共查询到20条相似文献,搜索用时 31 毫秒
1.
《Ceramics International》2023,49(7):11167-11177
Lanthanum cerate (LC: La2Ce2O7) is a potential material for thermal barrier coating, whose improved toughness is a crucial necessity for the pathway of its industrialization. Herein, we demonstrated a promising approach to develop graphene/carbon nanotube hybrid composite coating using a large throughput and atmospheric plasma spraying method. Graphene nanoplatelets (GNP: 1 wt %) and carbon nanotube (CNT: 0.5 wt %) reinforced lanthanum cerate (LCGC) hybrid composite coatings were deposited on the Inconel substrate. Addition of 1 wt % GNP and 0.5 wt % CNT in LC matrix has significantly increased its relative density, hardness, and elastic modulus up to 97.2%, 2–3 folds, 3–4 folds, respectively. An impressive improvement of indentation toughness (8.04 ± 0.2 MPa m0.5) was observed on LCGC coating, which is ~8 times higher comparing the LC coating. The toughening was attributed to the factors: such as the distribution of GNPs and CNTs in the LC matrix, synergistic toughening offered by the GNPs and CNTs; (i) GNP/CNT pull-out, (ii) crack bridging and arresting, (iii) splat sandwiching, mechanical interlocking, etc. Finally, this improved toughness offered an exceptional thermal shock performance up to 1721 cycles at 1800 °C, without any major failure on the coating. Therefore, the GNP and CNT-reinforced LC hybrid composite coating can be recommended to open a path for turbine industries. 相似文献
2.
《Ceramics International》2023,49(6):9000-9009
This study investigated the feasibility of depositing graphene nanoplatelet (GNP)-reinforced yttria-stabilized zirconia (YSZ) composite coatings. The coatings were deposited from an ethanol-based mixed YSZ and GNP suspension using suspension plasma spraying (SPS). Raman spectroscopy confirmed the presence of GNPs in the YSZ matrix, and scanning electron microscopy (SEM) analysis revealed a desired columnar microstructure with GNPs distributed predominantly in the inter-columnar spacing of the YSZ matrix. The as-deposited YSZ-GNP coatings were subjected to different isothermal treatments—400, 500, and 600 °C for 8 h—to study the thermal stability of the GNPs in the composite coatings. Raman analysis showed the retention of GNPs in specimens exposed to temperatures up to 500 °C, although the defect concentration in the graphitic structure increased with increasing temperature. Only a marginal effect on the mechanical properties (i.e., hardness and fracture toughness) was observed for the isothermally treated coatings. 相似文献
3.
Sony Priyadershini O.S. Asiq Rahman Krishna Kant Pandey Anup Kumar Keshri 《Ceramics International》2019,45(5):5768-5778
Addition of 0.5?wt% of graphene nanoplatelates (GNPs) and 1?wt% carbonnanotube (CNTs) in plasma sprayed Al2O3 coating showed the reduction of 93.25% in wear volume loss and 90.94% in wear rate. This could be attributed to the simultaneous effect of enhanced densification, presence of the transferred layer from the counterpart, strong interface between Al2O3, GNP and CNTs and toughening offered by the GNPs and CNTs. The lowest COF value of 0.27 was recorded on addition of 0.5?wt% of GNP in Al2O3 coating, which could be attributed to the graphitic lubrication on the worn track during the wear. 相似文献
4.
《Ceramics International》2022,48(14):19633-19643
Hafnia-based materials are very promising to serve as thermal protecting coatings at temperature above 1200 °C. In this work, two kinds of 8 mol% Y2O3 stabilized HfO2 ceramic coatings (YSH-SN and YSH-MX) with conventional and hybrid structures were prepared by air plasma spray (APS) method. The microstructure, thermal conductivity and the mechanical properties of the coatings before and after thermal exposure at 1300 °C were compared in detail. Results show that the as-sprayed YSH-MX has a hybrid laminated structure of monoclinic HfO2 and cubicY2O3 splats, and transforms to monoclinic HfO2 and cubic YSH after thermal exposure, while the YSH-SN is composed of major tetragonal YSH phase and transforms to monoclinic HfO2 and cubic YSH afterward. Thermal conductivities at ultra-high temperature (1600 °C) before and after thermal exposure for those two coatings are close, and the fracture toughness in the direction parallel to the interface exceeds 2.1 MPa m0.5. The YSH-MX coating with a hybrid structure provides insights to conveniently prepare gradient coating or other coatings with complex structures. 相似文献
5.
