High-strength ceramics through colloidal control to remove defects

• DOI: 10.1038/330051a0
• Publication Date: 2003-06-12T21:36:21Z
• Authors: N. McN. Alford; J. D. Birchall; K. Kendall
• Keywords: Agglomerate; Alumina ceramic; Mechanical strength

Although the theoretical tensile strength of alumina is ∼46 GPa (ref. 1), conventional powder processing rarely gives products better than 0.5 GPa because large defects, ∼50–100 µm in size, are invariably trapped during powder compaction2,3. Thin-film, fibrous, melt-processed and vapour-deposited ceramics can achieve higher strengths of several GPa (refs 4–6), but such processes are much more expensive than simple sintering of powder compacts. Here we show how colloidal control of powders to remove agglomerates can be used to give high-strength sintered ceramics: for example, a commercial alumina powder can be improved from 0.37 to 1.04 GPa in bend strength.