共查询到19条相似文献,搜索用时 46 毫秒
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热障涂层是高温下具有良好隔热性能的陶瓷涂层,在燃气轮机、内燃机、火箭发动机和其他高温热防护方面有重要应用。稀土或碱土金属氧化物稳定的氧化锆热障涂层材料已应用近60 a,其中最常用的是氧化钇稳定的氧化锆(YSZ)。近20 a,国内外发现了许多新材料,如稀土锆酸盐、铝酸盐和钽酸盐等。与YSZ相比,新材料在高温稳定性、热导率、抗烧结或热膨胀性能方面有优势,但断裂韧性低、成分复杂、单一陶瓷层的热循环寿命短。为了提高新型热障涂层的寿命,要严格控制涂层的制备过程、保持化学计量比,采用双陶瓷层结构的涂层。 相似文献
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热障涂层的高温失效问题是热障涂层材料研究的重要命题,本文对国内外学者在热障涂层高温失效试验、失效机制、失效的动态监测和寿命预测方面的研究进展进行了综述。热障涂层的失效主要源自涂层中存在的热生长氧化物(TGO)的失效,文中总结出了国内外学者对TGO研究的几个重点方面,以期为热障涂层的高温失效问题提供研究思路。 相似文献
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主要介绍了关于高温合金表面热障涂层体系中界面失效行为的研究进展,针对热障涂层中的基体/粘结层界面、粘接层/TGO界面和TGO/陶瓷层界面,进行了高温服役过程中的退化失效及结构演变行为分析,提出了影响热障涂层界面性能的研究重点和方向。 相似文献
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《Journal of the European Ceramic Society》2022,42(2):649-657
The corrosion resistance to calcium-magnesium-alumino-silicates (CMAS) is critically important for the thermal barrier coatings (TBCs). High-entropy zirconate (La0.2Nd0.2Sm0.2Eu0.2Gd0.2)2Zr2O7 (HEZ) ceramics with low thermal conductivity, high coefficient of thermal expansion and good durability to thermal shock is expected to be a good candidate for the next-generation TBCs. In this work, the CMAS corrosion of HEZ at 1300°C was firstly investigated and compared with the well-studied La2Zr2O7 (LZ). It is found that the HEZ ceramics showed a graceful behavior to CMAS corrosion, obviously much better than the LZ ceramics. The HEZ suffered from CMAS corrosion only through dissolution and re-precipitation, while additional grain boundary corrosion existed in the LZ system. The precipitated high-entropy apatite showed fine-grained structure, resulting in a reaction layer without cracks. This study reveals that HEZ is a promising candidate for TBCs with extreme resistance to CMAS corrosion. 相似文献
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《Ceramics International》2019,45(16):19710-19719
Because gas turbine engines must operate under increasingly harsh conditions, the degradation of thermal barrier coatings (TBCs) by calcium-magnesium-alumina-silicate (CMAS) is becoming an urgent issue. Mullite (3Al2O3·2SiO2) is considered a potential material for CMAS resistance; however, the performance of mullite in the presence of CMAS is still unclear. In this study, mullite and Al2O3–SiO2 were premixed with yttria stabilized zirconia (YSZ) in different proportions, respectively. Porous ceramic pellets were used to conduct CMAS hot corrosion tests, and the penetration of molten CMAS and its mechanism were investigated. The thermal and mechanical properties of the samples were also characterized. It was found that the introduction of mullite and Al2O3–SiO2 mitigated the penetration of molten CMAS into the pellets owing to the formation of anorthite, especially at 45 wt% mullite/55 wt% YSZ. Compared with Al2O3–SiO2, mullite possesses a higher chemical activity and undergoes a faster reaction with CMAS, thus forming a sealing layer in a short time. Additionally, the thermal expansion coefficient, thermal conductivity, and fracture toughness of different samples were considered to guide the architectural design. Considering the CMAS corrosion resistance, thermal and mechanical performance of TBCs systematically, a TBC system with a multilayer architecture is proposed to provide a theoretical and practical basis for the design and optimization of the TBC microstructure. 相似文献
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《Ceramics International》2023,49(8):12390-12407
Along with continuous progress in inlet temperature of turbine engine, calcium-magnesium-aluminum-silicate (CMAS) deposition has become one of serious challenges for traditional yttria partially stabilized zirconia thermal barrier coatings at elevated temperature. Although lots of materials with superior CMAS resistance have been proposed, there is few comparative research on performance of corresponding coatings reported especially when subjected to thermal cycling and CMAS simultaneously. To this end, some coatings were prepared in present study, and thereafter failure behavior in condition of thermal cycling and thermal cycling-CMAS was systemically investigated and compared. Experimental results showed a varied lifetime and cracking behavior in thermal cycling test and thermal cycling-CMAS test, indicating that CMAS infiltration affected failure behavior of coatings. Besides, it was numerically found that CMAS penetration would lead to a promotion of thermal stress, which increased the tendency for cracking during thermal cycling. And the phenomenon that channel crack was the precondition of delamination crack was revealed. 相似文献
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《Ceramics International》2016,42(11):12922-12927
