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1.
李国浩  巴德纯  倪岩松  谭帧  陈红斌  杜广煜 《表面技术》2021,50(7):310-317, 336
目的 提高YSZ涂层的服役寿命.方法 采用火焰喷涂和等离子喷涂的方法,在GH4169高温合金上分别制备NiCoCrAlY粘结层和8YSZ陶瓷层.在制备陶瓷层之前,通过低压喷砂的方法对粘结层表面进行处理,改变粘结层的表面粗糙度.利用X射线衍射仪(XRD)、扫描电子显微镜(SEM)、3D测量激光显微镜,表征涂层的物相、微观形貌和表面粗糙度.使用马弗炉进行1100℃的热震实验,表征YSZ涂层的热震性能.结果 通过喷涂方法制备的粘结层,表面较为粗糙,喷砂处理后,有效地改善了表面情况,表面粗糙度下降了1~3μm.随着热震实验的进行,陶瓷层和粘结层中间形成的热生长氧化物(TGO)不断增厚.喷砂处理后,涂层的氧化速率降低.热震实验后,涂层边缘处会萌生微裂纹,随着裂纹的累积扩展,最终贯通,形成局部的涂层剥离.失效前后,YSZ没有相变发生.结论 涂层失效多发生在TGO界面处,粘结层的高温氧化引起TGO层生长增厚,会导致涂层的失效.平整的TGO生长界面可以减少接触面,降低粘结层的氧化速率.平整界面可以避免局部起伏造成的TGO过度生长.经过表面喷砂处理改善粘结层粗糙度的涂层,具有更优异的抗热震性能.TGO层的形成和生长,容易导致微裂纹的萌生和扩展.粘结层表面处理后,能够为TGO的形成和生长提供相对平整的界面,有效提高TGO的质量,进而提高涂层的抗热震性能.  相似文献   
2.
为了研究SiC晶须对等离子喷涂YSZ(Y2O3部分稳定的ZrO2)涂层显微结构的影响规律,采用喷雾造粒技术制备了晶须含量分别为0%、1%、2%和3%(质量分数)的团聚YSZ颗粒(0#、1#、2#和3#粉末),利用等离子喷涂技术(APS)分别制备了0#、1#、2#和3#等4组涂层。利用扫描电镜(SEM)及金相显微镜等测试分析设备研究SiC晶须分散工艺和定量表征方法,以及团聚颗粒的形态和涂层的显微结构,并分析了含晶须涂层的成型过程。结果表明:机械搅拌时间增加至5 h时,晶须具有较好的分散程度,对应的晶须面积分数为11.03%。含晶须的团聚颗粒主要呈“水滴状”和“纺锤状”,1#、2#和3#粉末中“水滴状”和“纺锤状”团聚颗粒的数量比例分别为16.5%,22.7%和39.3%。由于非水平态晶须对颗粒中未熔融原粉末在冲击和铺展过程的阻碍作用,涂层的孔隙率随着晶须含量的增加而增加,0#涂层的孔隙率为3.89%,1#、2#和3#涂层的孔隙率分别是0#涂层的3.15倍、4.17倍和7.52倍。  相似文献   
3.
Cubic zirconia single crystals stabilized with yttria and doped with Gd2O3 (0.10–5.00 mol%) were prepared by the optical floating zone method, and characterized by a combination of X-ray diffraction (XRD), and Raman, electron paramagnetic resonance (EPR), ultraviolet–visible (UV–Vis), photoluminescence excitation (PLE) and photoluminescence (PL) spectroscopic techniques. XRD and Raman spectroscopy showed that the crystal samples were all in the cubic phase, whereas the ceramic sample consisted of a mixture of monoclinic and cubic phases. The absorption spectrum showed four peaks at 245, 273, 308, and 314 nm in the ultraviolet region, and the optical band gap differed between samples with ≤3.00 mol% and those with >3.00 mol% Gd2O3. The emission spectrum showed a weak peak at 308 nm and a strong peak at 314 nm, which are attributed to the 6P5/2 → 8S7/2 and 6P7/2 → 8S7/2 transitions of Gd3+, respectively. The intensities of the peaks in the excitation and emission spectra increased with Gd3+ concentration, reached a maximum at 2.00 mol%, then decreased with higher concentrations. This quenching is considered to be the result of the electric dipole-dipole interactions, and this interpretation is supported by the Gd3+ EPR spectra, which showed progressive broadening with increasing Gd3+ concentration throughout the concentration range investigated.  相似文献   
4.