《Ceramics International》2016,42(16):18657-18665
The present study has been conducted in order to investigate the effect of the surface morphology of SiC inner coating on the bonding strength and ablation resistance of the sprayed ZrB2-SiC coating for C/C composites. The microstructure of SiC inner coatings prepared by chemical vapor deposition and pack cementation at different temperatures were analyzed by X-ray diffraction, scanning electron microscopy, and 3D Confocal Laser Scanning Microscope. Tensile bonding strength and oxyacetylene ablation testing were used to characterize the bonding strength and ablation resistance of the sprayed ZrB2-SiC coating, respectively. Results show that SiC inner coating prepared by chemical vapor deposition has a smooth surface, which is not beneficial to improve the bonding strength and ablation resistance of the sprayed ZrB2-SiC coating. SiC inner coating prepared by pack cementation at 2000 °C has a rugged surface with the roughness of 72.15 µm, and the sprayed ZrB2-SiC coating with it as inner layer exhibits good bonding strength and ablation resistance. 相似文献
6.
7.
Novel hybrid ablation thermal protection coatings (FHMP-ATPCs), employing iron trioxide (Fe2O3) powder, hollow glass microspheres, and mica powder as the fillers in hydroxyl-terminated silicone oligomer-bridged epoxy resins (PSG) copolymer, is investigated using an aerothermal-vibration coupling test system. The ablation behavior and structural reliability of FHMP-ATPCs with varying coating thickness were studied. During the test, the total enthalpy of airflow and dynamic pressures are 23 MJ/kg and 300 Pa, accompanied by the random vibration with a frequency of 20–2000 Hz and a total root-mean-square acceleration of 14.9g. The maximum surface and back-face temperatures of the coating with the thickness of 2 mm reached 836.2°C and 156.4°C, respectively. Results also showed that the reduction of thickness obviously suppressed the surface temperature and increase in back-face temperature yet maintaining high structural reliability. Compared with DGEBA-based coatings, the PSG-based coatings showed excellent structural reliability during the test. The study provides a solution for obtaining high performance ATPCs, which are highly desired for supersonic vehicles. 相似文献
8.
Darja Lisjak Kirsten Bobzin Katharina Richardt Marion Bégard Giovanni Bolelli Luca Lusvarghi Arto Hujanen Pertti Lintunen Massimo Pasquale Elena Olivetti Miha Drofenik Thomas Schläfer 《Journal of the European Ceramic Society》2009,29(11):2333-2341
Thick coatings of barium hexaferrite with the compositions BaFe12O19 and BaCoTiFe10O19 were prepared using atmospheric plasma spraying (APS) technology. The coatings were prepared from pre-reacted powders of the desired composition. The as-deposited coatings were poorly crystallized, but their crystallinity was improved with a subsequent annealing. The crystallization mechanism of the sprayed hexaferrites was studied during annealing up to 1300 °C, using X-ray powder diffraction combined with thermal analysis and with electron microscopy including microanalysis. Single-phase coatings were obtained after annealing treatments at 1100–1300 °C. Their magnetic properties showed that they would be suitable for absorbers at microwave and mm-wave frequencies, depending on the coating phase's composition, the crystallinity and the thicknesses. 相似文献
9.
《Journal of the European Ceramic Society》2023,43(14):6473-6481
Environmental barrier coatings for SiC/SiC composites are limited by the melting temperature of the Si bond coating near 1414 °C. Systems without a bond coating may be required for future turbine applications where material temperatures go beyond 1350 °C. Enhanced roughness SiC substrates were developed to assess coating adhesion without the bond coating. Two EBCs with different YbMS/YbDS ratios were produced via modified plasma spraying parameters. Coating microstructure, thermal expansion, and modulus were measured for comparison of coating properties. Cyclic steam exposures at 1350 °C were performed to assess oxidation resistance. The EBC with increased concentration of Yb2SiO5 secondary phase displayed a higher CTE, which is typically expected to decrease adhesion lifetimes due to an increase in stress upon thermal cycling. Yet, the EBC chemistry with increased Yb2SiO5 concentration was able to experience longer cycling times prior to coating delamination, likely due to interface interactions with the substrate and the thermally grown oxide. 相似文献
10.
