scholarly journals Effects of rare earth oxides and fluorides on flexural strength and thermal conductivity of hot-pressed SiC ceramics

2021 ◽  
Vol 129 (11) ◽  
pp. 654-659
Author(s):  
Jingren LI ◽  
Wenzhong LU ◽  
Hai JIANG
Keyword(s):  
Thermal Conductivity ◽  
Rare Earth ◽  
Flexural Strength ◽  
Rare Earth Oxides ◽  
Sic Ceramics

Mechanical and Thermal Properties of Silicon Nitride Hot Pressed with Adding Rare-Earth Oxides

2005 ◽  
Vol 486-487 ◽  
pp. 181-184 ◽  
Author(s):  
Dae Ho Choi ◽  
Byung Kyu Moon ◽  
Rak Joo Sung ◽  
Seung Ho Kim ◽  
Koichi Niihara
Keyword(s):  
Thermal Conductivity ◽  
Thermal Properties ◽  
Rare Earth ◽  
Silicon Nitride ◽  
Flexural Strength ◽  
Grain Growth ◽  
Rare Earth Oxides ◽  
Lattice Oxygen ◽  
Mechanical And Thermal Properties ◽  
Si3n4 Ceramics

Mechanical and thermal properties of Si3N4 ceramics with various rare-earth oxides (La2O3, CeO2, Lu2O3, Dy2O3, Sm2O3, Nd2O3, Yb2O3, and RuO2) were investigated. Flexural strength of silicon nitride with addition of 5vol% Nd2O3, CeO2, Dy2O3, and Sm2O3 showed higher value than that of silicon nitride with Lu2O3 and La2O3 added because they form denser microstructure and smaller elongated grain. Thermal conductivity of silicon nitride with an addition of 5vol% RuO2 was more enhanced than that of silicon nitride added with Nd2O3, Sm2O3, and Dy2O3 because the addition of RuO2 depressed grain growth. It is also associated with lattice oxygen governing thermal conductivity of Si3N4 when added rare-earth oxides.

Effect of the Rare Earth Oxides on Sintering Behavior and Microstructure of ZrB2-SiC Ceramics

2008 ◽  
Vol 368-372 ◽  
pp. 1740-1742 ◽  
Author(s):  
Xue Ying Li ◽  
Jie Cai Han ◽  
Xing Hong Zhang ◽  
Xiao Guang Luo
Keyword(s):  
Fracture Toughness ◽  
Grain Size ◽  
Rare Earth ◽  
Grain Growth ◽  
Rare Earth Oxides ◽  
Sintering Behavior ◽  
Sintering Aids ◽  
Sic Ceramics ◽  
Sic Composites ◽  
And Control

In this study, two rare earth oxides, Y2O3 and La2O3, are used as the additives in the sintering of ZrB2-SiC composites to improve the sinterability and control development of microstructure during densification. The results show that the use of rare earth oxides (5vol.%) improves the powder sinterability, hindered excessive growth of matrix particles and increase fracture toughness of ZrB2-SiC composites, in comparison to ZrB2-SiC with additions free. Nearly full dense materials are obtained by hot pressing at 1900°C. XRD analyses indicate that lanthanum-containing phases were formed in the composite with La2O3. Microstructure observations by SEM reveal that the grain size of ZrB2-SiC with Y2O3 and La2O3 composites are less than the sample without additives, which indicates Y2O3 and La2O3 may restrain the grain growth and increase the fracture toughness. The fracture toughness of ZrB2-SiC composites with Y2O3 and La2O3 reached 5.0MPa·m1/2 and 5.5MPa·m1/2 respectively. Therefore, the additive Y2O3 and La2O3 are very effective as sintering aids for the ZrB2-SiC composite.

Effects of rare-earth oxide and alumina additives on thermal conductivity of liquid-phase-sintered silicon carbide

2003 ◽  
Vol 18 (8) ◽  
pp. 1854-1862 ◽  
Author(s):  
You Zhou ◽  
Kiyoshi Hirao ◽  
Yukihiko Yamauchi ◽  
Shuzo Kanzaki
Keyword(s):  
Thermal Conductivity ◽  
Silicon Carbide ◽  
Rare Earth ◽  
Liquid Phase ◽  
Point Defects ◽  
Rare Earth Oxide ◽  
Low Oxygen ◽  
Sic Ceramics ◽  
Sintered Silicon ◽  
Thermal Conductivities

SiC ceramics were prepared from a β–SiC powder doped with two different sintering additives—a mixture of La2O3and Y2O3and a mixture of Al2O3and Y2O3—by hot pressing and annealing. Their microstructures, phase compositions, lattice oxygen contents, and thermal conductivities were evaluated. The SiC doped with rare-earth oxides attained thermal conductivities in excess of 200 W/(m K); however, the SiC doped with additives containing alumina had thermal conductivities lower than 71 W/(m K). The high thermal conductivity of the rare-earth-oxide-doped SiC was attributed to the low oxygen content in SiC lattice, high SiC–SiC contiguity, and lack of β– to α–SiC polytypic transformation. The low thermal conductivity of the alumina-doped SiC was attributed to the point defects resulting from the dissolution of Al2O3into SiC lattice and the occurrence of polytypic transformation.