The single-ceramic-layer (SCL) Sm2Zr2O7 (SZO) and double-ceramic-layer (DCL) Sm2Zr2O7 (SZO)/8YSZ thermal barrier coatings (TBCs) were deposited by atmospheric plasma spraying on nickel-based superalloy substrates with NiCoCrAlY as the bond coat. The mechanical properties of the coatings were evaluated using bonding strength and thermal cycling lifetime tests. The microstructures and phase compositions of the coatings were characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD), respectively. The results show that both coatings demonstrate a well compact state. The DCL SZO/8YSZ TBCs exhibits an average bonding strength approximately 1.5 times higher when compared to the SCL SZO TBCs. The thermal cycling lifetime of DCL SZO/8YSZ TBCs is 660 cycles, which is much longer than that of SCL 8YSZ TBCs (150 cycles). After 660 thermal cycling, only a little spot spallation appears on the surface of the DCL SZO/8YSZ coating. The excellent mechanical properties of the DCL LZ/8YSZ TBCs can be attributed to the underlying 8YSZ coating with the combinational structures, which contributes to improve the toughness and relieve the thermal mismatch between the ceramic layer and the metallic bond coat at high temperature. 相似文献
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《Ceramics International》2021,47(22):31868-31876
Calcium-magnesium-alumina-silicate (CMAS) and molten salt corrosion pose great threats to thermal barrier coatings (TBCs), and recently, a coupling effect of CMAS and molten salt has been found to cause even severer corrosion to TBCs. In this study, the crystallization behavior of CMAS and CMAS+NaVO3 is investigated for potentially clarifying their corrosion mechanisms to TBCs. Results indicated that at 1000 °C and 1100 °C, CMAS was crystallized to form CaMgSi2O6, while at 1200 °C, the crystallization products were CaMgSi2O6, CaSiO3 and CaAl2Si2O8. The introduction of NaVO3 in CMAS reduced the crystallization ability, and as the NaVO3 content increased, glass crystallization occurred at a lower temperature, with crystallization products mainly consisting of CaAl2Si2O8 and CaMgSi2O6. At 1200 °C, CMAS+10 wt% NaVO3 was in a molten state without any crystallization, which suggested that NaVO3 addition in CMAS could reduce its melting point, indicating enhanced penetration ability in TBCs and thus increased corrosiveness. 相似文献
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《Journal of the European Ceramic Society》2017,37(1):289-296
Calcium-magnesium-alumina-silicate (CMAS) attack has been considered as a significant failure mechanism for thermal barrier coatings (TBCs). As a promising series of TBC candidates, rare-earth phosphates have attracted increasing attention. This work evaluated the resistance characteristics of LnPO4 (Ln = Nd, Sm, Gd) compounds to CMAS attack at 1250 °C. Due to the chemical reaction between molten CMAS and LnPO4, a dense, crack-free reaction layer, mainly composed of Ca3Ln7(PO4)(SiO4)5O2 apatite, CaAl2Si2O8 and MgAl2O4, was formed on the surface of compounds, which had positive effect on suppressing CMAS infiltration. The depth of CMAS penetration in LnPO4 (Ln = Nd, Sm, Gd) decreased in the sequence of NdPO4, SmPO4 and GdPO4. GdPO4 had the best resistance characteristics to CMAS attack among the three compounds. The related mechanism was discussed based on the formation ability of apatite phase caused by the reaction between molten CMAS and LnPO4. 相似文献
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《Journal of the European Ceramic Society》2017,37(6):2501-2508
In this study, first, Gd2Zr2O7/ceria–yttria stabilized zirconia (GZ/CYSZ) TBCs having multilayered and functionally graded designs were subjected to thermal shock (TS) test. The GZ/CYSZ functionally graded coatings displayed better thermal shock resistance than multilayered and single layered Gd2Zr2O7 coatings. Second, single layered YSZ and functionally graded eight layered GZ/CYSZ coating (FG8) having superior TS life time were selected for CMAS + hot corrosion test. CMAS + hot corrosion tests were carried out in the same experiment at once. Furthermore, to generate a thermal gradient, specimens were cooled from the back surface of the substrate while heating from the top surface of the TBC by a CO2 laser beam. Microstructural characterizations showed that the reaction products were penetrated locally inside of the YSZ. On the other hand, a reaction layer having ∼6 μm thickness between CMAS and Gd2Zr2O7 was seen. This reaction layer inhibited to further penetration of the reaction products inside of the FG8. 相似文献
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Y.X. Kang Y. Bai W. Fan T. Yuan Y. Gao C.G. Bao B.Q. Li 《Journal of the European Ceramic Society》2018,38(7):2851-2862
La2Ce2O7 (LC) is receiving increasing attention due to its lower thermal conductivity, better phase stability and higher sintering resistance than yttria partially stabilized zirconia (YSZ). However, the low fracture toughness and the sudden drop of CTE at approximately 350?°C greatly limit its application. In this study, the LC/50?vol.% YSZ composite TBC was deposited by supersonic atmospheric plasma spraying (SAPS). Compared to YSZ or double layered LC/YSZ coating, the thermal cycling life of LC/50?vol.% YSZ coating with CMAS attack increased by 93% or 91%. The latter possessed higher fracture toughness (1.48?±?0.26?MPa?m1/2) than LC (0.72?±?0.15?MPa?m1/2) and better CMAS corrosion resistance than YSZ owing to the formation of Ca2(LaxCe1-x)8(SiO4)6O6–4x with <001> orientation perpendicular to the coating surface. The sudden CTE decrease of LC was fully suppressed in LC/50?vol.% YSZ coating due to the change of temperature dependent residual stresses induced by YSZ. 相似文献