《Ceramics International》2020,46(15):23417-23426
Yttria stabilized hafnia (Hf0.84Y0.16O1.92, YSH16) coatings were sprayed by atmospheric plasma spraying (APS). The effects of thermal aging at 1400 °C on the microstructures, mechanical properties and thermal conductivity of the coatings were studied. The results show that the as-sprayed coating was composed of the cubic phase, and the nano-sized monoclinic (M) phase was precipitated in the annealed coating. The presence of M phase effectively constrained the sintering of the coating due to its superior sintering-resistance. The Young's modulus kept at a nearly same level of ~78 GPa even after annealing, and the coating annealed for 6 h yielded a maximum value of hardness but revealed a declining tendency in the Vicker's hardness with prolonged sintering time. The thermal conductivity increased from 0.8-0.95 W m-1 K-1 at as-sprayed state to 1.6 W m-1 K-1 after annealing at 1400 °C for 96 h. The dual-phase coating is promising to serve at temperatures above 1400 °C due to its excellent thermal stability and mechanical properties. 相似文献
11.
《Ceramics International》2022,48(24):36539-36555
In this study, La1-xNdxMgAl11-xScxO19 (x = 0.1, 0.2, 0.3; abbreviated as LNMAS-1, 2, 3) coatings which are supposed to possess better properties than LaMgAl11O19 (LMA) were plasma-sprayed and their high-temperature performance were comparatively investigated. Results show that addition of Nd3+ and Sc3+ as dopants to LMA endows corresponding coatings with reduced thermal conductivity and enhanced thermal expansion coefficient, while maintaining advantageous phase stability, although still being subjected to amorphization in plasma flame and following crystallization upon high-temperature service. Furthermore, the doping could cause adherence increasing between topcoat/bondcoat, benefiting from improved melting condition, especially in LNMAS-2 and LNMAS-3 coatings, which is related to the specific powder morphology and lowered melting point. During exposure to 1350°C, mechanical performance and structure integrity of doped free-standing LNMAS coatings can be well preserved even after 400 h aging. In thermal cyclic fatigue test, LNMAS-2 and LNMAS-3 coatings undertake thermal cycling lifetime of ~181 and 191 cycles at 1100°C, respectively, 40% durable than that of LMA coating. These preliminary results suggest that LNMAS-2, 3 might be promising candidates for advanced thermal barrier coating applications. 相似文献
12.
Abdulrahman Khamaj W.M. Farouk W.M. Shewakh A.M.I. Abu-Oqail A. Wagih Mohamed Abu-Okail 《Ceramics International》2021,47(12):16511-16520
In this study, high-energy ball milling accompanied by compaction and sintering were employed for manufacturing Cu-based hybrid nanocomposite reinforced by Al2O3 and GNPs. This hybrid nanocomposite is proposed to meet the specification of heat sink applications, where excellent mechanical and thermal performance is demanding. Different processing parameters were experimentally considered such as sintering temperature and weight percentage of GNPs, 0, 0.25, 0.50, 0.75, and 1 wt %. The weight percentage of Al2O3 was fixed at 10%. The results demonstrated that the mechanical and thermal performance of the fabricated nanocomposites were superior for nanocomposite containing 0.5% GNPs and sintered at 1000 °C. The hardness, the thermal conductivity and the coefficient of thermal expansion (CTE) were improved by 21%, 16.7%, and 55.2%, respectively, compared to composite without GNPs addition. The improved mechanical and thermal properties were attributed to the low stacking fault energy, small crystallite size, high dislocation density, and low lattice strain of the composite prepared at this composition. Moreover, the better dispersion of the nano-particles of GNPs and Al2O3 inside the matrix helped for the strength and thermal conductivity improvement while maintaining low CTE. 相似文献
13.
