Oxidation Behavior and Mechanical Property of Si3N4 Ceramics with Rare Earth Oxide Addition

2007 ◽  
Vol 336-338 ◽  
pp. 2478-2480
Author(s):  
Xu Guang Tong ◽  
Jian Bao Li ◽  
Hong Lin ◽  
Xiao Zhan Yang ◽  
Jun Yang
Keyword(s):  
Mechanical Properties ◽  
Rare Earth ◽  
Oxidation Behavior ◽  
Rare Earth Oxide ◽  
Oxidation Products ◽  
Oxidation Test ◽  
Oxide Addition ◽  
Nitride Ceramics ◽  
Before And After ◽  
Si3n4 Ceramics

The effects of rare earth oxides (Lu2O3 and La2O3) on the property, microstructure and oxidation behavior of hot-pressing sintered Si3N4 ceramics were investigated. The silicon nitride ceramics with Lu2O3 and La2O3 as addition have been fabricated by hot-pressed at 1800°C for 1h under a pressure of 25MPa. Oxidation test was carried out at 1400°C in air for 100 hours. Mechanical properties, SEM and XRD were measured before and after oxidation. The results showed that Si3N4 ceramics doped Lu2O3 had good microstructure and mechanical properties than those doped La2O3. Oxidation test showed a parabolic weight gain with oxidation time at 1400°C in air and the oxidation products of the ceramics were SiO2, Re2Si2O7 and Re2SiO5 confirmed by XRD and EDS. The rate-controlling step was the diffusion of ion. The samples doped Lu2O3 showed superior oxidation resistance to those doped La2O3.

Effect of rare-earth species on the wear properties of α sialon and β silicon nitride ceramics under tribochemical type conditions

2004 ◽  
Vol 19 (9) ◽  
pp. 2750-2758 ◽  
Author(s):  
Mark I. Jones ◽  
Kiyoshi Hirao ◽  
Hideki Hyuga ◽  
Yukihiko Yamauchi
Keyword(s):  
Rare Earth ◽  
Grain Boundary ◽  
Wear Behavior ◽  
Rare Earth Oxide ◽  
Lower Amount ◽  
Boundary Phase ◽  
Wear Properties ◽  
Sintering Additives ◽  
Nitride Ceramics ◽  
Worn Surfaces

The wear properties under low loads of β Si3N4 and α sialon materials sintered with different rare-earth oxide sintering additives have been studied under dry sliding conditions using block-on-ring wear tests. All the worn surfaces showed an absence of fracture and smooth surfaces with the presence of an oxygen-rich filmlike debris indicating tribochemically induced oxidation of the surfaces. Extensive grain boundary removal was observed on the worn surfaces thought to be due to adhesion between this silicate phase and the tribochemically oxidized surfaces. The resistance to such oxidation and the properties of the residual grain boundary phase are thought to be important parameters affecting the wear behavior under the present testing conditions. For both the β Si3N4 and α sialon materials, there was an increase in wear resistance with decreasing cationic radius of the rare earth, thought to be due to improved oxidation resistance, and this was more remarkable in the case of the sialon materials where the incorporation of the sintering additives into the Si3N4 structure results in a lower amount of residual boundary phase.

scholarly journals Effects of rare earth oxide addition on NdFeB magnets.

1987 ◽  
Vol 11 (2) ◽  
pp. 235-238 ◽  
Author(s):  
K. Ohashi ◽  
T. Yokoyama ◽  
Y. Tawara
Keyword(s):  
Rare Earth ◽  
Rare Earth Oxide ◽  
Ndfeb Magnets ◽  
Oxide Addition

Effect of rare earth oxides addition on the mechanical properties and coloration of silicon nitride ceramics

2020 ◽  
Vol 40 (4) ◽  
pp. 1132-1138 ◽  
Author(s):  
Ning Liu ◽  
Jingxian Zhang ◽  
Yusen Duan ◽  
Xingbang Li ◽  
Shaoming Dong
Keyword(s):  
Mechanical Properties ◽  
Rare Earth ◽  
Silicon Nitride ◽  
Rare Earth Oxides ◽  
Nitride Ceramics

Microstructure and Mechanical Properties of Rare-Earth Doped Si3N4 and Si3N4/SiC Ceramics

2010 ◽  
Vol 65 ◽  
pp. 78-85 ◽  
Author(s):  
Peter Tatarko ◽  
Štefánia Lojanová ◽  
Zdeněk Chlup ◽  
Ján Dusza ◽  
Pavol Šajgalík
Keyword(s):  
Mechanical Properties ◽  
Rare Earth ◽  
Aspect Ratio ◽  
Ionic Radius ◽  
Earth Element ◽  
Rare Earth Oxide ◽  
Sic Ceramics ◽  
Microstructure And Mechanical Properties ◽  
Significant Difference ◽  
Rare Earth Doped

Microstructure and mechanical properties of Si3N4 and Si3N4 + SiC nanocomposites sintered with rare-earth oxide additives (La2O3, Y2O3, Yb2O3 and Lu2O3) have been investigated. The composites exhibited smaller grain diameter compared to that of monolithic materials. The aspect ratio of β-Si3N4 grains increased with a decreasing ionic radius of rare-earth elements in the Si3N4 monoliths as well as in the Si3N4-SiC nanocomposites. The hardness of both systems increased with a decreasing ionic radius of rare-earth element. The fracture toughness of the materials with coarser microstructure and higher aspect ratio was higher due to the more frequent toughening mechanisms. No significant difference between strength values of monoliths and composites was observed and the strength in the composites was determined mainly by the present processing flaws. Significantly improved creep resistance was observed in the case of composites and for materials with smaller ionic radius of RE3+.

Sign in / Sign up

Export Citation Format

Share Document