Indentation size effect and wear characteristics of spark plasma sintered, hard MWCNT/Al₂O₃nanocomposites

Abstract

Magnesia doped multiwalled carbon nanotube (CNT)/a-alumina nanocomposites have been fabricated by spark plasma sintering at 15008C under 50 MPa in argon. Owing to combined grain refining effect of nanotube and magnesia, nanocomposites possessed smaller matrix grains and extensively lower matrix crystallites than pure alumina. Thermal expansion mismatch between matrix and filler rendered up to four times higher compressive lattice microstrain to the nanocomposites over pure alumina. Despite very low CNT loading (e.g. 0?13 wt-%), nanocomposites offered considerably higher hardness (as high as 24?42 GPa), negligible indentation size effect (Meyer exponent ¼ 1?90621?941) and enhanced elastic response over pure alumina. Up to 0?27 wt-% nanotube loading, much higher wear resistance was observed for the nanocomposites over pure alumina. The presence of uniformly dispersed and structurally intact nanotubes coupled with lower matrix grains and crystallites having compressive lattice strain were the key factors behind achieving such improved mechanical properties of the present

The Effects of MWCNT Addition to Physical Properties of ZTA-MgO Cutting Tool

“…A study by other [8] stated that addition of CNTs can help refine the matrix grain but will raise the sintering temperature, while introduction of MgO to the matrix can minimize sintering temperatures and grain size. Owing to combined grain refining effect of CNT and MgO resulted in fracture toughness as high as 24.5 GPa only with 0.13 wt.% CNT, which was 18% over than pure Al2O3 and smaller matrix grains in the nanocomposites [9]. Zharikov [10] reported that Al2O3-MgO composite with 8 vol.% MWCNTs obtained two times higher in flexural strength and fracture toughness as compared to the Al2O3 + 0.25% MgO only.…”

Effects of optical absorbance with ablation characteristics in femtosecond laser irradiation of carbon reinforced Al2O3composites

“…Liu et al 9 achieved a 30.75% increase in flexural strength and a 27.20% increase in fracture toughness in Al 2 O 3 ceramic composites by adding grapheme platelets. Recently, Sikder et al 10 fabricated hard sintered multiwalled CNT/Al 2 O 3 nanocomposites, resulting in a yield 18% higher than that of monolithic Al 2 O 3 . Previous papers have focused on mechanical, electrical and thermal properties, while this paper focuses on another useful property: improved optical absorbance.…”