Oxidation behaviors and mechanisms of Yb2O3-doped silicon coatings fabricated by vacuum plasma spray
Fengqi Mao Yaran Niu Xin Zhong Yawen Wang Xiao Zhu Le Zhang Qilian Li Xuebin Zheng 《Ceramics International》2021,47(14):19906-19913
Environmental barrier coatings (EBCs) have been widely studied for the protection of ceramic matrix composites (CMCs). The phase transition of silica thermal growth oxide (TGO) has been proved to be an important factor for the durability of EBCs. Yb2O3 could react with SiO2 TGO and form silicate which may improve the stability of TGO and prolong the service life of EBCs. In the present work, Si coatings doped with different contents of Yb2O3 were fabricated by vacuum plasma spray. The oxidation behaviors of the composite coatings were evaluated at 1350 °C and compared with the pure Si coating. The evolution of phase composition and microstructure of mixed thermal growth oxide (mTGO) was characterized in detail. The results showed that the newly formed oxidation product, namely Yb2Si2O7, could reduce the vertical cracks in mTGO layer and the mTGO/coating interface cracks, leading to a better binding performance of the mTGO layer. The oxidation mechanisms of the Yb2O3-doped Si coatings were analyzed based on microstructure and phase composition observations. 相似文献
14.
Alumina-silica composite coatings were prepared on the surface of graphite paper by chemical vapor deposition using AlCl3/SiCl4/H2/CO2 as precursor in the temperature range of 300 to 550°C. X-ray diffraction (XRD) and scanning electron microscopy (SEM) were
used to examine the phase composition and the microstructure of the coating, respectively. The results indicated that a dense,
uniform, and adherent alumina-silica composite coating can be prepared on graphite paper substrate by chemical vapor deposition
at 550°C. Alumina-silica composite coating is composed of particles or nodules of varying size. Each particle is often composed
of a number of finer particles. The phases of the 550°C composite coating include γ-alumina and amorphous silica. The elemental
chlorine content in the composite coating decreases with increasing deposition temperature. The surfaces of the alumina-silica
composite coatings are affected by deposition temperature. There are some obvious micro-cracks in the 300°C composite coating,
which are attributed to a mismatch of the coefficient of thermal expansion between composite coating and graphite paper. The
550°C alumina-silica composite coating can be completely turned into mullite after heat-treatment at 1350°C for 0.5 hr in
argon atmosphere. 相似文献
15.
《Journal of the European Ceramic Society》2020,40(3):660-671
In the present study, graphene nanoplatelets (GNPs: 1–2 wt. %) reinforced TiN coating were successfully fabricated over titanium alloy using a reactive shroud plasma spraying technique. All coatings were completely oxide free, while the addition of GNPs suppressed the non-stoichiometric TiN0.3 phase. Improvement of 19%, 18% and 300% in hardness, elastic modulus and fracture toughness was achieved by mere addition of 2 wt. % GNP. The addition of GNP in TiN also reduced the wear volume loss and the wear rate of the coatings for the entire range of temperature (293–873 K). Moreover, GNPs also manifested the coefficient of friction (COF) of the coating. Post wear characterization revealed that the presence of GNP throughout the wear track even at 873 K. The multi-layer structure of GNPs assisted in long term lubricity to the surface and increased the wear resistance of the coating. 相似文献
16.
Xin Zhou Wenjia Song Jieyan Yuan Qingmei Gong Hao Zhang Xueqiang Cao Donald B. Dingwell 《Journal of the American Ceramic Society》2020,103(10):5599-5611
About 6-8 wt% yttria-stabilized zirconia (YSZ) is the industry standard material for thermal barrier coatings (TBC). However, it cannot meet the long-term requirements for advanced engines due to the phase transformation and sintering issues above 1200°C. In this study, we have developed a magnetoplumbite-type SrAl12O19 coating fabricated by atmospheric plasma spray, which shows potential capability to be operated above 1200°C. SrAl12O19 coating exhibits large concentrations of cracks and pores (~26% porosity) after 1000 hours heat treatment at 1300°C, while the total porosity of YSZ coatings progressively decreases from the initial value of ~18% to ~5%. Due to the contribution of porous microstructure, an ultralow thermal conductivity (~1.36 W m−1 K−1) can be maintained for SrAl12O19 coating even after 1000 hours aging at 1300°C, which is far lower than that of the YSZ coating (~1.98 W m−1 K−1). In thermal cyclic fatigue test, the SrAl12O19/YSZ double-ceramic-layer coating undertakes a thermal cycling lifetime of ~512 cycles, which is not only much longer than its single-layer counterpart (~163 cycles), but also superior to that of YSZ coating (~392 cycles). These preliminary results suggest that SrAl12O19 might be a promising alternative TBC material to YSZ for applications above 1200°C. 相似文献
17.
