO-MgO-Al 2 O 3 -SiO 2 (CMAS) resistance. After heat treatment at 1400 °C for 100 h, the 4S16CZ coating maintained a single non-transformable tetragonal phase (t'), exhibiting excellent high-temperature stability. Additionally, at the test temperatures (25 °C–1000 °C), the thermal conductivity of the 4S16CZ coating ranged from 0.79 W/(m·K) to 1.02 W/(m·K), lower than that of the ZrO 2 coating stabilized by 7.6 wt% Y 2 O 3 (YSZ, 0.88–1.13 W/(m·K)), The CTE of the 4S16CZ coating was from 8.3 × 10−6 K−1 to 11.2 × 10−6 K−1, which was comparable to the YSZ. Moreover, the thermal shock behaviors of 4S16CZ TBCs and 4S16CZ/YSZ TBCs were evaluated at 1050 °C. The thermal durability of the 4S16CZ/YSZ TBCs was higher than that of 4S16CZ TBCs due to the buffering effect of the YSZ layer. The main reasons for the failure of both TBCs were the oxidation of the bond coat, thermal mismatch stress, low fracture toughness and sintering effects. In CMAS isothermal corrosion tests, CMAS exhibited low wettability on the 4S16CZ coating. Compared with the YSZ coating, the 4S16CZ coating showed better resistance to CMAS attacks. • The 4S16CZ coating exhibited excellent high-temperature stability, low thermal conductivity, and high CTE. • 4S16CZ coating showed better phase stability and higher resistance to CMAS corrosion than the YSZ coating. • The poor thermal cycling life was related to the TGO growth, thermal mismatch stress, low fracture toughness and sintering effect. [ABSTRACT FROM AUTHOR]