《Ceramics International》2022,48(17):24888-24897
In the furnace cycle test, the growth of oxide film leads to the propagation and coalescence of multiple cracks near the interface, which should be responsible for the spallation of thermal barrier coatings (TBCs). A TBC model with real interface morphology is created, and the near-interface large pore is retained. The purpose of this work is to clarify the mechanism of TBC spallation caused by successive initiation, propagation, and linkage of cracks near the interface during thermal cycle. The dynamic growth of thermally grown oxide (TGO) is carried out by applying a stress-free strain. The crack nucleation and arbitrary path propagation in YSZ and TGO are simulated by the extended finite element method (XFEM). The debonding along the YSZ/TGO/BC interface is evaluated using a surface-based cohesive behavior. The large-scale pore in YSZ near the interface can initiate a new crack. The ceramic crack can propagate to the YSZ/TGO interface, which will accelerate the interfacial damage and debonding. For the TGO/BC interface, the normal compressive stress and small shear stress at the valley hinder the further crack propagation. The growth of YSZ crack and the formation of through-TGO crack are the main causes of TBC delamination. The accelerated BC oxidation increases the lateral growth strain of TGO, which will promote crack propagation and coalescence. The optimization design proposed in this work can provide another option for developing TBC with high durability.  相似文献   
5.
为了提高5YSZ陶瓷基体的致密度和调节其烧结收缩率,通过流延法成型,优化了分散剂、消泡剂、球磨时间、固含量和胶含量。优化的条件为:分散剂含量0.9%,消泡剂含量0.63%,球磨时间22h+22h,固含量64%,胶含量29%。在优化的条件下,浆料分散均匀,生瓷带无气泡,5YSZ陶瓷基体烧结致密,且与Al2O3印刷层共烧良好。  相似文献   
6.
《Ceramics International》2020,46(14):22438-22451
In this paper, two coating techniques, the high velocity oxy-fuel (HVOF) and air plasma spray (APS) techniques, were used to deposit a bond coat of NiCoCrAlYTa on the Inconel 625 substrate, followed by applying a topcoat of yttria-stabilized zirconia (YSZ). The samples were preoxidized in an argon-controlled furnace at a temperature of 1000 °C for 12 and 24 h to characterize the microstructure of a thermally grown oxide (TGO) using the two coating techniques. The most suitable preoxidized samples were further tested for isothermal oxidation at 1000 °C for up to 120 h, and a hot corrosion test was performed at 1000 °C for up to 52 h or until spalling occurred. As-sprayed and oxidized samples prepared with different coating techniques were evaluated in terms of their microstructure using different characterization methods, such as field emission scanning electron microscopy (FESEM), variable pressure scanning electron microscopy (VPSEM), energy dispersive X-ray spectroscopy (EDS) equipped with energy dispersive X-ray and X-ray diffraction (XRD) analyses. In addition, the mechanical properties of these samples were evaluated using adhesion tests. The results show that the YSZ/NiCoCrAlYTa coating applied with the HVOF technique forms a more thin and continuous layer of TGO than that obtained when applying a YSZ/NiCoCrAlYTa coating using the APS technique, indicating that a severe brittle oxidation interface exists between the two layers. The results also indicate that the mechanical strength obtained from the adhesion test of the coated samples is observably affected by the oxidation behaviors obtained with the different deposition techniques chosen.  相似文献   
7.