The paper presents the characteristics of some ceramic coatings obtained by a plasma spray method. The ceramic coatings Al2O3, Cr2O3 and Cr2O3?+?5% TiO2 were evaluated. Also the influence of the NiCr interlayer on the functional properties of sprayed coatings was studied. Other parameters studied included: thickness; microhardness; adhesion of the coatings; resistance to abrasive wear and thermal cyclic loading. The addition of TiO2 to the Cr2O3 material increased the coating density, but did not substantially reduce the hardness. On the other hand, the lowest loss of material thickness was seen for Cr2O3; while the Al2O3 and the Cr2O3?+?5 wt.% TiO2 material showed a higher loss. The loss in the case of the latter two was about the same. Relatively, higher values of abrasive wear resistance were observed in the Cr2O3 coatings, as compared to the reference material (Al2O3 coating), and the highest microhardness values were measured in the Cr2O3 coating. Finally, the metal interlayers in all coatings increased their resistance to thermal shock. All the coatings, using the interlayer to reduce differences in coefficients of thermal expansion, were suitable for the purpose of the thermal loading up to 1000?°C. 相似文献
18.
《Journal of the European Ceramic Society》2019,39(11):3292-3300
ZrC-TiC coatings were fabricated by vacuum plasma spray and their ablation resistance were evaluated and compared with ZrC-SiC coating by a plasma flame with a heat flux of 4.02 MW/m2. The microstructure and phase compositions of the as-sprayed and ablated coatings were characterized and the function of TiC addition on the ablation resistance was investigated. The results showed that the ablation resistance of the ZrC-TiC coating was much better than that of the ZrC-SiC coating under the present ablation conditions. The decrease of surface temperatures with the increasing of TiC content were observed. (Zr, Ti)O2 eutectic phase in liquid state was observed. The low vapor and decomposition pressures of TiO2, combined with the formation of (Zr, Ti)O2 liquid contributed to the excellent ablation resistance of the ZrC-TiC coating. This work affirmed that TiC could be an ideal addition to improve the ablation resistance of the ZrC coating in harsh environment above 2000 °C. 相似文献
19.
《Journal of the European Ceramic Society》2023,43(14):6427-6439
The oxidation of SiC and the formation of a thermally grown oxide layer (TGO) limit the lifetime of environmental barrier coatings. Thus, this paper focuses on the deposition of denser Yb2Si2O7 coatings using electrophoretic deposition to reduce the TGO growth rate. The findings showed densification for Yb2Si2O7 can be achieved with an optimized sintering profile (heating/cooling rate, temperature, and time). However, the addition of 1.5 wt% of Al2O3 to Yb2Si2O7 promoted densification and lowered the required sintering temperature, 1380 °C using 2 °C/min heating/cooling rate for 10 h provided efficient coating density. Moreover, adding Al2O3 reduced the TGO growth rate by more than 70 % compared to the Al2O3-free coatings, without cracking in TGO after 150 h of thermal ageing at 1350 °C. Results within this study suggest electrophoretic deposition with Al2O3 addition produces promising Yb2Si2O7 environmental barrier coatings on SiC substrate with low oxidation rates and increased lifetime. 相似文献
20.
Junjie Xu Yanbo Liu Zhuang Ma Shizhen Zhu Yijin Wang Haikun Chen Kangzhi Ma 《Ceramics International》2021,47(1):400-408
To improve the emissivity of ZrB2/SiC coatings for serving in more serious environment, ZrB2/SiC coatings with varying contents of high emissivity Sm2O3 were fabricated using atmospheric plasma spraying. The microstructure, infrared radiative performance and anti-ablation behaviour of the modified coatings were investigated. The results showed that as the content of Sm2O3 increased, the density of the coatings increased because of the low melting point of Sm2O3. When the content of Sm2O3 was 10 vol%, the coating had the highest emissivity in the 2.5–5 μm band at 1000 °C, up to 0.85, because of the oxygen vacancies promoting additional electronic transitions. Due to the high emissivity, the surface temperature of the coating modified with 10 vol% Sm2O3 decreased by 300 °C, which led to little volatilisation of the sealing phase. Further, the mass ablation ratio of the above coating was 3.19 × 10?4 g/s, decreasing 31% compared to that of a ZrB2/SiC coating. The formed dense surface structure of the coatings showed considerable oxygen obstructive effects. These findings indicate that the modified coatings show considerable anti-ablation performance, which provides effective anti-ablation protection for the C/C composite substrate. 相似文献