Improving CNT distribution and mechanical properties of MWCNT reinforced alumina matrix

In this work, an attempt was made to improve the distribution of CNTs in CNT/alumina nanocomposites. The composite powders containing 1 and 3 vol% of CNTs were produced and calcined at 500 °C for 2 h. Surface coating with boehmite nanoparticles was used to improve CNT distribution in alumina matrix. Calcined powders were shaped into compacted samples by cold isostatic pressing at 180 MPa and sintered at 1600 °C for 2 h in flowing gas atmosphere (95%Ar+5%H2). Phase analysis of the calcined composite powders showed complete transformation of boehmite into gamma-alumina. The maximum flexural strength was 465±31 MPa corresponding to addition of 1 vol% CNTs. Evaluating the fracture toughness via DCM method revealed a constant enhancement and the highest toughness was 4.7±0.3 MPa.m1/2 corresponding to composites containing 3 vol% of CNTs.