scholarly journals Thermal Conductivity and Sintering Behavior of Sm2Zr2O7 Ceramics with Y3+ Substitution for Different Lattices

2021 ◽  
Author(s):  
Zhaolu Xue ◽  
Xin Wang ◽  
Mengchuan Shi ◽  
Haiyuan Yu ◽  
Xin Zhang ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
High Temperature ◽  
Solid Phase ◽  
Temperature Stability ◽  
Crystal Phase ◽  
Sintering Behavior ◽  
Thermal Barrier ◽  
High Temperature Stability ◽  
Promising Candidate ◽  
Sintering Method

Abstract Sm2Zr2O7 is one of the most promising candidate materials for ultra-high temperature thermal barrier coatings. In this paper, a series of (Sm1-x1Yx1)2(Zr1-x2Yx2)2O7-x2 ceramics with different lattice sites replaced by Y3+ ions were successfully prepared by the high-temperature solid-phase sintering method. The effect of Y3+ doping on microstructure, phase composition, thermal conductivity and sintering behavior of modified Sm2Zr2O7 ceramics were investigated, respectively. The results showed that (Sm1-x1Yx1)2(Zr1-x2Yx2)2O7-x2 were composed of a single pyrochlore crystal phase within 20% Y3+ ions doping concentration. Compared with pure Sm2Zr2O7, the fracture toughness of each (Sm1-x1Yx1)2(Zr1-x2Yx2)2O7-x2 ceramic was significantly reduced. In terms of reducing the thermal conductivity of Sm2Zr2O7, the substitution of Y3+ ion for Zr4+ was more obvious than the substitution of Y3+ for Sm3+. Thermal conductivity of Sm2(Zr0.9Y0.1)2O6.9 was 1.315 W·m-1·K-1 at 1200 °C, which was the lowest among the studied ceramics.. Sm2(Zr0.9Y0.1)2O6.9 ceramic exhibited a lower grain growth rate at 1400 °C, and still remained a single pyrochlore crystal phase after sintering for 100 h, indicating that Sm2(Zr0.9Y0.1)2O6.9 had good high-temperature stability at 1400 °C.

Investigation on Microstructure, Wave Absorbing Properties and High Temperature Stability for (Mg0.2Ni0.2Co0.2Cu0.2Zn0.2)O High-entropy Ceramics

2021 ◽  
Author(s):  
Shen Bao ◽  
Yongqiang Chen ◽  
Fei yue Hu ◽  
Xiao han Wang ◽  
B.B. Fan ◽  
...  
Keyword(s):  
High Temperature ◽  
Temperature Stability ◽  
High Temperature Stability ◽  
Promising Candidate ◽  
High Entropy ◽  
Microwave Absorbing Properties ◽  
Interface Defects ◽  
Conventional Sintering ◽  
Salt Phase ◽  
Sintering Method

Abstract In this work, high entropy (Mg0.2Ni0.2Co0.2Cu0.2Zn0.2)O ceramics were fabricated with three different precursors by conventional sintering method. SEM and XRD analyses revealed the microstructure is related to the precursors while the phase composition is independent with the precursors. Compared with S1 and S2 samples, the S3 samples show well distributed small pores located inside the grain or at the grain boundary. While all the samples exhibit a single rock salt phase. The RL values could reach to -30.5 dB (S3) at 6.8 GHz under the thickness of 4.0 mm, the excellent microwave absorbing properties stem from the bonding interface defects, the micro-pores and many grain boundaries. The (Mg0.2Ni0.2Co0.2Cu0.2Zn0.2)O ceramics keep stable under 1200 oC for S3. The results demonstrate that (Mg0.2Ni0.2Co0.2Cu0.2Zn0.2)O ceramics may be a promising candidate for microwave absorption materials at high temperature.

La2O3 Doped Y2O3 Stabilized ZrO2 TBC Prepared by EB-PVD

2006 ◽  
Vol 317-318 ◽  
pp. 501-504 ◽  
Author(s):  
Mineaki Matsumoto ◽  
Norio Yamaguchi ◽  
Hideaki Matsubara
Keyword(s):  
Thermal Conductivity ◽  
High Temperature ◽  
High Resistance ◽  
Thermal Transport ◽  
Temperature Stability ◽  
High Temperature Stability ◽  
Microstructural Observation ◽  
Low Thermal Conductivity ◽  
Ysz Coating

Effect of La2O3 addition on thermal conductivity and high temperature stability of YSZ coating produced by EB-PVD was investigated. La2O3 was selected as an additive because it had a significant effect on suppressing densification of YSZ. The developed coating showed extremely low thermal conductivity as well as high resistance to sintering. Microstructural observation revealed that the coating had fine feather-like subcolumns and nanopores, which contributed to limit thermal transport. These nanostructures were thought to be formed by suppressing densification during deposition.

