Effect of second phase on mechanical properties and toughening of Al2O3 based ceramic composites

Byungkoog Jang, Manabu Enoki, Teruo Kishi, Hee Kap Oh

Research output: Contribution to journalArticle

22 Citations (Scopus)

Abstract

This work considers the fabrication of Al2O3 - based composites with three different types of microstructure: nano composites with the nano-dispersed second phase, hybrid composites with both micro- and nano-sized dispersed second phase, and elongated composites with needle-like in situ dispersed second phases. Methods for improving the mechanical properties of Al2O3 ceramics were investigated using Al2O3/5 vol% SiC composites fabricated by hot-pressing. Very fine SiC particles were dispersed uniformly in an Al2O3 matrix. However, larger SiC particulates existed in grain-boundaries of alumina. The flexural strength was inversely proportional to the square root of the matrix grain size. TEM observation indicated that propagating cracks were deflected by the dispersed SiC particulates. High density Al2O3/SiC/YAG hybrid composites having an equiaxed second phase were fabricated in the temperature range from 1000 to 1800°C using SiC and Y2O3 powders as additives. YAG (yttrium aluminum garnet, Y3Al5O12) was formed as the second phase from the reaction between Al2O3 and Y2O3 above 1400°C. Also, Al2O3/LaAl11O18 (lanthanum-β-alumina) composites, having an elongated second phase, were successfully fabricated using La2O3 powder as additives. Microstructural observation of the hot-pressed samples were done by SEM + TEM; the planes were analyzed by XRD. Mechanical properties such as the flexural strength and the fracture toughness of the composites were investigated and exceeded the mechanical properties of the monolithic Al2O3. Additionally, the composites having elongated grains showed higher toughness, due to grain bridging, than the composites having an equiaxed second phase.

Original languageEnglish
Pages (from-to)1275-1286
Number of pages12
JournalComposites Engineering
Volume5
Issue number10-11
DOIs
Publication statusPublished - Jan 1 1995
Externally publishedYes

Fingerprint

Toughening
Mechanical properties
Composite materials
Aluminum Oxide
Garnets
Yttrium
Bending strength
Powders
Alumina
Transmission electron microscopy
Aluminum
Lanthanum
Hot pressing
Needles
Toughness
Fracture toughness
Grain boundaries
Cracks
Fabrication
Microstructure

All Science Journal Classification (ASJC) codes

  • Engineering(all)

Cite this

Effect of second phase on mechanical properties and toughening of Al2O3 based ceramic composites. / Jang, Byungkoog; Enoki, Manabu; Kishi, Teruo; Oh, Hee Kap.

In: Composites Engineering, Vol. 5, No. 10-11, 01.01.1995, p. 1275-1286.

Research output: Contribution to journalArticle

Jang, Byungkoog ; Enoki, Manabu ; Kishi, Teruo ; Oh, Hee Kap. / Effect of second phase on mechanical properties and toughening of Al2O3 based ceramic composites. In: Composites Engineering. 1995 ; Vol. 5, No. 10-11. pp. 1275-1286.
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