Processing and characterization of high-density zirconia–carbon nanotube composites

Mechanical and electrical properties of low SWNT content 3YTZP composites

“…To the best of our knowledge, absence of decrease or increase of hardness with increasing CNT content in ceramic matrix composites has only been reported for Al 2 O 3 with 1 vol% SWNT composites, 34 since most of the authors report a decrease of hardness, even for composites with low CNT content. 11, [14][15][16] The decreasing trend reported by previous authors for 3YTZP/CNT composites is shown in Figure 4(a). This tendency is usually linked to a decrease in the composite density, 11 an increase in nanotube agglomeration 17 or a weakening of interfacial bonding when the grains are wrapped by CNT and, therefore, the direct contact area and bonding force among grains decrease with increasing CNT content.…”

Nanoindentation and fracture toughness of nanostructured zirconia/multi-walled carbon nanotube composites

“…It was reported in a previous work [6], that t-m transformation is reduced in 3YTZP/CNT composites because of the small grain size. With the addition of 2 vol% MWCNT with grain size similar to the present study, t-m transformation at the fracture plane of Vickers indentation cracks was less than 5% at distances less than  2.0 µm below the fracture surface.…”

“…to 3Y-TZP matrix reported an increase in indentation K Ic using different techniques for the processing of 3Y-TZP/CNT composites [6][7][8][9]. Values up to 13 MPa.m 1/2 have been reported for the addition of 1 wt.…”

Effect of high SWNT content on the room temperature mechanical properties of fully dense 3YTZP/SWNT composites

“…Most of the studies about CNTs reinforced zirconia reported heterocoagulation or use of dispersants for the processing of the composite powder [13][14][15]23,24 , sometimes combined with other techniques such as slip-casting 14 or spray drying 25 . Regarding the densification step, hot pressing 13,25 or conventional 14 sintering were used by some authors.…”

“…Among the reported studies on CNT/3YTZP composites, highly densified samples were only obtained in studies using SPS 19,23,24 . Nevertheless, a decrease of hardness in the composites when compared with the monolithic ceramic, even when they are fully densified, and an increase of fracture toughness only for low percentages of CNTs1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 4 al 8,9 reported an increase of fracture toughness on nearly fully dense 3 mol% yttriadoped zirconia reinforced with 0.5-5 wt% MWNT with no detrimental effect on hardness.…”