Sintering Behavior of Plasma-Sprayed Sm2Zr2O7 Coating

2010 ◽  
Author(s):  
Jianhua Yu ◽  
Huayu Zhao ◽  
Shunyan Tao ◽  
Xiaming Zhou ◽  
Chuanxian Ding
Keyword(s):  
Thermal Conductivity ◽  
Thermal Expansion ◽  
High Temperature ◽  
Thermal Expansion Coefficient ◽  
Thermal Barrier Coating ◽  
Expansion Coefficient ◽  
Sintering Behavior ◽  
Thermal Barrier ◽  
Barrier Coating ◽  
Plasma Sprayed

Plasma-sprayed thermal barrier coating (TBC) systems are widely used in gas turbine blades to increase turbine entry temperature (TET) and better efficiency. Yttria stabilized zirconia (YSZ) has been the conventional thermal barrier coating material because of its low thermal conductivity, relative high thermal expansion coefficient and good corrosion resistance. However the YSZ coatings can hardly fulfill the harsh requirements in future for higher reliability and the lower thermal conductivity at higher temperatures. Among the interesting TBC candidates, materials with pyrochlore structure show promising thermo-physical properties for use at temperatures exceeding 1200 °C. Sm2Zr2O7 bulk material does not only have high temperature stability, sintering resistance but also lower thermal conductivity and higher thermal expansion coefficient. The sintering characteristics of ceramic thermal barrier coatings under high temperature conditions are complex phenomena. In this paper, samarium zirconate (Sm2Zr2O7, SZ) powder and coatings were prepared by solid state reaction and atmosphere plasma spraying process, respectively. The microstructure development of coatings derived from sintering after heat-treated at 1200–1500 °C for 50 h have been investigated. The microstructure was examined by scanning electron microscopy (SEM) and the grain growth was analyzed in this paper as well.

Manufacturing parameters influencing fire resistance of geopolymers: A review

2016 ◽  
Vol 233 (4) ◽  
pp. 721-733
Author(s):  
Ikmal Hakem Aziz ◽  
Mohd Mustafa Al Bakri Abdullah ◽  
Heah Cheng Yong ◽  
Liew Yun Ming ◽  
Kamarudin Hussin ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Compressive Strength ◽  
High Temperature ◽  
Thermal Behavior ◽  
High Temperatures ◽  
Fire Resistance ◽  
Temperature Stability ◽  
High Temperature Stability ◽  
Technological Parameters ◽  
Manufacturing Parameters

Geopolymers exhibit various unique properties and characteristics, including high compressive strength, high temperature stability, and low thermal conductivity. As a relatively new and perspective material, the behavior of geopolymers subjected to high temperatures is being intensively studied nowadays. This review summarizes the recent achievements in the development of geopolymer-based fire resistance materials. Technological parameters, which influence thermal behavior of geopolymer-based materials, are also discussed. Besides that, recent applications of geopolymers according to their composition are presented.

Fabrication and Optical Properties of Sm2Zr2O7-NiCr2O4

2012 ◽  
Vol 512-515 ◽  
pp. 459-462 ◽  
Author(s):  
Tao Li ◽  
L. Liu ◽  
Q. Xu ◽  
S.Z. Zhu
Keyword(s):  
Thermal Conductivity ◽  
Optical Properties ◽  
Thermal Properties ◽  
Rare Earth ◽  
High Temperature ◽  
Thermal Barrier Coatings ◽  
Thermal Barrier ◽  
Promising Candidate ◽  
Barrier Coatings ◽  
Different Content

Sm2Zr2O7 is one of the promising candidate materials for the next generation thermal barrier coatings because of its excellent thermal properties. But at high temperature the thermal conductivity of rare-earth zirconate increases because of radiation conduction. NiCr2O4, which can absorb the infrared photons intensely, was introduced to reduce the radiation conduction of rare-earth zirconate. NiCr2O4 powder was prepared by coprecipitation. The bulks of Sm2Zr2O7— NiCr2O4 with different content of NiCr2O4 were prepared by using non-pressure sintering. The phase and microstructure of the samples were characterized by XRD and SEM. The optical absorption was also investigated. The absorptivity of the composite, which was generally higher than that of pure Sm2Zr2O7 prepared by coprecipitation and non-pressure sintering, was enhanced with the content of NiCr2O4 increasing. The enhancement of absorptivity will reduce the radiation conduction of rare-earth zirconate potentially.

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