Effect of Multiwalled Carbon Nanotubes on Improvement of Fracture Toughness of Spark-Plasma-Sintered Yttria-Stabilized Zirconia Nanocomposites

Abstract

Highly dense yttria-stabilized zirconia (YSZ) nano-ceramics reinforced with TC-CVD-synthesized multiwall carbon nanotubes (MWCNTs) were fabricated using spark plasma sintering at a temperature of 1350°C, the heating rate of 100 °C/min and pressure of 50MPa with a dwell time of 10 minutes. The identical parameters were utilized for fabricating composites with a varying weight ratio of YSZ and MWNCTs. The samples were characterized for their phase transformation, microstructure and elemental composition using x-ray diffraction (XRD), scanning electron microscopy (SEM) and energy-dispersive spectroscopy (EDS). The physical and mechanical properties such as density, porosity, hardness, fracture toughness and wear were also investigated. The increase in the MWCNTs concentration has resulted in the deterioration of the hardness due to CNT agglomerations. The wear resistance of the composites revealed MWNCTs enhanced wear resistance of YSZ nanocomposite by undergoing MWNCTs pull-out and crack branching mechanisms. Further indentation method and single-beam V-notch beam (SEVNB) methods were utilized to study the effect of MWCNTs on the fracture toughness of the nanocomposites. The fracture toughness of YC1 (6.58 ± 0.3 MPa m1/2) was 21% higher than the YSZ (5.21 ± 0.2 MPa m1/2) due to the toughening mechanisms attributable to crack deflection, branching and bridging of MWCNTs.

Influence of Nanoparticles Reinforcements on Aluminium 6061 Alloys Fabricated via Novel Ultrasonic Aided Rheo-Squeeze Casting Method

“…Although in many applications the use of micro sized reinforcements has failed to provide the required strength. So, researchers have tended towards nanoparticles which need special reinforcing mechanisms such as Orowan mechanism, thermal discrepancy and load transfer mechanisms to strengthen the cermet according to applicational requirements [6][7][8]. Many researchers have worked on the reinforcement of aluminium alloys using single reinforcements such as SiC and TiO 2 [9,10].…”

Development of high-performance aluminium 6061/SiC nanocomposites by ultrasonic aided rheo-squeeze casting method

“…The surface topographies of the samples were obtained using a scanning electron microscope (ZEISS SUPRA 55), and simultaneously quantitative elemental analysis was conducted as per ASTM D4541 [26] , [27] . The density was measured using Archimedes method of liquid displacement using water as a liquid medium, and porosity (%) was calculated from the density [28] . Vickers hardness was measured using a diamond intender at a load of 10 N and a dwell time of 20 sec as per ASTM E92 (Vickers hardness machine, Krystal Elmec, India).…”

“…Tensile test (UTM Zwick, Germany) was carried out as per ASTM E8/E8M-11 at a standard displacement of 0.5 mm/min. Wear behaviour of the samples were studied using a pin on disc tester (Ducom TR-20LE-PHM-400) as per ASTM G99 standards at a sliding speed of 2 m/s and varying load (20 N and 40 N) and sliding distance (600 m and 1200 m) [28] , [29] . Thermal expansion (CLTE) was measured (Anter Unitherm Model-1161 V) under argon atmosphere as per ASTM E228, and thermal conductivity (TC) was measured (Netzsch LFA-467) as per ASTM E1225-13.…”

Multi-walled carbon nanotubes (MWCNTs)-reinforced ceramic nanocomposites for aerospace applications: a review

“…However, few reports of Arunkumar et al reported that the physical techniques were not able to be satisfactory in providing only through single physical techniques therefore he utilised two or more techniques to support higher homogeneous distribution. The report also specified that with increase in CNTs content, the rate of uniform distribution reduces owing to increase in Vander Waal force of attraction between CNTs particles [31].…”

“…Various research has been conducted to enhance the fracture toughness of the ceramics by reinforcing them with various materials including metal and ceramic additives. Although with the potential of CNTs being a suitable reinforcement material, research work on incorporating CNTs has proved to be effective to ceramics composites as studies have demonstrated enhancement in fracture behaviour [31][32][33].…”