热浸镀Al–Si合金涂层是一种有效的现代钢铁防腐涂层,但熔融Al–Si合金腐蚀已成为热浸镀Al–Si合金生产线沉没辊及其备件亟待解决的关键问题之一。本工作采用大气等离子喷涂技术制备Y2O3部分稳定ZrO2(YSZ)/NiCrAlY防护涂层,研究了喷涂功率对YSZ涂层组织和力学性能的影响和涂层在700℃下Al–Si熔体中的腐蚀行为。结果表明,YSZ涂层是由板条和层间柱状晶粒组成的典型层状结构,随着喷涂功率从37 kW增至46 kW,层间柱状结晶呈长大趋势;YSZ涂层主要由t-ZrO2相和少量m-ZrO2相组成,喷涂功率对涂层相组成无明显影响;喷涂功率为40 kW的YSZ涂层具有较高的显微硬度642.4 HV0.3和结合强度62 MPa。此外,当带有涂层的样品在700℃的Al–Si熔液中腐蚀240 h后,YSZ涂层与高温Al–Si熔液之间的界面没有反应层生成,同时Al–Si合金熔液中的Al和Si元素也未渗透进YSZ涂层内部,表明YSZ/NiCrAlY防护涂层有效地将Al–Si合金熔体阻挡在涂层表面。  相似文献   
8.
Aero-engines operating in dust-laden environments often encounter a lot of dust/sand that causes a severe problem to the TBCs by means of erosion. As the turbine entry temperatures are rising, molten sand is also a big concern to the life-time of TBCs.This paper deals with the TBC behavior under the combined influence of erosion and corrosion attack. Variations in TBC morphology, CMAS infiltration time and CMAS composition and their influence on the erosion resistance at room temperature were investigated. Two different EB-PVD 7YSZ morphologies consisting of a different porosity arrangement were tested in the erosion/corrosion regime. The more ‘Feathery’ structure has a better resistance to erosion compared to a more columnar ‘Normal’ structure, which leads to less degradation of the TBC. However, under the influence of CMAS infiltration the effect was found to be reversed. In general, CMAS-infiltrated EB-PVD TBCs exhibit a higher erosion resistance than the non-infiltrated ones.  相似文献   
9.
Image analysis and quantification were performed on porous scaffolds for building SOFC cathodes using the two types of YSZ powders. The two powders (U1 and U2) showed different particle size distribution and sinterability at 1300?°C. AC impedance on symmetrical cells was used to evaluate the performance of the electrode impregnated with 35-wt.% La0.8Sr0.2FeO3. For example, at 700?°C, the electrode from U2 powder shows a polarization resistance (Rp) of 0.21?Ω?cm2, and series resistance (Rs) of 8.5?Ω?cm2 for an YSZ electrolyte of 2-mm thickness, lower than the electrode from U1 powder (0.25?Ω?cm2 for Rp and 10?Ω?cm2 for Rs) does. The quantitative study on image of the sintered scaffold indicates that U2 powder is better at producing architecture of high porosity or long triple phase boundary (TPB), which is attributed as the reason for the higher performance of the LSF-impregnated electrode.  相似文献   
10.
Al2O3 was deposited as a top coat on a standard 7YSZ layer (or layers) by means of EB-PVD technique and the corresponding morphology of the Al2O3/7YSZ coatings was studied in detail. This multi-layer TBC system was tested against calcium-magnesium-aluminium-silicate (CMAS) recession by performing infiltration experiments for different time intervals from 5?min to 50?h at 1250?°C using two types of synthetic CMAS compositions and Eyjafjallajökull volcanic ash (VA) from Iceland. The results show that the studied EB-PVD Al2O3/7YSZ coatings react quickly with CMAS or VA melt and form crystalline spinel (MgAl2-xFexO4) and anorthite (CaAl2Si2O4) phases. The presence of Fe-oxide in the CMAS has been found to be key element in influencing the spinel formation which was proved to be more efficient against CMAS sealing in comparison to the Fe-free CMAS compositions. Even though a rapid crystallization was assured, shrinkage cracks in the EB-PVD alumina layer produced during the crystallization heat treatment have proven to be detrimental for the CMAS/VA infiltration resistance. To overcome these microstructural drawbacks, an additional alumina deposition method, namely reaction-bonded alumina oxide (RBAO), was applied on top of EB-PVD Al2O3. RBAO acts as a sacrificial layer forming stable reaction products inhibiting further infiltration.  相似文献   
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