The Compaction, Sintering, and Mechanical Properties of Al₂O₃–CeO₂ Composite Nanopowders

Abstract

In the present work, compaction, sintering behavior, and mechanical properties of Al 2 O 3 -CeO 2 composite nanopowders were investigated. Al 2 O 3 and Al 2 O 3 -CeO 2 composite nanopowders were prepared by a sol-gel method. The effect of CeO 2 on compressibility, sintering rate, final density, and mechanical properties was studied. The aggregation strength of nanopowders reduced from 158 to 101 MPa by adding 5 wt% CeO 2 . The amount of CeO 2 had a strong effect on the sintering behavior and final microstructure of nanopowders and it inhibited alumina grain growth and suppressed densification process. The activation energy for grain growth increased from 428 to 554 kJ/mol by adding 5 wt% CeO 2 to the nanopowders. The addition of 5 wt% CeO 2 improved fracture toughness (by 28%) and flexural strength (by 17%) with respect to monolithic Al 2 O 3 .

High Surface Area Ceria for CO Oxidation Prepared from Cerium t-Butoxide by Combined Sol–Gel and Solvothermal Processing

“…The latter has many advantages because the materials composition and texture can be influenced by the proper choice of precursors and processing conditions. Inorganic cerium salts, such as Ce(NO 3 ) 3 ·6H 2 O [ 5 – 9 ] CeCl 3 ·7H 2 O [ 10 ] or ceric ammonium nitrate (NH 4 ) 2 [Ce(NO 3 ) 6 ] (CAN) [ 11 ], were mainly used as precursors for sol–gel processing of ceria (including the citrate-gel route) because they are commercially available. Qi et al [ 12 ] found that the choice of the precursor [Ce(NO 3 ) 3 and (NH 4 ) 2 Ce(NO 3 ) 6 ] influenced the structure, surface state, reducibility and CO oxidation activity of Cu doped CeO 2 materials.…”

Fabrication, microstructure, and mechanical properties of novel three‐layer structured bionic ceramic cutting tools

“…So, the holes are distributed at grain boundaries, weakening the grain boundary strength and grain strength. As the temperature increases, surface diffusion is activated, which facilitates the formation of sintered necks between particles 34 . Then, the sintered necks grow to fill the holes gradually.…”

“…This is due to the lack of sintering drive caused by lower sintering particles. 34 Then, the sintered necks grow to fill the holes gradually. As shown in Figure 8C, the energy from the heat source triggers the vibration of atoms at 1700 • C because of the significant thermal expansion coefficient of Al 2 O 3 .…”

Increased electrical conductivity and the mechanism of samarium‐doped ceria/Al2O3 nanocomposite electrolyte

“…Normally, there is an optimal concentration for an acceptor so that its excessive doping can result in the decrement in the concentration of nonbounded oxygen vacancies as well as the electrical conductivity of doped ceria due to the defect association reactions . In the last two decades, multiple novel methods have been employed to further increase the conductivity of doped ceria, such as codoping of multielements, grain‐boundary modification, introduction of heterogeneous interface, and so on . When an insoluble phase, such as alumina, is introduced into the matrix of doped ceria, the heterogeneous interface can be formed, which can contribute to the increment in the electrical conductivity of the doped ceria due to the variation in interfacial space charge potential or the scavenging of intergranular impure phase, such as SiO 2 …”

“…3,4 In the last two decades, multiple novel methods have been employed to further increase the conductivity of doped ceria, such as codoping of multielements, [5][6][7] grain-boundary modification, [8][9][10][11] introduction of heterogeneous interface, [12][13][14] and so on. 15 When an insoluble phase, such as alumina, is introduced into the matrix of doped ceria, the heterogeneous interface can be formed, which can contribute to the increment in the electrical conductivity of the doped ceria due to the variation in interfacial space charge potential or the scavenging of intergranular impure phase, such as SiO 2 . 16 As a frequently used heterogeneous phase, alumina has been introduced into the matrix of YSZ or doped ceria to form the composite electrolyte so as to improve their performances, including the electrical and mechanical properties.…”