The wettability of SiC ceramics by molten E2O3(ss)/AlN (E2O3(ss)=solid solution of rare earth oxides)

2007 ◽  
Vol 33 (4) ◽  
pp. 527-530 ◽  
Author(s):  
S. Ribeiro ◽  
S.P. Taguchi ◽  
F.V. Motta ◽  
R.M. Balestra
Keyword(s):  
Solid Solution ◽  
Rare Earth ◽  
Rare Earth Oxides ◽  
Sic Ceramics

Thermal Conductivity and Mechanical Property of Si3N4 Ceramics Sintered with CeF3/LaF3 Additives

2010 ◽  
Vol 105-106 ◽  
pp. 171-174 ◽  
Author(s):  
Bai Bing ◽  
Teng Fu ◽  
Xiao Shan Ning
Keyword(s):  
Thermal Conductivity ◽  
Mechanical Property ◽  
Rare Earth ◽  
Rare Earth Oxides ◽  
Sintering Additives ◽  
Rare Earth Fluoride ◽  
Earth Fluoride ◽  
Si3n4 Ceramics ◽  
Rare Earth Fluorides

In this paper, rare-earth fluorides were used as sintering additives instead of rare-earth oxides, the influence of the type and the amount of the fluoride on the thermal conductivity, hardness and strength of Si3N4 ceramics was studied. Results show that the thermal conductivity of a sample sintered with CeF3 is nearly 10% higher than that of the sample sintered with Ce2O3, while the samples sintered with LaF3 increases further 15% as comparing with the samples sintered with CeF3. The strength of the samples changes reversely. These results express that the thermal conductivity of Si3N4 ceramics can be improved by using rare-earth fluoride additives instead of the oxides, and the type of rare-earth fluorides has a significant impact on the properties of Si3N4 ceramics.

Rare earth oxides stabilized La2Zr2O7 TBCs: EB-PVD, thermal conductivity and thermal cycling life

2019 ◽  
Vol 357 ◽  
pp. 427-432 ◽  
Author(s):  
Zaoyu Shen ◽  
Limin He ◽  
Zhenhua Xu ◽  
Rende Mu ◽  
Guanghong Huang
Keyword(s):  
Thermal Conductivity ◽  
Rare Earth ◽  
Thermal Cycling ◽  
Rare Earth Oxides ◽  
Cycling Life

High and Room Temperature Mechanical Evaluation of SiC Ceramics with Alumina and Rare Earth Oxides Additions

2008 ◽  
Vol 591-593 ◽  
pp. 593-597 ◽  
Author(s):  
M.K. Hwang ◽  
Cosme Roberto Moreira Silva ◽  
Maria do Carmo de Andrade Nono ◽  
Claudinei dos Santos ◽  
Francisco Piorino Neto
Keyword(s):  
Rare Earth ◽  
Room Temperature ◽  
Grain Boundary Sliding ◽  
Rare Earth Oxides ◽  
Argon Atmosphere ◽  
Oxidation Reactions ◽  
Creep Tests ◽  
Creep Mechanisms ◽  
Sic Ceramics ◽  
Boundary Sliding

In this work, the mechanical properties of SiC samples with (5 wt%) alumina and (5 wt%) rare earth oxides (REO) additions were investigated at room and high temperatures. The possibility of using REO instead of pure yttria could bring cost reductions to obtain sintered SiC ceramics. The powders were mixed, milled, sieved and hot-pressed at 1800°C in argon atmosphere. Hardness and fracture toughness were evaluated at room temperature. The compressive creep behavior was carried out under stress range from 150 to 300MPa and temperatures of 1300, 1350 and 1400°C. After creep tests, the surface analysis of the samples by XRD and SEM showed indications of oxidation reactions, cavity and cracking. The possible creep mechanisms activated in this system were diffusion, grain boundary sliding and cavitation

Effects of Rare-Earth Oxides Doping on Microstructures and Properties of Al2O3/TiAl Composites

2011 ◽  
Vol 675-677 ◽  
pp. 143-146
Author(s):  
Fen Wang ◽  
Xiao Feng Wang ◽  
Jian Feng Zhu ◽  
Liu Yi Xiang
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Rare Earth ◽  
Flexural Strength ◽  
Rare Earth Oxide ◽  
Rare Earth Oxides ◽  
Oxide Content ◽  
The Matrix ◽  
Al2o3 Particles ◽  
Positive Effect

Effects of rare-earth oxides addition (0.38~1.52 mol% of Sm2O3, Eu2O3 and Er2O3) on the property and microstructure of the hot-pressed (1300°C, 2h, 35 MPa) Al2O3 (12 wt %)/TiAl insitu composites have been investigated. The results show that the doping of rare-earth oxides has a positive effect on both mechanical properties and densities of Al2O3/TiAl composites. Densities enhanced with increasing of rare-earth oxides. The flexural strength and fracture toughness were higher than other samples when the rare-earth oxide content was 0.38 mol %. The matrix grains and Al2O3 particles were significantly refined, and Al2O3 particles evenly distributed in the matrix.

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