Mechanical properties and oxidation resistance of α-alumina/multi-walled carbon nanotube composite ceramics

In this study, alpha-alumina/multi-walled carbon nanotube (alpha-Al2O3/MWCNT) composite ceramics with 5 wt.% CNTs additions were synthesized using ball-milled and hydrothermal crystallization methods, respectively, followed by hot-pressing. The mechanical properties and oxidation resistance of the two types of composite ceramics were measured using micromechanical testing system, thermogravimetry, and differential scanning calorimetry. Compared with monolithic Al2O3 ceramic, the fracture toughness and flexural strength of the composite ceramics synthesized using ball-milled method were improved by 61.1% and 17.2%, respectively due to the distinct "pinning" effect of MWCNTs, and the other type of composite ceramics' were improved by 80.3% and 24.6% due to the obvious pull-out effect of the ceramic-coated MWCNTs and the smaller grain size. At the same time, the weight losses of the ceramic samples exposed to air at 1000 degrees C for 1 h were inconspicuous. It indicates the composite ceramics have excellent oxidation resistance. (C) 2010 Elsevier B.V. All rights reserved.