Arunkumar Thirugnanasabandam*, Karthikeyan Ramachandran, Ram Subramani R, Anish Mariadas, J. Theerthagiri Jayaraman, Rajender Boddula and Madhavan Jagannathan Pages 849 - 856 ( 8 )
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 an 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°C/min and external pressure of 50 MPa. The sintered samples were tested according to ASTM standards to verify the mechanical properties of the samples. Furthermore, lattice strain and crystalline size was determined by XRD and the crack bridging mechanism was studied by FESEM.
Results: It was observed that the uniform distributions of MWCNTs were achieved through ultrasonication 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 the lower density of the reinforcement material and an 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 mechanisms of MWCNTs which is the reason for an increase in the fracture toughness of SiC.
Fracture toughness, multi-walled carbon nanotubes, silicon carbide, spark plasma sintering, nanotechnology, crack bridging mechanism.
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