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Effect of MWCNTs on Improvement of Fracture Toughness of Spark Plasma Sintered SiC Nano-Composites

Author(s):

T. Arunkumar *, R. Karthikeyan , R. Ram Subramani , M. Anish, J. Theerthagiri, Rajender Boddula and J. Madhavan   Pages 1 - 8 ( 8 )

Abstract:


Background: Silicon carbide (SiC) ceramics are promising engineering material due to its phenomenal properties, such as strong corrosion resistance, high-temperature hardness, wear resistance, high thermal conductivity and high stability in aggressive environment. The key problem of SiC is low fracture toughness due to its brittle nature and to circumvent this, herein high ductile material like MWCNT was used as reinforcement by different proportions.

Methods: Nanocrystalline powdered Silicon Carbide (SiC) of particle size of 40 nm and x % weight ratio of SiC (x = 95%, 90% and 85%) + y % weight ratio of multiwalled carbon nanotubes (MWCNTs) of particle size of 20 nm (y= 5%, 10% and 15%) composites were ball milled and fabricated using spark plasma sintering process with temperature rate of 100 oC/min and external pressure of 50 MPa. The sintered samples were tested according to ASTM standards to verify the mechanical properties of the samples. Further, lattice strain, crystalline size was determined by XRD and crack bridging mechanism was studied by FESEM.

Results: It was observed that the uniform distributions of MWCNTs were achieved through ultrasonification and ball milling processes, which play a predominant role in increasing fracture toughness. The fracture toughness of the composite improves drastically from 3.71 MPa m1/2 (100% SiC) to 10.21 MPa m1/2 (85% SiC-15% MWCNT). The theoretical and relative densities of the materials were gradually reduced due to the increase in MWCNTs which is due to lower density of the reinforcement material and increase in porosity of the samples.

Conclusion: The MWCNTs act as a bridging aid in sintered samples, FESEM image signifies some pull-outs and crack branching mechanism of MWCNTs which is the reason for increase in the fracture toughness of SiC.

Keywords:

Silicon Carbide, Multi Walled Carbon Nanotubes , Fracture toughnes , Spark plasma sintering

Affiliation:

Department of Mechanical Engineering, CMR Institute of Technology, Bengaluru 560037, School of Mechanical Engineering, Sathyabama Institute of Science and Technology, Chennai 600119, School of Mechanical Engineering, Sathyabama Institute of Science and Technology, Chennai 600119, School of Mechanical Engineering, Sathyabama Institute of Science and Technology, Chennai 600119, Centre of Excellence for Energy Research, Centre for Nanoscience and Nanotechnology, Sathyabama Institute of Science and Technology (Deemed to be University), Chennai 600119, Chinese Academy of Sciences (CAS) Key Laboratory of Nanosystem and Hierarchy Fabrication, CAS Center for Excellence in Nanoscience, National Center for Nanoscience and Technology, Beijing 100190, Solar Energy Lab, Department of Chemistry, Thiruvalluvar University, Vellore 632115, Tamilnadu



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