Effect of grain morphology and grain size on the mechanical properties of Al2O3 ceramics

Koyama, Takashi; Nishiyama, A.; Niihara, Koichi

doi:10.1007/bf00355953

Cited by 30 publications

(10 citation statements)

References 19 publications

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“…1,2 Generally, ceramics with submicrometer-sized grains are harder and stronger but less tough than ceramics with larger grains. [3][4][5][6] In addition, the presence of anisotropy in the form of elongated inclusions or grains has been found to enable crack deflection mechanisms and, therefore, to increase the energy needed to propagate a crack through the material. 7 Functional properties coming from the crystalline lattice, for instance piezoelectricity, or thermal and ionic conductivities, also depend strongly on grain orientation.…”

Section: Introductionmentioning

confidence: 99%

Processing of dense bioinspired ceramics with deliberate microstructure

Ferrand

Bouville

2019

J Am Ceram Soc

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The architectures of biological hard materials reveal finely tailored complex assemblies of mineral crystals. Numerous recent studies associate the design of these local assemblies with impressive macroscopic response. Reproducing such exquisite control in technical ceramics conflicts with commonly used processing methods. Here, we circumvent this issue by combining the recently developed Magnetically Assisted Slip Casting (MASC) technique with the well‐established process of templated grain growth (TGG). MASC enables the local control over the orientation of platelets dispersed among smaller isotropic particles. After a high‐temperature pressureless heat treatment, the grains of the final ceramic follow the same orientation as of the initial platelets. This combination allows us to produce 95% dense alumina part with a grain orientation following any deliberate orientation. We successfully fabricated microstructures inspired from biological materials with ceramics that present periodically varying patterns with a programmable pitch down to a few tens of micrometers. The periodically textured dense ceramics exhibit matching variation of local hardness, confirming the capacity of the process to tailor local properties. This unique micrometer scale control over the local mechanical properties could be applied to adapt ceramic structures to complex loads using this inexpensive and scalable process. In systems where functional properties also depend on anisotropic grain orientation, the principle presented here could enable the creation of new multifunctional ceramics.

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Section: Introductionmentioning

confidence: 99%

Processing of dense bioinspired ceramics with deliberate microstructure

Ferrand

Bouville

2019

J Am Ceram Soc

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“…The thermal expansion coefficients are different along different crystallographic directions of alumina grains (α a = 8.6 × 10 −6 °C −1 and α c = 9.5 × 10 −6 °C −1 ), which leads to residual stress in ceramics. The big and inhomogeneous residual stress can cause self-forming microcracks inside materials [37]. However, small grain size and narrow distribution can reduce the tensile stresses caused by the anisotropy of thermal expansion coefficients among different grains, thus enhancing the wear resistance of materials [38].…”

Section: Discussionmentioning

confidence: 99%

Wear Resistance Mechanism of Alumina Ceramics Containing Gd2O3

et al. 2018

Materials

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Excellent wear resistance of alumina ceramics is a desirable quality for many products. The purpose of this work was to improve the wear resistance of 99% alumina ceramics in an Al2O3–Gd2O3–SiO2–CaO–MgO (AGSCM) system. The content of Gd2O3 varied from 0.01% to 1%. A test of wear rate was performed in a ball milling apparatus in a water environment according to the Chinese industry standard. The compositions and microstructure of this material, as well as the effect of bulk density on wear rate, were studied. The effect of Gd2O3 on phases, grain growth mode, and grain boundary cohesion was investigated. It was found that Gd2O3 could refine grain size, form compressive stress of the grain boundary, and promote the crystallization of CaAl12O19. The wear rate of this material was as low as 0.00052‰ (the Chinese industry standard wear rate is ≤0.15‰). The mechanisms for wear resistance of AGSCM ceramics were also determined.

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“…First the refinement of the Al 2 O 3 matrix resulting from the highly efficient milling action and the suppression of the TiC grain growth is beneficial for the improvement of strength. 11,12) Secondly, the reduction in the flaw size of composites with fine reinforcing TiC particles is accepted as an important reason for the increase in strength. In accordance with the theory of material mechanics, the relationship among the strength ( b ), fracture toughness (K IC ), and critical (biggest) flaw size (L), that is, the depth of a surface flaw or the half-size of a body flaw, satisfies the following relationship:…”

Section: Evaluation Of Propertiesmentioning

confidence: 99%

“…Intergranular and transgranular factures coexisted in the particulate composites both Table 1) showed that fine-grained materials did not exhibit a value higher value than the coarsegrained materials, as indicated in literatures. 11,12,[15][16][17][18] The low fracture toughness in the fine-grained Al 2 O 3 -TiC composites of this study could be attributed to the following reasons. The fracture toughness of the monolithic Al 2 O 3 decreases with the reduction in grain size.…”

Section: Evaluation Of Propertiesmentioning

confidence: 99%

Effect of Fabrication Method on Microstructure and Properties of Al<SUB>2</SUB>O<SUB>3</SUB>–TiC Composites

et al. 2005

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Al 2 O 3 -TiC composite powders were prepared by high-energy ball milling (HEBM) and wet-planetary ball milling (WPBM) from different starting materials, and subsequently sintered by Spark Plasma Sintering (SPS). The effect of the fabrication method on the microstructure and properties of Al 2 O 3 -TiC composites was investigated. The results showed that Al 2 O 3 -TiC composites with fine and homogeneous microstructures were prepared by SPS from high-energy ball milled reactants, which had excellent comprehensive properties: bending strength of 944 AE 21 MPa, Vickers hardness of 21:0 AE 0:3 GPa, fracture toughness of 3:87 AE 0:20 MPaÁm 1=2 , and electrical conductivity of 1:2787 Â 10 5 SÁm À1 . The relationship between microstructure and properties and the strengthening and toughening mechanisms was discussed. In comparison with the traditional WPBM route, HEBM was a favorable technique used to produce a high homogeneous microstructure and promising mechanical and electrical conduction properties.

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Effect of grain morphology and grain size on the mechanical properties of Al2O3 ceramics

Cited by 30 publications

References 19 publications

Processing of dense bioinspired ceramics with deliberate microstructure

Processing of dense bioinspired ceramics with deliberate microstructure

Wear Resistance Mechanism of Alumina Ceramics Containing Gd2O3

Effect of Fabrication Method on Microstructure and Properties of Al<SUB>2</SUB>O<SUB>3</SUB>–TiC Composites

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Effect of grain morphology and grain size on the mechanical properties of Al2O3 ceramics

Cited by 30 publications

References 19 publications

Processing of dense bioinspired ceramics with deliberate microstructure

Processing of dense bioinspired ceramics with deliberate microstructure

Wear Resistance Mechanism of Alumina Ceramics Containing Gd2O3

Effect of Fabrication Method on Microstructure and Properties of Al<SUB>2</SUB>O<SUB>3</SUB>&ndash;TiC Composites

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Effect of Fabrication Method on Microstructure and Properties of Al<SUB>2</SUB>O<SUB>3</SUB>–TiC Composites